I had some rusting on my left rear wheel hub (which I found out is really part of the brake pad structure). My dealer replaced it without a problem. I don't know if that falls under the "paint" warranty, which I thought was 36,000 mi or 3 years. Mine was replaced at about 3000 miles. I would check with the dealer. So far the other ones are fine.
Looking to get rid of the am/fm/cd that came with the Santa-Fe. Would like to replace it with a better unit. Also a new unit with a cassette included am/fm/cd/cassette. I do realize Hyundai has this type of equipment but there unit lacks volume and quality. Will probably also end up replacing speakers down the road. " Thanks "
I just purchased my '02 Santa GLS V6 w/6000 miles. When I start it in the morning there is a loud ticking from the engining. It goes away after about 5 minutes and only happens when the engine is cold. Has anyone has this? Is this normal? I've never experienced anything like it with previous cars. Any suggestions? Thanks!
by "ticking" do you mean something "tapping"? All my GM engines had a "tapping" noise in them when the engine was still cold. Almost like an oil circulation problem. If the ticking sounds like a spark arcing, then it might be the belt. Then tend to get squeaky or ticky on most cars when cold or damp. I can't test this now, since its 99 degrees here!
This may be of some help to you..... First the ticking sound that you are hearing when the vehicle is cold is MOST likely from the A/C compressor....and will have to be replaced. I have the same problem and after a shop visit I was told that it is indeed that. After initial warm up it goes away.if so then I would suggest thatyou have it checked out. Mine acted up at 2500 miles after I started using the AC on my new 2002 LX. Radio....yes it could be alot better....one solution that i will advise is to have an amplifier installed under the front seat of the driver OR passengers side and if it is of sufficient power will add alot more power to the radio's performance. Step two would be to change the speakers, but first go the easier route to have an amplifier installed.....this should work out for you. If you'e near a Circuit City store give them a try OR go to a place that handles car sterios. Good luck it's still a great vehicle!
I noted the ticking when I started a Santa Fe on the sales lot 2 weeks ago for a test ride. The salesman quickly spoke up about the oil and how it settles in the casing or oil pan of a Santa Fe. The noise went away after a few minutes but since I have zero knowledge of this car I leave it to others to help.
I've been sitting on the sideline for well over a year. ($$ issues) Just as I was test driving my final 3 in preparation for Thee Buy (Liberty, Escape, Santa Fe) the boom lowered again. My company is moving my section to N.H.
I'm going back into a hole until the move happens and where it takes me. Funny but my final 3 back then were the RAVioli, CRV, and Forester. Now its totally changed. But so has the market. Next time I emerge and start test drives I'll probably say "There isn't enough road to get to 88 mph?" And the salesbot will answer, "Where we're going we don't need roads."
I have 2002 Santa Fe, when I start or stop the car I get a snapping or cracking sound coming from the area of the rear drivers side door or the frame where the seat belt is connected. It seems like metal stress, I had the same problem on a 73 Chevy and it was a bolt that needed to be turned an 1/8 of a turn. I don't know how else to explain the sound. Of course the service department cannot hear the sound I am describing. I don't think it is serious but annoying. I checked the seat, belt security cover for the cargo area,jack, spare tire, etc. Any suggestions will be appreciated.
My post was # 310. I got my vehicle back from having a new AC compressor and belt installed.4,200 miles LX Santa Fe (warranty). Indeed it's becoming evident that there's a problem with some of their parts. This problem also showed up on another Santa Fe list and the results were to have it changed out. We'll see how it sounds tomorrow morning... Other than that I'm very satisfied with Hyundai.
I've got a 2001 2wd auto V6 Santa Fe, and in the last month, it's been in the shop three times for a transmission code. The code is a 0755, having something to do with the underdrive. Has anyone out there had a problem with the transmission such as this?
So far the transmission control module, a valve solenoid and associated wire harness have been replaced, and it sits in the shop waiting for the main engine harness to come off the backorder list so that it can be replaced.
Each trip to the dealer has been precipitated by the clunk getting worse, and the conditions under which it occurs getting more common with every day driving, not just the initial parking lot maneuvers.
I have a 2001 6 cylinder GLS. Put 56,000 miles on it in a year and a half(I use my vehicle for my job which involves major traveling). I absolutely love it, but am considering trading it in on a new 2002 with 4WD which I need for the winters here.(although I had no trouble in the snow without the 4WD). I would appreciate any input from other 4WD owners. Any problems with the 4WD models? I just now took mine in for the back window wiper and the CD/amfm radio.(CD player cuts in and interrupts radio)??? Other than those two things, I am extremely pleased with my Hyundai. I can't even think about choosing another vehicle. I test drove the Jeep Liberty, and in my opinion, it cannot match the style, performance and quality of my Hyundai..Thanks for any info you can give me.
memsl....no problems with the radio that I can tell. I live between Philly and NYC and there's a constant battle of the Mhz going on right over my Santa Fe! I do believe that an in-glass antenna is less "potent" than an exterior one. The in-glass ones were popular in the '70's but fell out of favor for that very reason. I generally don't have too much trouble picking out the stations I want, but to do a scan or seek is almost pointless where I live!
jreidell1...I have a 2002 4WD GLS V6 and have had only one problem with the "throttle position sensor", which was quickly fixed. Other than that, nothing. But with only 6600 miles, I might not be the best example. I did have one chance to drive in the snow and it was grrreat...
Your never too old to learn ...... I have a 02 SF LX and have noticed others stopping and passing me ....then something occured to me....what I thought were tail lights, stop lights or hazard lights are nothing more than "reflectors" that are encassed like regular lights. Clever idea ? I wonder if there was more to it than just putting something there on the rear bumper in addition to what they use for stop backup and turn signal lights. Anyone care to comment or better yet just learn about this now? Radio reception... I agree could be a better means than the window antenna. Also some stations just don't seem to have enough power ..people at Circuit City told me that they will be much more dynamic with an amplifier installed under either front seat for about $520.00. Has anyone opted for this ? New owners of LX's, there's been a problem with the air compressors and have to be changed out...after about 2,000 miles if you hear a ticking sound from the AC compressor then it's defective but should be checked out for certain. The dealer replaced it along with a new belt. All is well from here on.....
I own a 2002.5 GLS FWD w/ALB & TC. We have put 8000 miles on it in only three months and we absolutely love it!!! If you are considering a purchase, there is one minor detail you should know: As mentioned by others, the in-glass antenna is VERY much weaker than an external. We live in a fringe area for FM radio, with most of the good stations approximately 50 miles away. While we have no problems with our other vehicles in picking up these stations, we do in our Santa Fe. If you are in your car a lot (as we are) and you don't live in a major market, you may want to consider an aftermarket antenna of some type, or pick up satellite radio.
Other than this, we have no problems to report. Took it to NYC and back (about 1600 miles total) last week, and it was a dream to drive and ride.
We have had our 2002 V6 for about 5000 miles. It has been a truly great car. I've had a number of SUVs including GM Jimmys and Blazers, Sierra, Ford Bronco, and a Subaru. Have test driven everything. No doubt the Hyundai Santa Fe is the best for the $ (the BMW, Acura and Lexus are the best if you can afford them). We have had no radio reception problems, in fact it is better than on our Passat (which we just traded for a Honda Civic Hybrid). The sound is really pretty good, just make sure not to leave the retractable cover covering the back.
We have had two minor problems. The accelerator cable was sticky from the first, but got worse, and the shifter button sometimes sticks. Both have been replaced and are now fine. As for the ticking some have heard, when test driving Santa Fe's before we bought, one of them had the same problem. The dealer said the car had not been driven in almost a month and that oil settling was the cause. But as I have read several who found out that the AC compressor was at fault, I would beleive that.
It is a great car, but I guess part of keeping the cost down involves less QA/QC. With 5/10 year warrantees, I can let that pass.
Have a deal on a new 4-cyl auto 2WD. Have read back 200 posts.By so doing have some qualms, have not picked up or handed over final check to dealer. Any advice on owners of the same would be appreciated, posts or e-mails OK. Just found this board today, so far have not read anything that bad to deter my sale, only nice to know possible problems and what to look out for. Thanx in advance for any comebacks. 2 Dogs
Would strongly suggest the 6-cyl over the 4-cyl. MPG not that much more for the 4, and with the weight of the Santa Fe (heavy for a small SUV) you should be more satisfied with the extra power. Remember, the power is already a little less than some of the others. The only combination I did not try during my test drives was a manual on the 4-cyl. I suppose that might be a good combo.
....I can't really quell any qualms (how's that for 2 Q words?!). I had qualms about buying the Tribute and backed out of the deal AFTER I put in a deposit (after there were 4 posts on the Escape problems board in 2 days after I put down the deposit). I decided on the Santa Fe and there was one problem with a throttle position sensor at 469 miles. I thought I was in real trouble, but that, as it turns out, is the only problem so far and it was easily fixed (unlike the stalling problem on the Trib!). I have 6700 miles on it now and its great (except for my little ding which I will mention in my next post). Hopefully, other owners with longer ownership will respond. Check out the Hyundai Santa Fe board also....
I recently purchased a 02 Santa Fe GLS 4WD. I love my SUV. It looks good & it drove well until @ 3200 miles in 3 mos my fuel line was busted leaking a full tank of gasoline. It took Hyundai's tow service which is free 4hrs to tow my SUV to the nearest Hyundai dealership. The tow service told me they would be there in 60 minutes or less. It took the Hyundai dealership 9 days to repair my SF. They had to get the parts from overseas because they ordered the part 2x's from there US CO. & the parts were defective. I also have a cracked transfer case that the dealership claims that can't see. The SF is a nice SUV but be careful of their service departments & there free Roadside assistance. Now I'm looking to trade my 3 month old Sante Fe for another SUV, I just don't feel as safe in the Santa Fe as I did before the busted fuel line.
I have a 2001 GLS V6 AWD. Every time I press the door lock/unlock button, there is a strange "ding" sound coming from the left end of the dash. It comes almost half a second after the usual thud sound and it sounds like a spring being released. There does not seem to be anything wrong with the door lock. But the sound is definitely anonying.
Have had my Santa Fe GLS for 2 weeks now and loving almost everthing about it.
According to the manual there is a "low fuel indicator" which should come on when I am low on fuel (duh). However I have not seen this light come on yet. I intentionally did not fill up my tank as I was curious to see the light go on- until I finally got nervous that I'd run out of gas. When I filled up it took 17.02 gallons of fuel; the listed capacity is 17.4. Hence I had less than 1/3 of 1 gallon left of gas and the indicator had not come on. Geez, had I been on a highway or someplace quasi remote I wouldn't have been able to get to a gas station.
What has everyone else experience been with this indicator?
My Skylark power lock made a springy kind of noise when used, and my Elantra makes a much quieter noise, but still there. It's just the mechanism, but quiet.
I have had my 2002 Santa Fe LX for only 60 days and the check engine light came on a few days ago. When I called the service center they told me it would be at least a week till they could look at it and that driving it with the light on wouldn't hurt it. Now 5 days later the car will not shift out of first gear when going up any hill when in automatice mode. Has anyone else had this type of problem?
Update to #333. My shifting problems apparently were caused from a boken catalytic converter! I can't imagine how this could be broke on a 60 day old car! So far I am not too impressed with the service record of the Santa Fe! I have already had it in the body shop to have a part of the rocker panel repainted because it was peeling. It started peeling after I had the car 1 week!
....put a post on the NHTSA consumer complaints board. We have 7K miles on ours and only 1 problem with a sensor. That was at 500 miles. Its been fine since. Hopefully this will be the only issues you have to deal with.
jimbeaumi....the mechanic said that the shifting problems were caused by the cars computer trying to compensate for the broken catalytic converter. The mechanic also said that it might have caused other problems on the car, I guess I will find out when the part comes in.
Yes I'm sure the mechanic said the catalytic converter, because I asked him twice because I couldn't believe that : 1. it had broke after 60 days and 2. it was causing shifting problems! He seemed just as suprised as me that it needed replaced!
Well I still don't have my car back. I called the garage yesterday at 4:30 and they said the part came in and they were just about to starting working on it. I called again today at 3:15 to see if it is done, and they said that they just pulled it in the garage and are about to start!!! They certainly don't seem in a hurry to get my car back. It will be a week in the garage tomorrow and I still have the rental car they gave me. Anyone else have trouble with hyundai garages doing the work once they have the car?
Something smells a little fishy here. Was the cat physically damaged? If so, between that and the problems with your rocker panel I would speculate that you may have gotten a car that was damaged and then repaired. How many miles were on it when you bought it? Since both the catalytic converter and rocker panels are on the underside of the vehicle it makes me wonder whether someone did a little "off-roading" on a test drive. Sickening, but stuff like that happens - and the dealership can still legally sell it as new! When you get it back, I'd take it to a reputable body shop and ask them if it looks like it has been repainted or repaired - they can tell.
Oh, and what do you mean by the rocker panels? The rockers on the Santa Fe are covered by that plastic cladding, which I don't think is painted at all.
Jason...I bought the car when it was still in Korea. It is very hard to find LX models in my area, so I had to put the down payment down before it was on the lot. I actually did see the car when it firs came on the lot, it was still covered with the plastic, I think the miles were somewhere around 5. The rocker panel I'm referring to is the gray part of the car, right at the base of the drivers door. Actually, I have seen 3 other Santa Fe's in parking lots around here, that have had a problem with peeling in this area!
However, I am a bit leery that the garage keeps changing the story on the progress of my car. Makes me wonder if there is something else wrong with it that they are not telling me about. Also, I was under the impression that the Catalytic Conerter was part of the exhaust system, and is not that hard to replace. I thought they could finish a job like that in about 30 minutes!....but when I talked to them today at 3:15 they said they didn't think they would finish it today....they are open till 6:00.
I am not sure where the catalytic converter is on the SF, but on the Elantra it is up near the front of the engine, where it can heat up more quickly. That would make it much more than a 30 minute job.
I've had my 2002 Sante Fe for all of 11 months (6100 miles) and have encountered the following problems and have received no assistance from the main Hyundai Headquarters or the local dealers.
1) Excessive acceleration (fast idling) on startup - car revs to 1700 RPM for approximately 90-120 seconds. 2) Premature brake wear - As a result of the above, the car needed new front brakes after only 6000 miles. 3) Premature paint peeling on 2 spots on the front hood.
Yes, the catalytic converter is part of the exhaust system. It also has no moving parts - it looks a lot like a muffler, filled with some different metals that react with and convert exhaust gases from bad gases (C0, NOx) into harmless gases (Nitrogen, Oxygen).
My point is that the only way cats really go bad is from
1. Age - the catalyst is slowly used up. This generally takes well over 100k miles to happen.
2. Physical damage - you ran over a rock big enough to crack the sucker.
I'd ask them about exactly what's wrong with the cat - better yet, have your brother/uncle/cousin/father-in-law who knows cars pretty well call them - someone who will be able to tell if they're blowing smoke. I would imagine it would take some damage to the O2 sensor (generally mounted just upstream of the cat) to cause the check engine light, etc. you've been seeing, so ask them if the oxygen sensor is being replaced as well.
Well I finally got my car back today. It seems that they actually repalced a lot of parts that they didn't tell me about. Here's what they did: 1. Manifold Catalytic 2. Gasket Exhaust MA 3. Sensor Assy-Oxygen 4. Gasket exhaust PI (X2) 5. Pipe-Exhaust FR 6. Gasket-Exhaust PI I talked to the mechanic to find out what kind of damage that the Cat. actually had. He described it as being burned out. When I asked him what could burn out a Cat. he said he didn't know, but he assumed it was probably defective from the day it came off the ship. I just hope it was something defective with the Cat., and that the engine didn't somehow make it burn out. I am also hoping that now that I have the new Cat. I might get better gas mileage. I have been getting approx. 16/gal so far.
Technically, a catalyst isn't used up as it does not change in the chemical reaction. It becomes depleted only in the sense that "erosion" carries it away. Your conclusion is correct though!
Erosion or contamination describes it better than "used up". Of course on older cars you also have the rust factor. My 15 yr old Alfa is due for a new cat as well - a bad distributor caused some severe backfiring, enough that I found several walnut sized chunks of substrate (the honeycomb looking stuff that houses the catalyst) on the garage floor behind the muffler. Don't call the EPA on me - I haven't replaced it yet, because the reduced backpressure makes it sound really cool ;-) Emissions inspection due in a couple of months, tho.
Shawn- Good to hear they got it fixed, and that they replaced the oxygen sensor. Things actually make a little more sense now. If your cat was faulty from the get-go, the increased backpressure and excess heat could easily nuke the O2 sensor, which in turn would cause the check engine light / poor running you encountered. MPGs should improve with time - ours has improved to about 22 in mostly city driving. We have 24k on the clock.
Is there anyone out there experiencing a strange grinding noise when the air conditioner is turned on. Seems this only happens at first start up of the day, and only for a second .At the present there are no Tec. Bullettins or Service letters on this problem. Thanks,,
Experienced exactly what you're talking about. After sitting for long period of time. First time turning on the A/C, I get a large grinding clunk sound. A/C works fine so I never took it in. The Hyundai service dept here is a joke. And being that it only did it after sitting awhile (a day or more), they'd never figure it out. One other odd thing I've noticed, when the compressor kicks on the headlights and driving lights dim. And on one occasion had total electrical shutdown for one split second (radio, lights). And lately it's been hard to start in the mornings like the battery's going dead. It's not a daily driver and it's a 2001 with 21K miles. If you've read my older posts, you'll know that this vehicle has spent at least 2 months total in the shop since I bought it Feb 2001. I'm not dissing the car. I like it a lot, but you can bet I will be trading it in before my warranty's up...
Comments
the clutch has just started slipping
any ideas why and has anyone had this problem
Thanks
no my toy is a 1992 160+K miles on it.
First the ticking sound that you are hearing when the vehicle is cold is MOST likely from the A/C compressor....and will have to be replaced. I have the same problem and after a shop visit I was told that it is indeed that. After initial warm up it goes away.if so then I would suggest thatyou have it checked out. Mine acted up at 2500 miles after I started using the AC on my new 2002 LX.
Radio....yes it could be alot better....one solution that i will advise is to have an amplifier installed under the front seat of the driver OR passengers side and if it is of sufficient power will add alot more power to the radio's performance. Step two would be to change the speakers, but first go the easier route to have an amplifier installed.....this should work out for you. If you'e near a Circuit City store give them a try OR go to a place that handles car sterios.
Good luck it's still a great vehicle!
I've been sitting on the sideline for well over a year. ($$ issues) Just as I was test driving my final 3 in preparation for Thee Buy (Liberty, Escape, Santa Fe) the boom lowered again. My company is moving my section to N.H.
I'm going back into a hole until the move happens and where it takes me. Funny but my final 3 back then were the RAVioli, CRV, and Forester. Now its totally changed. But so has the market. Next time I emerge and start test drives I'll probably say "There isn't enough road to get to 88 mph?" And the salesbot will answer, "Where we're going we don't need roads."
Indeed it's becoming evident that there's a problem with some of their parts. This problem also showed up on another Santa Fe list and the results were to have it changed out.
We'll see how it sounds tomorrow morning...
Other than that I'm very satisfied with Hyundai.
So far the transmission control module, a valve solenoid and associated wire harness have been replaced, and it sits in the shop waiting for the main engine harness to come off the backorder list so that it can be replaced.
Each trip to the dealer has been precipitated by the clunk getting worse, and the conditions under which it occurs getting more common with every day driving, not just the initial parking lot maneuvers.
jreidell1...I have a 2002 4WD GLS V6 and have had only one problem with the "throttle position sensor", which was quickly fixed. Other than that, nothing. But with only 6600 miles, I might not be the best example. I did have one chance to drive in the snow and it was grrreat...
I have a 02 SF LX and have noticed others stopping and passing me ....then something occured to me....what I thought were tail lights, stop lights or hazard lights are nothing more than "reflectors" that are encassed like regular lights.
Clever idea ? I wonder if there was more to it than just putting something there on the rear bumper in addition to what they use for stop backup and turn signal lights. Anyone care to comment or better yet just learn about this now?
Radio reception... I agree could be a better means than the window antenna. Also some stations just don't seem to have enough power ..people at Circuit City told me that they will be much more dynamic with an amplifier installed under either front seat for about $520.00. Has anyone opted for this ?
New owners of LX's, there's been a problem with the air compressors and have to be changed out...after about 2,000 miles if you hear a ticking sound from the AC compressor then it's defective but should be checked out for certain. The dealer replaced it along with a new belt. All is well from here on.....
Other than this, we have no problems to report. Took it to NYC and back (about 1600 miles total) last week, and it was a dream to drive and ride.
We have had two minor problems. The accelerator cable was sticky from the first, but got worse, and the shifter button sometimes sticks. Both have been replaced and are now fine. As for the ticking some have heard, when test driving Santa Fe's before we bought, one of them had the same problem. The dealer said the car had not been driven in almost a month and that oil settling was the cause. But as I have read several who found out that the AC compressor was at fault, I would beleive that.
It is a great car, but I guess part of keeping the cost down involves less QA/QC. With 5/10 year warrantees, I can let that pass.
The rear fog lights are a requirement in many other countries. See following link for one man's effort to re-light the reflectors.
http://pub108.ezboard.com/fhyundaisantafemessageboardfrm52.showMessage?topicID=48.topic
Any advice on owners of the same would be appreciated, posts or e-mails OK.
Just found this board today, so far have not read anything that bad to deter my sale, only nice to know possible problems and what to look out for.
Thanx in advance for any comebacks.
2 Dogs
Every time I press the door lock/unlock button,
there is a strange "ding" sound coming from the
left end of the dash. It comes almost half a
second after the usual thud sound and it sounds
like a spring being released. There does not seem
to be anything wrong with the door lock. But the
sound is definitely anonying.
Anybody noticed this before?
thanks!
Have had my Santa Fe GLS for 2 weeks now and loving almost everthing about it.
According to the manual there is a "low fuel indicator" which should come on when I am low on fuel (duh). However I have not seen this light come on yet. I intentionally did not fill up my tank as I was curious to see the light go on- until I finally got nervous that I'd run out of gas. When I filled up it took 17.02 gallons of fuel; the listed capacity is 17.4. Hence I had less than 1/3 of 1 gallon left of gas and the indicator had not come on. Geez, had I been on a highway or someplace quasi remote I wouldn't have been able to get to a gas station.
What has everyone else experience been with this indicator?
Thanks,
Glenn
Probably the noise made by a relay.
1. it had broke after 60 days and
2. it was causing shifting problems!
He seemed just as suprised as me that it needed replaced!
Oh, and what do you mean by the rocker panels? The rockers on the Santa Fe are covered by that plastic cladding, which I don't think is painted at all.
-Jason
However, I am a bit leery that the garage keeps changing the story on the progress of my car. Makes me wonder if there is something else wrong with it that they are not telling me about. Also, I was under the impression that the Catalytic Conerter was part of the exhaust system, and is not that hard to replace. I thought they could finish a job like that in about 30 minutes!....but when I talked to them today at 3:15 they said they didn't think they would finish it today....they are open till 6:00.
Shawn
1) Excessive acceleration (fast idling) on startup - car revs to 1700 RPM for approximately 90-120 seconds.
2) Premature brake wear - As a result of the above, the car needed new front brakes after only 6000 miles.
3) Premature paint peeling on 2 spots on the front hood.
Here - this is a good basic explanation. http://www.howstuffworks.com/catalytic-converter.htm
My point is that the only way cats really go bad is from
1. Age - the catalyst is slowly used up. This generally takes well over 100k miles to happen.
2. Physical damage - you ran over a rock big enough to crack the sucker.
I'd ask them about exactly what's wrong with the cat - better yet, have your brother/uncle/cousin/father-in-law who knows cars pretty well call them - someone who will be able to tell if they're blowing smoke. I would imagine it would take some damage to the O2 sensor (generally mounted just upstream of the cat) to cause the check engine light, etc. you've been seeing, so ask them if the oxygen sensor is being replaced as well.
-Jason
1. Manifold Catalytic
2. Gasket Exhaust MA
3. Sensor Assy-Oxygen
4. Gasket exhaust PI (X2)
5. Pipe-Exhaust FR
6. Gasket-Exhaust PI
I talked to the mechanic to find out what kind of damage that the Cat. actually had. He described it as being burned out. When I asked him what could burn out a Cat. he said he didn't know, but he assumed it was probably defective from the day it came off the ship. I just hope it was something defective with the Cat., and that the engine didn't somehow make it burn out. I am also hoping that now that I have the new Cat. I might get better gas mileage. I have been getting approx. 16/gal so far.
Shawn
1. Age - the catalyst is slowly used up.
Technically, a catalyst isn't used up as it does not change in the chemical reaction. It becomes depleted only in the sense that "erosion" carries it away. Your conclusion is correct though!
tidester
Host
SUVs; Aftermarket & Accessories
Shawn- Good to hear they got it fixed, and that they replaced the oxygen sensor. Things actually make a little more sense now. If your cat was faulty from the get-go, the increased backpressure and excess heat could easily nuke the O2 sensor, which in turn would cause the check engine light / poor running you encountered. MPGs should improve with time - ours has improved to about 22 in mostly city driving. We have 24k on the clock.
Good luck,
Jason