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Chevy TrailBlazer Loss of power

howdy all. got my 04 TB, 4.2L v6 in 06 with 13k miles, 23k miles now. was a salavage title (insurance mistake) so no warranty :( everything worked fine. So few mo later had to replace the battery since it's been sitting for a 3-4month and the stock one slowly went dead on me.

I'm a computer admin with some mechanics experience from working on Ninja 900cc..can do maintenance but not much of a troubleshooter when it comes to cars :(

I started noticing that once in a while i'd be driving in the range of 20-65m/h and have no power regardless how I push the gas pedal. Engine runs but tranny doesn't get invloved. I'd release the pedal and just roll for a couple of sec and push again and it'd be fine.
well, it's been over a yr now, and i find it doing it almost every time I drive it. it happens when engine is cold and when it's at normal op temp (I'm in Dallas, car warms up very fast). Most of the time it happens on the ramp getting on the highway and speeding up on the hightway but mostly in that range.

I haven't had any warning lights come on or engine lights... starts everytime, even in the winter. I change oil myself every 3,500 (Castrol GTX 5w30 with AcDelco filter). Tranny oil is still from the factory.

so one day it wouldn't pull while going up a steep ramp and tried releasing and pushing the gas pedal as always but the engine just died. I was able to pull over to the shoulder... switched to neutral and SOB started just fine!

I tried scanning the computer, but the scanner can't seem to establish a connection (keeps telling me to plugin the cable).

I'll take the dash apart this week to check if I forgot to connect the OBDII jack back after I run the fog light switch from the dash into fusebox.

Some guys were mentioning bad Neutral gear switch .. can I test that in some way or only a dealer can do that (where is it anyways)? Is it possible that I cause the problem by resting my right hand on the gear selector while driving?

Since the car didn't have warranty I made following upgrades after I got it: replaced the stock stereo with a mp3/USB deck (had to buy special harness with a chip) and installed a pair of fog lights with harness (7A on the same fuse as RPM gage, only I replaced 5A rpm fuse for a splitter with 2 5A fuses)

Thanx so much in advance for any ideas and advice.
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Comments

  • vbellvbell Posts: 11
    I own a 2007 Trailblazer...I6 4.2L, much like yours. I have had a similar problem happen twice in my brand new truck. The first time I was driving about 20mph- the truck lost power and dropped to almost 5-10 mph. With in seconds..it had kicked back in and it was fine. I have Onstar so I called them and had them do an emergency diagnostic- found nothing wrong. Exactly 30 days later- truck did it again, this time I was doing about 75 down the highway and it lost power and dropped to about 25-30 mph. Very scary on a busy highway!!! I took it to the dealer, they say nothing is wrong. I even contacted GM regarding this matter, they gave me free oil changes for a year becuase they dont know what is wrong. My father came up with this idea that maybe Onstar had something to do with it. We deactivated Onstar (its been over a month since Onstar has been gone now) and i havent had the problem at all. Just was wondering your thoughts on this, it seems like we are having the same problem. No one from the dealership or GM can figure it out, so its almost like I am conducting my own investigation!!!!!
  • unbelievable, isn't it :) Well, I haven't gotten around to checking my OBDII connections so I can't scan for anything :( I now mostly drive on cruise control cause it only happens when I'm pushing the pedal by foot (even though I check everything I can't see what's causing it) .... in mine, the injection controlled by a switch (when I push the accelerator down) the cable that goes to the throttle opener goes through a switch .. thinking to replace that and to see what happens.

    Now I started getting engine light during rainy weather .. i think one of the oxygen sensors .. but no idea which one. after i drive for an hour smth must be drying up cause the light goes away :)
  • ficussficuss Posts: 541
    this sounds like new feature that allows Onstar to cut your power if police request that action. Could it be that someone at OnStar is tweaking the system and testing randomly?
  • except I don't have Onstar ......
  • ficussficuss Posts: 541
    satvic: I was responding to a prior post by vbell with an 07 Trailblazer. OnStars new feature allows THEM to reduce your engine power when THEY want to. So if the driver of a car equiped with this feature decides to punch the accelorator to merge with traffic and OnStar decides to reduce the power at the same time, you won't merge very nicely. Now some will say that OnStar won't activate this feature unless asked to do so by the police, but that doesn't rule out accidental or unplanned activation. IMHO they have inserted yet another weak link in an already weak dependability chain.
  • I understood :) So, in this case my question is: is there smth in the system that can fail and cause the loss of power EVEN IN CASE where the Onstar was never installed on this particular car to begin with? Shouldn't there be some kind of plug to complete the circuit bypassing OnStar device features? any idea what it'd look like if it exists? :)
  • ficussficuss Posts: 541
    there are numerous conditions which would cause the engine to run at reduced power, all of which are by design. I would recommend taking a very close look at all of your gauges when this happens and report every item to the mechanic. How fast were you going, which gear was the car in, were you towing something, etc. Get a printout from the mechanic of all the possible reasons for programmed, reduced engine power. Then think of what may apply to your particular situation.
    One more thing, do a search of "reduced engine power" in the Ranier, Trailblazer, Envoy forum and see if anything sounds similar.
  • I've experienced the same with my 02 TB. The intermitten power loss , sometimes causing the engin to stall, was due to a O2 sensor. I've had it replaced three times, the last being about a year and a half now. The sensor was so corroded and in bad condition (supposedly due to water leaking onto it??) it was very difficult to replace.

    I've had no major problems since, other than the fact the SES light stays on all the time. Even after being reset. I seriously put black tape over it.

    I have 120K miles on it now.
  • i gotta try this cause every time I drive in rainy weather my engine light comes on. as soon as it dries up, light goes away. I wonder if it that's the same O2 sensor .. do you know how many are there? where is the one you've been replacing is located at? thanx so much
  • sounds like the same exact thing I went through

    seriously, every time it rained, or I washed my car (underneath and under each wheel well) it seemed to trigger the SES light. I am not sure which sensor they replaced, but know that the engine hesitation and stalling went away. The truck runs great now (outside the sway bar links needing to be replaced again) but the SES light is still on. At this point, it really does not bother me anymore.

    What do you want for $30,000, right :)
  • well, I paid $7k cash for my 04 with 13k miles but still feel robbed. Just reaching 30k miles and things starting to go out: little things: door switches, squaky and rattling noises.
    This is last american car for me :) seriously, the darn Honda Accord I had 10yrs ago was purring like a kitten at 180k miles with 32 mpg. Miss it :) Hope that O2 sensor is the last thing I have to replace before I get rid of it in spring :)
  • vbellvbell Posts: 11
    I am replying to your message to my post about my 07 trailblazer....I have done some more research on this issue. As far as Chevy is concerned they say that OnStar is NOT able to deactivate a vehicle while it is in motion. (even if told to do so by police). Its is considered unsafe. So even if my car was stolen lets say with a full tank of gas, as long as that person keeps driving the car and they have gas- they cant shut it off...lets say the person stops somewhere and shuts the vehicle off- now OnStar can come in and deactivate the vehicle making it so the vehicle will not turn back on. But they can not deactivate a vehicle while it is in motion- which kind of makes sense, but.......i still dont understand what my truck is doing. It hasnt happened again- Ive had OnStar reactivated for about 2 weeks now. Dont know what will happen..no one really does. Thanks for the relpy though!!!!
  • vbellvbell Posts: 11
    hey thanks for the reply....I've had the truck back up the the dealership for a steering wheel positioning sensor (nothing to do with the loss of power problem) but I was talking to the tech there and he says that my accelorator isnt run by a cable. Its basically all run by sensors. The problem is when they plug the truck in to the computer- nothings wrong, which is understandable because I dont have any warning lights to begin with when this happens. Anyways, I have reactivated OnStar...its been 2 weeks.. and nothing has happened since September. It only happened twice so maybe...just maybe it was a fluke in the system- which I find hard to understand on a brand new $30,000 truck. So I am basically waiting for it to happen again. The thing is I wanna get this all straightened out while I'm still under warranty. It all is really unbelieveable. I work for a heating and air conditioning company and I see less problems with new furnaces and air conditioners than I do with cars and they cost thousands of dollars less. Its amazing!!!! That is very strange with the Engine light in bad weather. Do you have Stabilitrak or any traction control system? I know that my Stabilitak light will come on in bad weather..but im not sure if its the same with your truck!!!

    Thanks again :)
  • vbellvbell Posts: 11
    Stavic...I know we've all been going back and forth with messages...but I do remember when I had OnStar deactivated from my vehicle they literally pulled a plug somewhere near the rear passenger tire. Didnt see them do it, so I dont know exactly where it is, but that is where the OnStar plug is in my truck...Good Luck!!!!!
  • ficussficuss Posts: 541
    vbell, my information came from a news report that stated that OnStar can now reduce engine power to newer OnStar equipped cars. They do not "deactivate" a car, they reduce power to a safe level so the driver cannot speed away. I would pose the question directly to OnStar, not Chevy or GM.

    Try googeling "OnStar can reduce power" and read the reports.
  • well, I think I figured out why the code scanner cannot get any reading out of the computer .. I changed the OEM stereo for a KENWOOD mp3 deck last year - DOH ! :) Well, SHEVY wiring runs through the stereo which makes the security system work etc...Also, you sistem chimes come out of your stereo when you open the doors etc.. SO, for those who consider another stereo, FYI you have to spend $100 or so for a special harness that contains a circuit box to preserve your security system capabilityes and has a speaker (for the chimes). I don't have the original harness anylonger to test my theory but I bet that after market harness with circuit is the reason my scanner can't read onboard computer.

    As far as the loss of power, I don't have OnStar system .. and this car never did! I am a very concervative driver, I never floor the pedal or push it pas 2k RPM..

    I am taking the vehicle into dealer on Monday to have them test the exhaust O2 sensor. I will have them check for the OnStart stuff........ will keep you posted.
  • We bought a 2002 Trailblazer from AutoRama about 4 months ago, if even that. But about 2 weeks ago I was driving and got lost on the highway and ended up 6 hours later home. But what would normally take me about 20 minutes up the highway from where I finally figured out where I was, it took me about 1 1/2 hrs. to get home. All of a sudden the power just went. I mean, I had power but only the first gear. Couldn't get out of it unless I backed off and barely touched the gas peddle. At first I was trippin cause when it first happened I kept tryin to make it go, but all I got was roaring so loud and the vehicle wouldn't go any faster at all. I could only get on the side gravel part of the highway and go no more than 20-25 miles per hour. Eventually I had to get over some lanes and I finally would get it up to atleast 40-45 but no more than 45. Thank God there was alot of traffic that was making everyone go pretty slow but alot of times I thought I was going to get in an accident since it was so hard to get it up to 45!

    So could it be the transmission? I had been getting on star to pop up in my little window above the steering wheel and I would push the buttons up above and I would hear a message from on star telling me that on star wasn't activated and to activate it I needed to call such and such number. I never have since it's an extra exspense that we can't afford right now.

    I'm really frustrated as to what could be the problem.

    Could it be from bad gas? The reason I ask is because I had stopped at a BP station in the outskirts of some town I was in.......yeah when I was lost......and before stopping there everything was fine with the trailblazer!!!

    I do remember that when I was lost, I had my 21 yr. old son in the vehicle with me. I was trying to get him to an insurance place so he could get insurance on his vehicle and ofcourse I got lost on the way there too, but he was yelling at me and needless to say I was pretty aggravated and I would go really fast a couple of times cause I was so frustrated at him yelling at me and not knowing where the heck I was. But this was way early on, I didn't have any problems at all til after I got the gas at the BP station.

    I guess I'm just wantin somebody to tell me that it isn't something serious and if it's just from bad gas then maybe it's a simple problem that I can fix myself.......probably not huh!

    But if anyone of you can help me out with this I would appreciate it. I've been reading on here and I'm so upset at all the problems that everyone is having. I've been so happy to have a vehicle, I thought was going to be safe and reliable for me to travel out of state to see my family, which I have a few times since we purchased it, but now I'm just heartbroken. I couldn't even spend any holidays with any of them this year.

    So I'll be prayin that somebody can help out on here! Thanks for listening!

    P.S. I'm not from this state so that's why I got so lost. :mad:
  • I really need some advice here. How can I get the codes from my 2002 Trailblazer myself?

    Is there a certain number of times to turn the on and off key switch on and then will it tell me if there is anything wrong with it by displaying codes?
  • pwingpwing Posts: 1
    I purchased my 2007 Trailblazer in March, 2007. Since then I have had 3 episodes of loss of power. Each one I was driving and I loss power, engine still running but no power to it. My check engine light went on and then off. I was lucky because I did not get in an accident. The only thing I could do was turn off the engine and restart and it was fine. It happened in August, December and now February. I took it each time to the dealer where I purchased it. In August, they said they couldn't find anything. In December, they found an error code and replaced a sensor and said they fixed it. Now in February, they found some error codes, replaced a module but told me they have no idea if the problem is fixed or not. Basically, I was told to drive until it happens again. I explained my concern of my safety - what would happen if I was going 65 mpg and this happened on a busy freeway. They said they can only deal with what the computer tells them. So at this point, I got it back from the dealer last night and found this website and hmmm it seems like I'm not the only one having this problem but still no one knows what is causing it.
  • br2ubr2u Posts: 2
    My 05 went to the dealer today for this same problem plus a few others. OnStar sent my monthly email with an diagonstic alert on the emissions systems. Service center replaced the O2 sensor. We'll see if this works. Gota take it and have the battery replaced also, I'm not paying their price. My dad has a 02 pickup that was doing the same thing. His would quit doing it when he added fuel treatment or injector cleaner but, two days ago it died. His turned out to be the fuel pump.
    For those of you considering going foreign, been there done that, good luck. I had a Kia Sorento. We loved the Kia but, it stayed at the dealer almost as much as we drove it. Always for the same problem. Always had to call Korea for permission on the minimum they could do to fix it. The last time it went in they stapled a wire on the transmission, we took it straight to the Chevrolet dealer and traded. At least with my Chevy I get service, don't have to wait on Detroit to make a decision and something always gets replaced not stapled, which at least makes me feel better.
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