1989 Dodge Shadow

kpetty

After $600 and no further ahead I am desperate for
a solution, can anyone help, all suggestions would
be appreciated. The TPS ( throttle position
sensor), Oxygen sensor and the EGR valve have been
replaced, no fix as of yet. The syptom:

Jerking when engine has warmed up at highway
speeds, normally takes about 15 minutes to occur,
once it starts I can pull over for about 20 seconds
and go again for about 20 minutes, it does
eventually clear up and run like a charm. If I
floor the accelerator pedal it picks up after a
short time, say about 1-2 seconds, this normally is
predominant in light throttle in 4 or 5th gear. It
is a standard 2.5 ltr engine. Gas mileage
deteriorates, probably due to the heavy foot that
attempts to correct the jerking. Please help, very
frustrated with the so called authorized dealers.

carnut4

I assume you and your dealers have checked the built in fault code-that should tell you what the problem is. Sounds like the MAP {Manifold Air Pressure] Sensor to me. Or maybe a vacuum leak somewhere. You don't say whether this car is fuel-injected, Turbocharged, or Carbureted-that makes a difference.

kpetty

It is fuel injected single point system, non turbo. The dealer did have a diagnostic tool on it but said it only revealed oxygen sensor issues. Today it ran like a charm, tomorrow!! well who the heck knows, sorry for the sarcasm, thats how I feel. I too suspect a vacuum leak, I have ordered the Vacuum Diaphragm and heated air inlet sensor, a stab in the dark I think, I'm not a mechanic but do attempt through books to resolve easier issues. I don't fully understand the operation of the flap in the air filter housing unit. It is up (open) when I turn the engine on but very quickly goes down (closed) when the engine runs, correct me if I am wrong but should the closing be a gradual process, as the engine warms up. Should it also open and close as the temperature fluctuates. I thank you for the MAP info I will certainly look into that.

carnut4

You know that door in the air filter housing is also controlled by a little vacuum diaphram and is supossed to respond to temperature changes- I had a Ford Fiesta with a similar setup, and that little vacuum motor was always going bad, causing the door to open when it shouldn't which in turn caused syptoms like yours-becausae the air entering the intake was not being kept at a constant temperature like it was supposed to. might check it out.

mzn

It never ceases to amaze me how much our users know. Thank you carnut4 for your helpful responses!

carlady/host

kpetty

It is nice, Carnut4 has been a tremendous help. His suggestions will be put to very good use.

Rankled

I have owned a 1989 Dodge Shadow the past 9 years.Although my car has very low mileage, I find repairs to be frequent. I've had numerous problems such as headlights burning out frequently, and shorts. Even the factory radio died.Right after the 7 year warranty expired, the map sensor died.Not even couple of years ago I had the driver's side weatherstriping replaced. Already the weatherstriping is tearing where the old one did. Is it just my car?

kpetty

I don't think it is just your car, I purchased mine privately August of this year, I do put a lot of miles on, I too experience premature failure of lights I did notice poor contacts at the fuse box which I corrected. It seems bad grounding is also an issue. Weather stripping on my drivers side door also requires replacement, generates a lot of wind noise. It is now at 200,000 km's for what I paid for it I still feel it is a good buy. As with most Electronic Fuel Injected vehicles that age it seems like most issues are that of poor electrical connectors. I just reseated the MAP sensor connector after Carnut suggested it may be a problem, sure enough it runs like a charm again.

Rankled

I am glad that carnut's advice helped you fix your problem. It is certainly hard to find a good mechanic to fix things these days especially a Dodge Shadow. As for when my radio quit about a year ago, it was replaced by a Pioneer AM/FM cassette deck for less than repairing the factory original.A dealer once told me that the struts need frequent replacement on these cars.But the rear shocks last much longer.

kpetty

Thanks very much for your help Carnut4, I replaced the MAP, Diaphragm and installed the missing pipe connecting the hot air intake to the manifold. It snowed this morning which seems to bring on the problem more rapidly. Feels like a Rolls Royce.