95 neon idles/runs like crap

[83rampage]

I noticed the other day driving on the highway that the car would shudder every once a while, almost like it would stop running for a split second, then continue on.

Get into town and at the first stop sign it starts idling rough, and acts like it has a very poorly tuned carburator (yes I know its fuel injected). It hesitated and coughed a bit when you tried to accelerate, but if you slowly feather the throttle, it will slowly start to go and once past 30 km/hr it runs fine. Did notice it seemed a bit harder on fuel lately, but maybe that's just me.

Its a bone stock 2.0 automatic.

No codes present.

Any ideas? MAP sensor? TPS?

[A.J.]

Sounds like a map sensor or a fuel pressure problem. If you fuel mileage took a crap maybe your O2 sensor is bad.

A.J.

[Vigo]

My 95 neon does the hard lurch while driving sometimes, it's a TPS problem i havent fixed yet. At various times the TPS reading will jump to full 5v when its not WOT, and usually going to another spot in its sweep for a few seconds will get around it and let me keep driving and continue to not fix it.

Mine also has a semi-constant high idle which probably isnt related, but no other performance problems relating to the tps issue.

Do you have a voltmeter?

[RattFink]

My 1999 Dodge Stratus 2.4 did the EXACT same thing. It would sometimes stall out at stops also. I turned out to be MAP sensor, it finally got so bad that it threw a code.

[shadow88]

To start with, any codes?

Yes, the TPS was a common failure. A faulty TPS doesn't always throw a code. Don't rule out fuel contamination if it turns out that a tps doesn't fix it. I've seen many of these neons rust through the fuel filler tube and the resulting water contaminates the fuel and ends up plugging #4 and sometimes #3 fuel injector with gunk. If that turns out to be the case, replace the filler neck and the injectors can be cleaned, but a junkyard will probably have a set for cheap.

[RoadWarrior222]

Ah good point, I was getting worried about the filler tube on my SILs neon, it was heavily rusted on top, I can see how that would perforate through, and rarely spill gas, but get water coming in from being thrown up off the wheels, I cleaned road grit accumulation off it before. I think if I owned one, it would get a shield fabbed up, even if it was just a bit of 2L soda bottle.

[83rampage]

Thanks for the replys.

For the benefit of some I'll restate that there are no codes presently. Ive been so busy since Friday I haven't even had a chance to crack the hood.

I am borrowing a fuel pressure gauge tonight to eliminate that possibility.

And I do have a multimeter. If you have resistences for the TPS it would be appreciated.

Odd it was mentioned fuel tank contamination because I did change the fill pipe about 3 months ago due to it being rusted through. It was leaking fuel when I filled up.

This car is close to retirement but I still need it for a few more weeks otherwise this would probably result in a permanent trip to picknpull.

[shadow88]

Right. I missed the no codes part, I just kinda skimmed it.

The fuel pressure will be the same if the fuel is contaminated, if you suspect that, it's best to remove #4 injector from the rail and have a look at the inlet side and maybe tap it on a table over a clean white paper towel.

I've only ever back probed a TPS with a voltmeter while the key was on and the engine off. You should see aprox. ,8V closed to 4.2V wide open. That's the normal range, but not what fails on them. What you need to see is a dirty or jumpy signal while you give it a slow sweep from closed to open before you condem it.