Stumble while driving

[Tim]

This problem just started today.

Whenever I am driving my '93L, regardless of speed/gear, it seems like the engine hesitates for a second and then catches again, lurching the car forward. It does this randomly, and will drive fine for a while but then stumbles.

This happens at all RPMs, but not at idle.

I replaced the plugs, wires, distributor cap and rotor (all but the plugs were original!) and it didn't make a difference.

I did a search and someone mentioned that the TPS sensor could be the cause but I am unsure.

Anyone have an idea? I plan to change the fuel filter tomorrow.



Regards,

Tim

[miami man]

maybe loose vaf plug..just a thought mine was loose.

[Tim]

I checked the VAF plug; it's on there pretty tight.

It sounds like the car is misfiring.

[packrat427]

TPS maybe ??

They act funny like that , when the contacts are dirty/worn /out of adjustment , or they get some play in the shaft .

[FestYboy]

replace TPS and clean your IAC valve. I'd say clean your tps as well bit if the contatcs are going bad , there's nothing you can do.

[Festiva GTX]

Check your coolant sensor... ?

[Tim]

I pulled the cover off the TPS and the contacts are shiny and do make contact when I move the throttle. I also replaced the coolant sensor and taped up some bare wires in the engine bay.

I haven't driven the car much because of school and no gas money, but here are a few observations:


It runs fine when the engine is cold. No symptons until the car is warmed up.

The car will lurch and stumble a lot when climbing hills, worse than on level roads.

When I downshift from 3rd to 2nd to take a corner, sometimes I press the gas pedal and nothing happens. The engine still stays running, and after a moment or 2 the car lurches forward.

The other day I was driving, and the car was stumbling, and the check engine light came on for about 10 seconds. After that the car drove fine for about 10 miles, then resumed stumbling.


Any clues? Would a bad/out of adjustment TPS do this? My next guess is the advance in the distributor is going bad.

[packrat427]

Mine done that very same thing Tim , push on the gas and it is like you shut the key off , then all of a sudden it would accel all at once with a jerk , intermittent check engine light also .

I cleaned my IAC valve and all the connections that cleaned and tightened , none of that worked for me .

I took a finger nail file and cleaned the contacts on the TPS , then sprayed them with contact cleaner , then checked the continuity on the positions of the throttle on the switch .

After that my problems went away and never came back .

It seems like everyone has a similar problem , but that fix does not work for everyone ?

I think the switch gets worn a little and I had to tweak mine just a hair after I had it on spec with the meter .

[miami man]

maybe it is a lean surge problem.

[kzbill]

do you have any oil inside the distributor?

[Tim]

do you have any oil inside the distributor?

I don't think so. When I replaced the distributor cap it was clean and dry.


I'm going to take a nail file and clean the TPS contacts as well, to see if that makes a difference.

[wrestler3025]

When you take off the cap, there are two additional phillips head screws. Take those out, and then take that cover off. Look for any oil spots that may be on the round disc.

[fishgoddess]

I had a '72 Dodge Dart Swinger that did that. It turned out to be the coil. When the car ran for a while the coil would heat up and oil would come out of it and it would die or start cutting out. On the other hand, I have a BMW that does that now (if I drive it for over 250 miles straight), and the coil is fine...go figure.

If it is the distributor...I have an extra...

[Tim]

I'll try pulling the other screw off this afternoon and take a look.


Regards,

Tim

[Tim]

I took the cap off but didn't see any other screws. It looks like the distributor is a single unit that can't be taken apart.

While looking around in the engine bay, I noticed that the connector on the ignition coil that the wiring harness plugs into is broken. I think this might be part of the problem so I'll try swapping coils out and see what happens.