still have the engine stumble
 

i have an 87 lebaron 2.5 auto, this car has a stumble both at idle in park in drive with foot on the brake and at any speed. i checked all the wires for breaks and even tugged them with a running engine.the vac hoses look good and vacum is at the high end of red, that is normal for this gage, the fuel looks even as best i can see it in the tb. the idle in park is 850 rpms so i increased it to 1000 rpms the rpms roll down from 1000 to 900 in an erratic fashion, not a rolling idle. in fact yesterday it almost stalled 3 times at stops.

i pulled the plug on the ecu and it stopped as it should. but when i pulled the plug on the tps it stumbled but stayed running, i figured it would stop as my geo metro did when i did that test to it years ago.

also i looked into the egr valve where it goes into the housing and i did not see it move when i reved it up so i took a driver and moved it when running and the engine stumbled bad but did not stop.

the codes are 12,55 normal after pulling the plug. but did not set any yet after and i ran it with these issued for about 2 minutes while doing other tests.

outside of hours of searching has anyone ran across this with this engine? i find no tsb's on the car and chrysler tech says they can't help to old. sure would like to get this figured out without just strapping on parts, has to be something. thanks bp.

ok i did a test on the tps with the meter set to 20 volts i pulled the plug and turned on the key. i probed the plug and got a=5.01 b=4.55 c=.02 then i put it back on and probed the wires from idle to full throttle a= 4.90 b=1.14 to 4.02 c=.02

i then probed the tps on ohms set to 2000k doing the same idle to full and got
a-b=003 to 001
b-t 001 to 004
a-c 004 to 004

now a is the bottom to c at the top these are the id on the plug. wires look like
yellow at a
orange black stripe at b
black at c

seems to be ok to me according to the you tube tests. will do more checking and send those along. thanks bp.

BEEN SO LONG since I had one of these era rides..Does this still have a traditional distributor? if so a problem area I found was the distributor bushings for the shaft wear and allow it to wobble causing the exact symptoms you describe. And this car is now HOW MANY YEARS OLD?????

thanks could be it but only 40k on the odo makes me think this would not yer be an issue. i did find the reluctor if that is what it is called that was loose in the distributor, i fastened it back down and it still di it. but one thing that puzzles me is the timing is steady. if it was bushings i would think the time also would bounce around. thanks i will check that anyway for a potential issue. bp.

Now that I know a little more about the condition of your ride... OLD, but LOW miles.
I would do a fuel pressure test, and quite possibly varnished injector nozzles. Run a can of Seafoam in the fuel tank! The codes you post show NO problem, they are start and finish codes. Leave the electronics alone, it is probably FUEL SYSTEM related!

thanks did seafoam once, may do it again 1 or 2 times just to see. i have to get a pressure tester how much should i be looking for? but as i look into the tb at the fuel it looks like a good round cone the butterfly is wet so it doesn't really look like fuel but ? i took the tps connector off and the engine still ran but it did do a bit of stumbling for a second then it went to a bit higher rpm and stayed there. the map sensor when i pulled the connector off it quit so it must need that active to run. i know it is something but have not yet found it. that may be the reason o have it now as the previous owner could not get it and just passed it along to me!

can anyone tell me just how to get the injector out without busting it up? i took off the cover to remove it and see about cleaning it but it was stuck and i did not want to break it just to clean it. or do i need to take the top off the tb and attack it that way? maybe a youtube? thanks bp.

There is a fuel pressure regulator mounted somewhere close to or on the throttle body. It has a vacuum hose attached to i, check that hose for cracks or broken. Also try running it with it disconnected and see if it changes the way it runs, or also apply vacuum with a hand pump to the fuel regulator to see if that changes things. That early injection system is sensitive to proper fuel pressure.
Like I said it has been YEARS since I have worked with those early systems. Check all vacuum lines due to age. Rubber lines get brittle and raise havoc on driveability.

thanks for the testing procedure on the regulator. i have checked ll the vacum lines and they do look good. the only bad one is the one going to the valve cover from the air breather housing. and that has some positive pressure on it coming from the valve cover. thanks for the help on troubleshooting this. bp

I do not have my books on these anymore, but straight idle pressure should read around 35-45 psi. I do not remember how or if under load press can be read. Being so old, I hope you have replaced the fuel filter that is in the main gas line!
Also, and it is not hard to do on these antiques is to check the timing belt and timing marks on crank, intermediate shaft(for dist.) and camshaft. you could be a tooth off on any one of those sprockets, and it would still run but exhibit these same symptoms also.
You are really testing my memory on such a year ride!..LOL And where on this planet are you, asthese cars are LONG GONE from my area around Buffalo NY!

rebel59 thanks i did do a timing belt change after i got it and it is not easy to line the marks so i wonder if that might be it. i did not drive it much when i got it as it was heading into winter and i did not have plates on it. so during the winter i changed out all the belts. so this fall and winter i will take it apart and check it. this is not an easy job being the marks are on angles and align to plastic parts and bosses that are not against the crank and distributor cog and cam. but i will double check it in the next few weeks as i put them away. thanks bob p.