Perhaps the O2 system circuit isn't performing.

I question whether the ECM is getting the O2 signal and the ECM is performing properly.
Since your symptoms are still present, perhaps verifying the circuit is necessary.

Has the new O2 made any significant change?




Edited by: bassasasin

 

Here is the latest with the car. I unpluggged injector #6 and there was very little or no RPM drop. So while I was at the junkyard SaturdayI picked up a couple injectors to try. Replaced #6 and the car ran better, idle was smoother, RPMs were up. Then yesterday I went to drive it and it ran really bad. So today switched injector #1, which was the injector I got the most RPM drop when unplugged. I moved #1 to #6 and I noticed that while on #6, the #1 injector had very little or no RPM drop. Both injectors click and vibrate as if they were working. Could this be because of a problem in the camshaft sensor, crankshaft sensoror ECM?

 

Have you done a compression check on this engine? I hope you don't have a timing chain problem or camshaft problem. Your symptoms don't quite indicate it.

As for the ECM or Camshaft sensor circuit being bad, Not so much, but you can disconnect it and see if during a cold start and warm up where the engine goes to a worse running condition changes.

You stated the ECM is pulsing OK and indicated it is changing the mix after a warm up. I believe the ECM
OK. However if the injectors are clogged or dirty they would have to
be cleaned or replaced, and they would not throw a code. I have seen injectors tested by putting them
under a strobe light to see if they spray instead of stream their
gasoline. This was quite a long time ago and now the tips are of
harder material.

If the injectors are dirty, as you seem to indicate.
It is good to note modern injectors don't wear out.. More often they just get dirty, clogged or leak at the "O" rings or possibly other places.

Richness is controlled by the length of time of the pulse from the ECM after it decides according to other sensors, not the cam sensor, a bad cam sensor or magnet missing should throw a code.

A disconnected cam sensor would throw a code but allow the engine to run and the ECM will guess on the timing for the pulse. Often it is suggested to determine Camshaft/magnet performance. At least that is what a 94' manual states. You might disconnect the cam sensor and allow throwing the code, at least to investigate.

Unplugging #6 and there's no drop indicates only that the whole cylinder has a problem. It could be injector, a compression leak, misfire, or vacuum leak effecting that cylinder. This would cause a loping engine effect, and not just a general failure as you posted.

I personally have not had to change any of my injectors but have had some discussions on them with others with problems on other engines.

A consistent bad running cylinder would have been indicated by the plugs not looking right with their color. On new plugs this may be difficult. Also during idle you would get a loping engine,

You had a very good idea to pick up the injectors. Even though the ECM appears OK, picking up another real cheap at the yard may eliminate it for a confidence check.


Edited by: bassasasin

 

I have not done a compression test on this engine yet. I did think about the the timing chain though. I have always said the engine sounds as if it were out of time.

 

You could try spraying carb cleaner or something in the intake while its running poorly to see if it helps?

 

I pulled out spark plug numbers 1,4, and 6. Didnt see anything in the way of excessive oil, strange colors or anything. Just some very light carbon on the end of the threads and electrode.

 

if you can disconnect the fuel return line and connect an other ose that would return into a gas can ,run the motor ,thae gas should fill your can in no time ,like 1 gallon in less then a minute wth the engine running.If that is not the case then a bad fuel pump is your problem.they seem to seeze if they have not been runnig for a while

 

After doing a compression check I found #6 cylinder had onlyabout 85 psi of compression, #4 had about 115psi. I checked #1 and it had about 170psi. I pulled the head off for cylinders 2-6 and found that the head appeared to be wavey. I held a straight edge steel ruler against the head surface that meets the block and found that between cylinders #4 and #6 I had a .007 in. gap between the head and steel ruler which I could slide a fellers gauge into. In other spots I had a .002 gap and in others a .007-.008 gap between the steel ruler and the head. I also noticed that the chambers of the head on cylinders #4 and #6 looked as if they had been steam cleaned. There was no carbon build up or anything in the chambers. When I checked the head for cylinder #1-5 I noticed the head was warped slightly, I found fit a .006 in.feelers gauge between the ruler and the head surface, which was right at the edge of the tolerence. I did not have the old heads checked to see ifthey was cracked, Ijust replaced them. After replacing both heads the car runs great and has ALOT of power. It's hard to hold the car under 65mph on the interstate. Thank You to all who replied to my post. If I have any further questions or problems with the car I will post again.

 

when you changed the tps, how did you adjust the voltage?


and was it between .33 and .44 mV?

 

sorry, read your last post after i posted.


glad to see its running good.