Lumina Euro 3.1 with Error Code 22 Hesitation surging

[luminacrazy]

Hello,

I have a 1990 Lumina 3.1 Euro with 338,000 miles that was still running a little rough after replacing a shorted fuel injector but I kept driving it that way because of the high cost of fuel injectors. All the fuel injectors had a normal Ohm range accept for the one that was shorted out and I replaced.
I was too cheap to replace all the injectors because they cost $100 each and I did not own the equipment to test them on a bench. Plus they were all in the normal Ohm range. I have since found a cheaper source for new injectors and a place that exchanges fuel injectors. The remaining 5 injectors also have approximately 170,000 on them and looking back at my service records I found that was about the amount of mileage I got out of the original injectors before having them replaced by the dealer.

Adding to the problem is that recently the check engine light came on indicating a code 22, low voltage on the TPS.

The car started surging while ideling and stalling when moving from park. I then immediately replaced the TPS and the error code 22 came back after resetting it. I have the shop manual and it indicates that the car possibly has a bad ECM or an open circuit, or shorted circuit. I then replaced the ECM and the error code came back. I disconnected the two wiring harnessess and plugged them back together and the car ran well for a day. There is no visible breaks or damage to the wiring harness other than age and high milage.


Now I don’t know if I should try finding a bad ECM ground wire or replace the fuel injectors, and or the temperature sensor. I checked the wiring going from the TPS sensor at the wiring harness plug and I was able to get a test light to work in that segment of the harness.

The car has newer ignition wires, coils (3), spark plugs, TPS, alternator, battery, fuel pump with filter and fuel pump screen and crank sensor and am familiar with the symptoms those components cause and it is not the problem. The fule pressure was in the normal range when tested before replaceing the shorted fuel injector.

I also think I have a leaking fuel injector because the exhaust smells very rich but could leaking fuel injectors cause the code 22 to be set?, or should I be looking for a shorted or open circuit it the wiring? The engine runs with an abnormally high idle and stalls out when starting out. It does run a little better after getting underway for a few minutes or more.
I have the shop manual but have no idea where the ECM ground and other grounds are located?

A mechanic said that there is an adjustment on the TPS sensor but the shop manual does not indicate any way to adjust the TPS sensor, and I think he is incorrect.

Any ideas on what would be the next logical step to take?

[maxwedge]

Get a scanner on it and look at the tps inputs to start with.

[richtazz]

If the mounting screw holes on the replacement TPS are slotted, than it needs to be adjusted. If they are round, it's does not. If memory serves me correctly, if it is adjsutable, it needs to be set so it's outputting .04 volts at idle and 4.5 at WOT. The change in reading should be smooth and linear through it's range of motion, with no gaps or sudden leaps.

[luminacrazy]

Thanks for the replies. I guess I am a bit hurting now because I never was much of an electonics tech but this old mule is trying to learn how to adapt to technology The holes on the TPS sensor are not slotted so I assume there is no adjustment, plus the shop manuel does not mention an adjustment on the TPS.

In the early 1990's I sold the big BEAR engine analyers. I could sure use one now, I think but I understand it has limits with a pre 1996 vehicle.

Anyway I guess I can check the TPS voltage using a standard clamp voltage meter/amp meter by clamping the meter's jaw around the wire lead coming from the TPS meter. If the voltage is low at the TPS then where do I check for the open circuit or poor ground at the wires coming from the ECM. Replacing the ECM did nothing? On a pre 1996 vehicle is it really worth checking it on a engine machine. I know its not the fuel pressure, ignition wires, coils or spark plugs and you cannot test the individual fuel injectors on a engine analyser without removing the intake manafold. Also the spark control unit under the coils was bench tested to be good at a local auto parts store. Plus the crank sensor was replaced a few years ago after the engine died suddenly and would not restart.