What a thing to win huh First I want to thank everyone for the help so far. Unfortunately, it still isnt running. Ive taken my other 30 page thread and made a consolidation in hopes someone could help figure it out.

The Car

1) 1989 Camaro Iroc - Owned 3 Years
2) 5.7 - Motor was completely rebuilt professionally before I purchased. Now has 36k on it and has ALWAYS fired and ran on first turn of the motor.
3) Automatic

Past Issues

1) Although the car has always started on the first turn of the engine, it will not start if while it is running, you shut it off and then IMMEDIATELY try to restart it. The motor turns like new and has spark, but will not fire or start. If left to sit for 60 seconds, it starts immediately.

2) Twice when first bought and after 4 hour drives, the car was shut off for fuel. When restarted it immediately shut off. Each time it started on the first turn, but died as if the key was shut off. Both times I was able to gt it running after maybe 40 starts and throttle feathering. Once started it showed no additional signs of malfunction. Has not happened since.

3) The car has always seemed to have a slight miss and slight yhesitation when the throttle is cracked quick. It has stalled a few times when coming to a stop.

Present Issue

1) Without warning the car started with an idle miss and ran as if 2 or 3 plugs were removed. A hard shutter as if sputtering without gas or the quick chug of a stick shift that had the clutch released with no gas. I nursed it home and it sat for 2 hours. Car started and ran as though nothing happened. It occured one time the following week. The next couple of days, it happened again, but did not recover.

Repairs and Tests

1) EGR, EGR Temp Switch Sensor, Coil and Sensor in plenum (underneath) After this step I began having start issues to where it would only start consistantly when cold. Severe miss is back within 2 minutes. New coil was removed and tested to in order to eliminate factory failure.

2) Distributor cap, Rotor Button and Pick Up Coil. Ignition module was taken to Autozone and tested repeatedly as good even when hot.

3) Plugs and Wires

4) Fuel Filter and Air Filters replaced.

5) Fuel Pressure tested and showed 43lbs with key in start position, 39 lbs at idle and held 41 lbs after shut off for 30 minutes.

6) Injector harness tested at 1.4-1.7 accept for No. 8 plug at 2.5

7) Battery and Alternator tested good.

8) IAC cleaned and replaced.

9) Coolant sensor disconnected per forum member to check ecm ability to throw a light - good. Car ran no differently.

10) Pink wire from coil to distributor only showing 10v while engine is turning over.

Others

1) Forum member mentioned Testing MAP - Did not understand directions

2) Forum member mentioned distributor should have magnetism. I could tell that it had some, but do not know what "good" level is.

At this point, I dont have the money to take it to a shop, but need the car. Greatly appreciate any information/help that you guys and gals can provide.

Thanks
Bob

 

that 2.5 on the # 8 injector isn't good... will it cause problems... might, yours a very slight possibility...

did you actually replace the Coolant temp sensor? or just unplug it? what i was trying to convey was that if the car is chugging and sputtering/barely idling and you unplug the CTS it should stall if the CTS was functioning properly... if it wasnt however i would expect to see very little change in the idle... you could also ohm out the wires from the CTS to the ecm make sure there isnt any thing funky there...

i should also mention that almost every sensor in these cars are designed to fail in a "safe" manner... either the ECM picks up the failure and overly corrects for it... limp mode. or the sensor fails in a manner that forces the ecm to dump lots of fuel...

when the engine is rough what does the exhaust smell like... will it make your eyes water?

 

Spitot, I had actually just unplugged the sensor the first time. What I did today, based on your last post was to unplug the sensor once the car was running rough. It did not stall. It appears that it didnt even change the way the car was acting. Now that was only after maybe 4 minutes of running, but long enough to be running poorly. As for the smell, it is a little rich, but I have a very poor sense of smell. There have been a few times that it has smelled very rich and the wife has mentioned it quite a bit. Ok, I went and got the wife to smell it. In comparison to our other 3 cars she said on a scale of 1-10 its about an 8. Youre not online so Im going to go get a sensor while I wait for replies.

 

Sensor is in and nothing has changed in the idle or running of the car.

 

Ohm each individual injector. If you have a low one or more that is your problem. Replace it or them.

 

1989, I have ohmed each injector connection. Do you mean the actual injector and if so, can you tell me how and what readings I should be looking for. I know its something simple stopping the motor from running at its best. Ive been hoping fuel pump, injectors, basically anything expensive and difficult wasnt it!

 

are the injectors leaking causing it to run rich, flooding the engine, and fouling the plugs? Even if with new plugs, it wouldnt take long for them to start fouling out again. Just a thought. Hope it helps.

 

The injectors do not seem to be leaking. The plugs that I just replaced were 3 years old (Bosch with the double prong). They looked good and clean.

 

Well, I was out of town again and hoping to have some input on this car. Unfortunately nothing Can anyone help me on how to check (if there is a way) the injectors. Thanks. I dont have a garage and have to get this thing on the street before it turns cold. Bob

 

honestly it sounds like you need a pro. Personally I would make an appointment with a GM dealer or a GREAT shop that works on F bodies. Have the entire motor put on the computer and go from there. The computer will read everything and will dignose the problem. Even some shops like my GM dealer will pout it on the dyno and check it that way. The price depends on the dealership (mine is 40 bucks but that is pretty cheap for diagnostics)

GOOD LUCK!! I'm pulling for ya.

 

Damn Ryan, why couldnt you be in Cincy! Ok all, I think I found the issue. Reading some other threads, I found how to check the injectors. The forum member stated that the injectors should read 14-16 ohms between the spades. I have 4 at 16, a 15, 14, 13 and the No. 8 plug that was showing funny ohms at the harness is also showing 1.8 ohms at the injector. This would definitely seem like a problem to me. Can anyone explain what the problem is, why it would happen and what it is doing to the car in real terms. Im an engineer in my thought processes and have real issues wrapping my hands around something I dont understand. Thanks

 

whats your fuel pressure at.. sounds to me its a fuel issue not a ignition issue

kinda had the same problem a few years ago. i replaced everything . pulled code after code. it was the pump

 

Yup, that could be the problem!

 

might sound silly but have you checked your oil pressure sending unit.( different problem than from above) i replaced everything including fuel pump again.. sender went bad putting car into limp mode... making the fuel pump come on initially to pressureize the lines but then the pressure would fall of steadily. Somedays it worked fine,mostly when I didnt need it. dont know if it helps but i feel for you. i spenta fortune replacing things

 

no it's a tpi it has 8 injectors

 

Does this thing have a Mass Air Flow sensor??

 

Seeing as his car is an 89 Iroc. I would guess so.

 

The computer wont diagnose anything, it will take a good tech to do that. I wouldnt doubt a MAF problem or one of a dozen other issues. A good tech, with or without a scantool, should be able to fix this problem easy.

 

With your start/stall issue once warm I would look towards the MAF. Try unplugging it when it stalls and dies then try it. It should default to a predetermined set of parameters and run without it.

 

The ECM does not have an oil pressure sender. That is only for the dash gauge.

 

I agree however, the oil pressure switch is actually what sends power to the fuel pump after the inital turn of the key. I had a similar problem with my tbi blazer and found that the oil pressure sender/switch was not supplying sufficient power to the fuel pump causing the car to run poorly. I fought this problem for a month. My suggestion is check the voltage to the fuel pump when it idles rough; if its low there is a good change this switch is bad. Good Luck

 

That is only if the fuel pump relay has also failed, at least on our cars.

The oil pressure switch is in parallel with the fuel pump relay. If the relay is operating correctly the switch wont have any effect.

 

the reason you have ohmed the injectors is obviously to check resistance across the injectors... the injectors are constantly supplied with 12 volts... the ECM shorts the batch to ground causing the injectors to fire...now the out of spec ohms will overload/overheat the injector drivers causing them to shut down/burn up... might be something to look at if you get desperate...
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right the switch wont have any affect but it will still be closed and the failure of the FP relay would be seamless

 

Can someone tell me where to find the oil sender and the fuel pump relay. Id much rather check the easy cheaper parts before pulling the fuel injectors out of it. Course at the ohms, I guess they are still bad huh? Spitot, you mentioned checking the drivers. Any details on that one too? Thanks

 

The injector drivers are large power transistors inside the ECM. If they are bad, you need a new ecm. They are solid state and have thermal protection, so you should be good.

 

'atom

Fuel Pump relay usually can be found on the firewall next to the brake booster. There should be a couple relays next to each other (AC, FP)

Injector drivers are actually internal to ECM - these are high current integrated circuits (IC's). Unless you have ECM test bench and a bench full of test equipment injector driver performance verification is not readily possible. Instead, you can measure coil resistance of each injector individually with a DVM - typical TPI GM injector should have coil resistance 13 to 16 Ohms.

//RF

 

the oil pressure sending unit is also located on the Drivers side just above the oil filter... sticks out of the block horizantally about 4in...

 

I hate to say this after your laundry list of things that you have done, but you might want to consider changing out you fuel pump,,, and heres why;
1. its a 20 year old electric part
2. it will smell rich because its not spraying thru the injectors its just drizzleing.
3. the car will chug and run if you feather it but will lean pop if you give it throttle
4 your car is already down and not driveable.
5.the most important... your in ohio and the weather isnt going to get any better.

 

I have the same problem runs fine till warm, shut off for 10-15 minutes, come back, it will start, but no power. In my case 90 spd density 305 tpi, I have just checked fuel pressure, which is constant. Does'nt split atom need to check fuel pressure, cold, warm then cold again? And if it is constant, it eliminates fuel as the prob.