I have an 89 IROC with a 350TPI. the car starts up fine, but the as it is driven, the oil pressure begins to drop. As it does, the car starts to idle erratically, sometimes causing it to stall. There is a slight hesitation at times. It is only present when the engine is heated. The timing is at 0. I have cleaned the air box. Replaced the IAC, TPS, and oxygen sensor, checked the vacuum on the egr valve, and checked the volts going to the MAF sensor. Everything seems to be normal. The engine light comes on one day and is off the next. Does anyone know what the problem could be?

 

Anyone? Please help!!!:lala: :lala: :lala:

 

Base timing on a 350 TPI is 6*, not 0.

 

thanks for telling me that, but right now, if the timing were to be brought up, i think that the problem could worsen. also, i do not think the timing would bring about a check light. does anyone know if the burn-off circuit could be the cause of this?

 

My original motor did that same thing w/ the oil pressure. Ok pres when cold, almost zero when warm. It turns out that the block was cracked and antifreeze was seeping into the oil through a crack in the lifter valley. I think that the oil/water combination got real thin when warm, which caused the pressure to drop. I don't mean to scare you but there is a good possibilty that you have a cracked block if you own a 87-89 Chevy Small block. I've owed 2... I've had 2 crack. 87-89 were thin walled castings that were very proned to cracking. Check your oil and look for milky colored oil. If it is a light brown color your in trouble.

I also had the rough running problems at the same time but I don't think that they were related. I had a bad alternator/battery and the voltage got to low for the Fuel injection. Try to bring up your timming. It definitly could be the problem.

 

Your oil pressure sender could be leaking. My 92 did the same thing, high when cold, low when warm, gauge showed 0 at idle. I noticed the sender all wet when doing an oil change one day and the problem went away. Actually, the stupid thing is leaking again. Oh well, it lasted a year!!!

 

thanks for all of your replies i will bump up the timing back to 6 before i begin any repairs. However, the car won't be drivable at 6 degrees because it will show its messed up traits and probably stall on me more. Does anybody have an answer for the burn-off circuit question?

 

Actually advancing the timing to 6 degrees BTDC will make it idle HIGHER.......this may be part of the problem in itself.

As for the oil pressure gauge.....what does it drop too?

First the simple, check the oil level.....is it full? Is the color like a chocolate milkshake or is it normal?

What weight oil are you using?

My engine has good oil pressure, but when warm at idle, the factory gauge shows @15psi at 650 RPM in drive.

I put a mechanical test gauge on it awhile back, and ACTUAL pressure was 25psi at 650 RPM when warm, in gear. That's plenty for a small block Chevy. Rule of thumb is 10 psi of every 1000 RPM.


HTH

 

My advice would be that if the car ran OK before, then don't play with the timing right now. Address that AFTER you fix the problem at hand. As far as the burn off circuit goes, I don't see how it could affect the syptoms you are describing (mainly the oil pressure issue). Give what you have told us to go on, I would recommend checking out the potential problematic areas suggested by the others already. There is really no sense in posting on a board asking for help if you are not going to consider the advice that is offered.

 

when i start the car, the gauge reads 60 (i asked a mechanic about that before while getting smogged and he told me not to worry, "the higher, the better" i was a little doubtful of his reply because when the car was well, it had been around 30) but as the car begins to run for about 10 minutes, it drops between 52-54, sometimes even in the 40's, i suppose it depends on the weather, but that is when the idling goes bad. the oil level is at the full line and somewhat a dark brown color (it's been about 2 months since the last change), but not at all milky. the oil i use is sae 20w 50.

i did not mention before that this had all started after the smog check. the headers fried the wires that control the egr valve... the dis wires(?) (i cannot think of what they are called at the moment... located on the right side of engine near spark plug wires) and the mechanics replaced those. they also adjusted the timing to be 0, saying that it was retard 10. i went back there to have them retake a look at it, but they were grasping at straws. their computer could tell them nothing. they said it could possibly be the ecm.

rockind78, i am offended at the fact you assume i did not/will not "consider the advice that is offered." i am describing all of the symptoms i have found, whether or not they are relevant to the problem at hand. i am doing everything i can possible. i've managed to fix every single problem up until now. if you do not have any useful information to contribute to me, please don't reply with any useless criticism, as it does not help me, nor my camaro.

 

You said the check engine light comes on and goes off. Have you been able to pull any codes? What is the condition of the plugs, wires, cap, rotor? Was all the wiring you mentioned that was damaged thoroughly? I am sure you are aware, but drivablity problems can be difficult to diagnose through speculation. If you do get any codes it may be worth you time to get your hands of a factory flow chart to pin down a problem. Just my thoughts.

 

1) Read things carefully before you respond...it helps everyone. I offered advice which I thought would be helpful. Whether or not you think so is YOUR call...not mine

2) My response wasn't meant to offend you, but when you don't acknowledge the first two or three posts to your thread, I have to assume you aren't taking their advice seriously.

Have a drink and relax a little.