nakota2k

So the rpm and oil pressure will drop then spike in sync multiple times until the motor eventually dies. Once I turn off and restart it runs like a dream again. Happens once a day or every other.

89' Iroc 5.7 350. 36k Original miles

When the motor dies I just restart it and its back to normal. I have had intermittent check engine lights usually around the time this oil pressure spikes and drops but it only lasts a minute or so and always goes away after I restart the motor. The car is all original. I have changed the air filter, but as for all the wires and what not Im not sure. I have had the car for a month. Owner said it was bone stock minus the stereo. The problem happens mostly after I accelerate hard, and only some times if I drive like a grandma.

camaronewbie

Oil pressure is related to RPMs - higher rpms means oil pump pumping faster means higher oil pressure. If oil pressure remains the same when RPM's increase, then you have a problem.

Now - your REAL problem - we need more info on what's happening - a gazillionj things can make engine idle low and die. Need to know:

Year
Motor (305, 350, 2.8, 3.1)
TPI, TBI, or carbed?
Tranny (auto or 5 speed)
Any mods?

Specific happenings when it dies.

Have you changed plugs? rotor? cap? wires? fuel filter? air filter?
Any SES light? What are the codes? Pull them for us.

etc etc etc - we need info!

nakota2k

.

camaronewbie

OK - pull the codes from the ECM - grab a paperclip and read this: https://www.thirdgen.org/service-eng...ht-error-codes

Then, write them down. Then, clear the codes by disconnecting a battery cable for 5 minutes (smoke break!) Then, drive the car another day - see if it continues. Then puill codes again, and write those down. Anything not showing on the second code test ignore, and see if that leads you anywhere.

If I were you, I'd change plugs, rotor, cap, wires, and definitely fuel filter as soon as I had a day off. No telling when (or if) last owner ever did any of this, given that it only has 36k miles on it.

Let us know what you find out after that.

nakota2k

Ok that paper clip thing is genius. I got 34 three times

34. Low voltage (high vacuum) at mass air flow sensor (or MAP sensor)

can I fix this myself?

nakota2k

Ok so I found the MAF sensor and took it out. It looks practically brand new. The wires look fine too as far as I can tell.

Update: I tried tapping on it while the motor was idling and it didnt do anything.

ASE doc

Code 34 "Low air flow indicated" also means low signal voltage. This is a case where a scan tool is generally used in diagnosis. However, since we're looking at MAF sensor signal voltage, a DVOM could be used. We want to see what the MAF signal is doing when this problem occurs. A scan tool is good here because it shows us what the ECM is actually seeing in case it's an internal ECM fault.

Check wiring to the MAF sensor. Since this problem is intermittent, we want to look for any loose connector terminals or damaged wiring. Use the DVOM to verify 12v on the red power circuit to pin E and less than .5 v on the ground circuits at pins A & B. Measure signal voltage at pin C. It should be about .5v with key on engine off, 1.4v at idle, and 4.5v at full throttle.

Any leaks in the air duct between the MAF sensor and the thottle body will cause this code. An unstable or low idle will cause this code. Verify there are no intake air leaks(vacuum leaks). Verify that the PCV system is all properly connected and working correctly. Verify that the air filters are clean and unrestricted.

nakota2k

I dont have a scan tool or DVOM. I may be able to get my hands on a multimeter, if that would suffice. Do you know where I can find a wiring diagram that tells me what the pins are labeled as? Thanks for the help.

camaronewbie

DVOM is a multimeter - Digital Volt Ohm Meter - you just want a digital one rather than an older analog one - because your looking for tenths and hundreths of volts.

If you have a Harbor Freight close by, they sell for about $5 with battery ready to go!

nakota2k

This is what I checked so far. What else can I check with my multimeter? Also I ran the motor with the MAF unplugged and popped a 33 and 34 code. According to the last picture I have a bad MAF sensor. Please let me know what you think before I go drop $150 on a new one.

ASE doc

Sounds like you found your culprit. The 5v on terminal "C" is referrence voltage across the diagnostic resistor. it's how the ECM knows the circuit is open. 13.5 at idle on terminal "E" is battery voltage as it should be. The flow chart is over simplified but generally fool proof.