So i have an 87 iroc z.
It has the 5.7 tpi motor.

Lately Ive noticed its been acting strange.

So upon start up, everything seems normal. (smokes like a !$*$!)

After cruising for about 15 minutes it started to idle funny (fluctuates). Its been doing this for a bit now, but i suspect thats due to not ever setting "Minimum Air" on the IAC valve after replacing it.

Its Always had a slight misfire when warm, but it has a new cap, rotor, pickup, and ignition control module. So those arent the issue.

I was driving it home this afternoon, and it suddenly dropped in idle to a shaky lope.
I hit the gas and it kept studdering and felt boggy.
let of the gas, and the idle went very low again.
I then limped it home, and when i pulled in, it stalled in Drive.

I read 4 codes.
13, 36, 33, 43

THINGS I TESTED:

1. Ignition coil. 2 out of 3 of the tests i did read normal Ohms.

But when i tried to read resistance from the secondary coil to ground, it read nothing...(manual says it should read infinite)

Could this be the issue?

2. TPS. I read the voltage on the TPS and its set at .58 volts.

I then pushed the tang down on the sensor to see if it lost voltage at any point.

It rose steady up through a little over 3 volts as i cycled through the travel on the tang.

but weird thing is, when i reached the bottom of the TPS travel, it suddenly read No voltage. Is this a sign? or is it normal.

3. MAF. I pulled it out, and it looked fairly clean, however i dont know how to test it (if you can)


Does anyone know how you can test the ESC module and the knock sensor?

ANYWAY, id like to see what you'all think.


any input is much appreciated!
THANKS

 

Did you ohm check your injectors? They are known to short out and cause idle problems when warm. Mine is doing a loping idle when warm too.

 

Thats a good idea. Makes sense too.

Ill have to try that.

Any other ideas?

 

MAF sensor is a definite possibility. My 87 IROC was acting similar not long ago. Replaced MAF sensor and it runs like a dream.