Keoman

iTrader: (3)

Hello.
So over the past couple of weeks I have rebuilt the top end of my L98 89 Iroc. While in the process I have encountered many fun obsticles. As of right now, the car runs, but does not run well. Long story short, I took it in to the Dealership after a lot of tinkering and checking and they were able to pin point the ECM problem as well as tell me that I have an intake leak. When carb cleaner is sprayed on the runners it reves the car. Car has a brand new ECM and lots of new parts/sensors to go with that. I'm not afraid to keep replacing parts to figure out what is wrong with my baby. I want it to run PERFECT.

Symptoms:
1) The car hunts for idle. Idle can sit steady or fluxuate depending on how my Camaro is feeling at the moment. Steady idle sits at ~600-650 RPM's (rough) and when its fluxuating, between 1900 & 1100.
2) Check engine light is on. Error codes 54, 12, 21.
3) I also just noticed after taking it for a 10 minute drive that if the car is shut off while hot, it will not start unless you feed it a little gas.


I will check and reset my TPS however I have no idea what 54 would indicate. (quad driver module? low voltages @ fuel pump? why?)

If anyone could write up or link a simple outline for how to check, pinpoint and fix Intake Manifold leaks, I would really appreciate it.
Thanks everyone

Viprklr

iTrader: (5)

Do a search on trouble codes.
As for your intake leak...just spray carb cleaner in pinpointed areas instead of a broad area. I would venture to guess that your leak is in the lower runners to the intake manifold.
Sometimes it can be a real pain to get all of those bolts tight.

Keoman

iTrader: (3)

Well as far as I can tell, the only leak was coming from the top of the runners on the passenger side. Not really sure why it's leaking. What would be the recommended torque on these things? I really don't want to strip the pleum.

eseibel67

18 ft lbs. for all runner bolts, both intake end and plenum.

Keoman

iTrader: (3)

I probably did more like 30 on em. Dont want any more leaks, I already have enough random a$$ problems as it is.

20$ to the first person that solves this..
http://www.youtube.com/watch?v=RmEUCWQTzsk

After video was shot I replaced the fuel filter, same symptoms. ECM is brand new. After video was shot, I was unable to pull codes off of the ECM.

DENN_SHAH

iTrader: (1)

are you able to date log yet?
i haven't kept up with your problem, so this maybe irrelevant.

from your other thread, the 16198259 shows to be a crossover replacement for the 165.
did you swap the PROM from your old ECM to the new one?
if the PROM is the wrong one for your car, the motor will not run right, if it even starts.
the PROM is the calibration part of the ECM and tells the ECM shat to do based on the inputs from the various sensors.
code 21 shows to be for the TPS sensor.

first thing, you'll need to do a sweep of the TPS voltage.
a scope would be the best thing to use, but you can do it with a DVOM, you'll need to slowly open the throttle while watching the reading from the test meter because of the slow update of the meter.
the voltage should rise as you open the throttle with no drop outs.
a flaky TPS can also cause idle problems.

a bad MAF sensor can also cause problems. unplug the MAF sensor and start the motor. if it runs a good bite better, you'll need to do some trouble shooting on the MAF system.
with the MAF unplugged, the ECM will be in limp home and should run the motor off tables inside the PROM.

Moe87

Taken from my Haynes manual:

Code 12 indicates the diagnostic system is working, so you can ignore that.

Code 21 is the throttle position sensor - Sticking or maladjusted, poor electrical connection, open or short in circuit, or defective TPS.

Code 54 is the mixture control solenoid - only for carb'd engines... defective pup, defective pump relay, defective oil pressure switch, poor electrical connection, open or short in circuit, or even an defective ECM

if you need any additional exerpts or diagrams from my manual (its for a bird but should work mostly...) pm me.

darbysan

I had a lot of trouble getting the runners to seal to the intake and plenum. Lots of vacuum leaks. Bought another new set of gaskets, and used a little Grey Silicon ( Sensor Safe) on both sides of the gasket.

Also, it is very easy to reverse or get one of the gaskets on wrong. If so, you will have a vacuum leak for sure ( Ask me how I know!!)

Keoman

iTrader: (3)

Datalogging works at random. I assume its a short somewhere in the harness. I did swap the MemCal ship from the old to the new. I will sweep the TPS tomorrow and see how it looks. I cant really blame the TPS yet until the computer stops PMS'n and works every time. I will do the MAF test, very good idea thank you. I will post my results.


Thanks Moe,
I wonder about that "short or open circuit" Lots of my peoblems seem to be coming about randomly so it verywell could be a short.

Keoman

iTrader: (3)

Darb,
I was able to get the intake leak fixed. At least now when you spray carb cleaner around the pleum and runners, it has no effect on the engine idle speed. Car runs better now that its fixed, but still not drivable.