travis_henry

I have a 89 Iroc l98 motor and i just bought edelbrock performer heads 2.02 int 1.60 exhedelbrock TPI high flow intake scorpion 1.6 roller rockers comp cam .495 int lift .502 exh lift 110 lobe sep, all roller cam. i got new injectors and everything. hydro cam by the way. Ok the motor runs awsome while holding the throttle open a little but it wont idle for crap. all the sensors are plugged in and new tps and idle air. i drove it around the block and it has crazy power but it wont idle for crap. Im at aloss any help please

John 89 Formula

check for vaccuum leaks
check the voltage at the new tps, should be 0.54 volts closed and should increase to 4.0 volts as you open the throttle.

travis_henry

ok thanks for the info. so just curious is the cam i put in it to big for the computer?

White'89

iTrader: (8)

TUNE.

giszo

White'89 is right. You have to tune the ECM according to the new engine specifications.

travis_henry

thanks for the reply but i got it tuned yesterday.

mlynch001

Any Trouble codes or "check engine "light?

Is the IAS Motor working (yes, I realize it is "new"), that does not mean it is working? TPS voltage should be .54 V closed and around 5V @ WOT. Did you set your minimum idle speed?

Check the manifold vacuum, if your manifold vacuum is low (under 12-14") at idle, your ECM will not be able to compensate.

You also have replaced the injectors, did you go stock size or larger? Large injectors and low vacuum will cause all kinds of problems.

Is your fuel pressure set to stock levels or higher than stock?

Are you running the stock MAF System or a later Speed Density system?

Is the camshaft a "computer" type cam? Or something else. That is a lot of cam for a stock ECU to deal with. Don't get me wrong, that is not a HUGE cam, but it takes very little in the cam department before it starts causing problems.

badmoon47

The 110 LSA on your new cam probably has alot more overlap than stock which causes low idle vacuum. The low idle vacuum causes the ECM to think you are under a load at idle and is probably dumping fuel into your engine thus bogging it down at idle. If you have access to a laptop with datalogging capability, you should be able to see the problem fairly quickly.

z28 TPI

I almost have the same thing. Not to hijack but im interested to see what the solution is. My cam is a little different its a little lower on the lift but almost the same specs. The vacuum is low about 12". The only question I have is how do you tune the ecm but its best left to a different forum all together.

dspencer24

iTrader: (3)

weelllll how does it run

badmoon47

At 12" at idle you are probably running VERY rich with a stock tune. You can either take it somewhere to have it tuned or learn to do it yourself. My engine pulls 14" at idle and had the same problems. I gave up having other people tune it "over the phone" and started burning chips myself. Got everything I needed from MoatesEFI for around $100. Turned out to be a great investment.

86T/A_Ram_Air

what kind of tune did you get? no offense but if your got a good tune you wouldn't have this problem

z28 TPI

Thanks badmoon47 I'm leaning more towards tuning myself since its 85 I'm gonna change to a higher baud rate ecm and go tuning. Thans for the advise.