LT1 modified mani with HEI up top where God intended, and a 52mm Tbody, I posted about operational problems here before but can't find the thread......

I finally got some 24 lbs injectors, and fired it up and for a day or so, I thought it was done, just some fine tuning....but today was the worst.....engine at 'idle' revs up and down the scale , tough to drive, but at least the engine is smooth when it runs, when I first drove it a couple daze ago I thought 90% of the issues were solved, and damn injectors were finally a match for the car....

BUT over the last couple daze the thing is totally unstable, and the 4 speed density computer, 1227730's have been through the damut, swapping TWO chips sets and the computers around, and finding basically same issue with all of them.....

Scanner says requested idle at ~700 rpm.....L98 cam L98 heads......but it's so unstable there, the engine dies when pulled into drive gear, and if I try curing that issue it revs up and down like KRAZY.....

SO I pull the idle air motor connection....no real change, pull the MAP sensor connector, no real change....Pinch ALL the air hoses nothing changes......idle revving 1500 down to stall speed.....

played with idle set speed on throttle body to no avail.....

anyone?? thanks guyz......

 

Vacuum leak? If it's hunting that bad I'd say that. What do your fuel trims look like?

 

I dunno about what 'fuel trims' look like on the ancient scanner I have.....maybe if I had some numbers I could look for something similar??

 

I agree, what is jumping around? Are the IAC counts going with he RPMS? Are the fuel trims bouncing around? Is it seeing knock coutns? Fuel Pressure jumping around drastically? It will obviously move some because of the manifold pressure change, but is it dropping below 30psi when it is trying to stall?

 

Nah, 30 psi is pretty steady......when engine is warm, say 200f what would be a normal IAC for this sytem???

no knocks FP is steady IAC motor is new, and does change with throttle position....but the question is with the idle count when cold, and again when hot/warm......what should the scanner read???


thanks guyz, once again.....


GENE

 

IAC should read high teens low 20's at idle

 

I assume this at full temp.....180+ ??

 

I believe so.