I havea 1988 IROC-Z that originally had a 305 but we put a 350 in, and we've had the 350 in for about a year now, and it has a really hard problem idling and staying started. We put in a JET performance chip, and we also had 26lb injectors put in it, i really havent done a whole lot to it, except for cold air and headers. When i cross the A and B pins on the ALDL connector, it idles fine at about 1200 rpm but smoke comes out the exhaust, and my dad said it looks more black, indicating rich, than anything else. I was just wondering what could be the problem. Also i pulled the IAC valve out and it looked pretty sooty and so i am gonna clean it and see if that helps, but is it possible I put too big of injectors in? thanks for any help.

 

Welcome to thirdgen.org, and Happy New Year...

My guess is you have too much injector...stock injectors for the L98 (350 setup) were 22lb/hr.

What makes you think you need 26lb/hr injectors?

If I were you, I'd install the 305 injectors (19 lb/hr) along with an adjustable fuel regulator and set the pressure around 45 psi (vacuum line to regulator discinnected).

Should give you a baseline to start.

You can make the 26lb injectors work, but you'll most definitely need to get into the DIY-PROM board and burn your own chips.

Which brings up another point, you'll prbably wnat to lose the Jet Chip, and start with the original one from the 305.

And before you ask ....the cal tables in the EPROM (stock or Jet)will only compensate for so much...the ECM is probably trying to shorten the injector pulse width as low as possible, yet due to the big injectors you have, it's not enough.

Stick around the boards, use the "search" function, you'll find a ton of info..anyything you don't understand will be explained probably more in depth then you want to know

One more thing...you may be able to mask some of the "richness" by increasing/advancing the base timing...remember to unplug the EST bypass when setting base timing.

 

I thought it had 26lb. but i looked at them today and turns out they are 24lb. are 24 still too big? thanks

 

We got it to idle long enough earlier today and we got a error code form the computer, and it turns out the MAF is bad, so I replaced it and it runs a whole lot better, thanks for the advice though, thanks. And by the way, this is one of my favorite thirdgeneration websites