okay so for the past many months i have been googling what my idle problem could be.
i have a 1991 zx NA

so my problem is, the engine idles ruff somwhere around 700-800 rpms as normal and doesnt serge or anything. but it seams to get a bit worse if not any better when warm. when we first got it, it seemed like it wanted to die but never did. it has gotten better over time. especially after a tune up.

out of all my searching ive come to the conclusion that its probably my injectors. the whole ethanol thing. i have not ohm tested the injectors yet but the coils check out good (says my mechanic)

now i can only feel it running ruff at idle and when driving it drives fine. but i wouldnt know for sure since ive never felt what "normal" is. the severity of the ruff idle is hit or miss. it has its good days and its bad. but never perfect.

could it be the idle air control valve? also? what would the symptoms of one being dirty or bad?

i would like to eliminate the smaller less expensive possibilities first. before i replace all the injectors.

any advice would be awesome.

 

Did you ever solve your issue? These cars are notorious for vacuum leaks so I would check all your hoses and connections. Those things are probably getting brittle after all these years. Another recommendation is to check all your electrical connections because those are probably getting oxidized and making weak connections.

 

A Star Grounding System is what you need, it just basically ties all your grounds together with a common wire, not using the frame or sheet metal, which is by far an inferior electrical connection. Run a wire from your battery neg to a common place, a copper block on the firewall perhaps. Run a ground to your intake /plenum, another to the ECU. you want to tie everything together. That is at least the 1st step in making sure your car has a solid electrical system.

 

Crx, No I have not, I'll check my Vacuum hoses. Where's a good place to start? Any certain hoses commonly fail. The only vacuum hoses I can think of are for the auto trans. And brake booster. Any other vac. Hoses.

I should also mention it only has 100,000 miles. But I was also told it sat around for quite some time. I assume out side. But the paint is still good.

Awesome predator I will do that. Wouldnt hurt for sure. I work mostly on old classic vehicles, its amazing how so many problems have been fixed simply by finding a good ground.

Any other ideas out there? Any thoughts on the iacv being the probkem?