Well, Tuesday I got my '87 i-rocz with a 305 in it, about 78K on it. Car looks in great condition, but I already got a problem.

When stopped at a light, the car's idle is around 500-600 rpm's, and then it will like jerk down. One time when I was sitting at a light today it actually stalled out Other than this issue, the car seems to run fine.

I put in some fuel injector cleaner thinking it was a clogged injector, but I don't think that is the case. I'm thinking it might be a timing issue since the car seems fine otherwise, but I'm extremely new to cars so if you guys could help lead me in the right direction and give me some ideas/advice, I'd really appreciate it.

Thanks in advance, and thanks for welcoming me to the community.

 

Welcome, and congrats on the new car

I'll pass this over to 3rd gen for you.

 

well first thing to do is eliminate the obvious

plugs, wires and maybe distributer and run some seafoam through it to clean the engine out.

maybe check your idle screw, someone could have messed with it.

 

Your idle seems about right for it when in gear. You say it seems to "jerk" down the idle. I'd investigate the obvious like teke said. Plugs and wires, distributor cap and rotor, then I would look to the oxygen sensor and finally at the Idle Air Control (IAC) valve which is located on the throttlebody underside. I know that when mine went out on me I had a hell of a time getting the car to stay running. But I had a combination of O2 sensor and IAC problems... $70 took care of it and a burned knuckle or 2.

 

Excuse me if this is a stupid question, but is the 305 form the Iroc-Z of that year carbureted? If it is, then why not just adjust the idle screw?

 

^There was two versions; the TPI (which it seems he has) and the Carb'd version.

 

True, I didn't catch the part where it siad he thuogh he may hve dirty injectors or that he put fuel injector cleaner in. Sorry about that.

 

His is tpi, when its idling, the rpms fluctuate up and down a few hundred rpms and once, it got too low and stalled out.

 

Sorry, forgot to say, it is TPI. I did take phenomic for a ride yesterday in it, so you can listen to his diagnosis, it's porbably better than mine. I also forgot to mention before we got it, the previous owner did just replace all of the spark plugs, and wires look new. Also, I talked to the previous owner, he said that he did replace the timing chain last year; so my guess this is probably a timing issue. We are bringing it over to him this evening so he can re-time it. We'll see what happens, I'll let you guys know. I really appreicate all of the feedback so far, thanks a lot guys.

 

Oh nothing to be sorry about; I was very confused on if he was reffering to a TPI or Carb'd motor, lol. I was aiming for TPI the way he was talking though

 

Ugh... Well; we took it over there that evening for the guy to look at it. He didn't time it, but I still think it needs to be timed. He adjusted the throttle so it idles higher, so its not stalling out but its still jerking a little bit...

I also replaced the PCV as the spring seemed a little funky in it, and I just replaced the battery today becasue he never did when he owned it.

I think it still needs to be timed...I don't know really what I'm going to do now...sorta in a dead lock.

 

Update:

Just ran some seafoam through and cleaned the intake with some intake cleaner; got a look of **** out. Now it seems like its not doing the jerking as "violently", but it is still doing it to some degree, which is noticeable.