JerryAtrick

1990 C4 Coupe L98 bought new,now 43K miles : Having STD easy mods, Chip, K&N, Stainless Headers, TB air foil, stainless exhaust.

I replaced the old injectors with ACC-180830 from Summit. Double checked everything then started it up. It started quickly BUT was idling at 4000 rpm (yup 4K not 400). I shut it down and tried 3 more times but same problem. I will be checking the SES indicator and note any codes later today. I am trying to get a jump on the problem by posting this now.
I have searched the forum's for some idea as to the problem:
1) could be a vaccum leak. Hose or connector open. Is this probable?

2) IAC - malfunctioning or not connected properly. Some indication in some posts the IAC solenoid can stick when laying plenum down? Can the IAC cause extremely high idle?

3) Life hates me - naw...
If anyone has seen this type of problem, I'd appreciate the input.

Jerry

383vett

Iac malfunction will not cause that idle. Sounds like a huge vacuum leak. Did you plug in the large vacuum hose that goes to the brake booster?

PatternDayTrader

Something is not connected properly.

Eljay

I think you can get shots for your STD

PatternDayTrader

Lol ... I wasn't going to be the one who said it ... lol.

aklim

I'd sell the chip and the air foil on Craigslist or Ebay. List it as a high performance mod and someone will help you recoup your money. Not sure about the headers and if they are shorty headers, probably not worth much gain.

Got a link to that injector? What size is it?

Not that high.

Virgin sacrifice might help?

aklim

Not all can be cured by a shot.

JerryAtrick

4 Tequilas GTG

JrRifleCoach

Well Jerry, first thing is to make one change at a time.
So pull the chip and make sure the airfoil isn't causing the TB plate to hang open.
And this time look for any hoses or connections that may be loose or cracked from handling.

Good Luck

C6_Racer_X

Sounds like the throttle plate is hung open.

Either that or there's a huge vacuum leak. Even the brake booster hose will only run the idle up to 2500 RPM or maybe 3K on most engines. Listen for the huge sucking sound.

And get that STD checked out and treated.

JerryAtrick

Thx for the reply. From the reply's it sounds like a vaccum leak. All the other parts were on the car for 10 years - only changed out injectors and this is result. I will break it down and double check everything looking for that leak.

JerryAtrick

Thx for reply. Vacuum leak seems the consensus Thought I assembled it fine, but seems I missed something. BTW, The STD is fine, but my AIDS is flaring up now......

JerryAtrick

Dude, I think its puff puff PASS time. I'm not selling anything, I was looking for support....

But hey, if your interested, these are my headers,lol

https://www.lmperformance.com/69612/...nd-y-pipe.html

aklim

The off the shelf chips do not do much. People who have taken the program apart found that the fan temperature was set lower which can get "up to" 20HP or whatever they claim. I doubt that you will see much of anything with the airfoil hence the suggestion to sell both and maybe get a tune that is going to net something you can see on the dyno sheet. Now why keep the chip and the airfoil, not sure. Me, I'd sell it to get rid of it and get some of the money spent back. It's your car and money keep it if you wish At best the chip won't hinder the headers.

Yes, they are better than shorty headers since you don't have to worry about CA emissions and can use them. Next thing is to dump the intake after you fix the issue and then get a dyno tune. Assuming your injectors are same as what you took out. I would get a scanner that can read your ECM and not the code reader which is a glorified paper clip.

PS. I did ask you about the injectors since I wasn't sure whether those were the right size which could give you issues if they are larger than stock and the ECM doesn't know that. Ask me how I know. BTW, ACC-180830 doesn't come up on Google or Summit hence the question. Please continue being huffy and I'll go puffy.

aklim

Oh wait. You mean ACC-150830

https://www.summitracing.com/parts/a...EaAqDeEALw_wcB

If so, here are the specs below. I can see why there may a problem.

I don't think your car came with 30pph. If I follow the sequence of events, your car has the mods and was working fine. You change to the larger injectors and neglected to mention it to the ECM and it ASSUMES it is 22pph so it is giving the same pulse width it was but you are dumping more fuel. A larger injector dumps more fuel than a smaller one at the same pulse width

JrRifleCoach

Like ^^he said. Can't just install a set of 30% bigger injectors without tuning for the change.

TheGreek!

Wouldn't that just make it run really rich? If the throttle plate isn't letting in any more air at idle than it was before the injector swap how could the idle suddenly go so high with more fuel without a corresponding increase in air intake?

aklim

I think the ECM will try to compensate. It might try to change timing and IAC hence the higher idle. With my car as a 383 and using 30 pph injectors, it ran terrible and fast too. Until it was told in the ECM that it has 30 and not 22 pph. Yes, it ran rich too but the idle was higher and a little smoky at idle.

I had fuel dumping into the right side because the left bank shorted out the fuse.. No signal, no pulse. O2 was on the left so it reported that it was very lean and the ECM dumped fuel on the right so rpm went up and headers glowed on that side.