So i posted on here a little while ago about my issue. still have the same problem. When i start it the rpms start out at 2300 rpms. After i drive for a little bit and it warms up the rpms will hunt from 2000 rpms to 1000 or so. Now ive replaced the whole throttle body and TPS with a used one. I also replaced the IACV with a used one. I took it into a shop yesterday and said it was an electrical problem and then the guy said it was IACV. But i replaced it already and am doubting his opinion. Any ideas?

 

vacuum leak?

 

nope got that checked out at the shop. they said it was an electrical issue then came up with it was the IACV. But if i replaced that already what are the chances of it actually being it? Im just not trying to spend $200 of un necessary money.

 

clean it again, are you throwing codes?

 

How did they check for vacuum leaks? You should ask them if the did a half *** job and just listen for leaks or spray carb/brake cleaner. The proper way to test for a vacuum leak is with smoke. ask them what method they used. And ask them how they know its an electrical problem? Dont be afraid to ask the garage.

 

no codes. when they hooked it up he said that the car says "everything is fine". And a smoke test is what thet did

 

You don't "hook" an obd1 car up, so that tells me something is sketchy there. I would continue to look for a vacuum leak and go from there. IACV could still be the problem. If it was on a used car, there may have been rust in it. or the small little ball that activates the car to idle down is seized... There are many things is could be.

 

well he said something about blinking lights or something. And yea i guess it could still be the IACV. I just want to narrow it down so i dont keep putting money into it

 

Same issue with my car. Found out today it was a faulty ECU. Was hoping I just needed an IACV, but no dice.

 

damn how do you check for a faulty ecu? and how much did it cost?

 

I was at the only Honda dealership I trust for several hours today. I asked them to check the vacuum lines, IACV, FITV, coolant, etc. They had to send out for a P28 ECU to replace and test; problem fixed.

However....that ECU was $800. I told them NO to that idea, and they recommended a good salvage near Charlotte NC to source a used P28 ECU. Used usually run $80-$150 (from my research). They may be cheaper or more expensive elsewhere, but those prices have been consistent with my findings.

I will add that I was puzzled, but thinking harder it kind of made sense; Since I've owned the car (nearly 2 years), I've had 3 random instances where my car mysteriously bogged down/died while driving in hot weather (95 + ambient temp), and I was driving a little harder than normal. My main relay was replaced the first time, and no issues until earlier this year. Dizzy replaced the 2nd time coming back from Myrtle Beach. Car ran better, but the issue happened again 2 months later. Dropped the car at the dealership for 2 weeks of tests over the summer; nothing. In talking later with other Civic Si owners, they suggested it might be my ECU. I never had it checked until now, so everything is starting to make sense. As long as it fixes both issues, I'm happy!

 

lol everything isnt fine. I would suggest to look for vacuum leaks your self. Look up "eric the car guy" on youtube for finding veaks with carb/brake cleaner. or "Scotty kilmer" homemade smoke machine/tester.

 

Well they already did a smoke test and before that I tried using carbon cleaner. Im really steering away from it being a vacuum leak

 

Click the IACV and FITV links in my signature.

To learn to check for codes yourself, click the CEL link in my signature.

 

Once the car is warmed up(surging idle) remove the intake hose at the throtle body cover the bottom hole (If I remember correctly) with your finger if the idle smooths out then the FITV is leaking and needs an overhall

 

See here's the thing. Before I took it in I replaced the throttle body with the FITV attached. I also replaced the IACV. The shop said it was the IACV but idk it doesn't make sense to me if I already replaced it. So your honest opinion?

 

Do the test instructor74 mentioned. What is the effect on the idle problem when you cover the hole in the TB leading to the IACV or FITV?

 

Vacuum leaks can be a serious bitch to pinpoint.
Twice I have had a hunting idle just like you described. Both times it was a
vacuum leak, both times spraying carb cleaner all over the place didn't do squat.


No, you should keep an open mind to help your cause here man.

 

well i took the throttle body to check the FITV and one of the vacuum hose nozels on the top of the throttle body broke off. went to the salvage yard and the only one they have is the one that i already took off. so if any of you know where i can get a cheap throttle body with the FITV attached for a 92 civic lx let me know!

 

Any way you can post a pic?

 

I can....if some tells me how to