1990 Civic Si w/b16a1 swap. The car has a very bad irratic idle but when you get on it its fine. No code is being thrown was told it could be 02 sensor. Like when sitting at stop light it goes up and down from 500rpms too 1600rpms but is totally fine when getting past 1600. Please help this is very annoying. Thanks in advance and also have checked all hoses and fitting for pressure.

 

i would check all your vacuum lines before you do anything because that could be the cheapest way to fix it. did you do the swap yourself??? also a oxygen sensor is a good thing to check

 

I had the same problem with an 89 Accord...ent up one of the injectors wasnt firing.

The car couldnt idle, but could move under its own power.

Need more info.

And I'm wondering if your timing belt might not have slipped a tad? Didnt think it could happen, but it happened to a buddy of mine....he let it go for too long and broke a valve and bent a few more. But I'm not sure if that would allow the car to run ok past 1600.

 

also stops every once in awhile and will be normal for 2-3mins and then goes back too irratic idle

 

and when 02 sensor was disconnected car ran the same. Isnt car suppose too run different or not at all with 02 disconnected?

 

maybe the O2, but maybe other things like the IAC.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 4drEF &raquo;</TD></TR><TR><TD CLASS="quote">maybe the O2, but maybe other things like the IAC.</TD></TR></TABLE>

yeah check that out

 

IAC's are a good cause for that and a bubble in the collent is another.

 

This is a chronic problem for this generation of Hondas. I believe it does in fact have something to do with the IACV, but I might be wrong. This would be a good thing for someone to write up an FAQ on.

 

Ok, being a honda tech. i see this sorta thing all the time in could be one of the following:

1-check vac lines

2-bleed the coolent, a air bubble messes up the sensor theres a bleeder valve right where the thermostat is follow the top raditor hose to the block its rght on top. (on accords anyway) heat car up make sureheater in on hot and crack it open bleeding outair the close it once coolent flow is stedy

3-clean the throttle plate (i saw firsthand this fix the same problem on a nsx) Take a rag and spray throttle plate cleaner on it, soak it good then rub it on and around throttle plate removing black ****

4-If this still hasent fixed your problem check the intake manifold gasket on small leak could cause this problem takea can of brake clean and spray around intake manifold gasket an vac lines if idle changes you found it

good luck