I just bought a '96 t4r for a winter driver and am having some idle issues. I searched and couldn't find a problem similar to mine. When cold it will idle at 1900 rpm and will stay there until temp gauge comes up to normal operating temp, then drops to 900 rpm. It doesn't gradually drop like my "97 as it's warming up. I took the TB off and cleaned the iac valve ( wasn't that dirty ), put back together and same problem. I'm getting a little concerned with winter coming and my wife backing out of the driveway if it's icy. Any help would be appreciated. Checked vacuum lines and can't find or hear any leaks.
high idle issues...please chime in
- Thread starter sawguy
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Pedrojr80
New member
Spray some break cleaner around vacuum hoses to see if you find a leak somewhere those cacuum lines or maybe around intake manifold. Have you check your engine codes yet?
gamefreakgc
Elite Member
This. Probably a leak somewhere and your engine might be trying to compensate.
Maybe check your grounds and battery too? I've had my engine go wonky with the bad battery I had. Complete shot in the dark with the battery though.
maxbrown11c
New member
Check to see if there is any lateral movement of the piece where your throttle cables are connect to. Of there is movement fore and aft then that could be causing it. I had a similar issue with a high idle in my 97. I cleaned the MAF, TB, and IACV and that didn't work. Once I found that this piece would move back and forth a few millimeters I shimmer it with a couple of washers and my problem went away. The reason it is important that it does not have forward and backward movement is because it is what the butterfly valve in the throttle body is connect to so it can get caught on the side of the TB if the linkage is allowed to move back and forth.
OK, after a little more research wondering why no DTC's, I discovered the PO must have taken the bulb out of the CEL so it doesn't display. Great...now I have PO100, PO110 and PO505. Where do I start? Would I have tripped a couple of these codes by disconnecting the MAF sensor and the IAC for cleaning? Any help appreciated
Went to obd codes.com and found some info. I am to clear codes, unplug iac and start engine. If PO505 resets it's not the iac valve. It's in the wiring harness back to the ecu or the ecu itself. The PO505 reset after I did this...so I guess I just live with this or start tearing into wiring. I hope someone else can use some of this info. BTW.. with the iac unplugged it idles at 650rpm...perfect
dirteater4
New member
IAC if you don't have any vacuum leaks. Mine did that after doing my valve cover gaskets. I cleaned out the throttle body and some residue trickled down into the unit. Got a new one, fixed. It'll take you 15-20 minutes to replace.
LittleCaesar
New member
Did you open up the old one to see if you could visually see anything wrong on the board? I helped a coworker fix his daughter's 98 Civic with a reman ECU. She had a very high idle and everything else checked out well. Turns out a couple of capacitors were failing in the old one.
Glad to hear it got fixed....
arty:
gamefreakgc
Elite Member
Wow, that's pretty rare. ECU's barely ever go bad unless they get wet.
I bought this a few months ago and after I got it home I realized the PO had done some 'work' under the hood. Wiring had been spliced in various places and a lot of stuff that had been shade treed. He might have shorted something and it affected the ecu. JMO. I got lucky this time.
