Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!
Hello, I have a 4 cylinder accord here with a high idle. Total trims are about negative 10%. Not much change with RPM. I don't see an IAC and am pretty sure the throttle body controls idle on it.
Service info says to look for vacuum Leaks but I do not suspect that with trims being negative. There is a bulletin about doing a relearn after a throttle body service for this code but I don't think that has been done.
I cleared the code and it is idling ok, but fuel trims are still negative. I don't really want to ship it but since it's not a Nissan I'm not sure what they are going to want to do.
So after I posted this I parked the car outside and I'm pretty sure the customer picked it up...
I did pinch off the purge line and it didn't do anything. I told the service writer that i suspected the throttle body was dirty but wanted to spend more time with it. They really don't like us spending much time on off brand stuff though, so I think it got away.
I forgot about pcv though. I believe it was due for an oil change soon, so maybe that was it. what is a test you can do for PCV before replacing it? I'm not sure if just blocking it off is a legit test or not? I may be over thinking it though.
Maybe disconnect the hose at the intake and just plug the intake port, so it is still being vented, just not routed back into the intake?
I don't suppose you caught any scan data during the high idle? The TP opening and the MAP would be the ones to watch.
Negative trims and high idle equals a valve adjustment problem, IMO. That's where the TP and MAP come in. If the TP is near closed, but the MAP is still over 1.00V, then it's vacuum leak or valve adjustment.
That relearn after a throttle body service is important, too. Especially if the battery went dead or was disconnected recently. Checking the 'Distance Since DTC Cleared' PID in the Generic side may help back this theory up.
I see that the car is gone, but I figure this might be useful if it shows up again? :silly:
Tutti57 wrote: what is a test you can do for PCV before replacing it? I'm not sure if just blocking it off is a legit test or not?
A qiuck and easy test is to disconnect the hose/valve on the valve cover side with the engine idling and check if there is vacuum present, if not the valve imay be stuck closed or the passages clogged. .When blocking the valve with your finger the rpm should drop slightly for an instant, around 50 to100 rpm.It will be more with a stuck an open valve.
Alternatively you could just pinch off the pcv hose with the engine at idle and watch out for this drop in rpm.
Another test ist to pull the dipstick and check for vacuum with a gauge.
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