Help with idle problems 1988 vette
Thread Starter
Racer
Joined: Jun 2002
Posts: 278
Likes: 0
From: Perry Ga
Help with idle problems 1988 vette
I have had the dreaded code 33 for sometime now. I changed out both maf relays, maf sensor, IAC motor and reset base idle timeing. The problem is it seems to run fine during the time I drive to work in the morning about 20 miles. Idles around 600rpmsto 700rpms. In the afternoon it seems to like to idle around 900rpms to 1000rpms. When putting in park she skyrockets to 1400rpms. This problem only seems to do this in the afternoons on the way home from work. Yesterday afternoon she was at 1400rpms when I shut her down. This morning she is back at 600 to 700 rpms. The only thing that I haven't replaced is the computer itself, I read were the computer has alot to do with the idle speed. Even when I come to a stopsign or redlight she takes a little time to get to 600 or 700rpms. Just wandering if anyone would think that the computer is going south. The code 33 still pops up if I clear the computer. I haven't cleared it in 2 weeks now, and no SES light has come on, but the code is still stored in the ECM.
Any thoughts on my problem would be helpful.
Any thoughts on my problem would be helpful.
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Check for a leaking EGR Valve diaphram. I had this problem on the IROC and it gave me such problems.
You can use manifold vacuum to open the valve at idle (connect a long vacuum hose between the EGR Valve port and say the FPR port on the plenum).
-clamp this temp vacuum hose off and start the engine
-open the clamp and see if the EGR Valve opens
-pinch off this temp vacuum line and see if the valve stays open
If the EGR Valve is ok, can you borrow a known good MAF (one from an '80s F-body will work) to sub for your new one?
You can use manifold vacuum to open the valve at idle (connect a long vacuum hose between the EGR Valve port and say the FPR port on the plenum).
-clamp this temp vacuum hose off and start the engine
-open the clamp and see if the EGR Valve opens
-pinch off this temp vacuum line and see if the valve stays open
If the EGR Valve is ok, can you borrow a known good MAF (one from an '80s F-body will work) to sub for your new one?
