Code 15, 33, 34 - erratic/weird idle - seems like misfire but not
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Joined: Oct 2003
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From: South Florida (NW_Broward)
Car: 1989 Firebird
Engine: 2.8L V6 MPFI
Transmission: Beat to heck 700R4
Code 15, 33, 34 - erratic/weird idle - seems like misfire but not
89 2.8L MAF car (Firebird). Throttle body heater bypassed - custom "pisswarm air intake", CAT gutted - 180* stat.
I've always had a code 33 set when the MAF was plugged in in this arrangement. I've replaced it with the same code set. It doesn't happen immediately, and the SES light comes and goes. It sort of stumbles at idle, and occassionally when I get on it. I also get the rare "press teh gas at a light and have the car stall". So I've gone back and forth between having the MAF unplugged, (which sets the code 34), and having it plugged in. Having it unplugged the car was running very well. In fact its been running reliably for over 30,000 miles this way with nary a stall or stumble.
***** Thats not really my question though just some background. Now even with the MAF unplugged I'm getting a loping or erratic idle, from 700ish-1500 randomly, no pattern. It "almost" seems like a misfire or even a vacuum line is loose or leaky. When i get on it, sometimes it falls, sometimes its great, sometimes the RPMs waver up/down 100 RPM*****
I figured a bad tank of gas was the cause actually. So I drained it and refilled along with some injector cleaner with no results.
its also doesn't seem to happen all the time - One day its just like it used to be, the next I'm chugging along on the turnpike, halfway to the destination and it starts acting up. Or maybe it starts acting up first, then clears up. I.e. the definition of erratic.
The 15 troubles me. I have a 180* thermostat for over a year now, and I've never had trouble like this until last week. Could the engine temp sensor have failed in such a way that it reads low like that?
Could it have just come unconnected?
Any help out there?
I've always had a code 33 set when the MAF was plugged in in this arrangement. I've replaced it with the same code set. It doesn't happen immediately, and the SES light comes and goes. It sort of stumbles at idle, and occassionally when I get on it. I also get the rare "press teh gas at a light and have the car stall". So I've gone back and forth between having the MAF unplugged, (which sets the code 34), and having it plugged in. Having it unplugged the car was running very well. In fact its been running reliably for over 30,000 miles this way with nary a stall or stumble.
***** Thats not really my question though just some background. Now even with the MAF unplugged I'm getting a loping or erratic idle, from 700ish-1500 randomly, no pattern. It "almost" seems like a misfire or even a vacuum line is loose or leaky. When i get on it, sometimes it falls, sometimes its great, sometimes the RPMs waver up/down 100 RPM*****
I figured a bad tank of gas was the cause actually. So I drained it and refilled along with some injector cleaner with no results.
its also doesn't seem to happen all the time - One day its just like it used to be, the next I'm chugging along on the turnpike, halfway to the destination and it starts acting up. Or maybe it starts acting up first, then clears up. I.e. the definition of erratic.
The 15 troubles me. I have a 180* thermostat for over a year now, and I've never had trouble like this until last week. Could the engine temp sensor have failed in such a way that it reads low like that?
Could it have just come unconnected?
Any help out there?
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