ECU, A/F problems...maybe...
06-25-04, 09:18 PM
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ECU, A/F problems...maybe...
*edit*Turns out to be longer than I thought, but I'm trying to make sure I provide as much info as I can.*edit*
So hears the deal...No shop can pinpoint whats going on with my car, and its running like crap. I need to figure out what I should check before having to fork out some money.
Symptoms:
Off idle, from a stop sign/light, etc, I'll be in first gear, have the car revved to right around 2k rpms, and slowly let the clutch out (ala normal driving). As I let the clutch out, the rpms, of course, start to fall as they should for a fraction of a second, then they fall to idle and the car almost dies if I don't get to the clutch in time. Then after putting the clutch in, I'll try it again, and sometimes it'll repeat, other times its just fine. Sometimes if I short shift into second gear after it happens into first, same thing happens, but not as bad.
Then today, while at a stop light, I notice the idle RPMs fall, and the car almost dies, so instinctively (the tranny is in neutral) I push the clutch in and RPMs return to normal. I assume that helped by taking the extra load cause by the half of the tranny connected to the engine via the clutch/flywheel off the engine.
And yet again, a while later, on my way back home, the same thing happened at a stoplight, only I put in the clutch, and the RPMs STILL kept falling and the car almost died. So I kept it revved up by tapping the accelerator. Each time I did, it would backfire repeatedly.
Thats the worst thats happened. I of course have the 3k RPM hesitation. Then other seemingly unrelated problems include letting out a bit of brown smoke right before shifting when doing a full throttle run, and then white smoke at startup.
And last, a one off incident, when running around 14 lbs of boost while trying to dial in my boost controller, we did a partial throttle run that still got into boost. Then the next full throttle run, brown smoke billowed out the tail pipe (solid plume, enough to not see the car behind us through it). Never happened again though.
Seems to not do it as much in hot weather, but if it gets cooler or a lot more humid it seems to do it a lot more.
Mods are: streetport, full exhaust, intake, boost controller set to ~14 lbs, Crane HI-6 ignition, Competition fuel pump, SX FPR, set 1:1, and running about 32 lbs. (or whatever its measured in) around idle. What I think is the culprit is this: non-sequential twins, with XS Engineering ECU, which was reprogrammed a long time ago, for the seq. setup and mods I assume. I get a EGR code periodically, on a non-cali '93 year car, so we're pretty sure they did a core exchange and sent back a Cali ecu.
My first thought is its running really rich all around, since its programmed for seq. twins, and the boost doesn't come in nearly as early. And after the incident today with it almost dieing then backfiring when keeping the revs up, leads me to believe its running really rich at idle.
So is there anything I should check before I go get a PowerFC? I'll probably put it on the dyno in the next couple of weeks to get the a/f readings and see if that shows anything funny.
Blake
So hears the deal...No shop can pinpoint whats going on with my car, and its running like crap. I need to figure out what I should check before having to fork out some money.
Symptoms:
Off idle, from a stop sign/light, etc, I'll be in first gear, have the car revved to right around 2k rpms, and slowly let the clutch out (ala normal driving). As I let the clutch out, the rpms, of course, start to fall as they should for a fraction of a second, then they fall to idle and the car almost dies if I don't get to the clutch in time. Then after putting the clutch in, I'll try it again, and sometimes it'll repeat, other times its just fine. Sometimes if I short shift into second gear after it happens into first, same thing happens, but not as bad.
Then today, while at a stop light, I notice the idle RPMs fall, and the car almost dies, so instinctively (the tranny is in neutral) I push the clutch in and RPMs return to normal. I assume that helped by taking the extra load cause by the half of the tranny connected to the engine via the clutch/flywheel off the engine.
And yet again, a while later, on my way back home, the same thing happened at a stoplight, only I put in the clutch, and the RPMs STILL kept falling and the car almost died. So I kept it revved up by tapping the accelerator. Each time I did, it would backfire repeatedly.
Thats the worst thats happened. I of course have the 3k RPM hesitation. Then other seemingly unrelated problems include letting out a bit of brown smoke right before shifting when doing a full throttle run, and then white smoke at startup.
And last, a one off incident, when running around 14 lbs of boost while trying to dial in my boost controller, we did a partial throttle run that still got into boost. Then the next full throttle run, brown smoke billowed out the tail pipe (solid plume, enough to not see the car behind us through it). Never happened again though.
Seems to not do it as much in hot weather, but if it gets cooler or a lot more humid it seems to do it a lot more.
Mods are: streetport, full exhaust, intake, boost controller set to ~14 lbs, Crane HI-6 ignition, Competition fuel pump, SX FPR, set 1:1, and running about 32 lbs. (or whatever its measured in) around idle. What I think is the culprit is this: non-sequential twins, with XS Engineering ECU, which was reprogrammed a long time ago, for the seq. setup and mods I assume. I get a EGR code periodically, on a non-cali '93 year car, so we're pretty sure they did a core exchange and sent back a Cali ecu.
My first thought is its running really rich all around, since its programmed for seq. twins, and the boost doesn't come in nearly as early. And after the incident today with it almost dieing then backfiring when keeping the revs up, leads me to believe its running really rich at idle.
So is there anything I should check before I go get a PowerFC? I'll probably put it on the dyno in the next couple of weeks to get the a/f readings and see if that shows anything funny.
Blake
Last edited by infinitebass; 06-25-04 at 09:21 PM.
06-25-04, 09:25 PM
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Oh, and when driving and having the throttle on, but no load (I.E. cruising down the highway or trying to keep a constant speed, and at the same time having no load on the engine) it starts to kinda buck. Essentially losing power, getting power, etc. Usually its just audible, but rarely you can actually feel it.
07-08-04, 01:28 AM
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When the clutch is down, it turns on the clutch switch, and the ECU will bring the rpm up just a little. That could be the reason why the car tend to stall less when the clutch is on.
Do you have an aftermarket flywheel?
Do you have an aftermarket flywheel?
Last edited by osdesigns; 07-08-04 at 01:31 AM.
07-08-04, 12:12 PM
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Yes, has an aluminum flywheel.
Disconnecting the O2 sensor worked. I'm now trying to get off my butt and go get some ring terminals for the wire I have so I can try grounding the downpipe.
There's actually another thread on this in non-tech section thats got a bunch more info.
Blake
Disconnecting the O2 sensor worked. I'm now trying to get off my butt and go get some ring terminals for the wire I have so I can try grounding the downpipe.
There's actually another thread on this in non-tech section thats got a bunch more info.
Blake
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