RyanB's Baja - popping/backfire under load

RyanB · Post by **RyanB** » Thu Jun 14, 2012 2:33 pm

New ECU is in and it starts up! Need to look into a few issues though. It is running pretty rich. Also when warmed up I would blip the throttle and it would feel like it is misfiring and then take off like a bat outa hell. Previously with the earlier ECU it would gain power at a pretty steady rate but did not seem to spin up at breakneck speed. Odd differences. I need to drive the car 20 miles to get the ECU to calibrate. Maybe the rich problem will be solved once the motor has enough driving data to tune itself.

Post by **david58** » Thu Jun 14, 2012 6:54 pm

coolant temp sensor

RyanB · Post by **RyanB** » Fri Jun 15, 2012 8:40 pm

Well, tried to take it out for a spin and it's constantly popping/backfiring while under load. Loses power and I have to back off the throttle. Have to baby it to get it around. Certainly did not do this with the old ECU. Not an issue I ran into before. looks like I'll have to do some research on this issue.

Post by **Piledriver** » Fri Jun 15, 2012 9:40 pm

Doe that ECU have any logging capability?
(or perhaps even via the LC1? Don't think it has a tach input tho...)

RyanB · Post by **RyanB** » Tue Jun 19, 2012 9:31 am

From what I can find out, the only thing I am going to be about to get out of it (and it hasnt worked yet) is the codes. From my perspective, as soon as the turbo builds boost is when the problems start.

baja5 · Post by **baja5** » Tue Jun 19, 2012 5:34 pm

RyanB wrote:From what I can find out, the only thing I am going to be about to get out of it (and it hasnt worked yet) is the codes. From my perspective, as soon as the turbo builds boost is when the problems start.

Maybe your wastegate isn't opening and it's going into overboost. The ecu will cut out power when that happens.

RyanB · Post by **RyanB** » Tue Jun 19, 2012 8:23 pm

RyanB wrote:Well, after thinking about this issue today... I thought well the LAST test says I should have less then 5 ohms resistance from sigrtn(46) to pins 40 and 60. Well 40 and 60 are simply grounds.

For the heck of it (what did I have to lose at this point right?) I went ahead and simply grounded 46.

OK. So some more interesting things have come to light... Today, for the hell of it. I took my old ECU out there and hooked it up. Low and behold, she fired right up. Woah. However, still running very oddly. Same as with the new ECU. Running rich at idle and pops/sputters when gassing it. Now, what did I do differently? See quote above. Previously, I couldn't get the car to run right until I grounded sigrtn. When I put the new ECU in I remembered that I needed to undo this. I never bothered until today to try the old ECU with that ground removed.

Now for the weird part. With the old ECU in there, I re-grounded sigrtn. The car idle jumped up, ran for about 30 seconds then died and wouldn't restart. I removed the ground and it started right back up. Really odd considering that previously it would run oddly when it WASN'T hooked up.

Now, pin 46, sigrtn is for the following sensors:
VANE
KNOCK
BAROMETRIC PRESSURE
COOLANT TEMP
THROTTLE POSITION

David did mention coolant temp sensor above. Would this sensor really make the car run as badly as it is if it went bad?

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