Ugh - AFR issues...bad ground?
08-02-2009, 08:29 PM
#1
Three Wheelin'
Thread Starter
Ugh - AFR issues...bad ground?
So, I think I've finally figured out my weird idle AFR issue. I installed a Vitesse MAF recently and have battled a few gremlins that popped up - got all of them resolved except for one.
When the car comes up cold until it gets warm my Zeitronix WB shows a healthy 14.7 AFR. Once the car gets warm (temp gauge right above the first white bar on the dash and engine fans coming on) the AFR creeps back down to 12.8/13.0 and stays there. If I turn on the lights the AFR pops back up to 14.7. Turn the lights off - drops back down to 12.8.
I re-grounded the AFR gauge to the DME harness to see if that had any effect. Didn't change anything.
I recently cleaned ALL the grounds in the car - including the negative battery and DME grounds on the bellhousing. Pulled off the connectors and cleand them with a Dremel, ground down to the chassis with a Dremel, dialetric grease and put everything back on. I got under the car and pulled off all the connectors from the starter last night and cleaned/Dremel'd all of those as well (and they were quite nasty).
Brand new Bosch battery shows 12.7v across with engine off. Engine running it's around 13.5 to 13.8 with no significant load. Turn on lights, engine fans, etc... and it drops no lower than 13.1 so that seems to be within paramenters.
I've got a new negative lead for the battery to the starter coming from Robby (think IceShark kit) but didn't get the positive kit. I'm hoping that might fix it as it seems directly related to heat.
Anyone have any other ideas? Problem here is I've got inspection coming up in a few months and don't think there's anyway that I can get this thing to pass running 12.8 at idle and it's stuck there - the piggyback has no effect - can't dial out enough fuel to lean it up. I'm already running the FQS at -5% fuel.
When the car comes up cold until it gets warm my Zeitronix WB shows a healthy 14.7 AFR. Once the car gets warm (temp gauge right above the first white bar on the dash and engine fans coming on) the AFR creeps back down to 12.8/13.0 and stays there. If I turn on the lights the AFR pops back up to 14.7. Turn the lights off - drops back down to 12.8.
I re-grounded the AFR gauge to the DME harness to see if that had any effect. Didn't change anything.
I recently cleaned ALL the grounds in the car - including the negative battery and DME grounds on the bellhousing. Pulled off the connectors and cleand them with a Dremel, ground down to the chassis with a Dremel, dialetric grease and put everything back on. I got under the car and pulled off all the connectors from the starter last night and cleaned/Dremel'd all of those as well (and they were quite nasty).
Brand new Bosch battery shows 12.7v across with engine off. Engine running it's around 13.5 to 13.8 with no significant load. Turn on lights, engine fans, etc... and it drops no lower than 13.1 so that seems to be within paramenters.
I've got a new negative lead for the battery to the starter coming from Robby (think IceShark kit) but didn't get the positive kit. I'm hoping that might fix it as it seems directly related to heat.
Anyone have any other ideas? Problem here is I've got inspection coming up in a few months and don't think there's anyway that I can get this thing to pass running 12.8 at idle and it's stuck there - the piggyback has no effect - can't dial out enough fuel to lean it up. I'm already running the FQS at -5% fuel.
08-02-2009, 09:58 PM
#3
Three Wheelin'
Thread Starter
I just replaced the dang thing with a brand new one a week ago (assuming we're talking about the same thing - blue tipped sensor in the front of the block with a clip connector attached to it).
I just went out and checked to make sure you can't put the clip on upside down - it only goes one way. Unless the brand new one I have is bad, I don't think that's the problem.
Just to clarify - it takes until the car is warm to do this. If I cold start it, I've got several minutes before it gets warm where I can turn the lights on/off and there's no change to the AFR - it's only after it gets good and warm and the idle drops down to 12.8 where this starts happening.
Very frustrating - not sure where to go next...
I just went out and checked to make sure you can't put the clip on upside down - it only goes one way. Unless the brand new one I have is bad, I don't think that's the problem.
Just to clarify - it takes until the car is warm to do this. If I cold start it, I've got several minutes before it gets warm where I can turn the lights on/off and there's no change to the AFR - it's only after it gets good and warm and the idle drops down to 12.8 where this starts happening.
Very frustrating - not sure where to go next...
