babydeuce

iTrader: (24)

5.3 conversion in a 63 nova. Car ran great all day, filled up with fuel, car started to load up, pop and choke when throttle was opened. DTC shows P0102. I figured I would unplug the MAF and run SD just to get it home. As soon as the MAF is unplugged, the car dies. I can start the car, but it refuses to idle. Any thoughts? From everything I have read, the car should still idle!

Jack

|2ocky

I'm not as good with things like this as some other people on the site, but I am pretty sure obd2 cars won't run with it unplugged.

BLK02WS6

iTrader: (2)

It should still idle and run with the MAF unplugged - probably the tune is off and the fuel trims are not learned yet without the MAF in the equation. Try to keep it running a bit and see if it doesn't improve. The other thing is if you have one of the newer MAF sensors with the IAT sensor in the MAF - when you unplug it, it is giving a false IAT reading. In that case, if you wanted to stay SD, you could either get one of the older IAT sensors and relocate it, or just figure out which wires are for the MAF signal and cut those, leaving the IAT sensor operational. Hope that helps...

sreve

iTrader: (3)

truck maf does have a built in iat unplugged the pcm will see an air temp of
-40*f

BLK02WS6

iTrader: (2)

Yeah, he didn't give the details whether or not he used the MAF from the truck or not... I've seen conversions with a mixture of all kinds of stuff.

That Chevy II conversion is one I've always wanted to do though! I had to sell my Trans Am awhile back because of family emergency issues... but if I ever get to build another car, it will be a shoebox Nova with a 440ci LS7 and healthy shot of juice - street car with a parachute

wait4me

iTrader: (10)

If the ecm is throwing code P0102 then it is ignoring the maf sensor even if it is plugged in.

I would check for a blown fuse, or to make sure all the pink wires in your harness are getting power. That would be the first step. If that aint it, try replacing the MAF.

Also, if you are running the right fuel pressure. It should run perfect with that code as it would be running speed density with o2 sensor fuel correction.

You are using the front o2 sensors right?

babydeuce

iTrader: (24)

Thanks for the replys. I am running a truck MAF, and never even thought about the IAT sensor. Fuel pressure is a rock solid 58 psi, and yes the front 02's are installed. The whole setup only has about 350 miles on it.

I did smack my header on a pothole pretty hard right before I stopped for fuel. I checked the O2 wires to make sure they were fine, all looks good. If I cracked the header, would the O2 sensor seeing "fresh air" cause the bucking and issues that I am experiencing?

Jack

wait4me

iTrader: (10)

Yes. BUT i would check to see what pressure you are supposed to be running. not all engines take 58psi. Some where regulated down. That too would cause your running rich issue.

babydeuce

iTrader: (24)

This is the same pressure it has been running since day one, I have put just over 300 miles on the engine at that pressure with no issues. Like I said, the car was running great before I got the gas and hit the header. I thought it might be bad gas, but I only topped off the tank with 3 gallons on a 16 gallon tank.

I am going to clean the MAF and put the car in the air to check the header out tomorrow, I will report back. Thanks for all the help!

Jack

lt170chevelle

iTrader: (2)

also the jar from the header hitting could have possibly fudged up your 02 sensor. Try unplugging them and see if it fixes your problem

babydeuce

iTrader: (24)

Follow up:

Scanned with EFILive..O2' are switching fine, MAF cleaned, and it shows to be registering a frequency with no issues. I cannot seem to find any cracks in the headers, so I am at a loss here. The car refused to idle today, so I had to crack the butterfly open. DTC still shows P0102. I have a short log if anyone wants to take a peek. Thoughts??

Jack

babydeuce

iTrader: (24)

Here is a short log...You can see that it dies on me a few times, and I have to keep my foot on the pedal to keep it running. Let me know what you see.

Jack

wait4me

iTrader: (10)

Just send me the TuN file you are running. It looks like it has issues with the tune itself.

babydeuce

iTrader: (24)

Here is a copy of the tune.

Please note that the only issue I had with the tune prior to this incident was that is would occasionally attempt to die on me at idle only when the fan was on.

This is an 89 octane tune that I was very satisfied with.

Jack

babydeuce

iTrader: (24)

Bump for the afternoon crew....

babydeuce

iTrader: (24)

bump on more time...

SSAUTOCHROME

iTrader: (2)

When you uplug the MAF your ride is using the LOW OCTANE table settings when there is a MAF failure (limp home mode). You need to copy the HIGH OCTANE TABLE to the LOW OCTANE table for optimum timing. There is not reason to uplug the MAF either, especially if it has you IAT in it. You can simply tune the MAF out. How EFI LIVE dunno, I have HP Tuners. We simply turn the MAF enabled temp to the MAX temp the tuner software will allow. It then sets a MAF code that its malfunctioning but will then use your VE tables to get you home. Ultimate solution for code your throwing now: Bet your MAF needs to be replaced.