Tuning issue

[1NastyT]

I recently installed my new engine. It started fine and I ran it through a heat cycle. Everything was fine ran good no problems then I tore it down and re torqued the heads as advised by my engine builder and Tom at Champion. I put it all back together and and it hasn't run right since. I replaced the fuel pump it died,the maf twice and the iac,the fp relay the cam sensor is also new.I swapped the ecm and map sensor from a buddies car nothing seems to work I have checked vacuum lines and grounds the fuel pressure is @37psi. the engine seems to sputter and will not idle.When i rev it it blows out black smoke. It does seem to get a little better when I unplug the maf. The maf is a stock GM one. I bought a rebuilt 1 and thought that was the problem I am not sure where else to check. There are no codes in the ecm. the tps is @ .50 and the iac is @ 24 @ idle. Please help I want to drive it not just look at it.

 

[meanchicken]

Black smoke normally means you're running too rich....too much fuel....

 

[QUIP'6']

I recently installed my new engine. It started fine and I ran it through a heat cycle. Everything was fine ran good no problems then I tore it down and re torqued the heads as advised by my engine builder and Tom at Champion. I put it all back together and and it hasn't run right since. I replaced the fuel pump it died,the maf twice and the iac,the fp relay the cam sensor is also new.I swapped the ecm and map sensor from a buddies car nothing seems to work I have checked vacuum lines and grounds the fuel pressure is @37psi. the engine seems to sputter and will not idle.When i rev it it blows out black smoke. It does seem to get a little better when I unplug the maf. The maf is a stock GM one. I bought a rebuilt 1 and thought that was the problem I am not sure where else to check. There are no codes in the ecm. the tps is @ .50 and the iac is @ 24 @ idle. Please help I want to drive it not just look at it.

the tps should be .42 at idle and it will jump to .44 when started.

 

[1NastyT]

Thamks guys for your input i have changed the tps to .42 and still no difference.When I start it up cold it runs fine for about 30 seconds or so and then its almost like the computer is calling for to much fuel. I can't figure it out.I'll try again tomorrow.

 

[cuda6pak]

Have you tried an LS1/LT1 MAF and Translator? My car had a stock Autozone replacement MAF when I bought it and it ran like ****, switched it to the LT1 and Translator and it ran silky smooth.

 

[1NastyT]

I am considering that option I just cant imagine I have 2 bad maf

 

[meanchicken]

IMHO it's too early to blow a few hundred $ on an LT1 MAF and Xlator. Gotta figure out your issue first....then go for upgrades.

Unplug the MAF while the car is idleing. If the idle smooths out with the MAF unplugged.....bad MAF.
Or borrow a known good one from a buddy...

Are you able to get any other ScanMaster readings other than TPS and IAC?

Make sure all your fuel and ignition related witing harness plugs are clean and secure also...no pushed pins in the connectors...etc.

Touch everything that you touched when you did your post heat cycle tear down. Something changed.

 

[OneQuikSix]

IMHO it's too early to blow a few hundred $ on an LT1 MAF and Xlator. Gotta figure out your issue first....then go for upgrades.

Unplug the MAF while the car is idleing. If the idle smooths out with the MAF unplugged.....bad MAF.
Or borrow a known good one from a buddy...

Are you able to get any other ScanMaster readings other than TPS and IAC?

Make sure all your fuel and ignition related witing harness plugs are clean and secure also...no pushed pins in the connectors...etc.

Touch everything that you touched when you did your post heat cycle tear down. Something changed.

Good advice. I found my TPS connector suffered a loosened metal contact and was causing me trouble when trying to set my sensor on the new throttle body. Unfortunately, I'm still trying to work through some rough idle issues. At least I know what the problem is not.

 

[1NastyT]

Thanks guys for all your advice. I am pleased to say it finally runs great It was the Maf I put a translator pro and lt1 maf and actually drove it tonight.Off to the rmv tomorrow and hopefully to Musclepalooza on Sunday!!!

 

[meanchicken]

Cool!
Congrats and enjoy.