melition

I've got a technical question for everyone. Got a 97 c1500 with a rebuilt 350 vortec, longtube headers, no cats, egr delete, lt4hotcam and a pcmforless tune.

The trucks been running fine, but I replaced my plugs due to a cracked one during my longtube install and found that my old ones weren't good. Put my new ones in and took them out the next day and the first part of the ground strap was whitish like it was too much timing. The base of the plug looked very rich, covered in carbon. I hooked up a scanner but I couldn't read my knock. Although, my timing at idle is around 22-24 and my timing at 2000 Rpm was 31.

Seems ok, all except my long term fuel trims were up at 15-19%. Going up the longer I idled. I emailed Keith at pcmforless and he said it was fine, but I can't help but worry after spending a **** ton of money on the truck. Any second input here?

Thanks for the help!

chrmaka

I'd invest in a wideband A/F meter. Use that to work with Keith and make adjustment as need be. You're running rich. Also, Are you running stock plugs? you might need to drop to 1 colder heat range.

melition

I am running the stock plugs. Cheapie ngk plugs lol. But 31 degrees of timing doesn't seem like much to me for a 91 tune. 91 octanes all I can get around here. I am going to buy one, but I just haven't gotten the funds just yet. Just paid to finish up the exhaust. I monitored my 02 sensors and they are moving slowly, but I believe it's because of the richness. Lower Rpms like to misfire also when I first start up. Once it's running it doesn't misfire at all. Do you believe the running rich is causing the misfire and the dis colored plugs?

melition

I have greatly reduced the possible causes of all these issues and need some advice Please.

Basically, at idle my long term fuel trims are sitting very high. 20-25%. I thought my intake pipes were leaking but couldn't find any leaks. Finally I unplugged the maf and the fuel trims sat at -5% which is on par with my tune since I asked for it to be on the rich side. The maf was from the junkyard but it's been fine till lately.

Basically the breakdown is,
I did cam swap, ran good.
Got it tuned for cam and longtubes, ran great
Installed the longtubes, now it bogs off idle take offs slow or fast randomly and high fuel trims.

I believe this might be 02 sensors as they move very slowly and likely are original. Being 50 bucks a pop I really could use advice here please.

Thanks!