Jayred

So my old truck has had a 5.7 gen III, 243 heads, .566 lift cam, truck headers with true duals and no cats. Runs just fine all day long, probably could use a tune but its fine for my daily driver. I installed hedman mid length headers and when I started it it fired right up and ran fine at first. As soon as it warms up it revs and stumbles and eventually dies unless I bring the rpm's to 2k. I'm so frustrated.

O2 sensors are installed in the collectors approx 3 inches back from the 4 into 1's. 1 3/4 primaries. I checked all the connections, everything is hooked up correctly. It runs good at high idle so I dunno. Could it seriously be bad bad O2's? would they both have gone bad? If I get a code scanner will codes be thrown if the O2's are bad? I haven't driven it on the street yet because its so gd loud with the open headers as I still need to get it to the exhaust shop.

I plan on getting a tune by NicD. If its a simple tune fix that he can take care of then thats great but I don't want to bring him a truck with problems that he can't tune and waste his time and my money.

Suggestions please...

Thanks

soloman369

iTrader: (13)

Un plug maf and see if it runs better

Jayred

It runs the same with or without the MAF hooked up. Now it idles bad cool or warm. I'm going to get a code scanner and try to see if its throwing any codes that will point me in the right direction. Maybe switch out the O2 sensors one at a time?

dw456post

I think your gaskets are leaking, throwing off your afr and fuel trims. Where were the 02's before the headers were installed?

Ls1Ryan2002

Well the first thing to do is take it to a parts store and put your car on the scanner. As said above a possibility is your gasket leaking.

Jayred

Well actually it used to have exhaust leaks in 3 places; headers and collectors. I had a million reasons to install the headers. Headers are in great shape, brand new hedmans, gaskets are high quality and new, I used proper torque wrench settings. I took my time installing these the right way. If it was a pinhole leak in a weld would that hurt? I scanned it and got a p1336 crank positioning sensor error. Maybe I need to get it on the road and let the PCM relearn? Old O2's were on old cast truck exhaust manifolds right up next to the head. New ones are in the collectors right after the 4 pipes go into 1 3 inch pipe. I'll have to investigate this cps code, Its a new one for me.

2xLS1

iTrader: (25)

The wiring for the crank sensor runs close to where the headers are. Look for burned wires and shorts.

soloman369

iTrader: (13)

^^^ my second guess some ppl dont even realise that the wires run so close to the headers. i seen em burn the crank position sensor wire and all kinds of **** goes wrong.

Russ K

iTrader: (1)

Sounds like you have open headers. If so, then the O2's will read lean & max the fuel trims rich.

Russ Kemp

Jayred

Hey Russ, i think your right. I did some reading and other ppl with open headers that have the O2's a few inches from the opening have similar issues. I took it for a drive and it runs fine in gear and when exhaust is moving. I'm now deaf and all my neighbors want to kill me. It sucks being so loud because I can't really hear the motor and how it sounds through the gears. I'm gonna finish the exhaust, have Mr. NicD tune it, and enjoy. Thanks for all the help!