Engine backfire and glowing headers
Engine backfire and glowing headers All right so I've got a 2001 trans am with a ls7. Car ran fine till the trans acted up so I pulled trans and dumb me left the plugs out and in Va that's not good.. So long story I had to pull heads, rods and pistons. Cam crank and timing chain stayed in motor... Every thing was torqued and lubed as required. So fast forward everything gets put back where it belongs and motor started right up.. So awesome put trans back in and that's where this story goes wrong... The car started but would backfire through exhaust for a min or so and clear up.. Then it would start up day one and run just fine. Then next day no good backfiring and glowing the headers ( dumping raw fuel in headers). Then start up just fine without changing a damm thing... So on so forth till one day it will start and run for 20-30 seconds then stops running and when it refires it will just back fire and glows headers.. I've cked all the small things grounds on the back of the head are good ( cleaned both head and terminals) , cked the plugs all was good, ck the tune. Even adjusted the lifter preload ( yes LS7 rocker arms are adjustable). Then I adjusted the tune put more gas in and took gas out, added timing (5deg) no changes and put it back to 8 deg. Nothings a miss and nothing has changed. Tune is a speed density so all but a couple of sensors are left. I have pin cked both the cam and crank sensor harness all was good. Put the PCM in another car and all was good. No water or fuel in oil. 60 psi fuel pressure. 40-60 psi for oil pressure. No odd or funny noises. Car doesn't run hot. Data logged and nothing in there( cam, crank, map iat, tps and injector duty cycle. I am at a loss of where to go next.... So any ideas out there...
On The Tree
Joined: Mar 2006
Posts: 125
Likes: 10
I washed out an engine block once when I lived there, and in a matter of minutes, it rusted so fast before my eyes I couldn't believe it. One of the many reasons that I hated living in Norfolk, Virginia. The locals used to lovingly refer to it as No **** Vagina.
Trending Topics
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
Topdon ONE vs. Artidiag 800 BT2: Which is the Diagnostic Tablet For You?
Pouria Savadkouei
Gas Monkey Built a 6-Wheel Ferrari Testarossa With a Corvette LT4 Engine
Verdad Gallardo
7 Most Reliable High-Performance Engines GM Has Ever Built
Verdad Gallardo
Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin
Verdad Gallardo
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo On The Tree
Joined: Mar 2006
Posts: 125
Likes: 10
I think he means moisture got inside the engine when the plugs were out.
Broken inner valve spring or outter valve spring...bent valve...my friend had an issue on his lsx 454 tfs heads and ended up being a few crushed valve springs. But he also found out the installer used the wrong push rod length and you said you checked that.
Are the heads stock Ls7? If so with stock rockers, what makes the rockers adjustable? I have a LS7 in my TA since 07 and the rockers are not adjustable. I had to measure for the pushrods with comp short travel lifters and the rockers are torqued to 22ft lbs. Unless something different was done to the valvetrain stock rockers are not adjustable. And I've had mine apart a few times.
Not stock rocker arms... Please everyone not trying to be an *** but if your going to tell me that my rocker arms are not adjustable please move on... For the last time I have the harlin sharp ls7 arm and they are adjustable...
Timing or lean condition is the usual cause of glowing headers but since yours was intermittent I would suspect something else. Bad o2 sensor maybe? Do you have a wideband to watch AF ratio?
All I read in your first post was LS7 rocker. Don't see anything about them being Harlan Sharp. Reread a few times as age is winning its war. However,
here in Fl. humidity plays hell on the injectors when left sitting. I have seen them have problems after sitting. Just a possibility. Good Luck.
here in Fl. humidity plays hell on the injectors when left sitting. I have seen them have problems after sitting. Just a possibility. Good Luck.
TECH Fanatic
Joined: Jul 2007
Posts: 1,802
Likes: 333
From: Wilmington, De
Make sure you didn't pinch a sensor wire somewhere. If you have no vacuum leaks at the intake, I would suspect that a sensor has crapped out or a wire is pinched causing a sensor to short out. Start at the upstream O2 sensors and work your way on up.
Were the heads disassembled so the valves could be inspected for rust buildup? I had that happen on an LT1 that sat for a while. It would backfire and sputter at idle. We just cranked the throttle for a bit and it cleared the rust right off.
lol
It took me a moment to figure it out, too. I was thinking, "Why the **** does the state of Virginia care about leaving spark plugs installed in an engine while work is being performed?"
Were the heads disassembled so the valves could be inspected for rust buildup? I had that happen on an LT1 that sat for a while. It would backfire and sputter at idle. We just cranked the throttle for a bit and it cleared the rust right off.
It took me a moment to figure it out, too. I was thinking, "Why the **** does the state of Virginia care about leaving spark plugs installed in an engine while work is being performed?"