Hey guys, So I've got a 97' Trans am with the LT1/T56 combo. A little after I got the car about 6 months ago it started missing a little bit while normally driving and would "cut" out at high RPM. Checked my codes and I had cylinder #7 misfire code so I took off the spark plug wire and it was burnt in almost 2 pieces.
Replaced it and it was better for like 5 miles, Took it off again and it was burnt again.. I obviously didn't know how to properly run that wire. Replaced again, and ran it somewhat good, or so I thought. A little after that I got a loud exhaust leak off the header area. Looked closely down there and the last owner busted one of the studs of the upper Y-pipe. Figured I would just buy headers and a y pipe.

So About a week ago I put in 8 iridium plugs, 8 new wires, pacesetter longtubes/y-pipe. Felpro 1406 gasket, ARP studs, 2 new bosch o2's. I figured that would fix ALL my problems in one fell swoop. So me and my friend took it for a run a little after I started it, everything sounded great. Except it still cut out at around 4500rpm-redline.... Wasn't missing at all besides that though. Took it about 30m back home and it was missing very bad while accelerating. If I very slowly brought it up to speed it wouldn't be as bad but the moment I give like 1/4 throttle it would cut out bad.

Checked my codes again and I had a misfire in cylinder #3, Checked the wire and it wasn't even close to the headers. Checked it again later and it turned into a Multiple misfire! Now what I've noticed is when I first start it up it runs really good for about 2 minutes or so. After it warms up it will straight up explode almost out the exhaust at idle and "burple" a lot when I let off. Oh and supposedly the last owner replaced the opti last year.

You guys think it's my opti spark? or could my o2's be sending false A/F info?? Seems like it runs too rich to me. Thanks for your time! I've got waaaay too much money in this thing and would like it to be fixed...

 

So it runs fine until it goes to closed loop.
i think 02 issue.
Change o2 sensor. Maybe switch from left to right and see if that helps.
Did you use good quality 02 Extensions?

 

Try looking under your hood in the dark and see if you can see any currents going through your wires. I once replaced my LT1 spark plug wires with some alternative brand and it did just what you're describing. I went outside in the pitch black and started the car and looked under the hood only to see my very own lightning show. Took those crap wires off the car and spent some cash on a good brand and problem solved. It also helps to to make sure your wires clear any hot zones even if its just close enough to the header but not touching it can still make it toasty inside.


I like using heat shield boots when running plugs an affordable but worthwhile investment. I have Jet hots LT's so it helps a lot.

 

I didn't know there was such a thing as "good" o2 extenders?? I used these http://www.ebay.com/itm/Set-of-2-LS1...72.m2749.l2649

Think they're just garbage? and if so, what should I use?

I have the boots on them all actually lol but I'll go out tonight and see if I see anything.

 

If your plug wires are routed through ALL the stock looms/brackets they will not burn on stock or header exhaust. If not and you keep burning various wires you need to secure them away from header.

Depending on header you may need some form of heat shield for some of the plug boots. I use the GM factory metal ones on 2 of my plugs

As mentioned, in the dark look closely for plug arc. A spray bottle to mist them "helps"....and if you don't look from underneath also after not seeing any arc from up top....you didn't completely check. Been there

 

I agree, sounds like a issue with the ignition a heat shield that might help.

https://www.summitracing.com/parts/v...BoCSEoQAvD_BwE

 

Get rid of those iridium plugs and put standard copper ngk
tr55's in. The tips fall off those plugs like constantly.

Also make sure your firing order and wire routing correct, I had 3 and 5 mixed up and in ran fine for the most
part but would miss and throw codes.

 

This. Your symptoms sound like a plug wire may not be routed correctly. Don't use heat shield. Not necessary. Hopefully you have wires that are 8mm or less. Anything more and it'll be next to impossible to use the stock routing, which i the best unless you go over the valve cover. Check the O2 wiring as well to ensure it has not burned up.

 

Op has headers and "if" any cyl primary is close to plug boot the shield is needed to prevent that boot from decomposing/burning. IDK what headers he has but my #7 plug boot just crumbled after years from heat and #5 was fatiguing from heat also so I put on 2 of the factory heat shields I had...YMMV

FWIW I have had 2 sets of 8.5mm wire run completely through all my stock looms & brackets without issue. Snug but fits

 

Maybe B-body ones are different. I can barely get 8mm wires into the slots behind the power steering pump. As far as plug wires go, if not using the stock locations, perhaps that kind of shielding is necessary. If running through stock locations, not necessary at all. All it does is leave less room between plug wire and primary for a better chance of contact and eventually burning through.

 

I've got pace setter LT's. I did use the stock looms. For the most part, the metal tube thing was messed up when we got down there so I couldn't use that. I should get time tonight finally to look at the "light show".

Oh and I checked my voltage going to my B1S1 and B2S1 o2's and it was fluctuating between 0.1 volts to 0.9 or so. And both had a -8% at idle whatever that means.

 

Not sure what you mean by "metal tube." There should be a rail bolted to the block on each side where you can lay the plug wires in for the 3,5,7 and 4,6,8 wires. If they are not there, ziptie them by any means necessary.

 

Yeah haha that's what I meant. You think a zip tie would actually work? And not melt?

 

If you're talking primaries then absolutely not. I've always used the stock locations because it was so easy. If those rails aren't there I don't know where else you can tie them to. Preferably something that does not have the potential to reach 1200*F...

 

Alright so I just went out and started it, cylinder #5 was arcing right away. When I first got the problem about a 2 weeks ago I had cylinder #3 misfire code, took of the wire and it looked good so I put it back on. Then it changed to a multiple misfire. Checked today after I got off work and it changed to misfire #6? I believe...

Maybe I just didn't run them well enough?

OH and I noticed on the driver's side, whatever the sensor is that's in the block is broke and nothing is connected to it. Any idea what that one is?

 

Alright guys, So I unplugged both my o2 sensors and it ran waaaay better.

Still stuttered a bit but is much better, still have a misfire for number 6 now, haven't checked that out yet but does that I need a tune?

 

Are the headers you installed ceramic coated? If so, I think that's been known to foul O2 sensors during the initial burn off of the coating. I don't know if Pacesetters are coated inside & out, but that could potentially be an issue.

 

No. For peak performance you could probably benefit from a tune, but just to get it running normally, no tune necessary. Not sure what you mean by "way better." Are the misfires gone? You need to check every wire that is remotely close to your primaries and collectors to ensure none of them are damaged or burned up. There is a slight possibility your O2's are fouled. .

 

Well one of my driver side plug wires was burnt,changed it out ran better. Then I got a code for a #5 misfire I believe, so I'm sure it got burnt too.

But the miss isn't gone but with the o2's unplugged it doesn't miss as bad/often.

 

You really need to run your plug wires through ALL of the stock looms and brackets or find some way of securing them away from your headers. You have repeated burnt plug wires so until you resolve how they are secured to the motor they will continue to burn on your headers.

The pic I posted earlier shows the DS bracket and the PS is similar but shorter

use some dialectic grease on boot ends