Hey guys, I have a 1996 Firebird Formula. I bought the car with 101K Miles...my third LT1 F-body. The car was running like crap and the LOW COOLANT and SES light were on. I traveled 800 miles to pick up the car and my code scanner was at home, so I figured I'd tune it up and put a water pump on it before driving 800 miles home.

The car was hesitating at first, but cleared up at times and ran semi-fine. It never ran like my fairly stock 95 Z28 or even my stock 94 Z, and this car has a B&M shift kit, Edelbrock shorty headers, Magnaflow cat-back, K&N FIPK, and a Power Programmer...it had old Split Fire plugs, 6 MSD Plug wires and cylinders 6 & 8 had half MSD and half stock plug wires. Somebody had cut them in half and spliced them together to run along the a/c lines lmao. Anyway, I figured if I tuned the car up it would run like crazy.

After installing everything the car ran *alright* on initial start-up. No misses or anything. I took it out for a spin and it had some hesitation throughout the RPM's and the SES light came on while running it hard. After driving the car normally the SES light would go off. I then installed the power tuning to see if it would improve the perfomance. I was driving the car to the parts store to return the core water pump and stopped by the chinese restaraunt. Came back out, fired the car up, put it in reverse and it would barely move without stalling. I pulled it back into the parking spot and reved it a couple times...it felt sort of like it was hitting a rev limiter at 2500 RPM's at half throttle. Full throttle would make it past 2500, but it was missing in the high RPM's as well. Took it out the next night and it ran pretty good...not how it should be running, but it wasn't missing as bad. After running it hard for around 10 minutes, I felt the car lose power, idle rough, and it was missing. I figured it was a dead cylinder. Took it to my girlfriend's aunt's house and let it sit overnight. Started it up the next day and started unplugging the injectors. Cylinder 6 was dead. 4 seemed to be dead as well, but not all the time.

I had to be home so we drove the car on 7 cylinders for 800 miles. Anyway, the next day 4 was firing, so I put the plug from cylinder 4 into 6 and put one of the old plugs in cylinder 4. fired it up and 6 was still dead. I took one of the old MSD wires and temporarily replaced the number 6 wire. This MOSTLY took care of the miss until I took it for a test drive. it started doing it again. I ordered a set of Accel wires to replace the Advance Auto Parts brand ones I was stuck buying while in Florida. Hooked up the code scanner and pulled out a P0300 while idling, and a P0306 while driving down the road. BTW the plugs are NGK Iridium IX.

This is what the scanner is telling me -

1 CODE
P0300
MIL ON
MONITRS
2 Inc.
Catalyst
Sec Air
6 Ready
Misfire
Fuel
Comp
02 Snsr
02 Htr
EGR

It gives me the same information for P0306.

I've had 2 other LT1's and replaced the entire opti each time with no problems...this is the first time I've only replaced the cap and rotor button. After taking the distributor apart, the cap and button didn't actually look TOO bad. There contacts on everything were slightly corroded, but not burnt away or anything. Also, there was oil inside the opti...looked to have leaked through the timing cover seal into the unit, but I'm not sure.

I'm also not sure what else is done to the car as far as internal engine mods. The water pump and timing cover had been removed at one point in time. The harmonic balancer was replaced. Whoever had the car before the guy I bought it from had put some money into it. It has Eibach lowering springs, KYB Gas Adjust shocks and struts and weld-in sub frame connectors so??

I'm stumped. anybody have any suggestions as to where I should start with the troubleshooting? I'm going to put the plug wires on tomorrow, and maybe check some other stuff?? Any help would be greatly appreciated. Thanks ahead of time.

Paul

 

Start with the plugs and wires. Bookmark this: http://service.gm.com/gmspo/mode6/index.html It'll be helpful in the future.

 

Thanks for the reply moparman. I changed the wires today and it fixed 90% of the problems. 6 and 7 plug wires were toasted from the headers...I didn't see this because of the protective sleeves I put on before installing the wires last time. I re-routed the new ones as far away as possible.

Anyway, the MIL is no longer on, but the car isn't running the greatest. After installing the wires I fired it up and let it get to operating temperature. Tried to rev it up and the car wouldn't take fuel unless I let off the throttle a little bit. Wide open, the RPM's dropped to 500 and sounded like the engine was going to die. I drove it 5 miles to a gas station to see if it would throw any codes but none. Put a bottle of dry gas, another of fuel system treatment, and some octane booster in an empty tank and revved it a couple times..it cleared up immediately...I then topped it off with $20 of 93. It ran a helluva lot better on the way back home than I've ever felt it run, but it's still not impressive.

I'm going to check the fuel system tomorrow, as I think that's where the problems are coming from now.

I'll keep this post updated for future searches.

If anybody else has any input or suggestions, please feel free to reply.

 

Be sure to put a fuel pressure tester on it.

 

hahaha throwing a P0306 and P0300 again. This is the fourth time the cylinder 6 plug wire has been toast. I've gone through a new stock wire, an MSD wire and now an Accel. None of the wires ever look burnt, but? The headers aren't coated whatsoever and 6 and 7 are both entirely too close to them. I guess it's time to look into some other routing method.

 

You said, you have edelbrocks (TES?) headers there? I had them before, uncoated; wires can be routed in a way, that they will not burn. Examine boots for dryness/cracks. I ran Moroso blue wires and Taylor Thundervolts 11mm wires (still have them) without problems. Heat sleeves are of some help (DEI), but wires can still melt inside of them.
Your headers may be getting too hot, as a result of fuel burning in them. If your headers getting red from heat, wires will not survive and you need to fix that problem first. Just a thought.

 

valter, they're the Edelbrock TES headers...p/n 6602...must be an older version of what they're selling now? But...they don't actually get glowing hot, but they do put off some heat. I bought some wire loom seperators that came with some nice polished brackets with a large mounting hole drilled in each. The brackets have a place to attach the seperators, so I think I'm going to put two of them on the passenger side valve cover and run the wires that way...I think I've got the driver's side taken care of. Guess I'll order another set of wires tomorrow and use the ones I need, put back the burnt ones and return them as a defective set. BTW they're Accel 9000 series wires. Wish I would have looked at the Summit website before ordering, or I would have gotten something better. I was planning on trading the original Advance brand wires in on the Accel's though, but it wasn't a manufacturer defect... Anyway thanks for the reply. I'll take some pics after I get everything ran. Once I get the ignition straightened out I'm going to try to get everything else in order, but until then...

 

I got the problem fixed...I bolted 2 brackets to the passenger valve cover on the front and third valve cover bolts. The brackets hold 2 plug wires each, so I just ran #6 and #8 plug wires up above the headers to the first bracket/holder, then parallel to the valve cover to the other bracket...I then ran them down behind the alternator and met them up with the #4 and #2 wires. Looks good, everything is great...no burns, no misses!

Now throwing P0400...guess I'll be working on the EGR next.

Also picked up a bone stock 94 Z28 6-speed with nothing done to it and 111K on the clock. It will SMOKE this piece of crap pontiac for some reason...and I mean SMOKE it. Hopefully somebody will buy the firebird soon. Anybody interested? lol

 

i have a 1996 Pontiac T/A lt1 and it had P0 300 code pop on it one and i change all of the opti **** lol it did not fix but what i did find is that the intake bolts were lose after i got them back to spec the P0 300 code is gone in if your opti has vacuum line to it see if you can pull a vacuum in it if you can't you have a leek i found a crack in my cap just above Number 4 tower at the screw .i hope that help some ..

 

I used Taylor full metal jacket wires and have been okay so far. I also had issues with toasty spark plug wires.

 

13 year old thread folks.......

 

I am guilty of being blinded by new posts button >.<