1999T/A

iTrader: (4)

You would think this would have happened when I had all the wore out plugs and wires on the car . But nooooooo it waits until I give it a tuneup before it starts acting up . I mean the plugs were wore out to like .070 and a few of the wires were hard as a brick , you could break them like a stick .

When I did the headers , I changed the plugs and wires . The car ran great for like 4 days after the install , then after a WOT run on the beltline in Raleigh , it started missing and sputtering and backfiring real bad . I limped it to work and cut it off , then started it up again and it had appeared to straighten itself out . I think nothing of it and went on to work . When I get out to go home , I start the car , no problems at all . Jump on the beltline and get off on Lake wheeler road some 7 mins later and thats when she started back hesitating and backfiring . I limped it as far as I could , to my mother in laws house. It sounds like it has a performance cam in it when it stumbles. It seems to get worse when it warms up completely . It still stumbles when cold but not that much and you can get on down the road.

I have checked all the wires for cuts , burnt areas etc and there are none . As a matter of fact , there are no wires touching the headers at all . I did a real good job of keeping them out of the way .

The back two plugs on the driver side were glazed and not firing at all . I replaced those two again . The other spark plugs are soot black , but firing . It is puffing black smoke out of the tail-pipes during idling and if you get on it .

Any insight as to what could be the problem would be most appreciated . . .

Maybe it just needs a cap and rotor ? ? ?

98TADRIVER

iTrader: (36)

check to see if you bumped or cracked your coolant temp sensor, its on the drivers side in the head toward the front of the motor. my buddy did that, so it wasnt connected and the computer reads like -37 degrees so it was dumping fuel in there like a ****!

Ralls

iTrader: (32)

Or check for exhaust leaks. Maybe the bolts loosened up and unwanted oxygen is throwing off the o2's.

1999T/A

iTrader: (4)

I replaced the temp sensor with a Wells one since I broke it getting the manifolds off .

No leaks at all , and I checked the bolts and they are all tight as they can be .

I wonder if it might be the O2s . I had to replace one of them since I couldn't get it out of the manifold . I replaced it with a Bosch OE replacement from Advance . I used the O2 wire extender kit that came with the headers , where you have to use butt connectors to extend the wires. I made sure they were all nice and tight , but that dont mean anything. They could be having problems getting a signal to the PCM. I tried to solder them but they have aluminum wires and they wouldnt accept the lead solder .

every time it throws a code and the SES light comes on , it seems to run better until the SES turns off , then it runs like crap again .

This doesnt sound like an Opti going out does it ? Optis start missing @ high RPMs or totally fail and not start the car when they are going out right ?

thesoundandthefury

iTrader: (3)

Sounds like O2's. Does the stumble clear up when you go WOT?

If you used any kind've gasket sealer when installing your Mac's, that could be the culprit. When the hot exhaust gasses begin to cook fresh gasket sealer, the sealer smokes and the fumes can sometimes foul O2 sensors.

*EDIT* My bad, I was looking at the wrong car in your sig when I said "Mac's." Replace that with "LT's."

1999T/A

iTrader: (4)

It clears up a bit a WOT , but the plugs are so fouled that it doesnt stop studdering altogether .

It would make sense also that my driver side cylinders are gas fouling because that sensor was an old one from the manifold and the passenger is a new one . The passenger side plugs are just soot black , but they are firing .

I used no gasket sealer whatsoever in my swap . I used OEM MLS gaskets from GM .

Ralls

iTrader: (32)

I would get o2 extensions instead of the "do it yourself" ones. There could be a short somewhere and it's not getting the right feed to the o2, not necessarily the o2 at fault. There has also been quite a few complaints about the Bosch o2's.

1999T/A

iTrader: (4)

Welp , sure enough , I got a code 64 , BANK 2 (the new O2 I just bought) HO2S LEAN . Looks like I do have a bad connection . I am just going to buy new O2s and a set of O2 extension cables to make sure this wont happen again .


Thanks to all who responded ! Looks like this case is solved !

SlowGreenTA

haha. We did this EXACT same thing and had the EXACT same problem to my car. I was all ready too. I bought O2 extensions, was getting everything taken apart and going back up well. Little did we know that when I bought the extensions a year ago, I did so after installing my O2 sims. My rear O2 sensors are square type connectors, the fronts were flat connetors, and I got square connector extensions. so we had to DIY some extensions. The car is running just like you're describing here, just basically rediculously rich because of what I assume is now a bad connection on an O2. New extensions and O2 sensors are on the way!

-Josh

GreatWhiteZ28

iTrader: (15)

Excast thing happend to mine after my L/T intstall, had the "do-it-yourself" extenstions on and those were the problem, replaced those with the extentions and along with Delco 02s and never had another problem

1999T/A

iTrader: (4)

Where is everyone getting their Delco O2s ? I cannot find them anywhere except the dealer . . .

RK2K2WS6

iTrader: (1)

I had the same problem, i put the coolent temp. sensor on and it fixed the problem.