A couple of weeks ago I changed my plugs from bosch +4's to NGK TR6 coppers. My car was running rich before the plugs, but I could drive it fine. I also put on a new spark plug wire set. Now the car runs fine till it warms up, then it runs like crap and rich as hell. If I beat on the car it runs ok. the SES light will come on after about 20 min of driving, when the light is on, the car runs good. The light will then go away after a bit and the car will run like crap again. For some reason I cannot get a scan tool to work on my car, Ive tried a few. The plugs are black. I think this has somthing to due with the computer or its tune. What do yoy guys think? I think the car will run ok if I put the Bosch +4 plugs back in.

Car does not have any exhaust leaks
OPTI and O2's are delco and have less than 10k miles on them.

 

What is done to the car? Did you double check to make sure the plug wires aren't crossed? Did you try Autozone to have the car scanned? What did you gap the plugs at?

 

Car has heads, cam, + bolt ons. Autozones scaner would not work, Mine would not, and a tech II would not work either. Plugs are gaped at .035. NGK TR6 coppers.

 

The Bosch plugs could have been "burning" the mixture better than the NGKs. The car may be gumming up the plugs and getting a code saying the car is running rich (can't spark strong enough) and the computer leans the mixture out (making it run worse) which burns some of the carbon off of the plugs allowing it to richen the mixture back up (making it run good again). I'd say that you need to get it (re)tuned. This is just an idea. Keep that in mind.

 

The Autozone scanner will not work because they see the 1995's 16-pin OBD-II ALDL connector, and assume the can use an OBD-II scanner. You need an OBD-I scanner with an adapter plug to go from the 12-pin scanner connector to the 16-pin ALDL connector. Or you need to jumper the pins as Shoebox shows:

http://shbox.com/1/xraycable.jpg

Hard to explain why a Tech-2 wouldn't work, unless the fuse is blown for the cigaretter lighter - that also supplies the power to the ALDL connector.

 

Yep, didn't see the "95 LT1". OBDI w/ an OBDII plug. Pure genius. I've had that problem before.

 

I must be missing something: Is your car NA? If so whay are you using TR6s at .035?

 

Are the 6's the colder ones? I was wondering but I couldn't remember if the 55's or the 6's were colder. If you aren't running nitrous, the 55's would be better for you.

 

well I use the TR6 plugs cause I have 11:1 compression