LT1-LT4 Modifications - engine missing big time...

hey guys my car has been missin real bad, it gets werse when its under load (i.e. under 1500 rpm or when you get on it) and shoots black smoke out of the exhaust. the best way to describe it would be that it stumbles and there is a big power loss. i already replaced the optispark coil control module and the plug wires are in the right order. thanks for any help!

Are there any codes?

Check the ECT in the water pump and the O2 sensors.

the service engine soon light cuts on and off and it doesnt seem to run better when its off but i know that i checked it one time and it did give me an o2 sensor code, even though i have them plugged up i still have lt's and can i be stupid and ask what is a ect?? hahah

ECT is the temp sensor in the waterpump. If it goes back it can make false readings going to the pcm and make it run like crap.

Ah I see that's a good thought, I will most definitely check that! Any other thoughts while I got my sleeves rolled up?

My 93 did the same thing and it was a cracked porcelain on the number 5 plug. Obviously whoever installed it, tweaked it enough to crack it. Check to see if one of your exhaust header tubes are cooler then the others or if your still with the cast manifold soak with water one a cold start and check the plug with the last port to evaporate the water. If so, change that plug first.

Joe

http://shbox.com/1/4th_gen_tech1.html
This sight will become your best friend.

http://shbox.com/1/4th_gen_tech2.html#ect
This link has the table for checking the ECT.

Guys y'all are the biggest help ever, a dummy like me would be lost without y'all haha I'll check that sensor and the plugs and hopefully that just might be it!

I was in the same boat as you about a month ago, dude. Clueless and questioning. Once I get some money to buy some mods, I'm gonna seem just as clueless as before lol.

Hahah good to know I'm not the only one! Hahah

We all gotta start somewhere.

ok so update on the big problem, i checked all the plugs and they all seemed good except one on the passenger side which didnt have carbon on it so i replaced it and that seemed to help a little but not much, but whats weird about it is the black smoke is coming from the drivers side. so if its not a plug or a wire and ive replaced the distributor ignition control module and coil (and the mass air flow and map sensor ect for what its worth) then what could it be? injector dumping too much fuel? you tell me thanks guys

I am pretty much in a similar situation. After changing plugs, O2 sensors, cleaning MAF it still runs rough. I throw the famous code Po300. Ths is only after it warms up. When cold runs great.

I will look at that water pump thing too.

I guess my question would be wouldn't it be cheaper to have the car scanned while it is running to pin point the problem? I am getting tired of tossing money at it.