Car runs great in open loop. idles fine, drives fine... yet soon as it switches to closed loop it is just not cool at all. Idles rough, revs rough, cuts out almost dies while driving rough.

brand new gm O2's have been installed, checked plug wires and replaced them, check plugs and replaced them. I am losing my mind. Assuming its not the opti, or else it would run bad in open loop as well?

what else could be my issue? i have no SES codes, i can run datamaster and log it and post a video if needed. I am not sure what else changes in closed loop. any other sensors come into play? I am gonna check the MAF pink wire tomorrow just in case. I did just notice that my coolant temp gauge is acting up... it rises fast to the top like its overheating, then drops all the way down to cool and it will do it again... numerous times sometimes then it finally reads correct after some driving.. which sensor is that? block or waterpump? heard that can cause issues as well. ill record a video tomorrow if need be any suggestions would be great. thanks

 

Checked the coolant level yet? if it's low enough you won't get consistent readings off the coolant temp. sensor and the PCM won't get the AFR right on inconsistent temp. readings.

-ECT sensor
-Low coolant sensor

If these look ok and coolant level is good (bled the system since it started acting up?) data logging couldn't hurt.

Have a look here-the definitive how-to for checking the cooling system:

http://shbox.com/1/4th_gen_tech2.html#cooling

 

here is datamaster file

http://free-tjd1981.medialightbox.co...px?id=8iv396vf

 

im having the same problem

 

minus the coolant temp thing

 

the head sensor sends signal to the pcm. the water pump sensor goes to the gauge. 2 different sensors 2 different plugs. water pump will have 1 wire , head will have 2 leads. are there any mods done to the car? big cam or anything?

 

forged 383. stock everything else. hooker longtubes, madz28 tune, CAI, 1.6 roller rockers.. all emissions are removed.

 

This is weird, I know, but I had a similar problem that drove me nuts... until I replaced the coil wire. Car ran smooth and perfect until it switched, and then it would stumble, stutter, stall, etc.

 

are you using sims on the rear o2's? if its a 97 like in your name and actually has them.
by saying "all emissions are removed" you also mean the cats i take it?
how did you lengthen the front o2's harness?

 

totally spaced i dont have a sig on here. its in a 1995 no rear o2's. i used an o2 extension on the driver side and didnt need one on the passenger side. everything is removed but cats

 

what all did he program for ? did he disable all the emissions equipment in the ecm? you said no ses lights though. between open to closed the O2's come on. i know the ect, iat, map and maf are used for fueling before closed loop starts. can you pull the program on the ecu off and post it on another site? That doesn't require an account. also the datamaster file would be nice to look at on another site.

 

crap i didnt notice you have to have an account there! whats a free one? or i can send in email? csv version and or just the datamaster file itself if ya want.

he did disable all my emissions equipment, no SES lights are present now but the electric fan, code 77

 

here is a datamaster scan if anyone wants to take a look

http://www.mediafire.com/?mnywny2mztg

 

to throw more on the top, noticed today if i keep it revv'd around 2k maybe even less the headers glow pretty. thinking its running rich as hell.. just gotta figure out why