95 LT! open loop problem
Thread Starter
Drifting
Joined: Dec 2002
Posts: 1,890
Likes: 376
From: Montgomery NY
95 LT! open loop problem
Running out of Ideas have a 95 6 speed in the shop. when cold , less than 140 degrees the car bucks and kicks . pops back thru intake showing all signs of a lean condition . let off throttle to 25% and runs smooth again
just as it gets to 140 degrees and closed loop it runs like nothing happend.
history of what has been done already local Chev dealer replaced optispark
plugs and wires. replaced fuel pump . then said it must be fuel injectors.
thats when I came in as he it pulled from dealer and blessed me with this problem . I changed out engine computer with a good used one to test same problem . all sensors are within range fuel pressure at 44 psi under load no check engine lite and no codes . any Ideas?
sorry about 4 posts thought my computer was locked up and didnt think it posted
how do you delete the other posts?
just as it gets to 140 degrees and closed loop it runs like nothing happend.
history of what has been done already local Chev dealer replaced optispark
plugs and wires. replaced fuel pump . then said it must be fuel injectors.
thats when I came in as he it pulled from dealer and blessed me with this problem . I changed out engine computer with a good used one to test same problem . all sensors are within range fuel pressure at 44 psi under load no check engine lite and no codes . any Ideas?
sorry about 4 posts thought my computer was locked up and didnt think it posted
how do you delete the other posts?
Last edited by paulywannafly; Mar 6, 2007 at 09:12 PM. Reason: duplication 4 times
Racer
Joined: Feb 2006
Posts: 269
Likes: 0
From: Vancouver B.C.
Well, providing the used ECM is actually operating normally.....I'd first look for codes.
Once you have those, it may tell you specifically what is failing and you can repair that sensor or item.
My first thought was the tempertaure sensor (on the water pump) that the ECM reads from to establish HOW to run. But that's just a guess.
Again, the codes are critical.
Additionally, the FSM (factory service manual) would be/is critical to properly diagnose and isolate problems....so getting that would help immensely.
Best of luck.
Once you have those, it may tell you specifically what is failing and you can repair that sensor or item.
My first thought was the tempertaure sensor (on the water pump) that the ECM reads from to establish HOW to run. But that's just a guess.
Again, the codes are critical.
Additionally, the FSM (factory service manual) would be/is critical to properly diagnose and isolate problems....so getting that would help immensely.
Best of luck.
Thread Starter
Drifting
Joined: Dec 2002
Posts: 1,890
Likes: 376
From: Montgomery NY
No codes stored in either pcm along with no service eng lamp it does light up during the lamp test . while driving with a tech 2 hooked up all sensors
read normal you can watch the coolant temp go to 140f it goes closed loop and your driving a normal car again . just will not make power when in open loop
read normal you can watch the coolant temp go to 140f it goes closed loop and your driving a normal car again . just will not make power when in open loop
Team Owner
Joined: Mar 2001
Posts: 30,856
Likes: 293
From: Boston, Dallas, Detroit, SoCal, back to Boston MA
What's the outside temp?
It's not putting in the extra fuel the engine needs when it's cold.
The temp sensor is on the waterpump. It's real easy to shear off when changing the belt.
It's not putting in the extra fuel the engine needs when it's cold.
The temp sensor is on the waterpump. It's real easy to shear off when changing the belt.
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
Well the easy thing to do is let it idle for 5 or so minutes until closed loop. 
Not what your wanting to hear, I'm sure. Have you tested the injector coil resistance with an ohm meter? How many miles on the injectors? Have you checked for fuel pressure leak down? Checked the AIR system? You should be looking for things that do not cause codes. If your working on it yourself... a FSM (factory service manual) will be a great tool to have.
Not what your wanting to hear, I'm sure. Have you tested the injector coil resistance with an ohm meter? How many miles on the injectors? Have you checked for fuel pressure leak down? Checked the AIR system? You should be looking for things that do not cause codes. If your working on it yourself... a FSM (factory service manual) will be a great tool to have.
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