View Full Version : wierd intermittent running problems...clueless

11-15-2008, 11:50 PM
ok fellas here is what is going on. I just got back from iraq and picked up my car fresh from the tuner (respected tuner from here on LS1tech). The car ran perfectly smooth and pulled very hard. Over the course of the week the car continually ran worse and worse.

Known problem:

for some reason the coolant temp guage stopped working. I replaced the tempature sensor on the head and the guage did not start working again. I dont know what is going on there but im guessing when the shift light and the guages were installed a wire was knocked loose.


when i picked the car up it was about 3 days from the tuner and ran like any small cam car would. Nice loppy idle and stayed about 900 RPM. On about the 4-5th day after the tune the car would start and idle irratically. bouncing from 400-1300 rpm and eventually settle out at around 1100 rpm and fall to 900 rpm over 30 seconds or so. It has been like that ever since.

Driving manners:

when i picked the car up the car would drive from stop sign to stop sign around town smooth as could be and go through every gear all the way to 6th on the highway with no shaking or vibration. The car ran like it did when it was a bolt on car. Again 3-5 days after the tune the car will shake the shifter out of the console in every gear from 1000-2200 rpms and generally runs rough and shaky. When taking off from a stop sign i have to rev the car which is quite rough and sometimes it feels like something is holding it back from trying to get running. On WARM starts the car cranks for 3-5 seconds before it sputters and fires up. On the highway if i do try for 6th gear it begins to shake violently and will not pick up speed even if floored.


the car threw some codes that i had scanned at auto zone. One of them was for the temp sensor not working. The other one was for insufficient injector circut output or something of the sorts. This is the one that intrigues me because it wasnt there when the tuning was going on. I changed the TPS sensor because thats what the little slip reccomended. That did nothing for the problem.

What do you guys think i should start with. I plan to unplug an injector at a time to see if the are all working properly. If that doesnt work or show any differences i will prolly start pulling plugs and checking for spark. Other then that im clueless fellas. what do you sudgest?

thanks alot for reading the long post.


11-16-2008, 01:54 AM
after more digging my tuner says a few of the fueling tables are run off of the coolant temp sensor and its reading causing it to run extremly rich and causing cam surge and the rough idle....

i have already changed the sensor and it didnt fix the problem...where do i go with this? how do i troubleshoot the temperature sensor problem?

11-16-2008, 08:51 AM
A good place to start is checking all the fuses since the electrical system was worked on (shift lights and gauges were added).

From there you'll probably have to trace the wiring connection for a short in the sensor line. You sure you put the correct replacement sensor in it?

11-16-2008, 11:19 AM
this morning i am going to check all the fuses but the wieird thing is every part of the cluster works except the coolant temp so i dont think its a fuse. im pretty positive that i got the right sensor. it looked identical to the one that came out of it and its the one that advanced auto pulled up on the computer. I guess im going to be tracing wires. how far and to were does that wire run?