I recently had the head gaskets redone and the car was running fine. I don't use this car all of the time and started using it again. It starts and runs for a little while and then the RPM's start to surge and the car dies. It doesn't seem to do this while at idle. The car starts back up and does it again. I took it to the shop and 2 codes came up. Knock sen (est code) and Idle air valve were replaced. Same thing keeps happening. I read that it could be the crank sen and that there is 2 of them for this car. I had them do that sen and they said there is only one, they replaced it and the same code shows up (est). Any idears?

What is the fuel pressure when it dies, step one in the diagnosis, also post the engine when asking for help.

What is the fuel pressure when it dies, step one in the diagnosis, also post the engine when asking for help.

They checked the fuel pressure and said it was good. The motor is a 3.1 and they replaced the crank sensor on the block and car is still having the same problems. I have bought 2 senors for the car. Not sure where the second one goes? I read some where it goes behind the conveter? They said it goes behind the balancer but it's not there

They checked the fuel pressure and said it was good. The motor is a 3.1 and they replaced the crank sensor on the block and car is still having the same problems. I have bought 2 senors for the car. Not sure where the second one goes? I read some where it goes behind the conveter? They said it goes behind the balancer but it's not there

Mine is a 93 Cutlass Supreme ....one sensor is behind the harmonic balancer (24X). The long cylindrical sensor is at the bottom of motor near firewall in the same vicinity as the VSS sensor. To trace the 3X wiring out, you'll need to drain the oil and remove the oil filter to get access to the pigtail. Remove it and follow the wire until it leads to the 3X sensor.

I found that the 3X wiring itself was shorted out. Your best solution would be to replace the wiring (cut it out) and find butt-connectors with heat shring and replace wiring with new wire, like i just did. I also replaced the 3X sensor.

To replace the 3X sensor, you'll have to do it topside. I removed the the smog belt (ca car), serpentine belt (do with long breaker bar), powersteering pump (moved lines aside), alternator mount and alternator, radiator overflow tank and possible firewall connector (promotes easier access). Remove the airbox and disconnect and electrical tape both the main negative wire and it's smaller negative that grounds to frame. turn the key to on and leave in the on position and then put the car in neutral. Remove the (2) engine dogbones on the front of the motor and rotate the motor forward...the dogbones will have a locating hole on th e underside...you can then slip the bolt through to hold motor in place....best to use a long breaker bar or similar to rotate forward...takes a bit of effort.

See this post for details.

http://www.automotiveforums.com/vbulletin/showthread.php?t=768634&page=4



NOTE: the VSS sensor and the 3X sensor share the same color wiring (yellow/purple)...so it's easy to confuse them. You can easily access the VSS sensor by turning the wheel full left and removing the wheel. You see it as you look in....this is NOT the 3X sensor you want to get at.

Mine is a 93 Cutlass Supreme ....one sensor is behind the harmonic balancer (24X). The long cylindrical sensor is at the bottom of motor near firewall in the same vicinity as the VSS sensor. To trace the 3X wiring out, you'll need to drain the oil and remove the oil filter to get access to the pigtail. Remove it and follow the wire until it leads to the 3X sensor.

I found that the 3X wiring itself was shorted out. Your best solution would be to replace the wiring (cut it out) and find butt-connectors with heat shring and replace wiring with new wire, like i just did. I also replaced the 3X sensor.

To replace the 3X sensor, you'll have to do it topside. I removed the the smog belt (ca car), serpentine belt (do with long breaker bar), powersteering pump (moved lines aside), alternator mount and alternator, radiator overflow tank and possible firewall connector (promotes easier access). Remove the airbox and disconnect and electrical tape both the main negative wire and it's smaller negative that grounds to frame. turn the key to on and leave in the on position and then put the car in neutral. Remove the (2) engine dogbones on the front of the motor and rotate the motor forward...the dogbones will have a locating hole on th e underside...you can then slip the bolt through to hold motor in place....best to use a long breaker bar or similar to rotate forward...takes a bit of effort.

See this post for details.

http://www.automotiveforums.com/vbulletin/showthread.php?t=768634&page=4



NOTE: the VSS sensor and the 3X sensor share the same color wiring (yellow/purple)...so it's easy to confuse them. You can easily access the VSS sensor by turning the wheel full left and removing the wheel. You see it as you look in....this is NOT the 3X sensor you want to get at.

The sensor on the block has been replaced. The 24x sensor that is by the balancer is the one that has not been replaced. The guy said my car doesn't have one. This is the sensor with the wiring on it correct? I had purchased 2 sensors for the car.

The sensor on the block has been replaced. The 24x sensor that is by the balancer is the one that has not been replaced. The guy said my car doesn't have one. This is the sensor with the wiring on it correct? I had purchased 2 sensors for the car.

I don't believe that guy. It's a banana shaped sensor behind the balancer. I bought an autozone replacement. Wires are green/black/red and the connector is near the bottom of the radiator on the passenger side of the car. I would think that ALL electronic cars have one at the HB....but what do i know. Make sure you use an INCH/lb clickable torque wrench or don't overtighten it down like i did my 3X (probably the reason why i had to replace it.

If you haven't already done so, I would REPLACE the Ignition Control Module (it's 15 years old...think of all that years of heat on plastic and electronics), replace or repair the 3X wiring...again the wires are purple/yellow and trace them out to the sensor...if you don't, you could accidentally pull the wires for the VSS sensor...very important!!! (pick-n-pull junkyard or splice in fresh wire between connectors) from ICM to 3X sensor (my insulation was soft and Looose feeling from years of heat cycles...not gripping the wire firmly and exposed near the bend point at bottom of engine)

IMPORTANT: Make sure you use a harmonic balancer remover to remove the pulley AND a harmonic balancer INSTALLER to put the pulley back on. You will strip the center bolt threads, if you do not do this. Both tools can be rented @ autozone with money refunded upon return of the tool. Again see my original post that i linked in thread above for info. There will be some things like removing fender firewall splashguard, passenger wheel, remove holding screws on certain lines/firewall conn./ metal fluid lines to make removal of HB easier.

I don't believe that guy. It's a banana shaped sensor behind the balancer. I bought an autozone replacement. Wires are green/black/red and the connector is near the bottom of the radiator on the passenger side of the car. I would think that ALL electronic cars have one at the HB....but what do i know. Make sure you use an INCH/lb clickable torque wrench or don't overtighten it down like i did my 3X (probably the reason why i had to replace it.

If you haven't already done so, I would REPLACE the Ignition Control Module (it's 15 years old...think of all that years of heat on plastic and electronics), replace or repair the 3X wiring...again the wires are purple/yellow and trace them out to the sensor...if you don't, you could accidentally pull the wires for the VSS sensor...very important!!! (pick-n-pull junkyard or splice in fresh wire between connectors) from ICM to 3X sensor (my insulation was soft and Looose feeling from years of heat cycles...not gripping the wire firmly and exposed near the bend point at bottom of engine)

IMPORTANT: Make sure you use a harmonic balancer remover to remove the pulley AND a harmonic balancer INSTALLER to put the pulley back on. You will strip the center bolt threads, if you do not do this. Both tools can be rented @ autozone with money refunded upon return of the tool. Again see my original post that i linked in thread above for info. There will be some things like removing fender firewall splashguard, passenger wheel, remove holding screws on certain lines/firewall conn./ metal fluid lines to make removal of HB easier.

Your posts have been very helpful. I will call them today and see if they have made any progress. Thanks again

The key to all this is whether the car has spark and injector pulse when this happens and whether it will run spraying carb cleaner into the intake, has this been determined during all this back and forth about the crank sensor. Usually the ign module is more a problem on these cars than either sensor. I will never understand shot gun parts replacement without getting to the source of the problem, a scan will look at cranking rpms. if none the 3x sensor or wiring to the icm, or the icm is at fault. Check this link, this is not a full diagnostic procedure, it will only help, http://www.autozone.com/addVehicleId,1894202/initialAction,repairGuide/shopping/repairGuide.htm?pageId=0900c15280067e4d BTW, nicley done CaCutlassSupreme!!

The key to all this is whether the car has spark and injector pulse when this happens and whether it will run spraying carb cleaner into the intake, has this been determined during all this back and forth about the crank sensor. Usually the ign module is more a problem on these cars than either sensor. I will never understand shot gun parts replacement without getting to the source of the problem, a scan will look at cranking rpms. if none the 3x sensor or wiring to the icm, or the icm is at fault. Check this link, this is not a full diagnostic procedure, it will only help, http://www.autozone.com/addVehicleId,1894202/initialAction,repairGuide/shopping/repairGuide.htm?pageId=0900c15280067e4d BTW, nicley done CaCutlassSupreme!!

Sorry to steal your thunder Max. Listen to max (i stole his and zeroinfinity's ideas and ran w/ them), he helped me (yet again) fix my no spark problem. This time it was the insulation and the wires being melded together by years of heat AND OVER tightening of the 3X sensor, to the point of bending the securing tang...probably shorted the sensor also. I also just found out what that grinding noise was and replace the waterpump...that is EASY. Now pretty quite. All you can hear is a little bit of tranny whine in park, but i think that is normal.

i have found the same kind of problem on my 94 it was the cam sensor was the trouble i replaced it and it run fine , also the ecm under the coil i had to replace also but the sensor was the main cause but the ecm was bad also i changed them out car is running fine now. hope this helps

i have found the same kind of problem on my 94 it was the cam sensor was the trouble i replaced it and it run fine , also the ecm under the coil i had to replace also but the sensor was the main cause but the ecm was bad also i changed them out car is running fine now. hope this helps

I will know today if I have fixed the problem. I started to look at the wiring and it all looked good. After replacing the knock sensor and the crank sensor, by the way the car only had one (on the block by the fire wall) the second sensor that would go under the balancer is not on this car. When we changed the knock sensor on the car and still got the same code we figured it was a computer issue. I replaced the computer and I still got the same code est/knock sensor. Then replaced the chip inside the computer and sure enough the chip for the computer is called a knock sensor. It was very easy to replace, the computer is located under the washer fluid tank. The computer remanufactured from GM was $160 and the chip/knock sensor was $200. It's always better to replace eletrical stuff with new rather than from a junkyard. I could have gotten the computer and chip for $200 but I felt it was worth it to pay a little more and get the right parts from GM. Thanks to everyone for all of your help.