Author Topic: Crankshaft sensor going bad? (Read 6042 times)

tumbler · « **on:** March 08, 2009, 12:38:05 PM »

Hey Guys. I appologize for all the threads lately but I think I'm making headway on my problem.

This all started with a periodic buck/jerk for a second then back to normal driving conditions. It was getting worse and worse. It eventually progressed to the point where I have almost no power difference between lightly pushing the pedal and WOT. I can hear the car missing. It stumbles upon take off and idles erratically. I've tested the coil packs, cleaned the MAF and ICV, checked the fuel pressure and all has turned up good. I then found that I had a failing headgasket (false boiling in the radiator). I did the headgasket swap hoping it would solve my problems but its still there.

Test driving it today the car is driving just as it did before. Except now when it bucks/jerks the RPM needles goes crazy. For instance, I was cruising at 2.5K and right as the car bucks the needles bounces extremely fast to 5K rpm then back down. For this split second the CEL light came on as well but then shut off after the bucking stops. This will happen every 2 minutes or so, its hard to say. The RPMs DO NOT jump up when the needle jumps its getting a false reading.

I'm starting to think that it is an issue with the ignition timing. Is the crank shaft sensor responsible for determining spark advance? Is it also responsible for relaying RPM to the gauge? Now that I think about it if the spark is advancing incorrectly that would explain why I get very little (if any at all) power gain by mashing the pedal.

tumbler · « **Reply #1 on:** March 08, 2009, 01:17:39 PM »

Update:

I just went out and tested the resistance between both the cam sensor and the crank sensor.

Crankshaft sensor - 600 ohms
Camshaft sensor - 1,516 ohms

Seems like both these numers are off of what they should be. The crank sensor is 50 ohms less and the cam sensor is 266 ohms more more then they should be. My question for you guys is do these numbers show a problem with either of the sensors?

monty23psk · « **Reply #2 on:** March 08, 2009, 08:57:27 PM »

Do the pedal stomp test to see what code the computer is having issues with. That will give you a place to start.

tumbler · « **Reply #3 on:** March 19, 2009, 10:16:56 AM »

Well I initially did the stomp test and got the "no error" code. a few days later I do it again and get the Lambda control error. I had already ordered the crank/cam sensor since I had suspected that was the problem. I installed the two sensors yesterday and it didn't change anything. I'm starting to wonder if I should just part it out, I've got no idea what it could be and I've spent a ton of time on this thing. It misses like crazy when first starting out from a stop, bucks/jerks while driving and is consuming more fuel than usual. It runs better when I start it up and the engine is cold...

beemer1 · « **Reply #4 on:** March 19, 2009, 10:31:30 AM »

Had the same thing happen to me when going on a trip from NY to SC. Halfway through the trip my car started bucking badly. Pulled over let it cool down and all was fine until the engine was warm again. Needless to say it took forever to get to my destination! Stomp test revealed Lambda sensor = O2 sensor.

Steve

Jimmy Lewis · « **Reply #5 on:** March 19, 2009, 03:29:03 PM »

You have the same exact symptoms that I experienced when my CPS was going bad. Its probably a break in the cable somewhere and the signal becomes intermittent explaining the bucking and poor running. A working used CPS fixed my problem, I would look into it. Good luck.

tumbler · « **Reply #6 on:** March 19, 2009, 06:25:52 PM »

Quote from: Jimmy Lewis;68581

You have the same exact symptoms that I experienced when my CPS was going bad. Its probably a break in the cable somewhere and the signal becomes intermittent explaining the bucking and poor running. A working used CPS fixed my problem, I would look into it. Good luck.

I was sure that was causing the problem. I replaced both the camshaft sensor and the crankshaft sensor and I still have the same problems. I might try the O2 sensor as mentioned above. Will my 93 have a 3 or 4 wire 02 sensor? I'm hoping I can use the 89 mustang sensor trick...

My sensor was brand new...so maybe I should try to track down one I know is for sure working.

B318M42W · « **Reply #7 on:** March 19, 2009, 08:13:43 PM »

tried testing the TPS??? or checking/moving if the connections are good in the black box under the intake manifold?

tumbler · « **Reply #8 on:** March 20, 2009, 08:21:48 AM »

Quote from: B318M42W;68597

tried testing the TPS??? or checking/moving if the connections are good in the black box under the intake manifold?

How can I test the tps?

I had all the connections off to do the head gasket. I reconnected them during reassembly and it ran the same afterward, minus the overheating part.

tumbler · « **Reply #9 on:** March 23, 2009, 03:43:45 PM »

Bump. How can I test the TPS?

RED IS 91 · « **Reply #10 on:** March 23, 2009, 04:36:07 PM »

here ya go............
Don't you have a manual