Hello,

This morning when i started my 98 GST Autotranny wich have run smoothly without any recent problems, my RPM indicator was not moving at all. After driving 2-3 miles, it started moving up and down and also going a full 360 degrees round before settling. The RPM was as normal, only the indicator needle was crazy. What sensor is making the RPM indicator readings?

That was the first stage of my problem.. then after driving some more, the engine light came on and the car was performing poorly, so i drove over on a bus stop and found the engine running so poorly it almost stopped at idle. Engine also shaking a bit more than usual. After shutting off ignition and starting up again, it got better for a while, i could drive normally, but then again it hit back just like the first time.

To me it seems like one of my sensors is causing the problem, as the RPM indicator is having problems at the same time. I guess the RPM indicator readings is calculated from a few of the sensors, like the cranck position and angle sensor or something?

Maybe the poor performance is due to a defect knock sensor causing the idle timing to be adjusted by the ECU (again causing poor performance, to stop knock from coming again)?

My head is out of ideas, i have checked about all electric connectors i could find and cleaned them with contact cleaning spray.. still same problem.. MAF sensor also looks clean.. throttlebody also clean..

Anyone? =)

do you hear ticking on the front face of the engine when running or cranking?

The times it runs like normal i dont hear any extraodrinary ticking, when it runs poorly it is not ticking etiher but it seems like misfiring and sounding almost like a old VW Beetle, maybe due to the ignition timing adjustment made by the ECU or something.

I think this has to be an electrical issue as the RPM indicator sometime dies, other times go crazy and also because the car can run normal in between, but then switches to run poorly at once when the CEL lights again (almost like the ECU decides the change at once it notice the error).

check the plugs and see if they are getting carbed up or even oil foiled, that could tell u if it's a fuel issue or oil, stay simple to start..there is a gear that is in the tranny that has a cable feed to the rpm gauge probably check that too.

Hey dixxy how's that tickbite(flåttbitt) going?

HAB

Sent you an e-mail, pls keep thread topic..

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There is no problems with the plugs or plug-wires, the wires is NGK high performance wires (ME77) and also quality plugs. The sparks is also fine.

I have measured the intake air temperature sensor, giving me a reading of 2.28 kohms, and thats about 18 degrees celcius and correct. But maybe the problem is because of the MAF sensor? the engine acts just like it, thats for sure.. but that dont make so much sense as the RPM indicator is acting like it is..

no check engine light either? try checking codes u could have a code that hasn't matured yet.

CEL coming on only when the RPM indicator is moving and going crazy, otherwise it runs smooth as usual. Also it only occurs when the engine has been running for 15 minutes or so and at normal working temperature. (i reset the CEL just for testing purposes and found that the engine dont run poorly when reset, thats a good indicator of a sensor problem and nothing major)

A family member just changed the MAF sensor on a Mercedes and he told me his car had just the same symptoms, but that shouldnt f.... up the RPM indicator i guess..

i would check for pending codes.

I will on monday when the local dealer opens again, but im still trying to figure out and get an understanding already now =)

I was at my local Mitsu dealer that charged me USD 140 just for reading the error code (5 minutes of work).. Well.. the error code was "P0300 Misfire Detected", and it was believed to be a coilpack error.. i will check the coil further before ordering.. the part prices in Norway is unbelieveable, a coilpack cost about 900 dollars, but when ordering the same original part at www.extremepsi.com it cost only 149 dollars, and the delivery time is actually only 4 days from the US, so no wonder i order all my parts overseas..

Here is the latest overview: My RPM indicator plays dead until the CEL come on when the car has been driving for approximately 20 minutes, and then the RPM indicator moves like crazy (not the engine revs itself) and also the misfire starts.. when reseting the CEL and starting a cold car for testing, it runs smoothly for new 15-20 minutes until the same problem occurs. Seem to be a HOT car problem. Should a coil fault also make the RPM indicator go limp, or is the misfire due to a bad sensor? Any new suggestions?

Ive checked the plugs, they were changed last time about 1.5 years ago, two of them showed some wear and two were fine. But i'll replace all 4 today to see if this settles it. Random misfires could be it.

Problem soon fixed :57: today i looked in my chiltons manual and measured the coilpack. I found the high voltage side to be within the normal kohm range, but the low voltage side had twice the resistance it should and thus the coilpack will be changed.. also throwing in new plugs and plugwires at the same time :) thanx for the feedback..

Ive changed NGK plugs, brand new NGK plugwires and also the coilpack after the misfire code (0300). But still the rpm indicator plays around, CEL light only coming on when the RPM needle moves, when it acts "dead" my car runs fine.. any idea anyone? What more could there be to a random misfire/ignition problem? sensors?

Now i also changed my crank angle and camshaft position sensors, but still the same. My repair store says it might probably be the ECU that is f..... up. I have problems finding someone on ebay that will ship to Norway, so i guess i will ship it to a ECU repair shop instead. Anyone agree, disagree that it might be the ECU? All instruments reading ok on the testing tool.

i had the same problem with the shaking of mi engine and the rpms goin limp. when it went limp i turned the idile up and it didnt move but when it did decide to move it would wildly jump all over and he car would die. a friend of a frine d took a look at it and he found a vacum hose was unhooked. after rehookin it up the rpms were fine but mi cel came on and i took it and it gave the code for random misfire i was told it could b 2 things the ignition coil or the ignition control module. im gettn the coil this week and im hopen that fixes the misfire cuase the model is like $100 and u need 2 to replace them. but check ur vacum hoses and c if any r unhooked mine was on the side where the battery is im not sure if ur eingine bay is diffrent or not but i hope that helps