RPM tach and check engine light

[nick2003]

`I have a 93SC , sometimes the rpm needle goes limp and the check engine light then comes on, when that happens the car will sometimes stall and then I have a hard time starting it again. Eventually the rpm needle will go back to regular idling position and the check engine light goes out.

I had a diagnostic test done and the only code that came up was for the MAF
which was cleaned, could it be the crank sensor? Appreciate any help on this
annoying problem, the other day I was on the QEW and luckily coasted onto the shoulder after a few minutes the car turned over and the rpm tach was normal and no check engine light.

[charged92]

I had the same problem with mine a few years back. The only other symptom I had at the same time was the car would shake. Ended up being the ignition module. Hope that helps.

[fast Ed]

Those are often symptoms of a bad crank sensor, on the 89 - 93 cars too.

cheers
Ed N.

[nick2003]

Originally Posted by fast Ed N

Those are often symptoms of a bad crank sensor, on the 89 - 93 cars too.

cheers
Ed N.

yeah I think IM gonna replace the crank sensor , thanks for the info.

[93thunderbird]

mine also did that for about a week and then the crank snapped...

[Payton]

Originally Posted by nick2003

`I have a 93SC , sometimes the rpm needle goes limp and the check engine light then comes on, when that happens the car will sometimes stall and then I have a hard time starting it again. Eventually the rpm needle will go back to regular idling position and the check engine light goes out.

I had a diagnostic test done and the only code that came up was for the MAF
which was cleaned, could it be the crank sensor? Appreciate any help on this
annoying problem, the other day I was on the QEW and luckily coasted onto the shoulder after a few minutes the car turned over and the rpm tach was normal and no check engine light.

Have the same problem. took it to Ford, they suggested to change a crank sensor. I changed it, but no luck. Also, changed a TPS sensor, same results. Was adviced to change a DIS module. Looks like it didn't help either...

[crabmustang302]

Is our ring that is read by the crank sensor on the end of the crank or on the balancer? If its on the balancer your balancer could be breaking and causing the non read signal to the crank sensor.

Just a though

Garett

[SeanMatteson]

Originally Posted by crabmustang302

Is our ring that is read by the crank sensor on the end of the crank or on the balancer? If its on the balancer your balancer could be breaking and causing the non read signal to the crank sensor.

Just a though

Garett

Garett,

On the early style balancers ('89 to '93 inclusive), the sensor ring is mounted to the inner hub on the balancer. When the balancer fails, it's usually the outter ring that comes loose. If the balancer was about to fail, I suppose it's possible that the sensor ring might be moving around other than in the circle that it's supposed to follow, because things are 'out of balance', but the ring isn't mounted to the part of the balancer that typically comes loose (due to failure of the polymer that binds the outter ring to the inner hub)

It may be the same case on the '94-'95 style balancers, but I've never seen one up close to know.

...I'm not disputing your suggestion though. IMO, it is possible that nick2003's balancer is nearing failure, and occassionally the sensor ring moves away from the sensor enough that it fails to get a good reading.

Payton, did you remember to put some fresh heat-sink compound under the replacement DIS Module? That stuff is important.

Best regards,

Sean

[drummerzrok24]

I had the same problem a few days before I spun a rod. And it did it the same morning I was driving to school and about 10 minutes later it did it again, but then the squeaking and knocks started and that was all my engine did until it finally died later that afternoon.

[crabmustang302]

Thanks for the info Sean, I`m new to the SC`s, I have built several Turbo fords and put in stangs and such, It was just a thought when I was reading the thread and thought might help.

If all goes well I`m going to put a SC motor and trans into my 83 stang I have.

Sorry to get off topic, but if someone has a motor and trans and wiring harness and computer and any other parts needed, please pm me with what you have and a price.

Thanks
Garett

[Payton]

Originally Posted by SeanMatteson

Payton, did you remember to put some fresh heat-sink compound under the replacement DIS Module? That stuff is important.

Best regards,

Sean

Yes, Sean, I did put a lot of dielectric grease in between The thing is I bought a used DIS, there is no warranty it's working properly. After I changed it, I was driving my car for a week without a problem, and then, all of a sudden, it started to give a hard time again

[SeanMatteson]

Originally Posted by Payton

Yes, Sean, I did put a lot of dielectric grease in between The thing is I bought a used DIS, there is no warranty it's working properly. After I changed it, I was driving my car for a week without a problem, and then, all of a sudden, it started to give a hard time again

Payton,

Dielectric grease is not the same thing as heat-sink compound. You can buy heat-sink compound from Radioshack. I would try to replace the dielectric grease with heat-sink compound first, and see if maybe you've just overheated your DIS a little.

Regards,

Sean

[thekidz]

Hi Nick

This sounds like exact symptoms I had last year. Check engine light on rpm 0 check engine light off rpm normal. It was my cam position sensor that went. Cheapest sensor of the bunch and easiest to change. Give it a try

Good Luck
Craig

[Payton]

Originally Posted by SeanMatteson

Payton,

Dielectric grease is not the same thing as heat-sink compound. You can buy heat-sink compound from Radioshack. I would try to replace the dielectric grease with heat-sink compound first, and see if maybe you've just overheated your DIS a little.

Regards,

Sean

Oh, man, this heatsink compound is hard to find. I believe I was in about a dozen computer stores all over Downtown Toronto and it seens all of them were out of stock...
I was thinking about another thing: what if I put a layer of something with low heat conductivity rate in between??? Let say a plate of metal under the DIS module?

[fturner]

Originally Posted by Payton

Oh, man, this heatsink compound is hard to find. I believe I was in about a dozen computer stores all over Downtown Toronto and it seens all of them were out of stock...
I was thinking about another thing: what if I put a layer of something with low heat conductivity rate in between??? Let say a plate of metal under the DIS module?

The idea is to suck all the heat out of the DIS module into the a/c bracket that you can, not hold heat in it. A low heat conductive metal will only make the problem alot worse. You need to get that heatsink compound on there, as it conducts heat faster than the surrounding metals, and the a/c bracket metal will absorb heat faster than the DIS module.......... hopefully that is .

Unfortunately everything gets heat soaked after awhile and that shortens the life expectancy of the DIS module.... in other words, accountants got involved again in the design process and screwed it up as usual .

I've been reading that folks have used artic silver heat sink compound that is used with heat sinks in computers successfully with the DIS module, so you might want to check that out.

Frit