Questions and Answers

Dodge Intrepid Missing Q. 1994 Dodge Intrepid 3.3 liter 125,000 miles. Engine misfires between 1,500 to 2,000 rpm whether in park and revved up or in any gear while driving, hot or cold. Runs great below and above these rpm's. Have been to many repair shops and even the dealer, no fix. New EGR and VACC solenoid, plugs and wires, coil pack, coolant temperature sensor, cam and crank position sensors.

This is what I found at the 4 wire plug at the coil pack. 1 is 12V - okay. The other 3 are the driver circuits from the PCM and are supposed to pulse ground to the coil pack. The black wire is fine through the entire rpm range. However the red and white wires break up between 1,500 to 2,000 rpm.

I tried a used PCM, the salvage yard said that the car was driven in, no difference. (Yeah, I know what you're thinking!) Today I checked the crank sensor - okay. However the cam sensor seems to have a problem.

According to my Haynes manual I'm supposed to back probe the tan/yellow (+) and the blk/lt blue (-). The voltage is supposed to fluctuate from .3 (metal under sensor) to 5 volts (slots under sensor). Mine does the opposite! I'm assuming the new one is either wrong or defective.

Would this cause the problem that I described? Is my diagnosis and testing procedure correct? Any way to rewire existing cam sensor?

A. The camshaft position sensor generates a high/low voltage signal, as slots in the camshaft gear are detected. When a slot passes in front of the sensor, a 5 volt signal is sent to the PCM. When a slot is not present, the PCM receives a 0.3 volt signal. So you have the correct information. I would have tapped into the tn/yl wire and just ground the other teat lead. If you do that, you'll get the proper readings.

The trick is knowing at any point in time whether a slot or metal is under the sensor. But if it does cycle from .3 volts to 5.0 volts, it is working properly. In addition, if it were not working properly it would shut down the ASD and fuel pump relays and cause a no-start condition.

I think we have to look at the coil pack connector or the PCM connector for a problem. Get the male version of the terminal connectors and slide it into the female terminal connector. There should be a distinct grab felt. If it slides in like a swimmer through a shark, you'll have to tighten the female terminal. I use a very small pick to gently tighten the terminal and just enough to get a nice grab. Also, tug on the wire and make sure it is not broken at the crimp. I have seen this happen before.

Do this at the coil and PCM and I think you'll find the problem.