94 olds 98 cylinders 2 4 6 not firing

[brokanic]

Got a 94 olds 98 V6 3.8 cylinders 2 4 6 have no spark. So far I've changed out camshaft position sensor, new wires, new plugs. Any help would be greatly appreciated.

[maxwedge]

Welcome AF. Could be the coils or the ign. module,. possible a weak crank sensor signal also but less likely. A scope would check the sensor signal, the module can be tested by Autozone or some Napa stores also.

[brokanic]

Thank you Maxwedge for your prompt reply. I have since changed the ICM and all the coils but 2 4 6 still wont fire. I apologize for my lack of automotive knowledge but whats a "scope" that can check my crank sensor? I'd like to purchase one being a beginner DiYer. And will a faulty ECT have any effect on the firing?

[maxwedge]

An oscilloscope is beyond the means of most dyers, based on price and experience using it, look for cranking rpms on a scanner or test the cps with an ohmeter.Go to autozone.com, repair guides for the procedure. Forget the ect. The diagnosis of this may require professional help.

[Mickey#1]

You told us 2,4,6 aren't sparking but didn't mention what 1,2,3 are doing. I can't imagine 1,2,3 firing without 2,4,6 so we'll assume none of the cylinders are sparking. Check for 12 volts (key on) at the pink/black (pink some years) wire that goes to the ICM.

If that wire has no power then check the fuses under the dash on the passenger side.

If that wire has power then the crank sensor is most likely bad.

[brokanic]

Its really ironic but cylinders 1 3 5 are indeed firing. Its just 2 4 6 with the problem. You can see why Im hitting the forums cause Im at my wits end. Will try to ohm out the crank sensor and check the fuses on the passenger side compartment. Thanks again for all your help, if anything more comes to mind its much appreciated.

[Mickey#1]

I don't think that is possible. Each coil fires an even and odd numbered cylinder at the same time. How are you checking for spark?

[brokanic]

originally I thought the plugs/wires were bad so I replaced them. Fired the car up and problem was still there. removed all the spark plugs to there corresponding cylinder. and 2 4 6 were still perfectly white (platinums) while 1 3 5 had black soot around the middle diode. 2 4 6 are still perfectly white even after running/reving the car.

[Mickey#1]

I'll bet you're getting spark to all six cylinders & you have a fuel problem.
I'd check for for fuel injector pulse at each injector.
You can also check the resistance of each injector.

[brokanic]

Thank you Mickey for your help and patience. OHmd 2 4 6 injectors all are 14.3 while car is cool. Is there a way to visually check if my plugs are firing while car is running? I let the engine run a few and immediately pulled #6 plug out, it smelled like gas. Again thank you for your help.

[maxwedge]

Normal resistance is 11.0-12.5 ohms, cold. If one is bad it can pull down the voltage from the rest, but again I don't think this is your problem.

[Mickey#1]

You can use a spare spark plug to check for spark. Just remove a wire from one of the plugs, insert the spare and set the base on a metal part of the engine. Have someone crank (or start) the engine & see if the plug is sparking. Also make sure each plug wire is going to the correct coil. See picture.

A #194 light bulb can be used to check for injector pulse. Pull the wires away from the base of the bulb & insert it into one of the injector wiring harnesses. The bulb will pulse while the engine is cranking or running.

[brokanic]

I'd like to thank maxwedge and mickey for there insightfulness in troubleshooting my car. It was indeed the crankshaft sensor. Car runs like a charm and I learned quite a bit from the both of you. Once again thankyou very much.