Hey guys, my car is running like ****, un-driveable. The PCM says it's the crank sense signal. After going through EVERYTHING, all indications pointed to a bad opti spark pickup. I've changed the distributor to a brand-e-new one. Being that this is not a trivial job, I did a few things along the way, got a Y car water pump body, got my fan shroud to actually fit, buttoned up a few loose ends, etc. You know I spent like two days on my back...

The crank sensor problem remains. It’s not any fuses, wiring, plugs, grounds, etc, everything checks out good. I’ve pushed and pulled on harnesses, tapped on the PCM, re-plugged every plug, all the obvious troubleshooting routines and a few not so obvious. The car has ran great until about a week ago, something’s gone south on me.

Funny thing, the SES light does not come on. It shows good during the key on lamp test. The code is in the PCM and shows up when scanned. After clearing the code, it sets again right after starting the engine again.

I even gave the car a great big hug.

Any ideas would be considered and appreciated.

 

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I believe I'd just buy a new sensor.

 

OK dhdenney, I'll just go and do that. Exactly which sensor are you advising me to change and how did you come to this conclusion?

Honestly, with 3,700 posts as a tech junkie, I would've hoped for some real guidance. I’m not trying to be a wise-*** here but I have a real issue with this car and help is needed from the members of the forum.

 

The crank position sensor! I kinda thought since that was the code you'd know what I was talking about! You tested the wiring and all the grounds but didn't say anything about replacing the sensor.

 

OK, I see where you were going with that BUT...

The 94 LT1 uses the Opti Spark pickup(s) as the crank position sensor. Other than that, there's no crank sensor that I'm aware of BUT, I've been wrong before and if I am now, do tell so I can get my ride up and running again.

Thanks...

 

Oh you said the code read crank position sensor so I thought we were talking about an OBD2 car so that's my bad. I see it's a 94 in the sig. Probably where we got our wires crossed. What's the actual DTC number? What's the opti brand you put on there? I'm not sure what you meant by a new e-one.

 

I installed a brand new distributor from MSD.

The Snap-On scanner read a code 18 and displayed the crank signal info. I'm a little tossed by that because all the GM code sources tell me code 18 is: "Injector driver circuit voltage to PCM was wrong for 4 seconds."

........

 

My book also says injector circuit. Perhaps the scanner is incorrect (at least for this car). If you know someone with a scanner like LT1 Edit or Autotap, I'd look at that and see if the pulsewidths were off.

 

OK, I have the trouble shooting flow chart. It may take a day or two for me to get a noid light and set aside some real time to work on this. I'll post the progress. Meanwhile, if any other idea pops up, I'll be watching...

 

I don't guess you have the OBD1 cable then.

 

I just ordered the ALDL USB cable and scanning software from OBD Diagnostics. I'll be better able to tell what's going on. At a later time, I'll look into programing software.

Just for every bodies info, Bob Bailey the LTCC guy has been tremendous help off board. He's answered some key questions even though my problems are not with his system. Kudos to Bob!

 

OK guys, after being mis-guided by the Snap-On scanner, I went through the steps for code 18, injector circuit, to discover a ground in the wiring of injector seven. After fixing the circuit and clearing the code, all went back to normal and was running properly.

BUT somehow running like this, there was a lot of fuel being dumped. I’ll assume the grounded injector was just dumping full flow. I was out with the car when this started happening and had to fill the tank and "used up" more than a 1/4 tank in just 27 miles to get home.

THIS CAUSED so much oil to be washed down the (#7) cylinder it’s rings are shot. Hell, when I un-corked the oil drain plug, more than an extra gallon came out, mostly fuel.

THAT’S CAUSING very heavy oil consumption, thick clouds were following the car as I rolled it around the block a few times.

MY NEXT STEP is to save my nickels and dimes and go for that 383 short block that I knew was an eventuality. I already have good heads from the boyz at Advanced Induction

Thanks for the help Mr. Dhdenney. I did get that cable and my laptop works well with Free Scan. I’ll be looking for more software as well as tuning software. What’s "the best"?

 

ouch...

 

The cable and scanner is invaluable.