Ok, my friend's 87 Grand National is going psycho. He let a friend drive it (bad idea) and it never came back on it's own legs. We've been running through this damn thing like crazy trying to figure out why it cranks, but won't start. I ran the codes and it gave the code for "mixture control solenoid" so we went and got one only to find out that his car is injected, and doesn't even have a mixture control solenoid. We then checked for spark by pulling a plug and holding it to the block while cranking...no spark. Aha! I had an Olds quad 442 with this problem (and that god awful distributorless ignition) and it was the coil pak, so we replaced that on the GN...still no damn spark. We then replaced what takes the place of the mixture control solenoid on the injected GN (the IAC valve) and noticed that his old one was stuck in the opposite position the replacement was in (open, closed...I don't remember) and it STILL won't start. Way I see it...spark is started at the crank trigger sensor (those RARELY go bad) then goes to the ECM, then goes to the coil paks, then to the wires, then to the plugs. Plugs and wires are damn near new....could his ECM be fried?

Any help would be appreciated.

Kelly

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If you've gotta fix it, fix it better than stock.

 

I can't help much but you might want to try this site: http://www.turbobuick.com/

 

Actually, the signal is picked up by the crank sensor, and the cam sensor on the buick 3.8. Then the DIS module sends a signal to the ECM to fire the injectors, and such, and the module also fires the coils from this signal.

I would start by checking the crank sensor. I believe it will start if the cam sensor is bad, but I'm not sure.

The module is the most likely culprit. Typically, if the coil pack goes bad, it just won't have spark on two cylinders, and will usually start, but run badly.

Last thing, the IAC isn't really much like the M/C solenoid, it's just a way to control the idle, and does basically the same thing as opening the throttle a little. It is possible that if it is open all the way, it could make the car hard to start, but you would have spark if that was the problem.

What was the number of the code? Some codes are different for various engines, and this sounds like one of them!



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Working on:
'84 Z28 LG4 305
Added dual elec fans.
145 MPH IROC Speedo
Building 430 HP 350
using primarily GMPP parts.
Block is in shop!

Awaiting results from all 8 ASE tests.

Starting to look like the Kicker poster child!

 

it was a code 23...where the heck is the DIS module?


Thanks,

Kelly

------------------
If you've gotta fix it, fix it better than stock.

 

DIS is "Distributorless Ignition System". The module is directly below the coil pack, and is what the coil pack bolts to.

Lets see, 23..... Manifold Air Temperature (MAT) signal low. They later renamed this to IAT, or Inlet Air Temperature. The GM manual I have here says that in order to set this code, the signal voltage will indicate a temp. below -35* for greater than 3 seconds with the engine running more than approx. 4 minutes, and no VSS (Vehicle Speed Sensor), in other words, sitting idling for 4 minutes, and seeing -35*. Doesn't sound like your problem. Maybe the sensor got unplugged while it was running in the past?

If you'd like, I can scan the troubleshooting chart and DIS wiring digram from this book, and email it to you. If so, just email me at jporter12@hotmail.com

Oh yeah, they also call this system C3I. That means Computer Controlled Coil Ignition. GM has several names for the various systems, even though they are very similar in operation.

Good Luck!

------------------
Working on:
'84 Z28 LG4 305
Added dual elec fans.
145 MPH IROC Speedo
Building 430 HP 350
using primarily GMPP parts.
Block is in shop!

Awaiting results from all 8 ASE tests.

Starting to look like the Kicker poster child!

[This message has been edited by JP84Z430HP (edited November 28, 2000).]