Grand National No Start problem

ostrich

Master Mechanic
Aug 27, 2012
307
293
63
Ontario, Canada
I do have a second ECU. The problem is exactly the same on that one. Had not thought about an aftermarket one, since my car is pretty much all stock. Not really interested in getting to a new ECU and wiring harness until I've eliminated everything else.
As built6spdMCSS mentioned I would look at the Crank sensor. Had the same type of issue on an EFI conversion I did, no spark, no injector pulse (checked with a noid light). With no crank signal the ECM doesn't know the engine is rotating. Hard to test one unless you have an oscilloscope.

 

69hurstolds

Geezer
Supporting Member
Jan 2, 2006
7,405
15,622
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Plus three on the crank sensor. They're fairly cheap IIRC. Change it. Adjust it so it doesn't hit (turn the crank manually to ensure that it always has a smidge of clearance). What's the worse that could happen? It really isn't THAT difficult to change out I wouldn't think.

The only other thing that it possibly could be, in my limited knowledge opinion, may be the ignition module. They don't always fail 100%. But those GN ones are pretty pricey though, that's why I'd go with the crank sensor first. I thought those SFI engines activated all injectors at the same time during cranking. So if the ignition module isn't working, neither should your spark or injectors. I wouldn't think. But I don't follow the turbo car maintenance that much anymore.
 

87National

G-Body Guru
Apr 15, 2009
640
641
93
eastern SD
I have an INTERMITTENT no start problem on my Grand National. It cranks, but no start. When this happens, there is NO SPARK and NO FUEL INJECTOR PULSE.
However if I just let the car sit a day or two and come back to try again and it may starts right up.

I have changed the cam sensor with a brand new one and I switched the ECU with a different one, and I still have the problem.

Suggestions on what to look at next? Crank Sensor or Ignition Module were next on my list of possibilities. But not sure which one would be more likely to produce this intermittent problem. Seems like the Crank Sensor would be bad all the time if that was a problem, but I'm not sure.

Thanks
Have you posted this on turbobuick? Not sure if Steve Wood is active anymore...but he is an absolute wizard on diagnosing these types of issues.

Also, I have a pile of ign modules and coil packs.....as well as a few cam sensors, crank sensors, ECMs....etc. I can send you a box of parts to try out if you pay shipping both ways.
 
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Built6spdMCSS

Comic Book Super Hero
Jun 15, 2012
3,963
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Plus three on the crank sensor. They're fairly cheap IIRC. Change it. Adjust it so it doesn't hit (turn the crank manually to ensure that it always has a smidge of clearance). What's the worse that could happen? It really isn't THAT difficult to change out I wouldn't think.

The only other thing that it possibly could be, in my limited knowledge opinion, may be the ignition module. They don't always fail 100%. But those GN ones are pretty pricey though, that's why I'd go with the crank sensor first. I thought those SFI engines activated all injectors at the same time during cranking. So if the ignition module isn't working, neither should your spark or injectors. I wouldn't think. But I don't follow the turbo car maintenance that much anymore.
L98 TPI Engines as well as the 1993 LT1 ran off of SFI, also known as Batch Fire. Ignition Control Module (ICM) goes out you'll still have fuel, just no spark.
 

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