ss2z06

I've been dealing with an intermittent no start issue for quite a while now. It's only under very specific circumstances and I hadn't been able to narrow it down until recently. If the car sits for several hours(cold start), gets driven for less than fifteen minutes and then sits for 5-15 minutes it will crank but not start. If the car sits for over 30 minutes then it will start like normal; as if nothing ever happened. I hadn't been able to replicate it when i tried so I didn't have a second hand to test while someone tried to start it. I finally did the other day. I confirmed with a node light I had no injector signal. I used starting fluid and it instantly fired and stayed running. I do have good rail pressure. It's actually the injectors not pulsing. I have access to gm's tech site and I can't find what series of events has to occur to get them to receive a signal. If anyone has this information or any insight it would be greatly appreciated. I do already have a new crank position sensor, have checked the wiring on the pcm, and starter connections. Mods are in my sig just in case.

KB9GKC

Hello,

When the engine is cold use a hairdryer on the crank position sensor and warm it up well, then try and start car.

Use this method when repairing intermittent electronics.

Good Luck,

Douglas in Green Bay

ss2z06

Thank you for the advice. I've never heard of that and it's a good suggestion. I don't think it's my crank position sensor since it is brand new. I'm trying to figure out what other sensors can have the same impact. My thought is either the cam position or map sensor (s). One thought is coolant temp sensor but the Gage reads right so I don't think that would be it.

jft69z

Had a MAP sensor go bad on a ZR1 in the shop last year with the same symptoms. Any codes? Tried the heat gun and freeze mist on all the sensors during troubleshooting but didn't trigger a failure (surprised me too in the end). After a lot of time and data logging, swapped the MAP with a known good one and problem solved.

Driver side sensor near the rear on the supercharger lid.

Joe T.

ss2z06

I don't have any codes at all. Im glad to hear I'm not the only one that has had this. Did you have the exact same starting situation? Any other symptoms? I'll try a map sensor since I don't even know how to test that input given the situation. I will try the hair dryer first just to try. Thank you!

jft69z

Exact same symptoms. Crank/no start after getting hot. Cold start no problem. Let the car idle for a bit, usually ok, but other times it would just suddenly die out and no restart.

The car was on the track at the time when it first started. Well, first the I/C bricks blew out, car overheated and wouldn't restart until it cooled off. Then it got trailered to my shop where I put new bricks in, oil change, etc and thought all was good until it ran for a bit and died again while still at the shop. Eventually after checking all the obvious stuff, scanning and logging the crap out of it, the new MAP was the repair.

I'm guessing the overheat at the track may have been the last straw for the sensor. Still, even when spraying it with freeze mist when it was hot I figured that would have been a sign during the crank/no start condition what sensor was bad, but it just didn't help. It was pretty frustrating I can tell you that.

You can find freeze mist online, Radio Shack, etc. or just get cans of "canned air/air duster" etc. (Office Max, Walmart) and flip it upside down and spray it. That will cool the sensors off quickly, maybe it will help troubleshoot in your case.