I hate to re-post a follow up to my old thread but I'm running out of ideas...

History: car has headers & also trans was rebuilt 3 years ago. Gremlin has occured w/ 2 different batteries, currently an Optima.

The Gremlin: Only on the road course with warm tires and engine etc(I only do a few days per year), only in left hand turns entered at a good rate of speed and only if after the apex you get on the accelerator hard in 3rd gear(more torque than 4th), I keep having the ignition/powertrain cut off. The motor cuts off w/o a sound; there's no warning or sputter. The HUD goes away, I look down, all analog gages are zero just the same as when you turn the key off. I'm not 100% sure but I think the computer readout area where I display the oil temp digitally is also out but I don't think the clock radio is out.

There was also a puff of smoke from what appeared from the driver's seat inside the car to be the RT ft tire area.

The car re-starts almost immediately w/the turn of the key to off then back on. I say almost because when this happens I'm really concerned 1st w/steering off the pavement but once I did re-start while still on the pavement but near the grass. So it's very intermittent.

Zero codes.

I have not been able to duplicate this on the street or wide open parking lot (street tires). In the parking lot, I had it in 1st gear though and did left circles pulling g's and accelerating w/throttle w/the engine hot.

Checks to date: Looked myself & sent to good vette mechanic locally. Twice. He checked: Junction blocks, fuse box area, frame rail splices, ignition switch, grounds on the block, wiring harnesses in engine area.
Shook the PCM (heated w/heat gun) and found nothing.

Didn't check: harness that runs under the trans/torque tube area. Didn't pull intake manifold etc to get wires off of car and out of their looms to really see them because it's so time consuming (expensive).

Questions:

1. Would HPtuners or some other software pick up enough data fast enough to help see what is dropping out? Would it isolate it?

2. Has anybody had issues w/the engine cutting off after trans removal?
Could the heat associated w/the trans plus the torque and motion in the corner be causing the harness to cut the ignition?

Thanks--I appreciate any ideas!:o

Andy

 

Wow, still battling this issue... I don't remember the puff of smoke being discussed before.....has this always been the case when it happens?

What grounds have been inspected? G105 (left side of block is obvious) but was G106(above starter) checked?

Have you inspected the ignition switch contacts?

Have you inspected the wiring in the left door accordian tube?

Are any codes (H or C) generated at all?

 

PM sent.

 

It looks like you experiencing a major power disruption issue. Almost like your ignition switch is being turned OFF.

I have a schematic at home I will send you that shows the 12 VDC power input to the ignition switch. If that’s being disrupted, it will do the same thing.

What was done to check the ignition switch???

If the IPC goes dead,,,your either loosing the HOT at ALL times supply voltage OR the Hot in ON and START supply voltage.

You could attach a voltmeter to those fuse sources and when the car shuts off, see what one disappears.

You would have to be loosing POWER like "TURNING THE IGNITION SWITCH OFF" to not throw a bunch of history DTCs.

Do you have any thing of substantial weight on the Ignition Key that may be causing the switch to stress???

Sorry this is still going on. Should have yelled louder sooner! Lucky, Byron Hunter and I all like challenges!


Bill

 

My mechanic said he pulled it and looked at the wiring for chaffes or anything unusual. I could ask again for more details.

Where are these fuse sources? I need the instrumentation inside the car where I can see it. If I am on a road course (even off the pavement etc) I am not allowed to get out of the car under any circumstance.

Weight on the key...yeah I used to use the Key #2 with just the fob but of late I use one that has some keys on it. I can stop doing that...would that really fix it?

Thanks...that was a new idea. If nothing else I can put a bunch more weight on the key fob in the parking lot and see if it acts up.

 

Take a good close look at where the positive battery cable crosses over the frame to the starter and also how clean and tight the connection is at the solenoid.

 

Heres my post that details rebuilding the ignition switch. Believe me! This is more of a problem that you care to believe. Our cars are starting to age and were seeing more and more ignition switch failures.

- C5 ignition Switch repair - http://forums.corvetteforum.com/c5-t...ch-repair.html

Believe it or not, this is a simple FREE repair. It takes longer to remove the switch than it does to rebuild it.
If its not the issue, your ignition switch sure will feel a LOT better after the repair. You should also see better voltages on the HOT in ON and START circuits.

Bill

 

Solenoid is next to starter? If I remember correctly it's harder to see here because of the headers. But I did try and all seemed ok. I can have another look.

Bill's idea about weight on the ignition switch (ie keys! key chain) is very interesting.

 

Solenoid is on the starter. Did read the PM I sent this morning??

 

I've seen problems before caused by too much weight on the ignition key - stuff like extra keys, bottle openers, charms, etc etc... all these cause problems dangling away and jiggling with the extra weight hanging off the ignition cylinder....once the damage is done, usually removing the extra weight dosen't cure it... the cylinder needs to be rebuilt or replaced ...may or may not be the prob,,,. but you are definately loosing juice 100% as if the key is being turned off, since you're not getting any stored codes...

 

Sorry ... not trying to belittle your situation, but I've seen this happen several times while autoxing on various cars. A hard left and .... *sputter* *sputter* "I don't know! It just died ... oh wait ... why is the key off ... wtf?"

It's on left turns because a left turn makes that big clod of chit on your keychain turn the key counterclockwise.

Like Bill said, pull your ignition switch and clean the contacts (they will need it). And while you have it torn down, you can tweak the contact arms down just a hair, and this will have the effect of tightening up the lock tumblers making the key a little harder to turn.

 

I only after a re-read understand your PM about the ignition switch. Yes, there is no fluctuation of anything, it just cuts off as if somebody cut the "hot wire" with knife.

So if it is the switch--what exactly do I (or mechanic) look for on / in the switch? I haven't re-read Bill's write up. I read it months ago. Honestly, I figured anything having to do w/the turns couldn't be a switch right by my knee (but never touches!). I forgot that there are keys (weight) on the chain.

 

I'm pretty sure that I had to turn the key in the lock to off then back on to re-start. In other words, the lock cylinder had not moved!!! Ever!! But I could see if it was a vibration sensitive switch that I made it harsher than maybe the designers intended if they weren't thinking roadcourse+keys.

Whatever this is--it is because of WEAR. This same car handled the same loads for several earlier events with no issues.

 

Well, when you are grasping at straws, you have to alleviate all the possibilities. As already stated, the HUD and instrument cluster 12volts comes directly from the ignition switch via minifuse #19. So either you are losing 12volts to the switch, or from the switch to the fuse. That's why I asked in post #2 if the ignition switch contacts had been inspected. Just removing the switch and examining the wiring won't get it done.


http://forums.corvetteforum.com/c5-t...ch-repair.html

 

The switch makes a lot of sense and I'll have it pulled and cleaned if I don't get time. It really feels just like turning the key off-that's why I posted it like that to grab attention to that fact. I guess my mechanic was thinking it's the 12v to the switch and that wire would have to be traced back all the way to the battery.

Thank you all so much for the replies so far!

 

Yes but the key doesn't have to rotate all the way to [Off] to kill power. It just has to start lifting up those contact arms which is going to happen way before you get to the [Off] stop. Which of course means it may very well snap back to the [On] position once you're out of the left turn.

Try it for yourself. With the car parked and idling, very slowly turn the key counterclockwise and see how far you get before it shuts down.

Well of course it is. Spring tension is the primary force which resists the rotation of the key. And all springs wear out eventually.

 

I was siting at work today and remembered that there have been a couple of people who have had fuses that were LOOSE in the fuse holders. Check each instrument panel fuse especially fuses 19, 25, 47, 48, 50, Fuses 47, 50 and 19 should be tested and examined closely.

 

See below. If you loose this contact in the ignition switch..it's game over...no instruments, no ignition relay, fuel pump, coils, etc.

 

Here is a look at the curve of the spring out of a switch that needed cleaning baddly. The switch was really easy to rotate thru each of the switch positions:



I rebent the spring to this arc:



Once you rebend the spring for better contact, you will need to ASSIST the little contacts with a bent paperclip.

The extra pressure on the cam rods will make the switch feel nice and tight.

Heres a pic of the cam rods and bottom contacts:





BC

 

" If you loose this contact in the ignition switch..it's game over...no instruments, on ignition relay, fuel pump, coils, etc. "

Very Well stated!!!