Need Opinions (long)

[twr]

Okay, about the end of October I was giving a friend of mine a ride in the Outlaw (S/C car) I managed to shift from first to second very hard right at the rev limiter. There was a loud back fire and the car lost a lot of power. I drove it home and parked it.

I started the car a few days later to see how it would run. At that time it stumbled and had a lovely color of blue smoke coming out of the tail pipe under all throttle positions. So I decided to shut it down and deal with it after the first of the year.

Fast forward to last Friday...

We've had 4 snows and the road is still covered in snow, but the garage is finally clean and ready for the SHO to be pulled in and go under the knife. Of course the battery is stone dead. I jump start it and let it idle for a few minutes. That's when I noticed that there was no longer any blue smoke and the car is idling fine. I drove the car around the block and parked it in the garage and put a battery charger on it.

Saturday I decide to test my luck and start the car again. Fires right up with no hint of smoke and idles fine. Okay, so I decide to push my luck, since the GF has never been for a ride in the car, I decide to take her out for a spin. I drove the car hard pretty hard for 30 minutes, scared her and myself a few times. No motor issues at all, so I continued to drive the car around for the rest of the afternoon.

I still need to do a compression check on the motor which I will do this weekend to make sure it's all good. But in the mean time, I'm left scratching my head. I was fairly certain that I had to have broken something like a ring, ring land or possibly a piston. The smoke was blue as in oil getting into the combustion chamber blue, but it didn't have the normal signs of excessive blow-by.

My question is this, is it possible that the EEC saw something during the backfire that caused it to wig out and when the battery lost the charge it reset and thats why the car is now running fine??

 

[shomesomesho]

Very strange.

I've had my car backfire and sputter in limp mode when the rev limiter _and_ PIP period threshold was exceeded. The car ran like it had blown something, when in fact it was just firing on every other cylinder. But that all went away with a key-off/key-on cycle.

 

[twr]

Now that makes sense to me, however the blue smoke does not.

 

[shomesomesho]

Yeah, I can't explain the blue smoke. I didn't get the blue smoke when that happened. But then I don't have a supercharger (yet). Could the addition of a supercharger have something to do with it? I really don't know, just thinking out loud here:

Suppose you were in limp mode and running off 3 cylinders. The other 3 are basically dumping highly compressed, unburnt air:fuel at 12:1 into a hot exhaust. Would that be sufficient to cause backfiring and blue smoke?

Also, what are your rev limiter and PIP period set to in the twEECer?

 

[twr]

Yeah, I can't explain the blue smoke. I didn't get the blue smoke when that happened. But then I don't have a supercharger (yet). Could the addition of a supercharger have something to do with it? I really don't know, just thinking out loud here:

Suppose you were in limp mode and running off 3 cylinders. The other 3 are basically dumping highly compressed, unburnt air:fuel at 12:1 into a hot exhaust. Would that be sufficient to cause backfiring and blue smoke?

Also, what are your rev limiter and PIP period set to in the twEECer?

I know that I need to set them up differently, as they are set to close togther for a S/C application. I'll have to charge the laptop up

 

[twr]

Just spoke with Gary M. Still not sure what happened, either freaked out the EEC when it exceeded the pip period, however this condition should have cleared with key on and off. The other possibilty is that a piston ring unseated and re-seated. I'm going to do a compression check this weekend and will report back my findings.

Thanks

Terry

 

[Axianator]

Terry,

Before heading back out with your car, I would recommend adjusting the gap between your soft rev limiter scalars and the hard PIP period filter scalar within your current TwEECer calibration, ensuring that you maintain the minimum factory gap of ~700 RPMs between the soft and hard limiters to avoid the risk of repeating this incident and potentially causing further engine damage.