New weirdness

[KruxRedline]

So on my way to work this morning I had a little fun and had a WOT run from 1st to the top of second. Car pulled hard, made me happy. Went to second fine no problems. But when I shifted to third.... When I let the clutch out and went back to the gas the car kinda hesitated. Like all power was cut for a sec. I shifted into 4th and got the same thing. It runs fine with no hesitation after it decides it wants to be in 3rd/4th but the shift into it sucks.

I caught a light and decided to see if it was in all gears. No problem in 1st, or 2nd but same again in 3rd and 4th. I'm going to test drive it at lunch to see if it is still doing it.

Any ideas till then?

[Sp00ner]

Ummmm... that is odd... is it the normal GM stage tune?

[KruxRedline]

Yup. Regular Stage tune. Pulled just fine this morning and took it to 7k in 1st and 2nd so I know I actually have it eheh. Also the car was not really warmed up all the way. Just a little over the quarter mark on the temp gauge.

It kinda reminded me of the weird popping I had earlier this week, after the backfire, but not as severe.

[mgm1979]

How many miles you have on it? Are you the original owner? Is it ONLY when the car is cold (and without proper warm-up)? Reminds me of my carbon build-up on my head last winter - (damn, that's TWO cases today!)...Is it cooling off a bit overnight?
And as I think about it more, I DID have a couple cases of backfiring...it took about 4-6 weeks before Saturn owned up and pulled the head. Sure enough, the head had a bit more carbon build-up than what was anticipated, and that was after FOUR fuel system cleaner treatments...(so coulda been worse at some point???)

[BlueMonster]

The same thing happened to me about a month ago. I was on my way to work and the car wasn't fully warmed up and I was having some fun with WOT. 1st was great, second, even better shiftted to 3rd and for a split second it seemed as if I lost all boost. I let off the gas and slowed down. Before I went to work I took her down a backroad and hit it all the way through 1-4th. No hesitations whatsoever..Hasn't happened since

[Sp00ner]

Originally Posted by mgm1979

How many miles you have on it? Are you the original owner? Is it ONLY when the car is cold (and without proper warm-up)? Reminds me of my carbon build-up on my head last winter - (damn, that's TWO cases today!)...Is it cooling off a bit overnight?
And as I think about it more, I DID have a couple cases of backfiring...it took about 4-6 weeks before Saturn owned up and pulled the head. Sure enough, the head had a bit more carbon build-up than what was anticipated, and that was after FOUR fuel system cleaner treatments...(so coulda been worse at some point???)

I guess that would be build up on the exhaust ports? I just looked at mine the other day installing the header, but not sure what 'normal' would be!

One thing to keep in mind, when the car is cold, it's not running in normal closed loop mode. It's running in open loop. In addition, it's providing aditional fuel to an already rich mixture. So it's not going to run the same as if it's warm and ready. It really SHOULD be a bit hesitant and twichy.

[BlueMonster]

Originally Posted by Sp00ner

I guess that would be build up on the exhaust ports? I just looked at mine the other day installing the header, but not sure what 'normal' would be!

One thing to keep in mind, when the car is cold, it's not running in normal closed loop mode. It's running in open loop. In addition, it's providing aditional fuel to an already rich mixture. So it's not going to run the same as if it's warm and ready. It really SHOULD be a bit hesitant and twichy.

Spooner are you a mechanic? Lol, you and wop always have educated and precise answers about our cars..lol

[KruxRedline]

You know that is what it felt like. It felt like to much fuel. Like the time my nitrous kits fuel solenoid leaked in my intake on my old car. I started it up and took off and it sucked up all that fuel and just bogged almost to a stop.

[mgm1979]

Originally Posted by Sp00ner

I guess that would be build up on the exhaust ports? I just looked at mine the other day installing the header, but not sure what 'normal' would be!

One thing to keep in mind, when the car is cold, it's not running in normal closed loop mode. It's running in open loop. In addition, it's providing aditional fuel to an already rich mixture. So it's not going to run the same as if it's warm and ready. It really SHOULD be a bit hesitant and twichy.

I never really got to look at the head, I was overseas when they swapped 'em, but I imagine you're right.

True about the warm-up, but AFTER they put the new one in, I would intentionally not let it warm-up right, and punch it with NO issues, whatsoever. Now, about 12k miles later, that's not the case unless I let it warm up so I think a combo of the (lacking) warm-up and carbon build-up is the cause.

[Sp00ner]

Just keep in mind what MGM is saying, if it continues, or gets worse. You'll want to have that in mind.