Well i finally got my car tuned earlier in the week, everything is perfect except for one thing. We got it dynoed today and i put down 347rwhp and 356tq, the car refused to go above 5800rpm and the tuner and i (very reputable tuner btw) were just stomped. Everything on the engine and PCM side is perfect, so we are leaning towards the transmission side. The torque converter (yank 3600ss) locks and unlocks randomly but we don't know if that could cause this issue, transmission shifts fine, temp is good and fluid smells normal. The car has 40k miles and i never had any WOT issues before the H&C swap......Anyone want to take a guess?

Here's the video, i forgot my good cam at home so i recorded it with my blackberry, sorry for the crappy quality.
http://www.youtube.com/watch?v=AIPbLsP3mN0

 

Think you have the same setup like mine.. Our cams are alittle different tho... I put down 415 rwhp....... I also have the same stall. I don't know what my tuner did. Unfortunatly I was at work during my dyno runs....

 

The PCM locks the torque converter when all the parameters are met and unlocks it when any parameter is out of spec.
If the motor really won't pull past 5800 then there is something very wrong. And I would guess that that is what's causing the TC to act up. Not the other way around.

 

What's your setup? Something is seriously wrong. Maybe the cam is off a few teeth? Peaking that low makes it sound like something's advanced.

Either that or tranny problems like said before.

 

If it was a mechanical problem I would think it would show itself alot more. Being one tooth off I don't think it wopuld even be close to what it is.........

Is it peaking at 5800, or is it going to 5800 and will not rev any higher?

Why didn't they just throw something in it to get the lock up out of the question while tuning..... make it lock up at 150mph or something so it would not be an issue.

How does the car drive? Does the trans act up when driving

What kind of mechanical checks have you done? Checked EGT's on every cyl? leak down etc. no bad holes? bad valve job etc. or coil...

 

The cam isn't off, i triple checked it when putting the engine back together. My setup is TSP PRC 220cc 5.3L Stage 2.5 CNC Ported Heads, TSP V3 cam 231/234, Pacesetter LT's & ORY w/ magnaflow exhaust.

Like i said earlier, everything is perfect on the engine, no leaks, no missfires nothing! Idles great, sounds great and drives great. The transmission shifts fine, feels strong but the TC randomly locks and unlocks The car does not peak at 5800rpm it just floats there, almost sounds like a revlimiter but not quite, this tuner isn't some hole in the wall type of place, they are very knowledgeable and everyone that works there is a GM mastertech. I was thinking if putting the car in neutral and reving it until i hit the limiter could cross out some probabilities or does it not matter? Anyway i pick the car back up tomorrow, what questions should i ask the tuner?

 

Do you have a dyno graph with the A/F you can post?

EDIT: Did you check the valve spring pressures?

 

if they are master techs why can't they figure it out then?

 

I don't have anything yet, i should have it tomorrow when i pick up the car.

According to them it's the transmission, i'm just trying to get a second opinion before i go spending thousands.

 

but what in the transmission? they have to be able to check it out better than that.....

Is it a converter issue, electronic, etc. etc. Not saying they are wrong, but I would rather have a reason then just saying thats it.....



now when you drive it.....does it go through all the gears etc. like it should without issues?

 

Yeah it goes through all the gears just fine, including overdrive but i haven't drove it since the tune. When i drove it before the tune i never took the car past 3000rpm and not once did i bring it up to redline so i can't say if this was happening before the tune. Another thing the tuner mentioned is that the transmission was slipping at higher RPM, i just now remembered that

 

well thats an issue you need to resolve..... kind of pissing in the wind without a good trans

 

That sounds pretty bad. Something is definitely f-ed. Either motor or trans -- The car should go way over that in neutral unless the limiter or something mechanical is preventing it. If it is the limiter, then that's where they set it and NO, they don't know what they are doing, regardless of what they say.

 

When i get the car back today i'll rev the engine in neutral to see if it goes above 5800rpm. I'm almost 100% positive that it's a not an issue with the engine, but for now i'm stuck until i get it back, there's too many "what if's". I'll update this when i find something out.

 

I didn't get a chance to pick up the car this afternoon, i got slammed with some last minute stuff at work. I talked to the tuner and he said the engine rev's just fine past 5800rpm in neutral, and once again stated that i have a messed up TC or transmission going out or a combination of both. I'm going to try to pick it up again tomorrow, hopefully i'll have some better luck.