Average repaint cost?
- Thread starter longbedGTs
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longbedGTs
high on gas fumes
Yep, the engine does nothing at all until I let off the gas, no matter if I lift right away or lift 4 seconds later. Then it comes back and acts as if nothing has happened. No pops, no smoke, no noises...nothing. Just a glitch in the matrix. The 2nd log shows this better because I intentionally left my foot on the floor for a longer period of time. If I hold it at say 3/4 throttle, it's an animal and pulls way harder than the '86.
The car had so many small issues when I bought it last August. The guy I bought it from sold it to a guy that did all the work, then ended up buying it back from this guy at a later date. The guy I bought it from wasn't mechanically inclined and wasn't able to tell me much about what was done to the car. He spent approx $5K-6K in parts/labor in 2018 alone! Then, it developed a top end noise(which was a broken rocker support shaft) and I suspect got tired of dumping money into it, and put it up for sale(got it for $11,250). I spent $250 on upgraded parts and had a good running GN for the most part. I am slowly getting everything ironed back out and this issue seems to be the last hurdle before I can take it to the dragstrip. At this point, I'll be satisfied if it runs a clean pass(12 or 11s)
Forgot to mention earlier that the trans has been rebuilt as well. Would you say it's worth a shot to try the coil pack from the other car and see what happens? I can't try the MAF because the '86 still has the stock MAF that's a smaller diameter, and I don't have any reducing couplers handy. i could take a short video tomorrow if that would help with the "a picture(or video) is worth a thousand words" sort of thing. I still would like to add some weight to the governor to bring the shifts in a little earlier, but that wouldn't really be "fixing" this issue. More like avoiding it.
The car had so many small issues when I bought it last August. The guy I bought it from sold it to a guy that did all the work, then ended up buying it back from this guy at a later date. The guy I bought it from wasn't mechanically inclined and wasn't able to tell me much about what was done to the car. He spent approx $5K-6K in parts/labor in 2018 alone! Then, it developed a top end noise(which was a broken rocker support shaft) and I suspect got tired of dumping money into it, and put it up for sale(got it for $11,250). I spent $250 on upgraded parts and had a good running GN for the most part. I am slowly getting everything ironed back out and this issue seems to be the last hurdle before I can take it to the dragstrip. At this point, I'll be satisfied if it runs a clean pass(12 or 11s)
Forgot to mention earlier that the trans has been rebuilt as well. Would you say it's worth a shot to try the coil pack from the other car and see what happens? I can't try the MAF because the '86 still has the stock MAF that's a smaller diameter, and I don't have any reducing couplers handy. i could take a short video tomorrow if that would help with the "a picture(or video) is worth a thousand words" sort of thing. I still would like to add some weight to the governor to bring the shifts in a little earlier, but that wouldn't really be "fixing" this issue. More like avoiding it.
SCOOBY DOO
I'M NOT A MONSTER, I'M JUST AHEAD OF THE CURVE!!!
I've had a few do the exact same thing. Not saying it's his problem, but it would eliminate one more thing. It's an easy swap to try. New Denso would be a good idea as well.
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longbedGTs
high on gas fumes
The alky knob is on 6 at the moment. Where would the default position be?
SCOOBY DOO
I'M NOT A MONSTER, I'M JUST AHEAD OF THE CURVE!!!
longbedGTs
high on gas fumes
I'll swap out the coil pack and take it for a drive tomorrow. Thank you all so much for your help.
I'm wondering what the back psi is.. 3:1, or worse?
longbedGTs
high on gas fumes
The coil pack from the other car didn't solve the problem. Same symptoms as before.
No disintegrations
Well-Known Member
I found this quote from engine labs.
Billy Godbold, Valvetrain Design Engineering Chief at Comp Cams feels that enthusiasts are seeing something that might be mistaken for pump-up, and is still a problem that needs to be addressed.
“What we are talking about here is the bleed down rate and effective lash (clearance) that reduces the dynamic duration and stability of a hydraulic roller lifter system at high-RPM,” explains Godbold. “While valve bounce can lead to the hydraulic system holding a valve open, there is not an actual mechanism that can accurately be described as ‘pump-up.’ The valve bounces up, and the dumb hydraulic system just adjusts to hold it up for quite a while.”
Billy Godbold, Valvetrain Design Engineering Chief at Comp Cams feels that enthusiasts are seeing something that might be mistaken for pump-up, and is still a problem that needs to be addressed.
“What we are talking about here is the bleed down rate and effective lash (clearance) that reduces the dynamic duration and stability of a hydraulic roller lifter system at high-RPM,” explains Godbold. “While valve bounce can lead to the hydraulic system holding a valve open, there is not an actual mechanism that can accurately be described as ‘pump-up.’ The valve bounces up, and the dumb hydraulic system just adjusts to hold it up for quite a while.”
longbedGTs
high on gas fumes
I had this problem with a Thunderbird Turbocoupe(2.3 Turbo) after trying to launch off the 2 step. It would pump the lifters up and hang the valves open causing the engine to stall out. Trying to restart the engine after the stall, it turned over really easily and sounded like it had no compression(which it didn't). Wait a minute for the lifters to bleed down and it'd start no problems and run just fine. Solid lifters cured that problem.
It doesn't seem like the lifters are pumping up because it runs just fine the moment I lift off the gas pedal, even if it's a second after the noseover. Lifters I'd imagine, would stay pumped up for a longer period of time and the engine would run like crap. In my experience anyway, but I've never had a problem like this with any vehicle I've owned, so I'm truly in the dark here. As hensleyt and chuck alluded to earlier, maybe this is an issue with volume and the engine not being able to get rid of all the air fast enough that the turbo is pushing in.
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SCOOBY DOO
I'M NOT A MONSTER, I'M JUST AHEAD OF THE CURVE!!!
I mentioned the ignition module possibly failing under load. Have you swapped in a known good one.
See post #28
longbedGTs
high on gas fumes
Oh damn, I thought that was just another term for coil pack. I swapped over the entire assembly. Coil pack on top, ignition module directly underneath.
longbedGTs
high on gas fumes
Edited*
If this is true, then theoretically I should just be able to turn the boost down to move less air, right?
SCOOBY DOO
I'M NOT A MONSTER, I'M JUST AHEAD OF THE CURVE!!!
That eliminates both. Turn the boost down into the low 20's and see what happens.
mikestertwo
Well-Known Member
The problem seems to be rather abrupt at the 5800-5900 rpm like the ignition is being shut down. I also noticed the data also shows you are always in 4th gear like the transmission electrical connector is disconnected. I would also check the end play in the crankshaft to make sure the damper isn't moving out of the crank sensor shutting down the ignition. Just a thought.
No disintegrations
Well-Known Member
You're trying to rev an unknown valvetrain to over 6000. Not too many setups support that and you don't know what you have. If it is happy between idle and 5500 rpm. It may be a major clue. You really need to know the specs before you ask it to go to 6000.
longbedGTs
high on gas fumes
True. I need to get the governor taken care of to bring the shifts in sooner. I guess this is just one of those things that happens when you have the wrong combination of parts and/or reach their limits. I was never set on revving it this high, but I figured this problem could be "fixed while I was here" before adding weight to the governor which I was planning to do anyway.
As for lowering the boost level. I could only get it as low as 25psi...and that's with 0 preload on the wastegate arm. Boost came in very very slowly. Seems this turbo would be much better off with an external wastegate. The problem still remains, so...I don't know what else to do other than getting the trans shifting at a much better suited RPM(5K or 4,800ish?) and possibly look into a 6262 sometime in the future. Probably do a fuel pump as well just so I know what's in there. The PO had a shop replace the pump with an "LP450" but I have no idea what that is and have an issue with trusting unknown shops anyway.
SCOOBY DOO
I'M NOT A MONSTER, I'M JUST AHEAD OF THE CURVE!!!
Grumpy used a 6776 with a gated DP and controlled the boost. Think he used a Grainger valve.
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