Need help

[Wld87GN]

So I decided to make a few mods, nothing unusual:
60# injectors
6262 turbo
3 in down tube
upgraded SLIC intercooler
new headers
Precision stall convertor
alky kit
TT chip
all of the other typical upgrades you would expect.

So the problem is that 1/2 to 3/4 throttle it pulls hard, up to about 21-22# boost all is good. After that when I try for full throttle everything falls to sh!t.

I first thought fuel, but I tested fuel pressure, and I am good there.
I tried all new plugs and wires (just to eliminate possibilities)
The ONLY thing I can think is that I installed a new MAF and translator (it was used on another that did not have an issue about 2 years ago).

That is it... With that said, I love power up to about 3/4 throttle, after that... crap.

Any thoughts, suggestions?

 

[mtocrs1]

After 3/4 throttle crap?
I little more info. Falls on its face? Feels like a miss? Will not rev past x rpm?


Sent from my iPhone using Tapatalk

 

[Mr.Spool]

That is it... With that said, I love power up to about 3/4 throttle, after that... crap.

Any thoughts, suggestions

scanmaster/wideband afr numbers where the problem occurs?replacing the plugs is one thing how did they look?

 

[TTA308]

Original valve springs ?

 

[josh young]

have you replaced the coil pack or the module? I had a similar problem although it would start about 15 #'s of boost, it turned out to be the cam sensor cap.

 

[Wld87GN]

mtocrs1 - up to 3/4 throttle it feels good. any more than that and it feels like it is falling on itself... sputtering, and acting weird.

Mr.Spool - The plugs actually looked great, but I realized that they were the wrong plugs, literally the wrong plugs.

TTA308 - Yes they are original valve springs, I thought about that too, just not knowlegable enough to know if that would cause this issue.

josh young - Yes we replaced the coil pack. My issues really start about 21-22# of boost

 

[SS/GN]

I would say valve springs also. Pull drivers side V/C and you can probably push them down easy by hand. Most when old have about 40 lbs on the seat....................not enough.

 

[mtocrs1]

I would close the plug gap to something really tight. Like .020 and see if the symptoms changes. Free and easy test. My old car would quench the plugs at anything above 20 psi. Closed the gap and all ok.


Sent from my iPhone using Tapatalk

 

[huntsg]

If you changed the coil and ignition module I would look there. Put the old ones back in maybe?

 

[Wld87GN]

If you changed the coil and ignition module I would look there. Put the old ones back in maybe?

They were changed in my pursuit of trying to figure out what was happening.

 

[turbofabricator]

Valve springs for sure, but also check WOT TPS sensor reading.......might be too high/low throwing power enrichment off.

 

[Wld87GN]

Does anyone think there is a chance that the problem is the cam?

 

[TTA308]

Does anyone think there is a chance that the problem is the cam?

Yes sir, buy all means it can be the cam AND the springs and lifters...

 

[Wld87GN]

Yes sir, buy all means it can be the cam AND the springs and lifters...

Okay, so I don't disagree... however, can you expand? Are you saying that the problem may be any of the three items (cam, springs, or lifters)? Or it could be all of them? I guess the problem I have is trying to understand how the cam could be the problem? Are these cars known to have problematic cams?

 

[TTA308]

You never said how many miles are on it but they have been known to wipe a lobe, i would say new valve springs at a minimum, whether its the problem or not it will run much better.

 

[TTA308]

Think about it... you are putting go-fast parts on 27yo hardware and asking it to perform better than new... sometimes it will and other times will it show any weakness, you would be better off getting a basic rebuild no matter what the mileage is.

 

[Nick Micale]

..........So the problem is that 1/2 to 3/4 throttle it pulls hard, up to about 21-22# boost all is good. After that when I try for full throttle everything falls to sh!t.

I first thought fuel, but I tested fuel pressure, and I am good there.

What do you mean "I am good there"?

Did you check fuel pressure at 22+ psi, or voltage, or injector duty cycle, or O2's going lean?

Cam, valve springs, and mechanical stuff are the last things to check, fuel delivery at point of RPM failure is the first thing to check extensively as you will do expensive damage if that is your issue.

If you do not have a Powerlogger, you need one to verify the needed data stream.

 

[Wld87GN]

@ TTA308 - I hear ya, makes sense. I agree that it is possible, but I am merely trying to determine where the issue is. The car is 27 years old, the mileage is not exactly known...

@ Nick Micale - What I mean is that we tested for FP and it was good to go, but we are now checking the gage and sending unit to ensure that we are getting accurate reading. I do not have a power logger.

 

[TTA308]

A powerlogger is worth its weight in gold... best thing since sliced bread... and peanut butter.

 

[headslide]

A powerlogger is worth its weight in gold... best thing since sliced bread... and peanut butter.

Amen to that .I dont know anything but having a powerlogger is a big help in just reading data and learning what's going on with these fickle little motors