Need HELP! 87 GN

[Opie]

I have worked on this thing off and on all winter trying to get it ready for spring but I still have bugs that I cant seem to find or fix. The car was not running good when I got it bone stock. I thought by adding some new goooooo parts I would find the problem.
Mods: 60lbs INJ chip to match from GN1,hot wire kit, Stealth 340 Fuel Pump,"3" COLD AIR INTAKE" LT1 3'' MAF, MAF Translator, Accufab fuel pressure regulator, boost gauge, scanmaster G. Things I have replaced new plugs and wires and coil pack, crank sensor, O2 sensor Denso, TPS looks new I didn't replace. Below is my readings from scanmaster @ idle warm eng. in park

808MV
MAF 3
LV8 29
Volts 13.8
INT 128
BLM 129
Speed 0
Coolant 180
Air Temp 86.6
RPM 850
TPS.48
TAC 28
O2 CC 250
Any help on what I should look at next? Not looking for a race car just want it to run well. I have the translator set Mode on on on off, Maf base 3 LT1 3"
The car starts breaking up when the boost starts coming in back fire sounds like in the intake.
I really wanted to fix this thing myself so I could learn about my car at the same time but I am about ready to pay someone to help me!!!!!!

 

[jay dcpt]

What spark plugs? Have you looked at ignition module?

 

[Opie]

What spark plugs? Have you looked at ignition module?

NGK UR5
I have not looked at ignition module. I guess I could try one. I hate throwing parts at something

 

[TOOMANYTOYS]

Where are you located? Might be some members close by that can help for a few beers

 

[John Larkin]

Take yours to Autozone and ask them to test it for free. They will. But don't just buy another if it's bad. Some are questionable.

 

[Opie]

Where are you located? Might be some members close by that can help for a few beers

Jasper, AL

 

[Darkstar72]

No expert here and I hope they will chime in shortly, but from what I can see.

TPS is too high - shoot closer to .42 to .44 at idle
MAF reading seems low at 3 - perhaps bump up the MAF Translator off of base setting to 3% rich at idle

What is the plug gap on the UR5?

 

[rag231]

What fuel are you running? When you say breaking up when boost starts to come in ,are we talking 10lbs, 15lbs?

 

[Opie]

What fuel are you running? When you say breaking up when boost starts to come in ,are we talking 10lbs, 15lbs?

93oc Has soon as it starts making boost maybe 5 lbs

 

[Opie]

No expert here and I hope they will chime in shortly, but from what I can see.

TPS is too high - shoot closer to .42 to .44 at idle
MAF reading seems low at 3 - perhaps bump up the MAF Translator off of base setting to 3% rich at idle

What is the plug gap on the UR5?

I will adjust TPS I reset IAC and ajusted TPS this morning. I don't remember on the gap but I know I got the info here for mostly stock car

 

[Matone213]

I'm no expert but I was having the same issue only can get 5lbs of boost lots of knock turns out my vacuum line to the fuel regulator was plugged! I'm not saying yours is plugged but it could be fuel related. Just my 2 cents...good luck I been there you'll get it fixed!

 

[TurboBuRick]

Flat tappet cam? Probably worn cam lobe.

 

[Opie]

Flat tappet cam? Probably worn cam lobe.

I hope not only 63,000 miles on her

 

[Darkstar72]

I will adjust TPS I reset IAC and ajusted TPS this morning. I don't remember on the gap but I know I got the info here for mostly stock car

I also have a stock set up and I was told to set my gap at .030 by someone much more knowledgeable than myself. I know out of the box I checked the gap and they were .035.

 

[TurboBuRick]

Milage does not mean much. What you describe sounds like you have a worn lifter and cam lobe. It's very common on these motors. Most of the time it's #3 exhaust lobe. Pull the driver valve cover. Start the motor and look for a rocker not moving like the others. Pay close attention to #3 exhaust but don't rule out another one being the problem. Have some towels ready for the oil.

 

[brammja]

Check all your vacuum connections. Had same problem, mine was a tear in vacuum line where the vacuum line connected to the elbow on the turbo near where it connects to the intercooler. You could barely see it but once i cut out the bad piece and reconnected the line problem was fixed.

Sent from my iPhone using Tapatalk

 

[salvageV6]

Read the plugs, check the IGN Module, and pull the valve cover off as mentioned to check the cam.

What do the O2's on the scanmaster read when it starts to break up, voltage as well....

I'd invest in a powerlogger and check the numbers as you start to build boost to when it breaks up.

 

[jay dcpt]

Question. His short term fuel trim is right where it should be. Wouldn't that rule out a vacuum leak? I would be looking at the ignition. Assuming the engine was in good mechanical condition.

 

[jay dcpt]

And I no about the number 3 cam lobe but I have never experienced it personally. But wouldn't you see that at idle as well?

 

[Lil Truck]

Was the car running ok before the mods you made? If it did do you still have the stock maf ? Try it and see what it does, if it acts the same you can check it off the list. Double check the fuel pressure and then add 10 or 15 psi with regulated air and make sure you gain 10 to 15 lbs fuel pressure. If it works check it off the list. Just keep at it you will find the problem.