newbie needs help; sputter sputter spit spit

[luv2whelie]

This is my first post, so I'll try to make it a good one. My idle is rough, and the car pulls pretty well until it goes from vacuum to boost. I've checked all the vacuum lines, intercooler hoses (it's an '87), plugs, wires, and set the tps. When I go to boost, the car will pull really well, but will have a couple of sporadic and continuing complete misfires, popping and cracking. I do have a scanmaster and the readings are shown below:
AF 06
L8 45
Bat 13.6
Int 128
BL 150
rpm 850-900
tps .52, but only because i set the idle screw to keep it running. it's in spec with the screw out.
IAC 62
cc climbing to 255, then starting over
had a code 31, but found the wastegate controller unplugged.

My setup: Bored, balanced, blueprinted, Comp cams 69-248-4, Speedpro pistons .020, Melling oil pump, LT1 Maf for impala with translator, MasterPower turbo60mm, Precision turbo exhaust housing, adjustable fuel pressure regulator (at 38lbs idle), 50# injectors, Walbro 340 fuel pump with hot wire.

I got this car set up this way, but with none of the kinks worked out. The motor has maybe 3000 miles on it. Any ideas on rough idle and sputter upon acceleration? It also was fuel fouling plugs when i got it, but seems to be better now.

Help?
Please?
John McClung
Asheville, NC

 

[bmackinnon]

what are the 02 numbers when it goes to popping and farting? The bl is high, should be 128 ish, so it's adding fuel to make up for what it perceives as a lean condition... which could indicate a vac leak or weak fuel pump... need to monitor fuel pressure while driving to verify fp is rising lb. for lb. with boost.... but something else is wrong since it's idling like crap.... probably a vac leak that you haven't found yet...

 

[luv2whelie]

I'll have to check the O2 numbers under load. where do I look for vacuum leaks besides the hoses? I unplugged the 5 vacuum lines and plugged them off and no change in idle quality. I sprayed all around with starting fluid too and no change in idle. any suggestions?
John

 

[Hacksaw]

Also, check the ball on the passenger's side of the engine, and the cruise control for vacuum leaks.

Crummy idle could be from the IAC being dirty, vacuum leaks, or the EGR sticking slightly open. The IAC counts do seem high, so pull it out & clean it up. Clean the doghouse IAC passages & area where the throttle plate sits as well with throttle/carb cleaner.

Then, disconnect the orange battery to ECM wire for 10+ seconds, start & warm it up, then reset the IAC & TPS:

IAC Reset Procedure

Adjusting the TPS

I hope the cam isn't too wild for the ECM to work with! A heated O2 sensor may help idle when it's cold.

Here's a page on what the scanner numbers should look like:

Quick Reference Page For the '86/'87 Turbo Regals and '89 Turbo T/A

"As with the Integrator, a value above 128 means the motor is running lean and the ECM will attempt to compensate by richening up the fuel mixture."

Popping under boost could easily be fuel starvation causing lean misfire. First, change the fuel filter, if it's not new. Try adjust up the fuel pressure to ~40-42 pounds at idle, with the vacuum hose off of the regulator. Clean the fuel injectors if that hasn't been done lately.

The Wastegate solenoid could still be flaky/erratic, & thus bad.

Low octane can also force serious timing cut back under boost, to the point of making it look like something's wrong, but that should happen all the time when you get into it. What was the knock retard # on the scanner?

 

[luv2whelie]

Fixed it! Idle is still eratic, but I haven't reset the IAC yet. the IAC was gummed up. I couldn't adjust it in spec with my scanmaster. I changed it out, and got it to adjust in, but it still spit and sputter. I put a new coil pack on it and solved the problem. It ran so well, in fact, that it snapped the transmission, which was supposed to be built to 950hp. Back to the drawing board...

 

[luv2whelie]

It's been awhile since I updated this post, but here goes. Turns out I did still have the spit and sputter, and my transmission didn't go; my stall converter got the splines ripped out of it. Got a new one from PTS and got rolling again. This week I've gotten serious about ironing out the kinks in my car. I replaced the sticking wastegate, welded up exhaust leaks on over-ported header, installed a new turbotweek chip, and fired it up. My idle problem was completely cured, and the car ran good, but still popped and cracked a bit at full throttle and 18-20 lbs of boost. Turns out, I'm ignorant. Somehow I overlooked gapping the plugs last time I changed them!!! I'm hoping I was using a cheap gap gage when I installed them, so I won't have to admit that I didn't gap them at all. So what was my gap? .042!!! New gap .030 and not a spit or sputter in sight. Learn from the mistakes of others.......