My 87 GN Build

[Mnt86SS]

It's been a long time since I've posted here. Sold my 86 GN over a decade ago now, and have missed it since. I've owned a few GNs over the years, but never found the right one.

Started looking for another, but nothing was coming up that was workable and priced right. I kinda gave up looking for one, until I saw this thing in all its glory. Covered in flames and a Grim Reaper, it was interesting to say the least. Went up to Maine to check it out.

Turns out an Army recruiter drove it up to VT from TN, and the sellers Dad had to have it. Made him an offer and bought it on the spot, and immediately customized it. Unfortunately he passed away, and left it to his son. He took good care of it, keeping it 100% rust free. It was time to sell it, and I guess I was the first to see it in person. He knew I was going to repaint it, and was sentimental about the hood. It had his children's initials on the scoop, so I let him keep it. I knew I'd feel bad painting over it knowing how much it meant to him.


Just got done with the paint. It's a base clear, including 3 coats of clear which were cut down with 800 grit, followed by two flow coats of clear which were then cut with 1200 up to 3000 grit.

Heres a few pics of the progress. Next up is redoing the tint (it's waaaaay to light) and some other odds and ends.

 

[Mnt86SS]

Took it for its first drive down the street since 2014. Snapped a pic before the sun was totally down. After that I redid the tint. Went 5% on the rear and quarter windows, 35% on the doors, and an 8" 5% eyebrow. Looks so much better than that old blueish tint.

 

[TurboTGuy]

Looking Good!

 

[mblum]

Stunning! Looks great.

Those your 2nd gen TA's? That's a bucket list car for me kinda like the GN.

 

[Mnt86SS]

Stunning! Looks great.

Those your 2nd gen TA's? That's a bucket list car for me kinda like the GN.

Yeah, I have a few of them. Pontiacs run in the family.

Next step for the GN is various performance parts. Right now it's running 50lb injectors with a Turbotweek chip, Adjustable regulator, Walbro pump, 3" downpipe with external gate, Turbonetics gate with manual boost controller running 17lbs currently. It has some sort of converter in it.

I'm planning on putting meth injection on it, a larger turbo (currently a TA49) and a front mount intercooler.

 

[KC87]

Honestly, I like "your" paint job and wheel choice much better. Very nice.
That hood was atrocious. Was the seller a mortician and wanted it for a coffee table.
Post some more pics.

 

[Mnt86SS]

Honestly, I like "your" paint job and wheel choice much better. Very nice.
That hood was atrocious. Was the seller a mortician and wanted it for a coffee table.
Post some more pics.

lol

I'll grab some more pics soon. Just got done repainting the lower plastic valance as it was chalked up and gray colored. Also went back over the paint with a DA and some nice swirl remover. Looks awesome.

 

[Mnt86SS]

Finally starting to put some miles on it after being off the road since 2014. Got a couple questions.

The IAC counts at idle were around 25. The car had a slight stumble when slowly accelerating from a stop. I set the IAC count down to about 05 at idle and reset the TPS to .42, which is where I thought these cars liked to be, but it seemed to hate it. Would stall or buck when accelerating from a stop.

I ended up doing a reset by using a jumper wire in the ALDL plug and unplugging the IAC. Set the idle at 550rpm with the IAC unplugged. Plugged it back in and set TPS and it runs great now, but IAC count is over 30 at idle. Is this a big deal?

It seems to like it, and everything else seems to be fine. It's not detecting any knock under boost. Idles smooth cold or up to temp.

 

[Mnt86SS]

Also, heres a pic from a local car show this morning.

 

[salvageV6]

You should be okay with 30 counts, I liked the original hood.
If you look at the scanmaster as you start to accelerate and it's stumbling look at the O2's default on the display and see if the numbers go low or high, that should tell you if it's a rich or lean condition off idle.
Really nice new paint now too.

 

[Mnt86SS]

It seems to have developed a nasty stall condition off of idle in drive. Heres what I have:

02 Millivolts at idle: 370-425
AF: 04
L8: 31
INT: 128
BL : 145 (too high)
TPS: .46
IAC: 15 in park, 43 in drive foot on brake (likes to hang at 175 off of idle and acts like cruise control)
CCs: Look good. Bouncing from 0-255 quickly
MAL: 00


When I did a hard reset on the IAC and TPS it ran much better. Nothing has changed from then till now, but the stalling is back. Any idea where to start?

 

[scgnx2]

I would take the IAC off the Throttle body and clean it with brake cleaner. Take a good look at the connector and wiring too. Reset the IAC and TPS again.

 

[Mnt86SS]

I would take the IAC off the Throttle body and clean it with brake cleaner. Take a good look at the connector and wiring too. Reset the IAC and TPS again.

I pulled it out and it was a little dirty, but nothing out of the ordinary. It doesn't move freely though. Is it supposed to?

I plugged it back in, but left it uninstalled and noticed it didn't move at all with the key on. I could sometimes pull it out or push it in, but other times it was like it was welded solid.

 

[salvageV6]

TPS needs to be below .45 car running for best idle. I shoot for .42-.44 tops with the car running and charging.

 

[scgnx2]

I pulled it out and it was a little dirty, but nothing out of the ordinary. It doesn't move freely though. Is it supposed to?

I plugged it back in, but left it uninstalled and noticed it didn't move at all with the key on. I could sometimes pull it out or push it in, but other times it was like it was welded solid.

If I recall correctly, the IAC resets itself when you turn the key on/off. The tip should move when you do that. More than likely the IAC is bad or it’s not getting power. If it’s original, it’s like 35 years old and I would replace it.

 

[Mnt86SS]

If I recall correctly, the IAC resets itself when you turn the key on/off. The tip should move when you do that. More than likely the IAC is bad or it’s not getting power. If it’s original, it’s like 35 years old and I would replace it.

So I've been fighting this for a few days now. It's odd as it ran fine the other day, in fact I put 210miles on it last week.

Still has a nasty stall condition off of idle. It'll do it without touching the gas, just letting go of the brake in drive.

New IAC, reset with jumping the ALDL followed by resetting the TPS which is @ .38 key on engine off and .42 running.

I had a small vacuum leak at the vacuum block on the intake. Replaced all rubber lines, verified no leak.

I'm now getting a MAF code (34) on the scanmaster, but no CEL on the dash. I cleaned it, tried tapping on it while the car is running but haven't noticed anything, and still have the code.

The car does idle when the MAF is unplugged, but still stalls out. It's currently reading AF 06 at idle, and does climb when you give it gas (12-15) regardless of if it's plugged in or not.


Think it's a dead MAF? It's an original style, but looking at it, it looks like someone might have taken it apart before. It looks like theres crude cuts inside it, with what looks lile hot glue.

 

[BRAD_PADGETT]

Suck it up and pitch the old MAF in the trash. Get an LS1MAF with translator and live happily ever after.

 

[RED LS1]

I'm surprised you're having all those issues. All your procedures and numbers appear to be correct to me. If you sit still with your foot on the brake will it stall? Or when you release the break at a low RPM?

 

[Mnt86SS]

I'm surprised you're having all those issues. All your procedures and numbers appear to be correct to me. If you sit still with your foot on the brake will it stall? Or when you release the break at a low RPM?

In drive foot on the brake it'll idle all day smoothly. As soon as you release the brake and transition into part throttle it'll stumble and die.

I was planning on doing the LS1 MAF this winter, but I guess I'll do it now lol

 

[TIMINATOR]

Vacuum brakes? I had a stumble when releasing the brake a while ago, it was a bad diaphragm. If vacuum, plug the port off and see if anything changes. The computer will learn a vac leak and compensate while it can. Same with throttle shaft wear.
TIMINATOR