Need Help....GN starts and keeps stalling

[818GN]

Hi,

I have an 87 Grand National w/114k miles on it. I recently purchased this car and apparently it has had a fair amount of work done to it. The current issue is this:

Once started the car will run/idle ok for a few mins. After driving for 5-10mins, no faster the 35-45mph, the car 1. sputters, 2. Check engine light comes on, 3. Scan master turns off and on, and then stalls. It started doing it off and on, now it is more regular.

Here is the current combo.

109 block
center billet caps
main studs
Eagle forged crank
Girdle
.040" pistons
head studs
Adjustable FPR
Hot wired fuel pump
Tin Man Cold air kit
206/206 flat roller cam
stock rockers
rjc power plate
Razor Alky kit (just installed)
TE60 turbo
60lb injectors
Fbody radiator
Oil Cooler
Tranny Cooler
SLIC
3" ATR downpipe w/ wastegate (just installed)
Magnaflow exhaust
3200 stall converter
built trans
stock rear
Scanmaster


Found that the battery ground wire was ground to the frame instead of the engine block. That has been corrected and it is now grounded to the block, if that makes a difference.

Any ideas as to what could cause this?

 

[TurboTerry87gn]

Coil Pack amplifier going out?
If you remove the coils from the amplifier CCI it will be scammer this is USUALY one indication that the amplifier is on its way out. It only does it once the amplifier gets heat soaked. Try to borrow an amp to test your as they are not returnable.
Thats just one thing to look at but thats a common problem with these cars.

Good luck.

 

[bmackinnon]

Coil Pack amplifier going out?
If you remove the coils from the amplifier CCI it will be scammer this is USUALY one indication that the amplifier is on its way out. It only does it once the amplifier gets heat soaked. Try to borrow an amp to test your as they are not returnable.
Thats just one thing to look at but thats a common problem with these cars.

Good luck.

The 'amplifier' he refers to is actually the ignition module, which the coil pack sits on... and yes, the symptoms you are experiencing are typical of a failing module or coil pack as they get hot... aftermarket modules from autozone, oreillys, etc are fairly hit and miss, however I haven't ever heard of anyone having a problem exchanging a defective unit... gummyness is indeed a sign that the module 'may' be bad, but not a sure sign as they all get that way over time, and continue to work for a while... while a bit more expensive, I recommend using a genuine oem ac-delco module, such as available at nos4gn (dot com)... In addition, your symptoms could also be a failing fuel pump... need to verify the fuel pressure is correct when it starts acting up.... Welcome to the darkside!!

 

[TrAb]

When was the last time you replaced the coil pack/ignition module? If i was you i would go buy a ignition module and coil pack from autozone. Install it and see if it fixes the problem, if it does take them back to autozone and order you a nice original coilpack and ignition module. :wink:

 

[pajo]

module

Indeed it sounds like the module is going kaput --welcome to the buick world Pal .:biggrin:

 

[johnplogii]

Almost sounds more like a ground problem to me with the scanmaster acting up. Check the grounds on the back of the passenger side head. There are two seperate locations with several wires on each. Also check the pos batt cable where it runs past the passenger side header, sometimes it can get too close & short out on the header.

On a side note they put billet caps, a girdle & a steel crank in the motor then topped it off with stock rockers?

John

 

[davidf]

I think I'll pick up a new GM module and install it before it leaves me stranded. Better now than later.

 

[bmackinnon]

Almost sounds more like a ground problem to me with the scanmaster acting up. Check the grounds on the back of the passenger side head. There are two seperate locations with several wires on each. Also check the pos batt cable where it runs past the passenger side header, sometimes it can get too close & short out on the header.

On a side note they put billet caps, a girdle & a steel crank in the motor then topped it off with stock rockers?

John

The scanmaster will go crazy as described when the engine starts bucking and farting and going dead due to a bad module.... with the specific symptoms, I will almost guarantee a bad/dying module, coil pack, fuel pump, or maf.... likelyhood in that order... would be a good idea to verify the module/coilpack mounting hardware are tight as that is where they get their grounds, however...

With all due respect, mild cam, stock rockers... what's the problem? These things don't like to/don't need to rev anyway... stout bottom end for durability... I say nice!

 

[johnplogii]

At this point it doesn't really matter, the original poster hasn't been back here since his one original post. Maybe he is out buying the $500 worth of parts you guarantee are what he needs.

 

[818GN]

At this point it doesn't really matter, the original poster hasn't been back here since his one original post. Maybe he is out buying the $500 worth of parts you guarantee are what he needs.

The car is in the shop at the moment. I have not bought any parts yet, before I have a clear picture of the cause. The point of my post is to avoid spending $500 on needless parts I don't need. All the suggestions have been forwarded on and are being checked out.

I appreciate all the help so far. Thank you guys.

 

[TURBO 6]

I think I'll pick up a new GM module and install it before it leaves me stranded. Better now than later.

I keep a spare in my trunk. I had one go out on me 200 miles away. Wasn't fun.

 

[davidf]

I keep a spare in my trunk. I had one go out on me 200 miles away. Wasn't fun.

My thoughts exactly.

 

[818GN]

I keep a spare in my trunk. I had one go out on me 200 miles away. Wasn't fun.

I may do that as well. Good advice.

 

[TrAb]

Mine went out first day i had the car, i was 5 hours from home.

 

[bmackinnon]

At this point it doesn't really matter, the original poster hasn't been back here since his one original post. Maybe he is out buying the $500 worth of parts you guarantee are what he needs.

I'm just trying to help a new guy out, and I thought I was being respectful to you, and clarifying my earlier comment. Not sure of the reason for the attitude? Sometimes the best intentions are..... and fwiw... yes, I would agree that you should definitely check all grounds and + batt cable... geez...

 

[818GN]

All grounds and wires were checked. Looks like the culprit was a bad sunroof seal during a recent rain storm. Apparently, water got in, and went down the A-pillar, touching the computer and a few other wires/connections.

Next order of business is to get a new seal for the Astroroof.

Thanks for all the input guys.

 

[bmackinnon]

Ahhhh, yes! Glad you got it figured out. The ol' watered down ecm... another fairly common problem with these cars. You will be glad to know that the 7148 ecms are pretty easy to find in the boneyards and go for peanuts. Think I paid $25 a year or so ago. Do a search, and you will easily find a donor car list. In fact, there is a thread in the 'junkyard' section of the site that has the list...

Edit: here it is...
86-87 ECM
GM #1227148
Here is a listing of all that use it:
Note: Turbo Regals use different chips; don’t use the chips from these cars on you GN!!

1989 PONTIAC FIREBIRD TRANS AM V6 3.8L 231cid GAS FI T Engine VIN = 7
1989 PONTIAC FIREBIRD TRANS AM GTA SE V6 3.8L 231cid GAS FI T Engine VIN = 7
1987 BUICK REGAL GRAND NATIONAL V6 3.8L 231cid GAS FI T Engine VIN = 7
1987 BUICK REGAL LIMITED V6 3.8L 231cid GAS FI T Engine VIN = 7

1986 BUICK CENTURY CUSTOM V6 3.8L 231cid GAS FI N Engine VIN = 3
1986 BUICK CENTURY ESTATE WAGON V6 3.8L 231cid GAS FI N Engine VIN = 3
1986 BUICK CENTURY LIMITED V6 3.8L 231cid GAS FI N Engine VIN = 3
1986 BUICK CENTURY T-TYPE V6 3.8L 231cid GAS FI N Engine VIN = 3
1986 BUICK LESABRE CUSTOM V6 3.8L 231cid GAS FI N Engine VIN = 3
1986 BUICK LESABRE LIMITED V6 3.8L 231cid GAS FI N Engine VIN = 3
1986 OLDSMOBILE CUTLASS CIERA S V6 3.8L 231cid GAS FI N Engine VIN = 3
1986 OLDSMOBILE CUTLASS CIERA V6 3.8L 231cid GAS FI N Engine VIN = 3
1986 OLDSMOBILE DELTA 88 ROYALE V6 3.8L 231cid GAS FI N Engine VIN = 3
1986 OLDSMOBILE DELTA 88 ROYALE BROUGHAM V6 3.8L 231cid GAS FI N Engine VIN = 3

1986 BUICK CENTURY V6 3.8L 231cid GAS FI N Engine VIN = B
1986 BUICK ELECTRA PARK AVENUE V6 3.8L 231cid GAS FI N Engine VIN = B
1986 BUICK ELECTRA T-TYPE V6 3.8L 231cid GAS FI N Engine VIN = B
1986 BUICK ELECTRA V6 3.8L 231cid GAS FI N Engine VIN = B
1986 BUICK LESABRE V6 3.8L 231cid GAS FI N Engine VIN = B
1986 OLDSMOBILE 98 REGENCY V6 3.8L 231cid GAS FI N Engine VIN = B
1986 OLDSMOBILE 98 REGENCY BROUGHAM V6 3.8L 231cid GAS FI N Engine VIN = B

1986 BUICK REGAL GRAND NATIONAL V6 3.8L 231cid GAS FI T Engine VIN = 7
1986 BUICK REGAL T-TYPE V6 3.8L 231cid GAS FI T Engine VIN = 7