Diagnosis help

excobraguy

Member
Joined
Feb 25, 2007
87 Buick Grand National
rebuilt motor with low miles, ported heads
te62 turbo with external tial wastegate.
55 lb injectors, fast xfi, front mount
atr headers and downpipe....

thats my setup.

issue - under boost, engine falls on its face and has bad cutting out problem. spitting, sputtering, etc. it only does this sometimes, not everytime.

things i’ve done:
checked hose connections
put on new plug wires

before throwing wasted $ at it..... is there a list of things to check before spending money on doing part replacement mechanics? done that before, never again.

thanks, dean
 
Have you caught it on an xfi log?
 
Should be easy to see on a log.

Catch it and post a screen shot.

It's even easier if you have individual EGT logging capabilities. But either way, something is bound to show up.

Just don't blow it up trying to recreate the condition. Do some long slow pulls and creep up to it.
 
Should be easy to see on a log.

Catch it and post a screen shot.

It's even easier if you have individual EGT logging capabilities. But either way, something is bound to show up.

Just don't blow it up trying to recreate the condition. Do some long slow pulls and creep up to it.

D634B37E-71C8-45A0-A82E-8427169196CE.jpeg
 
It sucks when people get discouraged and sells the car. I have a buddy who was a die hard FORD guy and traded one of his Mustangs for a GN. I bet he had it a total of 60 days. He threw a ton of mods at it for performance and didnt take the time to learn and understand what he was doing. When it didnt hit his goals he sold it. Someone may have just purchased an easy fix. BMW's are cool too tho, my son has an 98 M3 sedan with an Active Autowerks supercharger on E85 putting down 500+, and a 2009 335i twin turbo about to get some treatment.
 
It sucks when people get discouraged and sells the car. I have a buddy who was a die hard FORD guy and traded one of his Mustangs for a GN. I bet he had it a total of 60 days. He threw a ton of mods at it for performance and didnt take the time to learn and understand what he was doing. When it didnt hit his goals he sold it. Someone may have just purchased an easy fix. BMW's are cool too tho, my son has an 98 M3 sedan with an Active Autowerks supercharger on E85 putting down 500+, and a 2009 335i twin turbo about to get some treatment.
this was my 4th gn ive owned. had nothing to do with not knowing the cars really. i just saw the black hole i was already getting into with this car and was smart enough to stop it before i got in too deep like my last one $$$$$$$! the gns are cool but getting really dated on looks, comfort etc. and the cost to own one is ridiculous. if you blow a motor its what, like 7-10k for a decent built block? i just went in the garage and said “$400 for tuning, $300 for dual fans, $700 for alky” uh stop!!!! and i did.
now i have a 335i bmw twin turbo that i was able to buy a tablet, mhd tuning software, gauges for the laptop, everything needed for $200! next is a complete top mount turbo kit and the car will be right at 650rwhp for under $4k. and its a 6 speed!
gns are great, just not for me anymore.
 
I think that the 335i twin turbo definitely came in under the radar for performance. I understand, maybe who ever purchased your car will get it running right and keep it for many years down the road.
 
I found in my last car that chasing power usually requires deep pockets and extreme patience....neither of which I have at my disposal. I will be just content going high 13s listening to my radio with ice cold a/c.
 
BMW's are cheaper than a 80's G body to modify and maintain?
look, im not trying to get into a pissing match with you guys about any of this. if you feel your gn is for you, great. im not knocking it at all.
mods, close the thread if you will. all people want to do is argue anymore about stupid shit.
 
I'm totally cool with your decision, just questioning the claim that a BMW is cheaper to maintain and modify. I would think it would cost more, alot more.
 
Maybe it’s just me, but this is a turbo Buick forum. Don’t know why anyone would be talking about a BMW in a Buick forum. We talk about how to with Buick’s,we all know it cost lots of money, that’s what we do. Some people cannot stand the cost of having a car that has a cult following. Most of us get that. Nothing wrong with driving a BMW or a Musturd, just go to those forums.
 
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