grand national lost power

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jdmorris

New Member
Joined
Mar 10, 2014
Messages
5
Hi all new to here and grand nationals. After repairing many things on mine I finally got it running ok. So I took it out and had a test drive. She was making a little more boost than it should like around 20 so iheaded home to adjust it. On my way home getting on the interstate it fell on its face. Now it runs fine until you get to about 10 pounds of boost and then it coughs and sputters. After reading some of your stuff I'm thinking head gasket. Any other ideas?
 
Off the top of my heads, I can come up with about 100 ideas! :)

Could be as simple as a hose blown off, or internal damage?

If you have no clue to what is under the hood, try to find someone that does, you could start by posting your location to find help.
 
Off the top of my heads, I can come up with about 100 ideas! :)

Could be as simple as a hose blown off, or internal damage?

If you have no clue to what is under the hood, try to find someone that does, you could start by posting your location to find help.

When I first got it the fuel pump hose was broke in the tank and there was alot of hack things done to it. I got a book by peter Hoffman and put everything back to the right way. I blocked of the ego and pcv to see if it was that. Checked all hoses and vacuum lines. It sounds and runs good until you try and push it. The scan master stays over 800 mv for the o2 when accelerating. I'm around cedar rapids Iowa. Who would be a good guy to take it to? I can do most of the work my self except the bottom end.
 
Check the connections to the up pipe, intercooler and turbo. If they breach at let's say 10 psi then it will fall flat on its face.

Posted from the TurboBuick.Com mobile app
 
Is the fuel pressure raising 1-1 with boost? What fuel pump is in there now?
 
When I first got it the fuel pump hose was broke in the tank and there was alot of hack things done to it. I got a book by peter Hoffman and put everything back to the right way. I blocked of the ego and pcv to see if it was that. Checked all hoses and vacuum lines. It sounds and runs good until you try and push it. The scan master stays over 800 mv for the o2 when accelerating. I'm around cedar rapids Iowa. Who would be a good guy to take it to? I can do most of the work my self except the bottom end.

I'm in Eastern Iowa and my Buick guru is in southwest WI probably 2 hours from you. Let me know if I can help. I'm in the CR/Iowa City area on business a lot.
 
I'm in Eastern Iowa and my Buick guru is in southwest WI probably 2 hours from you. Let me know if I can help. I'm in the CR/Iowa City area on business a lot.

I checked all the connections on the hoses they are good. Anytime your around the cedar rapid are send me a massage and stop on buy. The more eyes the Better. I think I'm going to pull the motor there are lots of oil leaks and it has a 100000 on it. I would rather go threw it to make sure everything is ok rather than hurt something. Then I will need some help tuning. The guy that had it before me did a lot of thing to it like turbo injectors chip regulator hot wire upper plenum throttle body and I put a new fuel pump. He said it ran good when he stored 4 years ago with his setup. What are some good things to do with the motor out?
 
I think I'm going to pull the motor there are lots of oil leaks and it has a 100000 on it. I would rather go threw it to make sure everything is ok rather than hurt something.

You might want to do a search and give that plan some more thought. There's been many a noob in recent history take apart a running engine 'just because' and end up in the hurt locker.
 
You might want to do a search and give that plan some more thought. There's been many a noob in recent history take apart a running engine 'just because' and end up in the hurt locker.
I was just thinking that.

I bought mine at 115k miles complete with oil leaks. Stopped the leaks, updated parts, ran 11's as daily driver.

Posted from the TurboBuick.Com mobile app
 
I always figure a blown hose or an ignition issue(coil pack, or control module). But the possibilities are definitely numerous. Good luck with your find and be sure to post back when you figure it out!!
 
I checked all the connections on the hoses they are good. Anytime your around the cedar rapid are send me a massage and stop on buy. The more eyes the Better. I think I'm going to pull the motor there are lots of oil leaks and it has a 100000 on it. I would rather go threw it to make sure everything is ok rather than hurt something. Then I will need some help tuning. The guy that had it before me did a lot of thing to it like turbo injectors chip regulator hot wire upper plenum throttle body and I put a new fuel pump. He said it ran good when he stored 4 years ago with his setup. What are some good things to do with the motor out?

Will do.

Posted from the TurboBuick.Com mobile app
 
Will do.

Posted from the TurboBuick.Com mobile app
I did put in a new ignition modular and new coil. After crawling around it some more I think it might be the passenger side header and turbo inlet pipe. I already repaired the driver side and the cross over pipe. What do you think could that cause it? I will let you guys know how it goes..
 
Did you ever find out what was wrong? My gn is having similar issues, my fuel line was also busted in tank but I repaired that yet it still has a problem.

Thanks leland
 
Did you ever find out what was wrong? My gn is having similar issues, my fuel line was also busted in tank but I repaired that yet it still has a problem.

Thanks leland
Welcome lelands6, It's best to start your own thread, because most answers are geared toward your specific mod's and will create less confusion for you when referring back.
 
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