At 2-3k rpm my gn falls on its face just bought it need help??? Thanks

[84turbonational]

HI,IM NEW TO THE FORUM LOVE THE SITE.......I JUST RECENTLY BOUGHT A 84 GN CAR IS IN GREAT SHAPE 114K ORIG MILES MOTOR IS ALL ORIG EXCEPT FOR NEW MAF AND LIVE WIRES.
AT ABOUT 2-3K IT WILL FALL ON ITS FACE.I DID A FUEL PRESSURE TEST ITS BETWEEN 30-40.IM WONDERING IF IT COULD BE MY CAT BOOST IDK???? HELP WOULD BE GREAT THANKS!!!

 

[Jerryl]

HI,IM NEW TO THE FORUM LOVE THE SITE.......I JUST RECENTLY BOUGHT A 84 GN CAR IS IN GREAT SHAPE 114K ORIG MILES MOTOR IS ALL ORIG EXCEPT FOR NEW MAF AND LIVE WIRES.
AT ABOUT 2-3K IT WILL FALL ON ITS FACE.I DID A FUEL PRESSURE TEST ITS BETWEEN 30-40.IM WONDERING IF IT COULD BE MY CAT BOOST IDK???? HELP WOULD BE GREAT THANKS!!!

There are many things that can cause that.
Do you have a scantool than can record and post the file?

Let's start with fuel pressure.
How did you measure it and under which condition? (idle, boost?)
What does the fuel pressure do under boost?
How much boost when it "falls on its face"? (I am guessing 2-5?)
How are you reading boost?
What plugs/gap are in the car?
What is the condition of the coil pack?
What MAF? What does it read at idle, 0/0, 5 PSI boost?
What condition are the grounds nd alternator in?
How fresh is the fuel?
Are the injetors clean?
How old is the O2 sensor?
Are you getting SES codes?
Is the cat open? (Can you see any light through it?)
Are the vacuum hoses hooked up correctly?
Are the TPS/IAC and vacuum stable/good?



Don't EVER Ass-U-Me it is stock!
Worked on a 27K original mile T-Type the other day that is "stock".
Well . . . it wasn't. LOL We are going to get it running right though. He is buying a scantool, pump/hotwire/chip for stock boost levels.

 

[BRAD_PADGETT]

Added to your list-Plugged up CAT. Brad

 

[Jerryl]

PS:
The thread in the Genneral Section states 3-4K.
This one states 2-3K.
Which one is correct? (BIG difference!)



http://www.turbobuick.com/forums/ge...tween-3-4k-rpm-fuel-prsr-30-40-maybe-cat.html

 

[84turbonational]

Car will fall on its face between 3-4k sorry about the other post.i don't have a scanmaster but I did put it on my snap on scanner it has no codes if I go into data display at an idle it says it's burning lean and if I drive it it says it is burning rich...if I come to a dead stop and hammer it will launch and at 3-4k it will fall on it face ad if I take my foot off of the throttle real fast and put it back on the throttle it will snap out of it then start back as I get into a higher rpm. It's kinda like if I start chirping or goosing the pedal it will just keep spinning the tires and it won't fall on its face at all... But as for plugs and such I haven't got that deep into it yet ... Thanks for the help.

 

[Jerryl]

Car will fall on its face between 3-4k sorry about the other post.i don't have a scanmaster but I did put it on my snap on scanner it has no codes if I go into data display at an idle it says it's burning lean and if I drive it it says it is burning rich...if I come to a dead stop and hammer it will launch and at 3-4k it will fall on it face ad if I take my foot off of the throttle real fast and put it back on the throttle it will snap out of it then start back as I get into a higher rpm. It's kinda like if I start chirping or goosing the pedal it will just keep spinning the tires and it won't fall on its face at all... But as for plugs and such I haven't got that deep into it yet ... Thanks for the help.

Are you getting KR?
ECM may be doing what it does best . . . protecting yor investment by pulling timing!

 

[84turbonational]

Yea what's ur waning of kr?

 

[84turbonational]

*meaning sorry

 

[Jerryl]

*meaning sorry

KR = Knock retard.

It is the ECM’s response to detonation by pulling timing to prevent engine damage.
IN our boosted world, THIS is your worst enemy!

A typical HA has about 16-18 degrees timing.
When the ECM pulls 10 degree timing for example, you are left with a sudden loss of power since the net timing is 6-8 degrees.
Typically, you can see the amount of timing pulled on a scantool.

If you have a scantool that connects to the ALDL connector like OTC or SnapOn, you will see about 1 frame/1.3 seconds.
With a “real scantool” :tongue: like Power logger, you can record and playback at 18 frames/sec.

My advise is:
1-Have someone with specific KNOWLEDGE about these cars help you get it sorted out before you ask about the best head gasket, or the best engine builder.
2-Read, read, read . . . . than read some more.

PS:
Between 3-4K RPM you are (should be) in boost mode which is why it is critical you stay out of the throttle untill you figure this out.
Between 2-3K RPM, you are just getting into boost, or are at low boost. You should still stay out but the damage will be MUCH LESS severe.

 

[84turbonational]

Ok thanks alot for all your help...

 

[Johngregston26]

left my mass air unhooked one day and she was doing the same thing...hard to predict

 

[Jerryl]

...hard to predict

X2 . . . . . and a lot harder without scantool data!