WOT bogs down on my 84 GN

Hot Air Beast

Hot Air Lover
Mar 10, 2007
251
8
18
74
Carleton Place, Ontario, Canada
I know I have referenced this condition in another thread, but now the car is in another shop and the owner is searching for a Snap On red brick so he can pull diagnostics, so I though I would try with you guys again.

I have searched the board and found that another member, with an 86 GN, seemed to have the same problem back in 2010 but never posted a solution - so - here goes again - My engine runs fine as long as I do not go WOT. I can ease up to 80-85 mph nice and smooth, but if I try WOT at any time, the engine bogs and actually seems to slow down. When I ease up on the pedal it goes back to normal.

Has anyone ever had this problem in the past and what did the problem turn out to be?
 

ScottHeidinger

Active Member
May 2, 2015
698
121
43
50
northeast Florida
Most likely not getting enough fuel (verify 1:1 fuel pressure rise with boost) or bad MAF. I would start with monitoring fuel pressure with temporary fuel pressure gauge where you can see it while driving. Never had a hot air but these are the things that have caused those issues with mine. Power logger file would help but I assume you don’t have one? Also verify no vacuum leaks or post turbo air leaks in the cold side plumbing. Have seen clamps that were not tight allow boost pressure to escape in inter cooler pipes if you have installed a inter cooler check that first.
HTH


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Hot Air Beast

Hot Air Lover
Mar 10, 2007
251
8
18
74
Carleton Place, Ontario, Canada
Hallelujah - time for a positive update.

The shop in Naples Florida gave up looking for a solution. To his credit, he did not charge me for all of the hours he put in.

As posted earlier I had measured FP at idle, swapped a number of MAFs, installed new O2 sensor, checked spark plug gap, etc. etc. and then taken it to a well respected shop in Naples Florida. When I got it back I decided to take a shot in the dark and swap the coil pac / ignition module. I sourced one from San Antonio and I just finished the swap. It was time for a test drive.

Gotta tell you guys – I am as happy as hell.

Car goes like there is no tomorrow.

Got on the I 75 access ramp – put my foot to the floor and didn’t let up until the needle was off the dial – 140kms/per/hr. - no hesitation at all.

WOT problem resolved.

Thank you all for your suggestions. Nice to have a thread come to a positive end.

Phil’s 84