Grand national dies when going into drive

Cameron McGinley

New Member
Aug 22, 2018
I recently did a full suspension swap to qa1 coilovers wilwood brakes front and rear, strange bolt in 9" rear end And tubular control arms in the rear along with new 3" chromoly driveline. To fit the driveline I had to cut off my flowmaster exhaust right after the cat due to it hitting the driveline. I also had to eliminate the stock proportioning valve and went with a wilwood adjustable prop valve right off the master cylinder. With all new custom length stainless steel braided brake lines with An fitting to each caliper from front to rear. My car has been on my lift for about a month now doing this suspension swap. I did the first test drive yesterday An did the proper wilwood brake in process for the brake pads which consisted of multiple hard stops to adjust the brake bias from front to rear. During each hard stop my GN would die and i did about ten of these hard brake stops in a total of about 15-20 min I then drove for a quick cruise for 10 minute and theat when the motor started to
Die out and lose power unexpectedly as we came to a stop sign An suddenly died. We then tried to start it An it would not start. I called for a quick tow from a buddy got it home An got it started again in my driveway but would only run in neutral or park An when I shifted into drive it would instantly die. My 87 GN has always ran and drove flawless 110k origional Miles motor is bone stock. It sat for 2 months with my painter prior to this suspension swap and drove home great from my painter which is 45 in away. Today I started the GN it fired right up I pulled it out of Munich neighborhood just fine and and as soon as I pulled out onto the main road An gave it gas it studderes and died and wouldn't start once again. I don't think removing my exhaust would have anything to do with this or eleiminatinf the factory prop valve. Any help would be greatly appreciated ????
Without a scantool, people are just going to start shooting suggestions/guesses out there.

Check your vacuum lines.
Check your MAF.

Sent from my iPhone using Tapatalk
Check your grounds and your fuseable links they get hot and act funny when old and need replacing. Plus check your cam , crank sensor and replace if nessary . If u ha e a tr6 then the cam sensor has to be set right or else it will act funny. Let us know how it went
As mentioned in post # 2......Data log it, and post the results. Include fuel psi, when you do that.
sounds like either the converter is stuck locked or more likely the trans is junk with direct clutches seized

another thing to check is the idle screw on throttlebody , the aftermarket accufab has a habit of loosening up and then the throttle blade is completely closed and it wont idle ..
check the iac count (and if on stock ecu check tps) for drop from normal , if zero IAC adjust screw and once its set put drop of blue locktite on the tip threads
Last edited:
its possible the short downpipe with no direction at end is heating the trans and the cooler lines and causing issues in the trans