Hey guys I just bought a 2005 g35 coupe yesterday that has the JWT 530bb kit running at 7 psi. The car seems to run perfect and was not giving me any problems until today while racing an M5. I pulled from 2nd to 4th and after letting of of the throttle the car shut off while driving and I had to turn the car back on. I tested this out a few more times and the car will turn off everytime after running it hard and letting off of the throttle. Can anybody tell me what this is?! I know a little about turbos but have no clue about this and I did search this everywhere but no answer that I could find. Hopefully someone here can point me in the right direction. Thank you!

 

The first thing I would check is the pressure signal source for the FMU. The FMU controls fuel pressure under boost and off boost the pressure is controlled by the OEM regulator. The install manual available on the JWT web site explains that the signal pressure source comes from the turbo outlet. The turbo outlet pressure never goes negative so only boost pressure will increase fuel pressure. If for example the signal line was incorrectly connected below the throttle plate it would see negative pressure under decal and possibly lower fuel pressure. The only way to know exactly what's happening with fuel pressure is to connect a test gauge that you can watch while driving.
Other than that possibility I would call Jim Wolf directly and see what he thinks. No one knows the kit better.

 

Or ask the PO if he can advise him on the issue . Maybe the PO noticed something, but this advice above is solid. What kind of shut down is it... Slow, forced, jerky...

 

I Honestly would have thought that your idle needs to be raised a little if you raced and neutralized immediately after, but you have an auto transmission, so the likelihood of you throwing it into neutral is much lower...

 

I have not updated my car yet on here so it still shows my old G. This one is 6mt.

 

Thank you for the help! I will get on that asap and comment back after!

 

Previous owner only had for 3k miles and sold so he could put more money into his supra. I have tried contacting the owner before that who had the kit installed but he has not replied to any of my contact attempts. The shut down is almost unnoticeable until you feel that your power steering goes out and the car won't accelerate hahaha.

 

An update from tonight. I was showing a friend the car and we went on a back road to do some pulls and it was fine doing small pulls but again I did a 2nd-4th pull and the car shut down then turned itself back on? Until I get it figured out I'm going to stay out of high boost because I'm not sure if this is a major problem or not. I will be contacting JWT tomorrow.

 

It is typical of a rapid decel with the JWT kit. I used to experience the same issue with the stock ECU controlling the throttle. You can try to fix it by raising the idle if you have UpRev cable and license. Otherwise, Jim Wolf did publish this:

http://www.jimwolftechnology.com/wol...BILITY_FIX.PDF

I've always had a Haltech so I added fuel, pulled timing to get the idle to bump back up. The new Haltech units control the DBW directly and do not have an issue with this.