Has anyone had to do this?

[240ZinTN]

I have been having a hard time getting my 240Z turbo conversion up and running. I did the Z31 MAF conversion and it would idle fine but would hesitate and stall out when I would rev the engine. I finally got it to rev by putting a "restrictor plate" in front of the MAF, reducing the intake area by half. Now it runs better than ever. Does anyone know why this would work?

I have a K&N filter mounted to the MAF and located in the corner below the coil. From there it is a staight shot ( 3" diameter pipe about 12" long) to the turbo. I am not running an intercooler and have the stock set up from the J pipe back.I am only running about 18" of exhaust pipe after the downpipe so I know the exhaust flow is not restricted. I blocked off the EGR and got rid of the Air regulator to clean up the intake manifold (before I ever got the car running-not the best idea). Would this be a contributing factor? Why would my car need to breath worse to run better?

[Guest 73TPIZ]

My setup is totally different than yours but with my SDS FI system it has what is reffered to as an accelerator pump function (similar to a carb accel pump). If i set it too mild, my car will stumble if i romp on the accel but climb normally if i ease into the throttle. If i set it more aggresive, it does fine. Sounds similar to what you may have. The sudden change of hitting the throttle dumps too much air without any burst of fuel to go with it. the restrictor plate you put in makes the rate of change more gradual, giving your fuel time to catch up.

 

If you have a air/fuel meter, watch to see if it goes waaay lean when you blip the throttle, and then finally catches up. That's how i could tell what mine was doing.

 

Others with more knowledge/experience will probably chime in soon.

 

Good luck with it.

[240ZinTN]

I don't have an A/F meter so I can't tell if I go lean when I blip throttle. I do know than it was running so rich that the exhaust was burning my eyes once it finally warmed up and I got the rpms over 3.5K. I would have to bounce the throttle, gradually increasing rpm and once it got up there it would run fine as long as rpm didnt drop below 3.5K. Once up there it would respond ok to changing throttle positions too.(?????) I plan on getting an A/F meter soon or borrow one.

[datsunan]

Sounds to me you did'nt set your timing right with the TPS closed or the TPS is not closing at Idle so your ecu never knows when you are at Idle.

[240ZinTN]

It turns out I had a kink in the fuel supply line going to the fuel pump and this was causing the presure to fluctuate. My guess is this would also cause the injectors to not be able to keep up with the increased air flow when I opened the throttle. It runs even better now but I have not had time to remove the restrictor plate. I will try it this weekend and hopefully it will not be needed (and hopefully it will run even faster with better airflow). I did get a chance to drive last night and was able to smoke the tires in first and second and chirp in third without much effort. I can't wait to get it on the track and see what it will do in the quarter mile.

[AnTmanS130T]

I had a similiar problem with my z31 ecu setup. Everytime I would come to a stop the car would die. Don't forget that the z31 base idle timing is different than the 280's. I put my base idle at 20 degrees and raised my idle to about 900-1000. Now it runs great without any idle / shutting off issues.