rb25 stumbles under load

[nissans13240sx]

Ok so the issue is when you free rev the car it revs fine. If you put it in first and try to move it, there is no throttle response it just tries to die. The car was running fine a few weeks ago. We just put a new headgasket and arp studs on. We have gone over everything atleast 4 times, cant seem to figure this one out. We put new plugs in it, tried 2 differnt MAFs, differnt ignitor, differnt ecu, checked knock sensors, check injectors, checked for vac/boost leaks and checked timing. We just keep running into dead ends so any suggestions would be great.

[USMCgetsome]

stock throttle position sensor or q45. Either way check the voltages. Were the mafs that you swapped known as good? I would start with the tps and wiring. I've seen those same symptoms with bad mafs and bad tps. How's the engines idle? Battery voltage/alternator as well chief.

[nissans13240sx]

lol chief.

Anyway it has a q45 throttle body, greddy intake mani and a q45 maf. Before we did the headgasket it was running fine. SAFC voltages for TPS appear fine. We also compression tested it to make sure it doesnt have a leak, 150psi across the board. Battery is a brand new optima. I dont think its the alternator dieing because it always restarts and theres no other indication of loss of voltage.

If the tps was bad would it still rev under no load though?

Thanks for the reply.

[USMCgetsome]

bad tps would choke! like it's doing now. Check it's voltages. Get back to us with volt/ohm readings asap!!

[nissans13240sx]

Alright I will let you know tomorrow. Thanks for the reply.

[nissans13240sx]

Ok TPS is around .5v closed and around 4.5v open. So I think thats good. We got it to sorta respond today. We moved the maf farther away from the turbo and that seemed to make a differnce. It still has a stumble at about 4000rpm.

[USMCgetsome]

how close do you have it to the turbo? Also, guess what's next. Check that maf voltage and wiring. Check your crimps or solder joints. AHORA!!!!

[nissans13240sx]

It was right next to the turbo before. Now its about 9 inches away. I have already pulled apart MAF wiring I havent found anything out of the ordinary. Any idea what voltages should be like at the maf? Also are SAFC setting for a q45 maf 1 and 4?

[ex_rabbit]

the best bet: sell it, and buy a new Versa.

lolz j/p im thinking its nothing electrical, b/c you said it runs fine when it isnt even in gear.. maybe there is a problem, drivetrain wise..? curious as to if you went over any of that stuff.. g/l in your further diagnosis

[USMCgetsome]

ok next on the list is fuel pump!!! also, check your ground on your coil igniter. grounds in general check them. get back to us!!

[nissans13240sx]

Well everything checked out good. It seems to be running ok now. I think the maf was just reading funny close to the turbo.