NEED HELP BAD ... car wont rev past 3k. HELP

[etmoron]

hey , i have a 1990 300ZX Turbo which i bought awhile ago but it had this one problem that i never really fixed .

well , i start the car and i try to drive it but it rev pass 3k rpms for some reason, the car just bogs and wont go faster and its running REALLY REALLY rich .

so i brought it to a shop and they said it was a MAF , and so i bought a used MAF and still the same problem .

just wanted to know if you guys ever heard this problem before ?

also when the car is fully warmed up , the idles jumps up and down from 1k to 2k .

some friends of my said it might be my ecu but im not so sure if im willing to fork out around 300 bucks for a used ecu just to find out that it wasnt the problem.

thanks in advance .

[MagikDragon]

first off, I'm pretty sure its been discussed before so go ahead and search if i cannot help you. the problem you described does sound to me like its your mafs. i had the same problem w/ my 240, if it cant sense the air coming in the ecu limits the revs. check the connections of your mafs. your ecu sends out codes to tell you why its limiting your engine. search and you shall find good luck.

Dragon

[evildky]

you really need to get the codes pulled and find out some basics, I'd suspect the knock sensor and or the CHTS

[Chris45601]

Yeh this problem sounds like a maf at first kinda like that maf wire is bad or something.. I mean because when i was messing around my girl started my car and tried to take off in it when i had the maf of and it wouldn't go above three grand so im leaning torward the bad maf wire but if it is the ecu go with a mega squirt and spark box cost you about for a tested and put togther 175 +shipping there nice i have one you'll notice the hp gain from you tinkering around with it, but if you don't wanna pay the 175 you can buy and make one for about 80 dollars from stuff laying arond radio shack but good luck with it man i hope you find out whats wrong

[kool-aid54]

man my n/a z did the same thing, I gave up but a TT is worth sticking it out. Try the maf return signal. see if it is getting a signal and try to see if that signal is making it back to the maf. Will it run with the maf plugged in?

[rsmithdrift]

I know exactly what your problem is. I stuck it out with my '84 when I got it. It'd hit 3200 rpm and make this god awful racket and run rich as hell. I took it to more than 10 places before one of them laughed at the incopetance of the others and had it fixed for $400. It was the timing belt. It jumped 4 notches on the right cam. Before you do ANYTHING ELSE to the car, get the timing belt replaced ASAP. I got lucky and after driving it 1,000 miles like that it runs absolutely perfect now.

Good luck, those VG30's are a royal bia to work on.

[300Plus]

my friend has been having the same problem on his 1982 280zx-T. We need help. We have replaced the Fuel Pressure Regulator and are about to replace the injector plug wires. It boggs and backfires at 3200rpm. the motor runs perfect when it is not acting up. It can't be a timing belt issue as the L28 is a timing chain. We have tried using carburator cleaner on the MAF but to no aval. PLEASE HELP us out here guys. Does anyone know the voltage on the MAF wires so we can check for proper signal? we are up for any suggestions!

P.s. We have the Fuel Pressure set to 44psi with the vacum line off and 33 with it on. Isn't this stock specs??

Thanks in advance guys

[nsrZ32]

Check out the TPS as well, that has the ability to limit the revs. I just replaced one one a Sentra the other day and it was causing that exact same problem.

[evildky]

my friend has been having the same problem on his 1982 280zx-T. We need help. We have replaced the Fuel Pressure Regulator and are about to replace the injector plug wires. It boggs and backfires at 3200rpm. the motor runs perfect when it is not acting up. It can't be a timing belt issue as the L28 is a timing chain. We have tried using carburator cleaner on the MAF but to no aval. PLEASE HELP us out here guys. Does anyone know the voltage on the MAF wires so we can check for proper signal? we are up for any suggestions!

P.s. We have the Fuel Pressure set to 44psi with the vacum line off and 33 with it on. Isn't this stock specs??

Thanks in advance guys

I'd suspect the fuel pump, is the car able to boost at all? the MAF wire harness has been known to so similar and is easily unplugged cleaned and plugged back in, if however it persists and isn't boosing I'd replace the fuel pump, I've seen this a few times now

[300Plus]

This week I'll have to make it over there to look at the MAF wiring. the car is able to boost but its around boost that is bogs. I would think boost leak but havent even looked into it since there is one pipe from the turbo to the intake mani.

[evildky]

This week I'll have to make it over there to look at the MAF wiring. the car is able to boost but its around boost that is bogs. I would think boost leak but havent even looked into it since there is one pipe from the turbo to the intake mani.

anyone who has messed with an L28ET will tell you boost leak and MAF first thing, but on more than one occasion I've found that once the fuel pressure starts to rise the failing fuel pump will just shut off, of course it resumes when the throttle shuts and the manifold vacume opens the fpr lowering line backpressure