My Z32 wont go past 40mph. What what could be the reason behind it. I had a new MAF sensor installed. Car runns rich though. When the car is in Park, runs and idles fine, revs up good too. When I reach 40mph though, is start hicking up, or cutting out, exhaust is like popping out arount 40mph. Got free flow 3in muflers, stock exhaust pipes.

Did any one have anything simmilar?

TreadStone
1990 Z32 NA 2seater

 

Fuel pump could be crapping out. ECU codes should be checked as well... you know how to do that right...?

 

I'm guessing crank angle sensor. Mine did something very similar. Black soot out the tail pipe and it would buck and jerk if you tried to get on it hard. ECU threw code 55 though....I just had to replace it and cross my fingers. I gut a used one from Z1. Try giving them a call. I think I paid $50 for it. New the CAS is over $500.

Another thing mine did was that the tach would bounce all over the place when the car would buck and jerk. See if your tach does anything similar.

It's not the fuel pump.

 

Well, tach is not jerking. Engine runs smooth. I cant go past 3xxx rpms.
Exhaust starts to pop, or like engine is choking, and the revs are cutting out.

When I turn my ignition on, I can hear my fuel pump turning on. Makes that hiiizzing sound. then it stops. But I had that on my prev Z and it was noromal.

Guys, you sure its not the cats? Why in the hell Nissan put 4 cats in the Z.. jeez..

anyways

 

To rob us of power.

 

you only have 2 cats. and they would not stop you from accelerating. they would only make it harder. unless they were completely blocked
a constantly humming fuel pump is likely to fail in the near future.

try cleaning all electrical connections you can get to.

 

Check the ECU, you can do it YOURSELF with a flat head screwdriver.

 

b300z

You got me thinking, cuz I do have some exposed wireing.. frikin, wire batch in the wire wrap were laying on headers by the tranny.. melted every thing. When i got it from the last owner

I lifted it up and secured it. but still

Well, here is what I did I put the car in park gave it a guys. .around 3K it starts to stumbple and starts to make that chocking poping sound..

not backfire sound. no softer,, but poping..

When I drive and give it a quick hard gas.. I got black sooot coming out of my mufflers..

One time I hit the gas in park and walked behind and found some black chonks on the floor

 

Why are you saying I only have two cats.. ?

 

i believe there is two cats and two resonators... sucks that your car is doin all of that. i myself am not sure what that could be, but im sure someone will come around to help ya out

 

Could these cars have the same problem as our S130's whereas if water gets in the TPS our cars will act the same way...doesn't need to be water...but some kind of liquid.

 

turbos have a set of precats and a set of cats. non turbos have no precats

 

moved to 300ZX (Z32) Performance / Technical.

 

I don't believe tt's have resonators... right?

 

I believe the stock TT exhaust system did. There were small cans in the exhaust between the cats and the mufflers.

 

I vote for crappy ingectors...but thats based purely off my astounding technical background and the plethora of information that Tread has given.

I have two cats too by the way. Thier names are Samson and Whiskers

 

Sounds like fuel pump to me.

 

Why did you replace the MAF? Was the car running fine before you had the new MAF installed? If so, then you need to start there. Did someone forget to plug the MAF in?

You should start with all the basics....fuel filter, air filter, plugs, etc. Clean the TB's also.

I'm still saying no to the fuel pump.

 

Yes, Muffler shops are wrong. Z32 NT Does NOT have 4 catz. 2 resin. 2 Catz.

b300Z you might be right about Electrical. I checked my Catz they dont look pluged. They are filthy inside, all charcoal black, but dont look pluged.

I'm replacing them any way. To my disbelive EXHAUST PIPES are on 2in in dia. My replacing Catz have 2.5 in In/Out they are bit bigger too.

Back to the Subject - I started car with no pipes. (damn laud) and still same problem. Will NOT go past 2800rpms.

That leaves me only one area. Electrical and frikin big area.

Quastion: What is the white wire for on MAF sensor connector? This white wire is much thicker (heavy gauge) then the rest of the wires on MAF Connector wires.

Any one have knowledge on MAF sensor connectors?

Problem IS (b300z might be right): I baught a Z32 MAF sensor it is a N62 model type which is for Z32. I baught with the connector (from ebay). Problem is: when I got started connect the wires to my Z. The batch of wires that were ripped from my Z (Damn #$@#4 thieves) has this white wire that apperntly was connected to my old MAF sensor. The one some as@$# stole from me, ripped it all out.

Any ways.. I belive it could be the possebility that its that wire is not connected. The rest of the wires matched perfectly. I soldered them and brushed them all in liquid electrical tape.

Tom
1990 300ZX Z32 NA 2Seater

here is the pic

 

Your problem has to be due to the MAF....it sounds like the car was running fine before the MAF was ripped out and now it isn't.

Get rid of the liquid electrical tape and re-splice all of the wires. I bet that solves your problem. Or, the MAF you bought off of eBay is crap.

Save your money....don't replace those cats....there's probably nothing wrong with the stockers.

 

looks like its too late for that

 

Too bad....I'm 100% sure that los gatos aren't a source of his problem.

 

Well, guys just had my ECU read. It was the MAF sensor/wirring all along. I also found out that color matching (wirring) in Z32 means nothing (heads up).

It's gona cost me just under 200 bucks. Wire test/wire match to the MAF sensor and that is if the MAF is not broken.

Cross my fingers and hope for better.



TreadStone
---------------------------
1990 Nissan Z32 NA 2str

 

I believe it's the fuel system (not to say that the MAF and wiring isn't bad, but it's not causing your car's inability to rev higher than ~2800rpm). The NA fuel pump is a 2 speed pump, and the higher speed kicks in right around 2800rpm or so. If your pump is not kicking into that speed, it'll be like the engine hits a wall at that rpm because it's not getting enough fuel to rev faster.

My last 300ZX had the same exact problem and it was the fuel pump.

While you're working on the fuel system, get an inline fuel pressure gauge, search for posts by me, and find one of my posts about diagnosing a bad FPR and dampener... something tells me those are probably shot too.