1990 300zx na Hesitation

[mada300zx]

1990 300zx naIt has 85k miles on it. I have a JWT Pop charger and a labree exhaust system. Other then that, this car is stock. I recently had the 60k mile service done to my car since the previous owner did not. I have personally cleaned my MAF sensor, throttle bodies, and intake. I replaced all spark plugs and fuel filter. I also just replaced all fuel injectors. I am getting a hesitation in low RPM's throughout all gears. After I pass about 2500 rpm the problem goes away and the car seems like it has a big boost like the problem instantly went away and the car wants to fly. I have read a lot of other posts and have not found anything that seemed relevant to my issue. I have had this inspected by nissan technicians and they seem to not really understand or see a problem. I know it's not just me because other people feel it while driving with me. It is very annoying and I really hope someone could point me in the right direction. Thanks for your time!

ps they tried to pull codes at nissan and came up with nothing.

[fowlladyZ]

hey man i have this exact problem... i was just abou tmake a post to ask about it..... the car really stuggles to make it out of 2500 but after that it is awsome

if anyone know please let us know

[mada300zx]

I hate to say it but I'm glad someone else has the same problem! Maybe we can figure the problem out! If you find out about what is causing this, please let me know!! Thanks

[tagzx]

+1My 94 na does the same. Makes it thrilling for a few seconds when merging in traffic, watching the rear-view...waiting for power. I previously thought it was a dead spot in my TPS, now I'm not so sure. I'll be watching this thread for suggestions.

[Touge-Z32]

This a common problem with our Z's as it's been covered many times so it could be a combination of problems that could effect acceleration.

http://www.ttxtz.com/tech.htmlhttp://ww ... et....html

[mada300zx]

This a common problem with our Z's as it's been covered many times so it could be a combination of problems that could effect acceleration.

http://www.ttxtz.com/tech.htmlhttp://ww ... et....html

WOW! I have been looking for something like this for a while now! thanks so much!!!!!

[fowlladyZ]

well that answers my question... thanx dude

[fowlladyZ]

Okay does anybody know if this 'head machining flaw' is limited to only the 1990 (so produced in 1989)? Does it make a difference if the car is NA or TT? I'm not sure if they share the same head..

Does happen to anyone with 5spd or only ppl with auto trans? My 1990 2+2 NA auto is giving me this same problem.

Also, is the failing part in question the CAM angle sensor, or CRANK angle sensor? Don't say its the CAS lol

[mada300zx]

well my z is a 5 speed so it definitely is not only the automatic. Today I checked the TPS. I will check the CAS tomorrow. It is the crank angle sensor not the cam angle sensor fyi. I'm not sure if the TT version makes a difference for this problem but I will let you know how it works for me.

[Ghut300zx]

you CLEANED your MAF?

thats useually a bad idea

[Ace2cool]

They sell MAF cleaning stuff kinda like carb cleaner or something like that.

[mada300zx]

W

you CLEANED your MAF?

thats useually a bad idea

why? I did it with no problems at all.

[fowlladyZ]

ya man i was just making sure it wasnt my stupid trany, alot of friends had been telling me they thought it was my trany going....i gues im happy to hear it isnt...

[zxFarside]

I have an '92 N/A auto that I think dose the same thing.

Like around 2500rpm it seems to get stuck and just sounds like its struggling and when you mash the gas it just guns off?

Do any of your cars that have this issue make odd sounds when this happens?

[mada300zx]

Sometimes mine will backfire when it comes out of that "hesitant point". But I have a 5 spd.

[zxFarside]

"back

Sometimes mine will backfire when it comes out of that "hesitant point". But I have a 5 spd.

When you say "backfire" is it a BANG! backfire or is it more of a pop sound?

[mada300zx]

"back

When you say "backfire" is it a BANG! backfire or is it more of a pop sound?

It's definitely a pop sound. It only does it once or twice a day. But the hesitating happens pretty much every time unless I'm stomping on the pedal.

[zxFarside]

It definitely a pop sound. It only does it once or twice a day. But the hesitating happens pretty much every time unless I'm stomping on the pedal.

Ok, so to narrow this down a little more, where would you say the pop sound comes from? Front of the engine or back of the engine.

[mada300zx]

It comes from the back of my exhaust.

[zxFarside]

Mhmm, sounds similar to what I'm dealing with. Only mine dose it from a cold start, once my car had driven 5+ miles it seems to clear up. If you jump in my car start it up and drive, holy crap it runs like a** but if i let it warm up in the driveway for a few min its not as bad.

[fowlladyZ]

mine doesnt backfire...or pop...where is this goin?

[zxFarside]

No where really.

Honestly I think a loose screw on the rear fender would make the z32 run like crap.

I just realized that half the people in this thread live in or around Charlotte lol.

[mada300zx]

I agree. I can almost swear that when I turn the radio on I lose power in a cylinder lol

[fowlladyZ]

me and my friends did a testturned the radio up high, put down both windows at the same time while turnign the wheet all the way and shifting into drive.... the car stalled.... hahahahahahahaha

[zxFarside]

How dose your car idle? High? Low? All over the place?

[fowlladyZ]

na, fine, right under 1grandbut wen ever i do aomething that takes power the rmps just drop haha...usely not enough to stall.. but wen they were all put together... HA

[zxFarside]

Mines about the same. The defrost saps a lot of power for me.

[nightops]

have you checked all the connections to the injectors- even though you changed out the injectors you would still be misfiring if your wiring is corroded. also check the coolant temp sensor at the front of the engine to see if that has corrosion. that would cause you to run in warm up mode. also vacuum leaks could be an issue i would tighten couplings as well. g/l

[z32partsmo]

Have you guys checked your CAS this sazme thing happened to my 91 na auto and it was a bad connenction on the CAS I unplugged it cleaned it up and put electrical greass on it put it back together and problem solved. Im not saying this will fix your problem, your CAS may be bad, but let it run and wiggle your wires see what happens.

[mada300zx]

I've pretty much come to the conclusion that I'm going to sell my car. There's 1,000 things I could check but I don't have time to do it. There's just too many negatives that I have to accept with these cars. This being my second one, I know a lot about the negatives. Yea it's a cool a** car but IMO not worth it right now for me. Maybe when I have more time and money I will upgrade to a twin turbo as my weekend car!