hi there everyone,

 

i am new to the forum and had my 300zx for some 8 months now. it is a 1992 twin turbo t-top:clap:.

 

Unfortunately is not all good news :sad: so in hope of a answer i came to this forum to see if any one could help me.

 

Yesterday i started the car and once the car warmed up a idle the rev drops up and down and up and down vice versa. Now this HAS happened to me before and it goes away it self after a bit.

However now it has gone worse :sad:

 

1. the car actually cuts out straight away and turns off only when the engine is warm. - happens a few times.

 

2. Majority of the times the revs drop so low that its like the engine is cutting out; steering cuts out, and the battery light comes on a few secs later its fine and car starts itself when i let go of the clutch. this happens alot more often than no.1.

 

It is pretty dangerous as it has cut out on me around corners and for 2-3secs have not been able to control/steer/brake the car.

 

so i am out to find solutions/suggestions to my troubled problem and thought this would be the best place.

 

Please any advice would be really appreciated.

 

thank you

oh it is a jap import and is the newer shape.

 

when driving it seems ok, sometimes do feel lack of power. As soon as i stop the rev needle goes up and down between 0-2000 revs, when it reaches near 0 the battery light turns on and cuts of.

Check around the connections in the engine bay, you may have some connectors that are corroded, will try and find a picture that points out the usual culprits.

 

Maf, ptu, temp sensor, throttle position sensor.

 

Paul

 

http://www.300zx.co.uk/forums/showthread.php?26120-Engine-by-numbers

Edited July 25, 201312 yr by 300_zedx

MAF sensor bust?

Hi and welcome....

 

firstly what have you done to diagnose it?

what work have you done to it? (i.e. preventative maintenance).

these cars need a lot of love and attention.. your's is 21 yes old now!!!

Like the other guys have said... you need to check all the electrical connectors first, for corrosion and good contact (including the battery & alternator).

you can then go form there to check for ecu codes, check the plugs, coil packs, ptu, tps, cas, injectors, fuel supply.... etc..

 

 

 

these are handy....

 

 

Ash's 6 P's

http://www.twinturbo.net/net/viewmsg...&msg_id=922678

 

 

Auto Transmission Diagnostic

http://twinturbo.net/ttnettech/autodiag/autodiag.html

 

 

Cleaning Electrical Connections

http://www.300zxclub.com/showthread.php?t=153696

 

 

ECU Diagnostics

http://www.zmods.org/index.php?page=ecu_diag

 

 

FAQ

http://www.300zxclub.com/forumdisplay.php?f=78

 

 

FSM

http://300zx-twinturbo.com/cgi-bin/manual.cgi

http://simsters.com/z32.htm

 

 

Hatch Lock Repair

http://s95014253.onlinehome.us/63104/13202.html

 

 

Hatch Strut Replacement Info

http://300zxclub.com/showthread.php?...=mcmaster+carr

 

 

Idle Tech

http://home.swipnet.se/e-solutions/IdleTech.html

http://home.swipnet.se/e-solutions/IdleTech2.html

http://www.twinturbo.net/net/viewmsg...&msg_id=920429

http://www.twinturbo.net/net/viewmsg...&msg_id=855473

 

 

Power Balance Test

http://www.300zxclub.com/showthread.php?t=179661

 

 

Spark Check

http://www.300zxclub.com/showthread.php?t=168129

 

 

Test Starter/Battery/Cables Function

http://www.300zxclub.com/showthread.php?t=168558

 

 

Throttle Body and IACV Maintenance

http://www.300zxclub.com/showthread.php?t=59296

 

 

Troubleshoot code 21 / no spark issue

http://www.300zxclub.com/showthread.php?t=169134

 

 

Vacuum Leak

http://home.swipnet.se/e-solutions/Vacuumleak.html

Hi,

 

i took it to my mechanics yesterday he did a very quick check for the connections, took some of and cleaned them up a bit and still nothing.

i have dropped it of with him today to see if he can have a proper look.

 

please that would be great if you could find a picture, it would really help.

 

thanks

local mechanic.... go and get it back before he changes you heaps of money with no results....

 

unless he is familiar with Zed's you are wasting your time... (unless you get lucky) but most of us on here have horror stories about local mechanics.

 

read all the stuff I gave you...

 

and like 300 Zedx says, take the front nose panel off and check the MAF connector.

 

best of luck... you could always take it down to Zedworld in Birmingham...

also the TechFAQ section on this forum is very good...

 

have a look in there...

 

this is the engine bay..

 

http://www.300zx.co.uk/forums/showthread.php?26120-Engine-by-numbers

 

also check out the FSM... the bible of Zeds

 

http://z32.wikispaces.com/Factory+Service+Manual

hi,

 

its not a random mechanic, hes a good friend, so he wont be charging me sky high prices.

 

thank you all for the posts, appreciate it all.

 

can someone show me where the maf connector is? i had a look at the engine bay and could not see it?

 

its my pride and joy, has been parked in a garage over winter and took it out as the weather was amazing.

i look after it and maintain it very well.

this problem has just started all of a sudden and is very annoying.

 

cleaned the water temp sensors- both of them no.14 and 15 from the engine bay link because they looked pretty poor but didnt help.

Hi,

 

yeah, the front panel between the lights has two bolts that hold it on... undo them...

 

bingo...

 

the ecu temp sender unit is the one with two connectors, the unit may be not working.. you can test the resistance as it cools down.

 

the other one is just for the clocks in the dash... no consequence to the cars running.

 

get your mate to have a look at the link I posted.... it will make a massive difference to him being able to fix it..

 

 

the MAF is where the air filter is... you should have changed it as part of your maintenance.

ill show my friend and see what happens.

just hope i get it fixed soon.

i think the sender unit had lots of black tape around so took it off and checked it out cleaned it up etc as well as all the other connectors cleaned out, none made a difference.

will look at the maf sensor. just dont understand why the car would cut out completely.

 

p.s. anyone know where the fuse is for electric door mirrors? cant move them or close them, think fuse has gone but cant find it!:ninja:

Hi,

 

i took it to my mechanics yesterday he did a very quick check for the connections, took some of and cleaned them up a bit and still nothing.

i have dropped it of with him today to see if he can have a proper look.

 

please that would be great if you could find a picture, it would really help.

 

thanks

 

Posted a link on thread number 3 for you.

 

Paul

Posted a link on thread number 3 for you.

 

Paul

 

oh yes i found that later on, thank you

Would be worth getting a diagnosis software of some kind (datascan or conzult etc).

 

There's another way to check for fault codes by putting a wire between 2 of the pins on the diagnostics port - But I can't remember which 2 - you then get (hopefully) a light flashing on the dash flashes slowly for the first number of the code and then quick for the second number of the code (might be the other way round)

Would be worth getting a diagnosis software of some kind (datascan or conzult etc).

 

There's another way to check for fault codes by putting a wire between 2 of the pins on the diagnostics port - But I can't remember which 2 - you then get (hopefully) a light flashing on the dash flashes slowly for the first number of the code and then quick for the second number of the code (might be the other way round)

 

was reading a forum just a bit ago about this. what the guy said was that if you locate the ecu unit under the fake floor on passenger side, it has a knob on the side that you rotate twice and it enters diagnostic mode, now that has the same thing it flashes etc as you said. (was mentioning postimeter or something a lot, was a quick read for me, so sorry if i havent said it right) however you are correct, slow is first number, fast is second.

 

can anyone confirm this so i can give it a go?

 

now Japanese fault coding is rare, i dont know anyone. my mechanic cant as his machine doesnt do jap as software is different.

Yeah, take up the ply floor. You will see the ecu, on the left hand side of it is a flat head plastic screw ( potentiometer). Turn that left as far as it goes ( half a turn I think) it will only go one way.A little red LED will light up. Then back to right all the way, then back to the left. Any stored codes will start to flash back at you via the LED. Search ecu codes on here for diagnosis. 55 is "all clear"

Don't forget to turn screw back when you're done

:clap:after lots of searching i finally found he thread...

 

here it is

 

http://www.zmods.org/index.php?page=ecu_diag

 

thoughts? yes i know that its auto and american.

Yeah, take up the ply floor. You will see the ecu, on the left hand side of it is a flat head plastic screw ( potentiometer). Turn that left as far as it goes ( half a turn I think) it will only go one way.A little red LED will light up. Then back to right all the way, then back to the left. Any stored codes will start to flash back at you via the LED. Search ecu codes on here for diagnosis. 55 is "all clear"

Don't forget to turn screw back when you're done

 

thanks, its - turn it fully clockwise. Wait at 2-3 seconds, then turn potentiometer fully counter clock-wise. The ECU is now in Diagnostics MODE II Diagnostics

 

will definitely give it a go or see if my mechanic is clever enough to do it.

 

oh any dangers before i do this? like to the ecu etc? always good to ask before you try.

No, I've done this on mine many times in the past with no issues whatsoever. It's just an inbuilt diagnostics mode.

STOP!!!

 

The issue you have is a simple one that has the potential to develop into more if you randomly or someone else randomly messes about with out knowing what your looking for.

 

So the fault is a simple base idle tick over issue and a probable fault with the connection on the auxillary valve.

 

 

The base idle is the mechanical setting that ensures that with no added tick over speed from the electronic idle stability solenoid that the engine cannot tickover less than 750 to 800 rpm depending on the setting which is done by adjusting the screw on the side of the valve ( back of the engine by the battery location)

 

 

Locate the unit and identify the yellow connector on top of it, un-clip it and spray WD40 or similar into both the connector plug contacts and the unit contacts itself.

 

 

 

Leave the plug undone and locate the adjustment screw ( sometime battery removal can aid this) spray WD40 or similar into the screw area and turn the screw in and out to free it up, now turn anti clock wise until the screw is level with the unit body.

 

 

Reconnect the yellow plug and start the engine, hope fully with an improved connection on the unit the tick over will be stable now, and it also may be a little too fast, so when the engine is up to temp, remove the yellow plug again and slowly turn the adjusting screw back in ( clockwise until the tick over is set at around 800rpm, reconnect the yellow connector, do not worry if the revs rise they will stabilise after a moment.

 

The idle control valve can play up even with a good connection so above is the first stage, if there is any more issues report back here.

 

Hope that helps

 

Jeff TT

Surely checking ecu codes can't damage anything though??

Surely checking ecu codes can't damage anything though??

 

 

No it will not.

 

Jeff

Couldn't it be an air leak too? When my maf was broke, my revs were going up and down like described,

Couldn't it be an air leak too? When my maf was broke, my revs were going up and down like described,

 

Lots of possibilities but as the op said its sometimes is ok it unlikely an air leak gets better and then worse at tick over speed.

 

Jeff TT

STOP!!!

 

The issue you have is a simple one that has the potential to develop into more if you randomly or someone else randomly messes about with out knowing what your looking for.

 

So the fault is a simple base idle tick over issue and a probable fault with the connection on the auxillary valve.

 

 

The base idle is the mechanical setting that ensures that with no added tick over speed from the electronic idle stability solenoid that the engine cannot tickover less than 750 to 800 rpm depending on the setting which is done by adjusting the screw on the side of the valve ( back of the engine by the battery location)

 

 

Locate the unit and identify the yellow connector on top of it, un-clip it and spray WD40 or similar into both the connector plug contacts and the unit contacts itself.

 

 

Leave the plug undone and locate the adjustment screw ( sometime battery removal can aid this) spray WD40 or similar into the screw area and turn the screw in and out to free it up, now turn anti clock wise until the screw is level with the unit body.

 

 

Reconnect the yellow plug and start the engine, hope fully with an improved connection on the unit the tick over will be stable now, and it also may be a little too fast, so when the engine is up to temp, remove the yellow plug again and slowly turn the adjusting screw back in ( clockwise until the tick over is set at around 800rpm, reconnect the yellow connector, do not worry if the revs rise they will stabilise after a moment.

 

The idle control valve can play up even with a good connection so above is the first stage, if there is any more issues report back here.

 

Hope that helps

 

Jeff TT

 

Don't retire! ;)