Hi chaps and chapettes, I wonder if any of you out there can point me in the right direction regarding a problem I have with me Z. I've got a '91 jap import TT auto and she's revving really high (6500-7000 revs) before she changes gear, particularly when she's cold. She did it Monday night, but by the time I'd gone 10 miles the problem had disappeared, untill I started her and drove her again about 2 hours later.

The other thing I've noticed is that with the AT button, to the right of the shift stick, put in the normal position (middle) the 'power' light on the dash comes on if I floor it, however, it doesn't go off again unless I flick the AT button to power then back to the middle again, all the while still revving up to 7000 revs before changing gear!!!!! Any ideas....anyone?

:confused:

done an autobox diag. Noticed the power light flashing randomly at all?

How do I do an autobox diag? And no, I haven't noticed the power light flashing randomly, it only comes on if I floor it, then it stays on, or, if I push the AT switch to the 'power' position.:confused:

deffinatly sounds like youve got a fault somewhere.

 

If you go over to http://www.twinturbo.net and hit the tech section there will be a tech to show you how to do it. It is easy as pie to do it.

I had a G reg Mk III Supra Auto which used to change on a dime. Never had a problem with it. However the Zed Auto can be, let's say, a bit twitchy.

 

I know that's not what you wanna hear and unless the box has failed I would try to live with it.

 

I had mine rebuilt and it doesn't perform aswell as AndyP's or Iain(MAC1's) cars that I've been in.

 

Z Auto boxes are very complex, my Soup gearbox was computer controlled but these babies are more OTT than that.

 

If you are not happy with the way that it changes I personally would suggest either an ALC from HKS but that only really effects the changes at top end or getting a proper fast road rebuild at SE in Essex.

 

Reason I say that? I had mine rebuilt by AGS in Watford. It was a soft rebuild replacing clutches and an exchange torque convertor.

 

OK for road driving but if you want the box to perform beyond the 400bhp point I would go for the SE fast road rebuild.

 

Just my opinions and I have been driven in and driven a fast road rebuild Z Auto and they are nothing short of awesome for an Auto.

 

;)

I have similar behaviour in my TT, but not anywhere near as bad as yours sounds. It seems to like to change to Power when cold and heavyish on the right foot, but I find if you lift off the gas for a moment it goes away again (this may be normal behaviour!).

 

Since you've got the Jap auto switch, does it behave itself in HOLD mode? I find it less hassle to drive like this for the first few miles than having to knock it in/out of POWER mode.

When was the box last serviced (i.e. fresh oil) IIRC this should be done every 2 years.

Have you done the diag checks yet ? Any probs ?

 

I suspect that you should be checking whether the A/T control unit is seeing the revolution sensor and speed sensor signals.

 

Lots of relevant info linked from here :- http://www.300zx.org.uk/tech_09.htm

Dunno about the waiting till 7K to change up, but the Jap Autobox automatically goes into POWER mode if you boot it, and also shuts off the air-con for a while to give you MAX POWER (sic) The effect lasts about 10 seconds after you stop booting it, and it goes back to the mode you had it in before.

Originally posted by x-biker

Dunno about the waiting till 7K to change up, but the Jap Autobox automatically goes into POWER mode if you boot it, and also shuts off the air-con for a while to give you MAX POWER (sic) The effect lasts about 10 seconds after you stop booting it, and it goes back to the mode you had it in before.

 

Yeah, the power light always came on when I floored it, and always used to disappear about ten seconds later, but it's been within the last month where it seems to be sticking.

LINE PRESSURE SOLENOID!

Line pressure solenoid? what's that do and where is it?

My friends Z power light flashes when he starts up from cold, what does this mean????

Originally posted by avalaugh

My friends Z power light flashes when he starts up from cold, what does this mean????

It means that you just totally hijacked this thread. :D

Has he got his ECU in Diag mode ?.

So does mine but that's because someone stole the autobox and replaced it with a manual !!! LOL ;)

 

Originally posted by avalaugh

My friends Z power light flashes when he starts up from cold, what does this mean????

Would a ALC help to stop this,even if it was the line solenoid,ie it would keep the pressure up,;)

Will an ALC help the problem?

 

Been there, done that and the answer is no. The ALC increases the pressure only slightly and bear in mind that it uses the LPS to increase the pressure anyway.

 

If the LPS is faultly which is what is sounds like (sticking) then the overall line pressure will be low - similar to if the box was low on oil. This results in late gear changes and a generally sloppy box. Providing the gears ARE NOT slipping but just over reving then thats likely to be the problem.

 

A word of warning. I had my auto box fully recon'd and upgraded and still had the same problems as you. All soleniods where checked and tested OK so its not an easy fault to prove. If a garage tells you that it tested ok replace it anyway.

 

Secondly, I didn't get an error code from the manual diagnostics check. However, It came up on a test drive with a consult plugged in. Why? According the the mechanic, the consult makes a number of calculations from all the other sensors used by the box and is able to conclude that the line pressure was too low etc etc.

 

So I would suggest getting a consult test done first with a thorough test drive replicating the problem so the consult picks it up.

 

The LPS is relatively easy to replace as there is no need to drop the whole tranny. You need to drain the oil and remove the oil pan on the box to get to the solenoids.

 

The speed and revolution sensor could also cause that type of problem but a consult test will check those for you.

 

Good luck!

 

Andy

i have a jap 300zx fairlady, autobox it was waiting till it got 2 7000 rpms then woodnt change 2 thrid gear so rang se who has dun most of my work was told i could use me local macanic had no car for 7 mounths they did it it came back and the gear want again se in essex told me that a normil rebuild would be ok with the work ive had dun , but the man said if it gose again then it my cars failt it must be 2 powerfull for the box :mad:confused: