Hi,

my '90 jap spec, TT has has started to rev really low (when idleing) to the piont of almost and sometimes stalling. i noticed a few months ago the revs were a little low but they went up when i put the de-mister on. but its got worse and is reving and spluttering at 500 revs till it stalls. it missfires when you rev the engine once its warmed up. ive done an ECU test and it gets a code 55(no fault) when the engines not running and a code 24(throttle valve full load) when running.i would really appreciate any advice anyone could give me. cheers SI-Z

possibly dodgy coil pack connectors or more likely ptu (or connectors on the PTU).

 

the de-mister thing is probably a bit of a red herring, increased load on the electrics will make the revs go up a little. (or if its the aircon you're talking about same thing applies)

 

good links to resources on 300zx.org.uk about the PTU, take the connectors off and remove all the crud off them with electrical contact cleaner. then make sure they are back on properly and give it a go. if that fails it may be worth having a go with a new PTU.

cheers ill give it ago

This might be worth a try. When it starts to stutter, pour some cold water over the PTU. If it starts to run fine the PTU is on the way out. Had a similar problem with my car (although mine was stopping completely) and the Z centre gave me this tip. It worked. New PTU and its fine. Information might be a load of rubbish and not work at all. That said you have nothing to lose.

Ive tried the cold water thing on the PTU but didnt help unfortunatly. the engines only running for about 2 mins or so now, then stalls im gonna get a diagnostics expert out to check it out. thanks for your comments, ill let you know how i get on

This might be worth a try. When it starts to stutter, pour some cold water over the PTU. If it starts to run fine the PTU is on the way out. Had a similar problem with my car (although mine was stopping completely) and the Z centre gave me this tip. It worked. New PTU and its fine. Information might be a load of rubbish and not work at all. That said you have nothing to lose.

 

pour cold water over the PTU????????? are you mad???

 

they suffer enough with corrossion in the connectors without this kind of madness, + if the water shorts out the connectors while your doing this your likely to get misfires not cure them!!

pour cold water over the PTU????????? are you mad???

 

they suffer enough with corrossion in the connectors without this kind of madness, + if the water shorts out the connectors while your doing this your likely to get misfires not cure them!!

 

lol - I think the recommended method was to cool it down by dabbing the fins with a damp cloth ;)

 

Steve :)

Mad maybe - but it bloody worked! Some commonsense was obviously required with this snippet of information. If your daft enough to throw a bucket of water over it then that's your look out. The idea is to cool the ******* down not drench it!

From memory the engine code 55 is correct for no problem.

The 24 I'm not sure about - should not show that as I recall.

In fact, once the engine is started I don't think it shows sensor malfunction codes at all. Once started it shows (either) the exhaust gas sensor readings (LED together with the "check engine" light on the dash). Or, if in the other position, it shows ECU failure - if it occurs.

Code 43 is throttle sensor open circuit or short circuited, 42 is a fuel temperature sensor fault. Long then short is the order to count - before you start the engine.

I think if a failure occurs during engine running it will keep the problem codes and remember them for next time you do a sensor check before u start it.

If the 24 is actually a 43 it means it's getting throttle position errors when running.

If it's really a 42 then it that's another problem - chase around the web (US 300ZX) or in the FAQs - u should find better info than I can give here.

Hope this helps.

JaquesOZ

its hardly a conclusive test anyway, the problem is a soldered contact wire breaks & when hot it expands & looses contact. so pouring water over it isnt a guaranteed way of diagnosing it!

If your really desperate and think it could be the PTU I can send you my old one. There was no problem with my car running on this PTU it would just cut out after about 5 miles.

Hi,

my '90 jap spec, TT has has started to rev really low (when idleing) to the piont of almost and sometimes stalling. i noticed a few months ago the revs were a little low but they went up when i put the de-mister on. but its got worse and is reving and spluttering at 500 revs till it stalls. it missfires when you rev the engine once its warmed up. ive done an ECU test and it gets a code 55(no fault) when the engines not running and a code 24(throttle valve full load) when running.i would really appreciate any advice anyone could give me. cheers SI-Z

SORRY CANT HELP WITH YOUR PROBLEM BUT MAY BE U CAN HELP ME, :confused: HOW DID U CARRY OUT UR ECU CHECK