Poorly Z

[Hammer67]

Help, any pointers would be appreciated.( 95 NA Z32 no mods 60k miles ) Perfectly OK when last used a couple of weeks ago. Started up today, clouds of black smoke running like a bag of nails. Ticks over OK but won`t go over 2500rpm when it spits and farts like buggery. The exhaust gas is very hot indeed and everything smells hot if that makes sense. Thanks in advance.

 

[JEZ 280ZX]

hi,
Sounds like your air flow meter is at fault.

 

[Mr.F]

Run the self diagnostic function on the ECU to pinpoint if any major sensors are at fault...

http://zclub.net/forum/articles/z32-diagnostic-testing

 

[Hammer67]

Thanks guys, have cleaned the connectors to the AFM and the engine temp sensor, all appear OK. Ran the diag on the ECU and have 3 codes, 34,12 and 13. Det Sensor, AFM and engine temp sensor. Unplugging the AFM with it running has no effect nor does bridging across the terminals on the engine coolant temp sensor connector. Whats the expert opinion on what to change first?

 

[RobZ32]

Check that the ECU plug is connected correctly as well as testing for continuity all the way to each sensor. You should be able to test the senders with a meter or better still conzult will show their output.

 

[Mr.F]

Symptoms fit bad AFM or corrupted AFM signal, but you will eventually need to clear the temp sensor fault for clear running.

 

[Hammer67]

Update.
Have fitted new AFM which has improved things greatly. Engine now runs much better but still hesitates at between 2 and 3000 revs. Disconnected battery to clear the fault codes and got the all clear code 55. Ran engine,(no change), ran diag again and now get single code 34. Repeated this a couple of times with same result. So I have code 34, detonation sensor, which I believe is an expensive nightmare. Anyone know the answer to this? Thanks

 

[RobZ32]

Check the connector its on top of the engine at the back near the center. If it is still in its fixing that is.

 

[Mr.F]

There is a relocation fix to the detonation sensor which saves lots of dismantling. The Nissan sensor is ridiculously expensive, but I may have a reasonably priced alternative available shortly. You will still need a new harness as you won't be able to disconnect from the original sensor which is buried under the inlet manifold...

 

[Hammer67]

Thanks guys, much appreciated. Rob ~ Connector looks OK. Mike, would be interested to know more about price and availability of your sensors please. Have found a video on the web showing the sensor relocation which looks straightforward so will have a crack at it. One other point my ECU doesn`t appear to have any LEDs for the diag but does flash the EML light ~ is this anything to worry about? Once again many thanks.

 

[RobZ32]

At some point during production they stopped fitting the LED in the ECU. I have 3 ECUs 1 with LED, 2 without LED all off of Z32s

 

[Mr.F]

I think it is the 16bit ECUs that have no LED - I have one from a '98 here and it has no LED.

Should have small stock of Knock sensors, MAFs and Lambdas tomorrow - check MJP Trade area for price announcement!

 

[Hammer67]

This is starting to hack me off. Have now soldered in a resistor to bypass the knock sensor and fitted a new temp sensor. ECU now happily reports a 55 and sticks with it. Engine still not happy, horrible flat spot/hesitation between 2 and 3k revs. Above this its fine,pulls well and ticks over nicely. Seems to be running rich with soot in the tailpipes and black exhaust fumes. Any ideas chaps or should I drive it into the sea?

 

[RobZ32]

So it sounds like your problem is fuel related.

At the 2k to 3k point the O2 sensors can have a large influence on fuelling. If faulty they will make the ECU keep adding or subtracting fuel in an attempt to correct to a 14.7 : 1 ratio. This fault may not be recorded in the ECU as I believe that it’s only the O2 heater circuit that throws an error. At high revs and idle the O2 sensors will not do this. This seems to fit your symptoms

It could also be fuel pressure problem or an internal fuel leak, Injectors or damper etc.

 

[Hammer67]

Thanks Rob. Interesting what you say about the O2 sensors not showing a fault code. I checked them with the ECU diag and they came up clean. Will have a look into obtaining a new pair of these jokers. All the injectors look fine and there are no obvious fuel leaks anywhere. Won`t drive it into the sea just yet.

 

[RobZ32]

If you can get someone with conzult to check it out they will be able to function test them may save you money if they are OK

 

[Mr.F]

Check the fuel pressure with a suitable gauge tee'd in between filter and feed to rail. As a simple test, see if the engine note changes when you pull the vacuum hose off the pressure regulator (the unit nearest the battery).

 

[Hammer67]

Update 2 Consult test only showed no response from TPS, replaced it ~ no difference. Can anyone recommend a specialist in the South East? I`m off work this week so would be good to get it sorted. Thanks.

 

[Hammer67]

Right, the Z is still dead. Found the RH oxygen sensor was dropping out so have replaced it ~ no difference. The fault appears to be only affecting the RH bank of the engine. Anyone have an idea what could cause this bank to run rich?

 

[pmac]

Right, the Z is still dead. Found the RH oxygen sensor was dropping out so have replaced it ~ no difference. The fault appears to be only affecting the RH bank of the engine. Anyone have an idea what could cause this bank to run rich?

Looking back thru your thread Im leaning towards two things...
1. Faulty injectors.
2. Internal ECU problem
Have you tried another ECU. Either another late NA one or even better an early NA one.
Mr F and Me have been having "injector discussions" this week