Every now and then.... and I mean perhaps less than once a week, I'll be accelerating out of a roundabout in third, when the car decides to really over fuel - *huge* cloud of black smoke that fills the view from the rear-view mirror.

If I ease off the accelerator then reapply it then acts the car behaves normally, and full acceleration is then available.

 

The ECU is showing up 55, so must be a dodgy MAF / wiring problem right?

Duffer / JD .. any ideas??

 

Cheers

Si.

 

p.s Nismo 555's, no EGR, no AIV's, decat, Turbo Technics stage 2's, stock ECU with SE chip.

I`d take a look at the temp sensor connection, this can be the cause of overfueling as the ecu will consider a poor connection as an overheat warning and as a measure to assist in reducing engine damage will dump more fuel in as petrol has a cooling property and of course an overrich mixture should be cooler too.

 

Low -zdr

I`d take a look at the temp sensor connection, this can be the cause of overfueling as the ecu will consider a poor connection as an overheat warning and as a measure to assist in reducing engine damage will dump more fuel in as petrol has a cooling property and of course an overrich mixture should be cooler too.

 

Low -zdr

 

Hi low-zdr.

 

I've recently replaced the coolant temp wiring, so hopefully not that. But your comments have got me thinking - perhaps fuel temp sender?

 

Mmm, I reckon a ConZult will reveal all......

I think the ecu temp sender deteriorates over time, I have noticed a difference when I replaced mine and there was no indication of a fault!

 

Maybe a boost leak, since it happens after a roundabout, the leaning of the car accentuates the leak?

I think the ecu temp sender deteriorates over time, I have noticed a difference when I replaced mine and there was no indication of a fault!

 

Maybe a boost leak, since it happens after a roundabout, the leaning of the car accentuates the leak?

 

Maybe worth changing the actual sender then too I guess - I've replaced just about everything else over the years :)

 

The smoking at this particular roundabout is a bit of weird one actually - let me explain...

To get to work in the mornings I drive 6 miles through a 30 limit with several sets of traiffic light and all manner of things to keep us driving slow. Nothing special there, but perhaps worth noting that the turbos have not yet had a chance to spool up yet (even though I've been driving 20 mins). Then I reach the end of the 30 limit, whereupon I'm at this particular roundabout which gets me onto the dual carriage way for my final .5 mile to work. So usually (like any Z driver) take full advantage of this new speed by planting the foot to the floor, then *smoke!*

 

What do you reckon then - something to do with the fact that I'm spooling for the first time? Perhaps one turbo is spooling faster than the other and causing one side to run rich?? (Dual boost gauge and blocking the balance tube would detect this perhaps?)

 

Si.

hello simon its jim here..just saying hi m8.and still have no Z yet

Dodgy MAF is a strong possibility. Best bet is to hook up a conzult, record a run and hope it happens. That way you can then look at the telemetry and see which (if any) sensor is playing up.

Water temp / fuel temp sensors could have a similar effect, but unlikely to cause it to overfuel that much.

Does it only happen in the wet (water on MAF element).

Try bridging the det sensor with a 1M resistor ;) Sounds like a similar problem I had ;)

Try bridging the det sensor with a 1M resistor ;) Sounds like a similar problem I had ;)

 

Hi Andy, I'll give it a go as I'll try anything to fix it. But in a way I hope it doesn't work - coz the knock sensor isn't even a year old yet :cry:

 

 

Dodgy MAF is a strong possibility. Best bet is to hook up a conzult, record a run and hope it happens. That way you can then look at the telemetry and see which (if any) sensor is playing up.

Water temp / fuel temp sensors could have a similar effect, but unlikely to cause it to overfuel that much.

Does it only happen in the wet (water on MAF element).

 

Hi John, somebody has offered my the loan of a conZult actually, so am keener than ever to take him up on his offer now. With regards to the wet, I don't know because I never floor it in the wet, BUT.. the car definitely runs a lot nicer when it is wet / foggy and even better when its cold AND wet - how ironic!

 

 

hello simon its jim here..just saying hi m8.and still have no Z yet

 

Hello Jim mate! There is a good thing about you not having a Z yet - and thats because it means you're holding out for a good one, so stick with it. :)

Every now and then.... and I mean perhaps less than once a week, I'll be accelerating out of a roundabout in third,

 

Try exiting roundabouts at less than 65mph, might help. ;)

Hi Andy, I'll give it a go as I'll try anything to fix it. But in a way I hope it doesn't work - coz the knock sensor isn't even a year old yet :cry:

 

Peter at Nisstek told me the other day that he removes the dett sensor from the cars that he works on because its useless,and can give false readings, so i wouldnt worry :)

Peter at Nisstek told me the other day that he removes the dett sensor from the cars that he works on because its useless,and can give false readings, so i wouldnt worry :)

 

 

A very foolish thing to remove!

A very foolish thing to remove!

Yes i must admit i was a bit suprised when he said it but i thought he was "the man in the know" After sitting in on the talks he gave at Billing, i was very impressed with his Knowledge of the Zeds :confused:

Yes i must admit i was a bit suprised when he said it but i thought he was "the man in the know" After sitting in on the talks he gave at Billing, i was very impressed with his Knowledge of the Zeds :confused:

 

Hmm, not sure if removing it is the way to go, I'm pretty sure you can adjust the sensitivity in the ECU. Although a well trained ear will hear det, so perhaps removing it is ok for those who religiously use a premium fuel and know what the listen out for. Nissan have had to cater for everyone too - Lets face it, not a lot of people actually know what det sounds like! Lots on this board do - but thats just because we're all generally experiencing the same problems as our aging cars start to show their wrinkles.

 

Si.