As per previous thread I have been getting Fuel Temp Sensor probs.

As was, the single wire connector broke on top of the sensor (the spade came off). Now this would obviously give me problems,

 

but

 

When it was disconnected car seemed to run ok? (it was only a short distance).

 

Now is the sensor putting a voltage out or does it just work on resistance?

Also, if wire is disconnected, would the resistance/voltage be so low ignition timings retard, etc. Does the ECU work out water temp is warm so fuel temp resistance but me at a certain OHMs.?

 

I just want to prove if its sensor or wiring.

Errrrrrm good Q :D Sensor works on resistance. The resistance would actually be through the roof - but I aint sure if the sensor is +ve or -ve temp coefficient so can't say which end of the scale it would be at. John dixon can probably elaborate more on the actual control the temp sensor has over fueling ;)

 

CheerZ,

 

Andy

I thought the temp sensor for the guage has nothing to do with the ecu as it has its own sensor next to it(2 pin type). if you ground the temp sensor to earth is will give your temp gauge reading off the scale hot.

:slap: please ignore my stupid suggestion as I was thinking of the coolant temp sensor for some stupid reason Doooohhh

I thought the temp sensor for the guage has nothing to do with the ecu as it has its own sensor next to it(2 pin type). if you ground the temp sensor to earth is will give your temp gauge reading off the scale hot.

 

LOL!! do you have a fuel temp tensor in your dash then?? ;) :D

It is used by the ECU and a malfunctioning sensor could theoratically put the car in safetyboost, since this is what happens when the ECU detects when the fuel is overheating (not very common).

The sensor itself is basically a resistor (to ground)

 

-Eric

Eric, as I understood it, the ECU just activated the PVPR solenoid on high fuel temp to increase fuel pressure if possible.

Yes, correct...but it also puts the car in safetyboost when the fuel reaches "dangerous" temperatures., but I have never seen this happen though...

 

disconnecting the sensor doesn't really harm anything, since the ECU uses a routine that will "guess" the fueltemp. based on how long the engine is running.

Though It may cause the car to have difficulties starting, when the engine is hot.

 

-Eric

 

 

 

Eric, as I understood it, the ECU just activated the PVPR solenoid on high fuel temp to increase fuel pressure if possible.

right then, can I temporarily to prove fault put a resistor of a certain ohmage in line to earth.

 

car has just died on me again.

 

Error 42

 

I left cable to sensor disconnected and car runs ok for about 2 mins then dies again?!!??

perhaps it works out it needs a resistance when temp is warm.

Nissan have none in and Im in for a big trip tomorrow.

Is there an aftermarket one I can fit if not?

I can fit a resistor this aft if its going to temporarily cure problem

 

Thanks

Jay, How does the engine cut out ? suddenly or slowly ?

Are you able to restart it ?

does the engine keep running if you keep your foot on the throttle ?

Try bypassing the pvpr solenoid: connect a small hose between the small outlet running from the plenum straight to the small pipe that runs to the FPR.

 

http://twinturbo.net/net/viewmsg.aspx?forum=technical&msg_id=856852

 

This will permanently bump up the fuel pressure.

 

-Eric

It seems fine then starts stuttering, then I pull over and to keep engine running I have to pump throttle but its runs very lumpy still stuttering, then eventually it dies.

Leave it all switched for 5-10 mins - starts up again and Im fine for another mile.

Reset ECU and it came back with a 42 code after doing what I just explained.

Sounds more like a classic PTU failure...

Just seen that link mate, Im not sure I follow it - is that a permanent recommended fix?

can it cause any other damage?

You can leave the bypass permanently and it is actually a good and simple modification...especially for cars running higher then stock boost.

 

It won't cause any harm at all, the car may run a little rich from time to time, since the fuel pressure in the fuelrail is higher then normal.

Lymopn, you say ptu fail but im getting error 42

wouldnt a different error code show for ptu fialure. I have cleaned ptu connections just to be sure but fault still persists.

 

I cant really follow them diags as the pipe from the manifold is different in mine, it has a t junction and has been split and runs off somewhere else (thats if Im looking at the correct part).

the code 42 is because of the disconnected fueltemp sensor.

Do you have a conzult to see the errors ? or are you using the manual procedure ?

A failing PTU doesn't always show up as an error.

 

As for the bypass on a RHD:

Lymon, thanks for the pic - the pipe in green is split on mine

I'll run out and have a look now

Lymon, the green pipe you have show in mine on the left hand entrance/exit if you get my meaning has a t junction in and splits and the pipe goes to somewhere down the drivers side behind the fusebox?

not sure what that hose is for...do you have an extra boostgauge or something ?

anyway..can you put the T-piece in the green bypass ? (see drawing #2)

 

http://300zx-twinturbo.com/temp/bypass2.jpg

oops, sorry mate - thats exactly what it is - I didnt realise the after market boost gauge tapped into there.

 

Lymon, I will try that and give it a run at 4 oclock

hopefully my friend you've saved my ass

 

Does this now mean the 42 error will not affect the car?

 

the ones I now leave unplugged - do I do anything with them or just leave them out the way for now?

I looked into this when I bypassed my PVPR and as far as I can tell, the FPR will see the correct pressure.

Basically there are 2 modes of operation for the solenoid:

OFF: FPR connected straight to manifold, so same as if bypassed. There is also a tee that charges a surge tank in the wing via a non-return valve on the same line.

ON: FPR conected to surge tank, so pressure at max boost all the time and rich running when not on full boost.

 

Basically the downsides are:

Harder to start as fuel pressure not boosted at start. Never noticed any difference though TBH.

PVPR protection gone, but really does next to nothing in UK climate and is a possible cause of problems. It can only up pressure to 3bar + max boost anyway, so won't help any even if on at high boost!

John, looking at the diagram then if I put the "green" piping in on mine is that all I have to do - do you think this would cure the problem for an error code 42.

Im running higher boost.

Just as an aside, I'd tee the gauge somewhere else. If it breaks your fuel pressure will drop - not good!

The pipes you have disconnected, you can now remove the pipes, the solenoid and the non-return valve / surge tank from the wing too.

John, any idea on where to T the boost gauge then?

It won't cure the code 42, but it will stop it messing with the fuel pressure.

It's most likely the connector, try taking it off and cleaning it.

have mate - replaced the connector too

Use the line that goes to the stock boost pressure sensor on the other side of the bay (small black box in the far corner)