Desperate for Help

[silatman]

I've bought a GU 3ltr Di that has just been rebuilt. It had aftermarket piggyback computers, a Safari DTronic plug and play direct to the ECU, a plug and play diesel smart module on the fuel pump and a plug and play diesel smart module on the MAF. EGR block and a dawes valve set at 17PSI. The auto box has had a Nomad extreme valvebody installed.

The car ran fine in the first two gears but did not seem to have full power once in 3rd and loses torque once over 80 - 90kph. I didn't test drive it on the open road and didn't push the car at all before I made an offer and bought the thing, yes I'm regretting it now.
I first noticed the issue when I took it on the highway for the first time about a month ago and have been hunting for power every since.
On the highway cruise control is useless as the car will sit in 3rd gear at 3500rpm in order to sit anywhere near 100kph. If you drive it on the pedal you can get it to sit in 4th but it's a hairs breath away from kicking back into 3rd and not at all pleasing to drive.
I am lucky to have access to a workshop and diesel mechanics so we started to fault find.......

Firstly the car when in park or neutral would not free rev and would hesitate and hover at 3000rpm, something I did not know whether was a factory thing to stop over reving when not in gear or a code from the aftermarket piggyback stuff for the same reason.
We removed all the aftermarket stuff and reverted the car back to factory specs, tested the car and found it would not go over 60 and would go into limp but would not throw any fault codes.
We then traced the piping for the Dawes and found it to be connected wrong so rerouted correctly and fixed the free reving issue when in park or neutral, on a test drive found the lack of power at 80 -90 and above still there but now it had slightly less due to no help from the aftermarket stuff but was much smoother. I have not reinstalled the piggybacks and don't think I will again, I just want the factory power from this engine.
We kept digging and realised the turbo actuator grub screw was missing so went to install one and realised the original screw was in there but sheared. We removed the turbo, drilled and tapped another screw, reset the turbo acuator to factory specs and reinstalled hoping that maybe the vents no closing under normal parameters were giving the ECU a false reading and that was the issue, no such luck.
We applied direct vacuum to the turbo to test and found the turbo to immediately spool to 17PSI but still had no power. (I have a Redarc Boost/EGT combo gauge on the dash)
We found online boost/RPM maps to compare and found that the vehicle should have around 10PSI at 2000RPM and around 16PSI at 3500RPM, mine has 5 - 6PSI at 2000RPM and tops out at 10.6PSI regardless of RPM applied.
The car blows zero smoke so I was/am concerned it's running lean.
We have decided that it must be fuel or ECU related so I was thinking injectors/fuel pump or an ECU issue caused by the piggyback stuff.
As you know this is where it gets expensive....
We have had the car hooked up to a G scan tool and have compared this to another patrol which is basically stock which has not given us any parameters different and has not shed any more light. There are no engines or gearbox codes.

We decided the smart money was going to be to send it into Nissan to get them to scan the car and hopefully point us to what is not working so I booked it in for diagnosis today.
The results came back as "we couldn't hook up to the ECU but we noticed wiring on the MAF changed so suggest you replace this and bring the car back"

To us this doesn't make sense, our Gscan connects no issues and gives us no reason to doubt the MAF at all, the wiring is correct and gives out the correct values.
If the MAF is disconnected the vehicle does Rev slightly better but we can't fault the MAF or the wiring and can't understand why the Nissan computer won't even connect to the ECU?

I think that about covers where we are, has anyone ever encountered this issue? Does anyone have any opinions on where too next?
Nissan were no help at all and to say I'm disappointed would be an understatement as the only advice they have given is we think all the wiring should be returned to normal and then bring it back and give us more money.

Any and all suggestions welcomed as I have planned a trip away camping at Easter with my son and am gutted at having to tell him we can't go.

[GQtdauto]

It all sounds like A MAF issue but can't explain why there is no error codes , have you tried a known good MAF out of another Patrol ?
Hopefully someone who knows more will be along to help .

[mudski]

Have you changed the fuel filter? If the issue still remains, by pass the fuel filter total and try again. A member here has some issue like this a while ago, I gave him a spare filter head I had and his issues went.
Atleast doing this you can eliminate this being the cause.

[silatman]

I have a brand new MAF installed and like I said all the values are factory correct according to the Nissan manual, another GU scanned at the same time with the same scanner.

[silatman]

I put in a brand new RYCO filter two days ago and checked the values on the scan tool. the new filter recorded a return to tank value of 60% at idle.
Nissan did recommend a genuine fuel filter over the phone when I booked the diagnosis initially but did not mention the filter at all today when speaking with them.

I was considering putting an inline fuel pump to deliver pressurised fuel to the filter but it shouldn't be needed just to be able to travel at 110kph in top gear.

[happygu]

Try this thread for help for a similar type problem
http://www.nissanpatrol.com.au/forum...in-ZD30-Patrol

[silatman]

So I bypassed the filter and hooked up an inline pump with no change to the car at all so the filter can be ruled out now.
I changed the MAP sensor today with a known working one and again no change.
The turbo actuator had been tested and was found to be in full working order.

I'm think at this stage the only thing left is to remove and test/replace the injectors or swap ECU's and recode to allow NATS to function
Both scenario's don't thrill me but are better than changing a fuel pump.........

[mudski]

So I bypassed the filter and hooked up an inline pump with no change to the car at all so the filter can be ruled out now.
I changed the MAP sensor today with a known working one and again no change.
The turbo actuator had been tested and was found to be in full working order.

I'm think at this stage the only thing left is to remove and test/replace the injectors or swap ECU's and recode to allow NATS to function
Both scenario's don't thrill me but are better than changing a fuel pump.........

I've never heard of the ECU being at fault but theres a first time for everything. It does sound fuel related to me. But being electronically controlled, who knows. Check all the injector lines too and see if the nuts are done up tight to the injectors and pump.

Good luck and keep us updated.

[happygu]

So I bypassed the filter and hooked up an inline pump with no change to the car at all so the filter can be ruled out now.
I changed the MAP sensor today with a known working one and again no change.
The turbo actuator had been tested and was found to be in full working order.

I'm think at this stage the only thing left is to remove and test/replace the injectors or swap ECU's and recode to allow NATS to function
Both scenario's don't thrill me but are better than changing a fuel pump.........

It looks like you are not getting enough boost from your figures above, and that will have a huge effect on the real power curve

[silatman]

Well I bit the bullet and decided to change the injectors as it seemed like the next realistic (cheapest) step to take.

I stripped out the old set and found them to be covered in carbon deposits especially number 1.
I had spoken to the last owner who told me that the injectors had come from a donor parts motor and were not even tested prior to installation in a newly rebuilt motor!!

After installing a new set I fired the car up and found no change in sound or when stationary free reving. Feeling dejected I drove the car home.

As soon as I started moving I realised that the car was completely different, it honestly felt as though someone had halved the weight of the car, obviously it was just that the vehicle had double it's "normal" power.
I drove home in complete shock at the new drivability of the vehicle - turns out it was injectors the entire time.

The lesson from my experience I suppose is if you plan on rebuilding an engine, then rebuild with new parts or at the very least test the secondhand parts you want to use BEFORE they go into the engine. It would have saved allot of heartache.

So happy with the performance now, it's no V8 but I never expected it to be. I always just wanted the power that should have been there and now given that I have found out allot of small issues with the rebuild done and fixed them along the way, it should be a very reliable car for years to come (fingers crossed)

I would like to say thanks to everyone who offered advice and appreciate the efforts you went to to help.