silatman
20th March 2018, 08:14 PM
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.
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.