d22 3.0ltd lost power and bad economy

[bigboar]

hi all, new to the forum and chasing some advice,
i have a 2004 3.0 ltr turbo diesel ZD30, about 12+months ago i started experiencing excessive power loss and fuel economy has totally dropped off.
i had no issues with climbing hills and easily gained speeds, and at the time was averaging 730kms to a standard tank.

now i struggle up hills, getting up to 100kms takes ages and doesnt go much further than that, economy has dropped to roughly 500kms a tank.
i have searched for answers but cant seem to find anything to help me. next step will be dyno.

anyway after a long weekend drive i am noticing that i dont feel any boost while accelerating, i can hear the turbo whine, but it gradually gains speed and doesnt feel like anything kicking in. i dont have a boost gauge so that was ordered today to fit and see if i am getting boost. i dont have excessive smoke so didnt think injectors were gone but may even be the case. it has done alot of kms 315000 just clicked over, since 180 its all highway and bush driving bugger all city work. i am at the point i hate driving it because when going away too many fuel stops and slow driving is killing me.
hopefully someone may lead me in the right direction, thanks

 

[180degrees]

replaced any of the filters lately? fuel filter could be pretty bad and causing problems?

 

[bigboar]

yer mate change the filter every 5000kms

 

[robmacca]

Just curious.... but could your wastegate for the turbo be jammed open ?? Would explain still hearing the Turbo but having no power ??

 

[bigboar]

i have no idea about turbos but will have a search to work out if it is jammed open, and have a look
thanks

 

[Moses19]

Check the nuetral postion switch. If this switch buggers up it tells the system you are in nuetral and leaves the waste gate open as if you are idleing.

 

[Old.Tony]

Welcome aboard, Bigboar.

I'd pull the hose off the front of the turbocharger and spin the turbo's compressor. It should turn fairly easily, it should feel smooth and not gritty.

If it's not right, that's your answer - turbo bearings. Wouldn't be a good thing to drive around with the turbo on the verge of self-destruction because if the bits get into the engine, it's all over.

There might be a fair amount of sludge in the intake manifold too. EGR and PCV output both enter the air intake and over time would build a fair amount of muck up.

There may be other reasons, but there's a couple of more common things to look at.

 

[bigboar]

thanks for the info will keep looking, if no luck it will sit go on a dyno soon and get a diagnosis

 

[jap55s]

Boost leak?

 

[charlie strayarc]

With 315000 km could piston rings be worn?
Compression test maybe?

 

[simonk8]

I too have noticed what you have described (also this problem seems to be described by a few on this forum) and am at the same conclusion of having a dyno test done to determine if it is in my mind or a real problem, just need to find some time to get it there. Would be keen to know if you have the test done and any conclusions you may reach.

From a controls point of view (the things we can all test at home, mechanical wear on the other hand goodluck!), there isn't many inputs, An extract from the manual:

"The amount of fuel injected under normal driving conditions is
determined according to sensor signals. The crankshaft position
sensor (TDC) detects engine speed and the accelerator position
sensor detects accelerator position. These sensors send signals to
the ECM.
The fuel injection data, predetermined by correlation between various
engine speeds and accelerator positions, are stored in the
ECM memory, forming a map. The ECM determines the optimal
amount of fuel to be injected using the sensor signals in comparison
with the map."

What is interesting from this, is that the ecu does not use the "charge air pressure sensor" (boost pressure) under normal control, so the map assumes a factory curve from the turbo.

So the ammount of fuel dosed is determined by the engine speed, accelerator position and compared with the map in the ecu. One thing I have noticed is that the taco does not correlate with the display read by my ecutalk http://www.ecutalk.com/ which displays the rpm reading direct from the ecu, they are a couple of hundred rpm out. I am yet to determine by measurement which one is incorrect, this may be causing an issue. However i suspect that the taco is just a "guide" on engine rpm, but why they are different is a mystery to me.

To summarise, a couple for things to check
1) TDC (rpm) sensor (5.7V at idle speed, 6V at engine speed 2000rpm)
2) Throttle position (0.4 - 0.6V at ecu with pedal fully released, 4.2V fully depressed)

Good explanations of how to test these are located in the manual:

http://www.navara.asia/showthread.php?t=3232

Let us know how you go.

 

[Old.Tony]

Interesting stuff there, Simon.

I'm not sure about the D22, I'd imagine that its MAPS would give it a clue about the boost pressure. In the D40, it has a MAFS to determine how much air is going in and what temperature it is at, but it also has a boost sensor on the intercooler. The MAFS is more accurate - just using the boost pressure alone won't tell me what temperature the air is at, so I'd be guessing how many air molecules were in a given volume. The MAFS provides that information, so regardless of boost pressure, if I can see 100 litres of air at 27C moving past the MAFS, I can work out precisely how much is going into the cylinder because it's a closed system.

And that's all it needs to ensure efficient combustion. The boost sensor on the D40 isn't a requirement for the fuel mixture. I would imagine that a formula applied to the output of the MAPS in the D22 would yield a similar result: air at a certain temperature occupies a certain volume and if you can measure the amount moving past, you've got the answer.

The tacho accuracy would be similar to the speedo. It's just a needle, it only has to be vaguely close and with the tacho I doubt there's an ADR requiring it to be anything near accurate at all, since it's not an instrument used to assist in controlling the vehicle. I'd suggest that your ECU - and your ecutalk program - are actually quite correct, since the ECU needs to know about RPM very accurately. If it doesn't, the CAS (crank angle sensor) is probably spinning along with the motor - and that will stop it dead in its tracks.

 

[simonk8]

Any further progress on this bigboar?

I have done a bit more reading of the manual. One error that keeps coming up on mine is:

DTC: 0403 - Accel Pos Sensor.

It is related to the idle position of the accelerator. The position in the ECU is self learning.

If you don't have a way of reading the DTC's (i.e. without consult or ecutalk), use the procedure of reading the MIL in the PDF attached.

I reset mine last night and "I think" it has improved the power, however, this could be totally perception, so I would like to get some one elses opinion on their vehicle. It would be best if you could determine if you have this code first before reseting it

To correct the fault:

1. Start engine and warm it up to normal operating temperature.
2. Let engine idle for 10 minutes.

I know this sounds like a bit of wishful thinking that this procedure would do anything, but i assure you it is straight out of the manual and after I did it DTC 0403 disappeared.

I would be interested to hear anyone's results (only applies to the ZD30) by doing this (i.e. not just the OP). But like I say, it is important to know if you have the fault, as otherwise the results (if any) would likely be totally perception.