Thread: The D2a Diesel with never changing fuel economy

Originally Posted by Blknight.aus

I've seen one case where the boost box was giving freaky signals to the ECU and causing low power as the engine was permanantly running on the predetermined boost values.

If you get a change in performace with it disconnected its probably not that.

did you remap the ECU to deal with the VNT's boost profile. If the MAP pressure readings are too far off "nominal" values for the expected conditions the ECU will ignore it and run on the default values. check what the MAF is doing while you're at it. If one or the other is wrong and the ECU decides to trust the dodgy one you get all sorts of weird running conditions.

I reconnected the Alive Tuning Turbo Boost Box this morning when I got to work as I cracked the ****s not being able to overtake this morning on the way to work as if I gave it to much throttle there would be no power as the ECU was cutting fuel due to the boost pressure level.

I used to get the exact same fuel economy prior to fitting the turbo boost box and winding up the turbo further.

Originally Posted by Blknight.aus

did you remap the ECU to deal with the VNT's boost profile. If the MAP pressure readings are too far off "nominal" values for the expected conditions the ECU will ignore it and run on the default values. check what the MAF is doing while you're at it. If one or the other is wrong and the ECU decides to trust the dodgy one you get all sorts of weird running conditions.

According to Bell Auto Services, the seller of the VNT, it can be fitted and run on a standard vehicle with just a turbo boost box fitted in addition. It can be run on the standard ECU tune and is compatible with most aftermarket tunes.

Despite this Jose from TD5Inside did a new MAP tune for me to suit the VNT.
My fuel economy did not change with the VNT fitted.
My fuel economy did not change with the VNT fitted and the new MAP (but the power did decrease as it is a more conservative tune over my previous - reference Jose's comments a couple of pages back).

Swinging one wayyyy out to left field.

have you tried a bog standard ECU in it yet?

Originally Posted by Blknight.aus

Swinging one wayyyy out to left field.

have you tried a bog standard ECU in it yet?

No, I haven't. The previous owner did though (Phil DiscoWhite) - he tried a number of different ECU's and tunes.
Jose did give me the standard ECU tune file the other day too, so I could flash that too it.

for humors sake, any chance you can get your hands on a similar, unmolested ECU to swap in and then read whats coming off of the engine?

It wouldnt be the first time I've seen an ECU with a bad diagnostics block in it (if it is it'll be the first time Ive heard of one that hasnt got other issues to go with it) but thats not quiet where Im thinking ATM

if murphy plays nice you might have a case of 2 faults and one is masking the other. reading the faults from the mechanical side of your vehicle (everything on the vehicle side of the ECU plug) with a different ECU might show some different info.
I was made aware of a fault on GM donk that was supposedly OK but would always run rich on one side regardless of what was done to it or the map that was chipped on. Turned out to be a short in one of the injector wires was causing the injector to stay open all the time but the ECU wasnt reporting it as the pin that fed that injector control had dry jointed on the ECU board giving just enough resistance to the short to make it read like a functional injector.

realistically Im starting to go with guesswork on this one as I havent had to work on your exact configuration before and I'm not in position to have a crack at it in person.

The only other thing I can think of is that it might be timing itself several degrees late from either a miss drilled flywheel or contamination on the timing holes on the fly wheel, or a bad map load.

Originally Posted by Blknight.aus

for humors sake, any chance you can get your hands on a similar, unmolested ECU to swap in and then read whats coming off of the engine?

I have a mate with an early model D2 (i.e. pre facelift). His ECU is standard and he gets much better fuel economy. Can I just straight swap his ECU into mine?

Originally Posted by twr7cx

I have a mate with an early model D2 (i.e. pre facelift). His ECU is standard and he gets much better fuel economy. Can I just straight swap his ECU into mine?

and not tell him?

fixed

any vacuum leaks from removing the EGR valve body?

A mate unplugged the small vacuum plugs, but didn't block them. His TD5 was rough at low revs under load (ie: easing off the clutch speed).

I noticed it while replacing his alternator, and once rectified the engine ran smoothly.

Might as well have a quick look for the simple stuff, I'm not sure how it would affect economy though, he was still getting 800-900 before the warning light came on, driving around town!!

I get about half that, but my tanks still got 20 litres when the light comes on.

Originally Posted by justfishing

Hello,

Originally Posted by justfishing

If you are running 32 inch tyres with normal gearing that will use a lot more fuel as the engine is working very hard to push you along, and why you use a lot less off road in low range and it much easier for the engine not working as hard.
Looks like you need the different gears for the crown and pinion. I want to fit bigger tyres but not untril I change the gearing and lose all the extra HP i have gained.
Ian

My fuel consumption does not go up when I switch to 32" tyres. In fact, on long hauls it actually improves because of lower RPM's (2050 vs 2300 with standard tyres).