Excessive fuel consumption from 11mm pump

Hi All,

I recently swapped an 11mm pump on to my AFN and its had a catastrophic effect on the fuel consumption

I've got .216 T4 nozzles and a 2052V turbo, but the engine is otherwise stock - not chipped. The pump has transformed the car - much more grunt across the range, more driveable at low speeds, revs easily to the redline etc, spools the turbo 200rpm sooner, and actually makes less smoke than it did before (ie virtually none).

I was getting 40-42mpg with the 10mm pump, but now I'm getting 34 ish with the same driving style The computer is reporting the same as it did with the previous pump, which sort of makes sense since none of the ECU parameters have changed.

Since it now makes less smoke than before, where the hell is all my fuel going? It would make sense if I was thrashing it everywhere, but most of my journeys are freeway where I'm doing the same speed as before.

Any thoughts on what might be wrong please?

(timing is bang on according to VAG-COM btw. I didn't bother to adjust the IQ since it doesn't smoke)

sad to hear this
will look for the answers on this ....

Since the pump moves about 20% more fuel and nothing (such as a tune) is telling it not to, I guess everything is working correctly.

What is your AFN mk3 or mk4? Did you put mk4 11mm pump assy on mk3, or just 11mm pump head on mk3 pump??? If it's a mk4 pump assy on a mk3 ecu it needs different timing / calibration. Obviously you need to be tuned to match software to new hardware. Your egt's are much higher now I am sure, and that is where your wasting fuel. Probably burns your eyes idling too.

Jeff

actually it should consume less fuel, as you will run more fuel with same air (still lean enough at part load as there is (or should be) no EGR), which means less pumping losses.. I have an AHU with R520 nozzles and 10mm pump, runs only around 2 psi boost at 120kph, uses almost no fuel (average under 5l/100 km)

if you have still EGR, get rid of it

jsrmonster said:

What is your AFN mk3 or mk4? Did you put mk4 11mm pump assy on mk3, or just 11mm pump head on mk3 pump??? If it's a mk4 pump assy on a mk3 ecu it needs different timing / calibration. Obviously you need to be tuned to match software to new hardware. Your egt's are much higher now I am sure, and that is where your wasting fuel. Probably burns your eyes idling too.

Jeff

Click to expand...

Its in a C5 A6, but basically the mk3 engine as you know it. I put the whole mk4 pump on, with modified bracket and wiring.

Would higher EGTs explain why the fuel is not turning in to smoke? Honestly it makes less smoke now than it did with the 10mm which is whats got me puzzled I set the timing to where VAG-COM said it should be for an AFN. Should I have set it for an ALH or something entirely different?

It does smell a little more at idle (not a lot though), although doesn't make any visible smoke.

I was really hoping it wouldn't need a tune since thats such a pain in the UK, especially with an MSA15 ECU I was working on the assumption (as Rub said) that it would use less fuel now, since its atomizing better from the higher case pressure, and it needs less pedal to cruise than it did before.

EGR is long gone btw.

Check your timing with the setting on AHH Passat, that is essentially what you've created.

You'll likely have to advance it a little bit.

should normally not matter as timing is closed loop, so once engine is running it will run the timing as from the map

This is true.

I kind of wonder why so many people say that running advanced static timing produces better MPG, maybe on the stock tune? Some run the timing way advanced out of spec too.

sooner timing get 'normally' better mpg, as tradeoff for noise and NOx, but then one needs to adjust the map, not the mechanical timing

Well I think Jeff is spot on that I'm basically turning excess fuel in to EGT. I just went for a run in it and normally I would be able to hold my hand over one tailpipe to see how much soot it's making. Not today though - the exhaust is more like the output from my central heating boiler Its searing hot and smells different too - more like a jet engine than a diesel...

So I guess a remap is inevitable. It was always in the plan, but since its such a pain I was hoping to do everything else first - cam, exhaust, 3 bar map, possibly even bigger nozzles. I guess I'll have to do it next though

Is there anything I can do to reduce the EGTs and consumption in the meantime? I'll check the timing against an AHH at the weekend in case that helps, although by ear its set where the engine likes it most.

Increasing IQ reduces fuel right? Is that going to help without slowing it down too much? I don't mind trading a little oomph for mpgs but I'm now more concerned about melting something than feeding it...

Thanks guys

Raise IQ by lowering metric (32768 = oem)
ie. try 32700 in field 001 (login with 12233)
that should raise IQ. set to lowest 32680 to raise IQ to highest.

It is ok to be at 3-5mg/R. Hammermod or tune to raise more.
Get your ecu socketed and install chips your self.
Jeff

Thanks Jeff. Oh, and for the record, having got a face full of said jet blast my eyes are burning something awful now!

I'm just really nervous about socketing my ECU because its an uber-rare variant - AFN with AWD and ESP and CAN-bus. It only came in 2000 Passat TDI Syncros in Germany, and its probably the only one in the UK. If I bugger it up I'm in big trouble! I used to work with surface mount, but I don't have the gear any more...

Not like I have a choice. Just sayin'

If its an 018xx 80pin motherboard with ABS/TC chip soldered onto its board, it's easily cloned to another MB. If its an 021xx 68pin MB, it is uber rare, and standard MB's will be missing caps and resistors for the data pins, and ABS/TC interface (deleted). These can be added but difficult. Kind of like the old honda vtec ecu modding with daughter board.

The older motherboards had this ABS chip spot blanked.

The software for your application is unique however, but easily obtained if you need a clone!
Jeff

basicly at idle there should not be a difference, not matter if you have relative (vcds IQ) of 3 or from 8, it still takes the same real amount of fuel to overcome the friction losses, the only things that can affect the egt at idle: timing and lambda, and offcourse the load on the engine

high egt at cruise is no problem.. think about it. as long as lambda is reasonable (lets say above 1.3) all the fuel will be burnt, now, because the 11mm pump makes more fuel in relative to the 10mm pump for a given QA setting, the boost setpoint (considering closed loop) will be lower with the 11mm pump, decreasing total airflow and exh manifold pressure, (= pumping losses), in the engine, which also lowers the BSFC..

if you see a lower egt with the 10mm, this is just because there is more air, lowering the exh gas mixtures temperature, bus this has nothing to do with the bsfc of the engine.. if the egt is higher because of later timing with same pumping losses, there is offcourse a worse BSFC

Mikkijayne said:

Thanks Jeff. Oh, and for the record, having got a face full of said jet blast my eyes are burning something awful now!

I'm just really nervous about socketing my ECU because its an uber-rare variant - AFN with AWD and ESP and CAN-bus. It only came in 2000 Passat TDI Syncros in Germany, and its probably the only one in the UK. If I bugger it up I'm in big trouble! I used to work with surface mount, but I don't have the gear any more...

Not like I have a choice. Just sayin'

Click to expand...

Whats your ecu part number?

m1ketdi - the ECU is 038 906 018 FT.

jsrmonster said:

If its an 018xx 80pin motherboard with ABS/TC chip soldered onto its board, it's easily cloned to another MB.

The software for your application is unique however, but easily obtained if you need a clone!
Jeff

Click to expand...

Oh goody! That makes me a lot less nervous I have a bunch of 018 P ECUs kicking about - can it be cloned to one of those?

If this is EDC15 ECU (not MSA15) it can be written with Galletto. There are few late 110hp engines with EDC15. Give the numbers of the ECU and somebody will be able to tell if it can be written with Galletto.

Hm, somehow I missed the above few posts. I'm unable to find information about your ECU however, so someone else probably can say if it is MSA15 or EDC15.

looks like MSA15, popp the cover off it and one of your 018P ECU's and take a look.

For what its worth, an 018EB works great with my 018Q chips but 018BD with my 018Q chips does not. It wouldn't hurt to try it out.

Mikkijayne said:

m1ketdi - the ECU is 038 906 018 FT.



Oh goody! That makes me a lot less nervous I have a bunch of 018 P ECUs kicking about - can it be cloned to one of those?

Click to expand...

Hmm 018 FT isn't one of those files that is easily found....

Anyone speak czech? I cant workout if this forum has the files we need. But I think it does. I just can't register due to poor google translate....

http://checksum.cz/forum/viewtopic.php?t=4323&sid=ce47dafee762d8f426719b266b1b5e97

No tuner here, but would it be worth the OP trying different timing adaptations via vcds? I know the mechanical timing has little effect on running timing, provided cam plate adjuster does not hit stops. But via adaptation the controlled position of cam actually gets changed, right?

Also, if case pressure relief valve is not working, case pressure will be low and case pressure is what the advance mechanism uses to move cam plate (??).

http://www.ebay.de/itm/VW-Passat-3B...875518196?pt=DE_Autoteile&hash=item2574ed98f4

not that rare....

Yeah I just found that *one*

Mikkijayne said:

m1ketdi - the ECU is 038 906 018 FT.



Oh goody! That makes me a lot less nervous I have a bunch of 018 P ECUs kicking about - can it be cloned to one of those?

Click to expand...

You will notice the 018P is probably missing the abs chip. It's 3/4"x3/4". You will see an empty pad there above the 2 plcc32 chips. At least the 018P I have here is blank.

Jeff

Rub87 said:

basicly at idle there should not be a difference, not matter if you have relative (vcds IQ) of 3 or from 8, it still takes the same real amount of fuel to overcome the friction losses, the only things that can affect the egt at idle: timing and lambda, and offcourse the load on the engine

high egt at cruise is no problem.. think about it. as long as lambda is reasonable (lets say above 1.3) all the fuel will be burnt, now, because the 11mm pump makes more fuel in relative to the 10mm pump for a given QA setting, the boost setpoint (considering closed loop) will be lower with the 11mm pump, decreasing total airflow and exh manifold pressure, (= pumping losses), in the engine, which also lowers the BSFC..

if you see a lower egt with the 10mm, this is just because there is more air, lowering the exh gas mixtures temperature, bus this has nothing to do with the bsfc of the engine.. if the egt is higher because of later timing with same pumping losses, there is offcourse a worse BSFC

Click to expand...

Rub,
Isn't there some contradiction above? The timing did not change but his EGTs went up. Additional fuel is being converted to EGTs. So he is more affected by EGT losses than pumping losses. Isn't that why boost is also increased a bit with timing advance for fuel economy tune. You may still stay above 1.3 but you take an EGT hit with 11mm due to reduced relative boost causing heat. I think if you add the EGT losses and pumping losses together and then explain it, it will make more sense.

Actually not, highernload with equal air and timing does increase egt, but not bsfc, as long as the afr is lean enough and there are enough kinematica in the combustion to make a good burn, and because there is no egr anymore, the amoubt of boost is anyway way too much atmpart load for optimal bsfc.. I'll try to find some trade off plot where you can see this

I have socketed my afn ecu and have run about 10 different maps so far....
It's pretty straight forward, give it a go! I have bought a spare though

Ok so I just checked the timing - its at 41-42, which for an AHH is just below the blue line in VAG-COM. Is that ok or is it worth tweaking it to get closer to the green line?

Also IQ was at 4 with the adaption set to 32686. It won't go any lower. Just out of interest I set it to 32768 which put IQ to 2.2 and seemed to make it a bit faster, although that could just be me Still no smoke except at full throttle standing start, but that just melts the clutch anyway.

Well I seem to have made a bit of a Jekyll & Hyde as far as fuel consumption goes!

Having turned the IQ right down the car is significantly faster, still no smoke, and on my 700-mile round trip to the office this week I got 42mpg average, cruising at 80+

That said, I had a bit of a blast at the end of the journey and managed to burn through 3 gallons (UK) in 80 miles

Remap after xmas I think