Rob Mayercik
Veteran Member
Previous thread on subject: http://forums.tdiclub.com/showthread.php?t=406347
Recap: 2002 Jetta ALH, automatic. Never tuned, ECU is 100% stock.
OEM injectors were found to be in need of refresh. Was persuaded to go with Titan-branded .205s, mileage dropped from 43-44 avg (41, if I really flogged it) to 37 avg with babying and much smoke. Swapped two years ago to a set of Bosio DLC520s from KermaTDI when the Titans were found to be not holding up well.
Since at the time the 520s were noted as "great for stock/fuel efficiency", I thought I'd be in good shape, but I was never able to consistently get back above 38MPG (and smoke was still heavier than I wanted).
Back in the spring, my fuel pump started leaking. Got a rebuilt 11mm pump and took the car and pump to my mechanic to fix (and also to deal with a spinning glow plug).
That turned into a bit of an adventure (though he eventually got the plug out and replaced), which involved pulling the head and coincidentally finding the turbo bearings pretty much shot (car was at about 320,000 miles at that point, I'm sitting at 333,000 now).
So, new turbo, freshly-rebuilt pump, and I'm smoking worse than before and struggling to hang onto 36MPG now (and I have a thick soot coating on the back of the car). Per my mechanic (a VW specialist in general and an ALH fan in particular), the car runs great other than really overfueling. I tend to agree with this - it starts with virtually no cranking and drivability is excellent.
I should also note that the MAF is no more than 2 years old, the N75 I replaced just recently because it was "singing" to me when I turned off the engine, the vacuum pump nipple isn't leaking, and the fuel filter was replaced when the new pump went in. I haven't checked the snowscreen or air filter recently, but the low mileage and smoke have persisted across at least two filters and one screen cleaning, so I don't currently consider them major contributors (though I will probably check the snowscreen over the weekend).
I figured at first it was me, so for the past two years I've been futzing with the IQ adaptation value in the computer, hoping to find the "magic number" and not succeeding. Finally, I reached back out to the Kerma folks for help.
After some dialog with the Kerma folks over this, and running them some data logs with my VCDS, it seems that DLC520 + 11mm pump is "not recommended for untuned cars". I was actually emailing direct with Charlie, and he said since my goal was to restore my MPG and get rid of the smoke I should go back down to OEM-sized nozzles.
Ok, so it seems like I blew it going with the DLC520s - I suppose I should have expected this given the size change to them from my originals. I've seen quite a few posts here about folks running that exact nozzle on untuned ALH automatics and supposedly getting OEM or better MPG and no smoke. Beats me how they're do it, but bully for them I suppose. Just shows how unique each of these cars can be.
I plan to reach back out to the Kerma folks in the next day or two to see what options they can offer me (work got busy again, haven't had the chance yet), but one thing I wanted to bounce off the collective minds here is the following:
I know the automatic-equipped ALHs got the smaller nozzles and the manuals got the bigger ones (see linked thread above). The Bosio "357" nozzles are reported to be equivalent to the manual ones, based on a rather thorough article I found online on injector sizes/upgrades/etc. (http://www.myturbodiesel.com/wiki/tdi-nozzle-upgrade-fuel-injector-faq/)
From searching around here, it seems as if the "manual" nozzles (or the 357s) are generally dismissed as a "waste of money" and that there's no real power difference between those and the original smaller ones on an automatic car. What wasn't as clear was whether upgrading a fully stock automatic ALH car to the manual nozzles (or the PP357s, equivalently) would be as indistinguishable in terms of MPG from the OEM automatic nozzles when paired with the OEM 11mm pump.
So, power isn't my aim. What I really want is to get my MPGs back up to the 43-45 I was getting on the original injectors.
So, should I be targeting only OEM Automatic-sized nozzles?
Will OEM Manual-sized nozzles/PP357 perform equivalently for me?
Thanks,
Rob
Recap: 2002 Jetta ALH, automatic. Never tuned, ECU is 100% stock.
OEM injectors were found to be in need of refresh. Was persuaded to go with Titan-branded .205s, mileage dropped from 43-44 avg (41, if I really flogged it) to 37 avg with babying and much smoke. Swapped two years ago to a set of Bosio DLC520s from KermaTDI when the Titans were found to be not holding up well.
Since at the time the 520s were noted as "great for stock/fuel efficiency", I thought I'd be in good shape, but I was never able to consistently get back above 38MPG (and smoke was still heavier than I wanted).
Back in the spring, my fuel pump started leaking. Got a rebuilt 11mm pump and took the car and pump to my mechanic to fix (and also to deal with a spinning glow plug).
That turned into a bit of an adventure (though he eventually got the plug out and replaced), which involved pulling the head and coincidentally finding the turbo bearings pretty much shot (car was at about 320,000 miles at that point, I'm sitting at 333,000 now).
So, new turbo, freshly-rebuilt pump, and I'm smoking worse than before and struggling to hang onto 36MPG now (and I have a thick soot coating on the back of the car). Per my mechanic (a VW specialist in general and an ALH fan in particular), the car runs great other than really overfueling. I tend to agree with this - it starts with virtually no cranking and drivability is excellent.
I should also note that the MAF is no more than 2 years old, the N75 I replaced just recently because it was "singing" to me when I turned off the engine, the vacuum pump nipple isn't leaking, and the fuel filter was replaced when the new pump went in. I haven't checked the snowscreen or air filter recently, but the low mileage and smoke have persisted across at least two filters and one screen cleaning, so I don't currently consider them major contributors (though I will probably check the snowscreen over the weekend).
I figured at first it was me, so for the past two years I've been futzing with the IQ adaptation value in the computer, hoping to find the "magic number" and not succeeding. Finally, I reached back out to the Kerma folks for help.
After some dialog with the Kerma folks over this, and running them some data logs with my VCDS, it seems that DLC520 + 11mm pump is "not recommended for untuned cars". I was actually emailing direct with Charlie, and he said since my goal was to restore my MPG and get rid of the smoke I should go back down to OEM-sized nozzles.
Ok, so it seems like I blew it going with the DLC520s - I suppose I should have expected this given the size change to them from my originals. I've seen quite a few posts here about folks running that exact nozzle on untuned ALH automatics and supposedly getting OEM or better MPG and no smoke. Beats me how they're do it, but bully for them I suppose. Just shows how unique each of these cars can be.
I plan to reach back out to the Kerma folks in the next day or two to see what options they can offer me (work got busy again, haven't had the chance yet), but one thing I wanted to bounce off the collective minds here is the following:
I know the automatic-equipped ALHs got the smaller nozzles and the manuals got the bigger ones (see linked thread above). The Bosio "357" nozzles are reported to be equivalent to the manual ones, based on a rather thorough article I found online on injector sizes/upgrades/etc. (http://www.myturbodiesel.com/wiki/tdi-nozzle-upgrade-fuel-injector-faq/)
From searching around here, it seems as if the "manual" nozzles (or the 357s) are generally dismissed as a "waste of money" and that there's no real power difference between those and the original smaller ones on an automatic car. What wasn't as clear was whether upgrading a fully stock automatic ALH car to the manual nozzles (or the PP357s, equivalently) would be as indistinguishable in terms of MPG from the OEM automatic nozzles when paired with the OEM 11mm pump.
So, power isn't my aim. What I really want is to get my MPGs back up to the 43-45 I was getting on the original injectors.
So, should I be targeting only OEM Automatic-sized nozzles?
Will OEM Manual-sized nozzles/PP357 perform equivalently for me?
Thanks,
Rob
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