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TDI rolling misfire
by
smoken u
on 13 Jul, 2010 18:46
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ok so heres the problem, just helped re build my friend (redneckvdub's) TDI (ALH) basically new everything, new se7en injectors from giles, new lightened flywheel, balanced crank, conrods and pistons, head job vavle guides everything....lol, engine runs great except is had a rolling misfire, in order to combat the lightened flywheel i have increased the idle fuel to 6.6mg/stroke and upped the idle to 978rpm, and checked my timing which is spot on, all through VCDS, misfire is still there. Now, I come from the land of the IDI where a misfire is almost always air, so i ran the car tonite off of a 10 litre jerry can (which it drank in under an hour idling) with a clear plastic line going into the pump bypassing the filter, and a clear return, no air but still a misfire. I should also mention the car occasionally stalls when letting letting off the go pedal, and the tach has a flutter to it that it did not before, now the the tach sensor cable was cut re-spliced, but it should work fine, not setting any codes. my idea is the pump cannot draw enough fuel from the tank to fire the larger injectors, resulting in a misfire, any help on this would be greatly appreciated.
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#1
by
dankcorey22
on 13 Jul, 2010 20:57
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Im guessing its a manual? Does he have a chip/tune? to help supply more air to those nozzles? if i were you i would mess around with the IQ in VAG-COM more that can sound like a miss with bigger nozzles. channel 1 in adaptation login 12233
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#2
by
smoken u
on 14 Jul, 2010 01:21
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standard trans, no chip, stock ecu, i was under the adapataion channel 1 in the engine ecu to reset idle fueling and speed, didnt notice really anything out of the oridinary, well at least to me, i am no expert lol
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#3
by
410
on 14 Jul, 2010 06:30
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If you search "hammer mod", you might find what you're looking for. I had a similar shudder at idle when I installed larger nozzles and got rid of it using this this technique. If you don't find it here do a search at tdiclub.
If this procedure doesn't fix your issue it is most likely the lightened flywheel giving you problems. Diesels produce a lot of vibration and the mass of the flywheel helps absorb a lot of it.
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#4
by
dankcorey22
on 14 Jul, 2010 07:59
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#5
by
smoken u
on 14 Jul, 2010 16:30
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ok i searched the hammer mod gonna try it, shudder is from mostly idle to 2000 rpm and slightly above like the symptoms say, ill give it a try, ill need to get one of those special sockets to loosen that special triangle bolt on the top of the pump.
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#6
by
410
on 14 Jul, 2010 18:13
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I wouldn't worry about loosening that special bolt. The top of the pump only has to move a few thou at the most. Loosen the three other bolts ever so slightly and tap the top of the pump towards the timing belt. Some may disagree but I had the engine running while doing this. A couple of taps and the idle smoothed right out. It's an amazing thing. But like I mentioned before, the shudder might not completely go away unless that lightened flywheel is replaced.
Oh by the way, I didn't loosen any of the bolts when I did mine and had great success.
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#7
by
greentdi
on 15 Jul, 2010 11:57
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When you say rolling misfire do you mean is has a dead miss when on the gas or once you let off the gas. Did you change the CR on the engine?
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#8
by
smoken u
on 15 Jul, 2010 19:43
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rolling misfire, well it has the same feeling as after youve just bled your injectors, misses a bit on an idle but very noticeable when driving mostly between idle and 2500 rpm, not just a vibration but an actual dead miss on acceleration, and no compression ratio was not changed, i tried the hammer mod tonite, it did nothing actually it caused the car to not start, with the pump top knocked forward, and set off the engine light and started the glow plug light flashing, oncve i moved the pump top back it started fine and ran as always with a miss, lights are still on but no big deal they can be scanned tommorrow, now i did learn a bit of info too, when my my got the injectors done at giles he didnt take the engine side harness as well for calibration, giles asked but we forgot
so im thinking that has somthing to with the misfire as well
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#9
by
oldskool rich
on 17 Jul, 2010 18:26
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sorry if sumone has already solved it, i couldnt be botherd to read past the first paragraph
i think ur problem is that ur injection pump has a centrafugal pump in the front that supplies the pump piston with fuel, if you have modified the pump or injectors this pump will now need to supply more fuel which it obviously cant do, easy fix is to put an electric inline pump b4 ur injection pump, i had the same problem on my AAZ after i installed 11mm pp, electric pump solved it straight away
in my opinion all TDIs should do this, injection pumps last longer if they are pressurised, the fuel lubricates the moving parts, its the same as ur engine having no oil pressure, nothing wrong with a bit of pressure as long as its not putting stress on ur seals, i seem to remember about 2 or 3 psi wen we tested ours, i started with too much pressure and then changed my fuel lines to be 8mm to keep it down
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#10
by
smoken u
on 18 Jul, 2010 06:44
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yup already thired that rich, didnt make any difference unfortunately, firday the car is going down to giles, so we can collaborate on it lol, ive also been reading about "relay 109" on the computer here apparently it causes intermittent stalling. anoter thing it did pull a code finally yesterday for the engine speed sensor, which i am assuming is the tach hookup on top of injector 3. we had to cut and splice the wires for that, so if its resistacnce sensitive it wont be reading entirely right anymore, i may try to find another one to install, if i can figure out how to get the old one off lol
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#11
by
oldskool rich
on 18 Jul, 2010 16:31
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sound like its just number 3 injector then, ive had similar problem with faulty crank sensor too, tbh not much to go wrong realy, maybe a broken spark plug
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#12
by
Vincent Waldon
on 18 Jul, 2010 16:38
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it did pull a code finally yesterday for the engine speed sensor, which i am assuming is the tach hookup on top of injector 3.
Just for clarity sake... the engine speed sensor is actually a transducer that plugs into the block and reads a disk attached to the crank... it's on the front of the block, down low, next to the tranny.
#3 injector has the "start of injection" sensor... tells the ECU when injection (needle lift) has actually occurred.
If you post the actual code you got we might be able to dig in a bit deeper for you.. or try a code search over at TDIclub.com.
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#13
by
redneck_vdub
on 18 Jul, 2010 16:50
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It threw the codes PO321 which was for the engine speed sensor, and P3105 which was for the flap in the intake, which I'm assuming is in the EGR valve that is now removed.
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#14
by
smoken u
on 19 Jul, 2010 01:37
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yeah, maybe instead of vw spark plugs i should have used the higher quality cummins ones (about 75 dollars a piece)
