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Engine Specific Info and Questions => TDI Engine -General Info => Topic started by: smoken u on July 13, 2010, 06:46:49 pm
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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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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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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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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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yeah i had to do the hammer mod also well because i have a 11 mm pump. that might fix your problem
heres info http://forums.tdiclub.com/showthread.php?p=949613 (http://forums.tdiclub.com/showthread.php?p=949613)
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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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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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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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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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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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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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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 ;D
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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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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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yeah, maybe instead of vw spark plugs i should have used the higher quality cummins ones (about 75 dollars a piece) ;)
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well we replaced the engine speed sensor with a new one, figuring that may help as it did run a code for a little while ago, didnt make a difference still has the missfire on idle all the way up to 2000rpm, the engine should be broken in this week hopefully so we will see if the missfire is any higher in the rev range, ive read on the net here (not so much on the fourm) about a power distribution relay also being called relay 109 causing simmilar effects, but i find it hard to think that a relay would be causing a missfire. must say im starting to get stumped on this one
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Do you think that it may be one cylinder giving you trouble or are all cylinders misfiring at random? If it's just one cylinder it's probably an issue with the injector as long as everything else with that cylinder is fine. Just a tiny piece of dirt can clog the newest of injectors.
I have narrowed down a misfire before by putting my hand on the exhaust manifold soon after start up. If one of the runners is cooler than the others, start with that cylinder.
Another way to check this but not recomended because of the dangers of high pressure diesel, is to crack the injector lines one cylinder at a time and listen for a drop in rpms. No drop means that cylinder isn't firing.
If it is all cylinders then I would think of what affects all cylinders, for example the lightened flywheel.
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I've heard of other guys runnin these lightened flywheels on the tdi's and have had no issues, so I find it hard to believe that the flywheel is my problem. The car runs excellent otherwise. I personally think it might be an injector (not saying Giles isn't good at what he does, because he is. But there might be a little piece of dirt or whatever in one of the injectors). The strange part is the "misfire" only happens at idle but more noticable when driving between 900 - 2200rpm because it's underload. And it smooths out between 2200 - 2800rpm then after that it gets rough again. It's boggling my mind lol.
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If you have scanner that can read measuring blocks, there are channels where you can see fuel delivery etc at each cylinder. I would check there. Actually check all the measuring blocks .
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Are you the guy that came to the shop and asked for a set and then Giles said there are only 3 ready, but then looked on a bench and saw a set of 4 that were in progress? He tested the missing one (#3) and the pressures looked good so he gave it to you?
Was I in the shop that day?
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No that wasn't me Tyler. I got my injectors done about a month and half ago, but they have only been in my engine since I got it running about two weeks ago.
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measuring blocks seems to be good place to start to check fuel delivery, and its not the flywheel, that would be more of a shudder this is a dead miss.