Running Rough

mustangmarty

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Nov 9, 2016
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Central Texas
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1996 Passat Wagon TDI
Just finished changing the timing belt and cleaning out the intake ports and intake manifold. My injection pump was leaking so I replaced the head seal and the top two seals while I was at it. Also I turned the motor over several times manually to make sure the pistons weren’t meeting the valves. Engine is running rough now. I don’t have a Ross Tech cable. But I do have an ObdEleven which showed my IQ at 1.6 to 1.8. Will this cause the engine to run rough?
 

Mongler98

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Mar 23, 2011
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COLORADO (SE of Denver)
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98 Jetta TDI AHU 1.9L (944 TDI swap in progress) I moved so now i got nothing but an AHU in a garage on a pallet.
big 10/4 on oilhammer's (check your timing marks). If you did not move the IP, then you should be fine on the timing advance but if your a tooth off, it will run like crap. i always have to adjust my belt at the cam a tiny bit to get it just right.

as for the IP, might be a bit of air left in it?
1.6-1.8 is low, my AHU does not start to idle rough until 1.2-1.4 so..... that might be the issue, bump it up to 2.5 and see if it runs good.

Let me ask you a few things, Exactly HOW did you clean the head's runners?
hope you did it right so that nothing got past the valve!
DID you do the cross pin sequence on the IP with the cam fully extended when you changed the IP head o'ring? if you did not, you dropped the washer off the cam and your ip needs to be pulled apart and fixed.
 

iluvmydiesels

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phila area
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i dont think IQ directly relates to your both static,ie- mechanical and/or injection timing. if static timed, that is crank and cam @TDC, pin in inj pump, thats the TDC static mark, set belt tensioner, (there are a few other steps), tighten cam bolt, etc, to turn engine over by hand, at least 2x(@-crank revolutions). after this start up, it shouldnt run *that bad, in fact it should (appear) to run just about normally. you need the vag-com cable and laptop and set inj pump timing. at this point its a guess, correct pump timing may correct the rough running. then again rough running is also an easy symptom of air infiltration in fuel system. other place to check is the pump work that you just did. is air getting in there, the seals you just re-did?
i doubt bumping IQ off the info youve given is a good starting point. either pump timing(re-check your mechanical timing first), or air in pump. seal job you just did. another thing, how long did you let motor run, can take a few minutes for an opened system to purge all the air out. esp if you opened pump, let idle for a few more minutes and see.(??).
the ross-tech cable is a little expensive, to say its more than a little expensive. you can try the partsplace cable if you want. i dont know personally as far as if PP cable works ok, i have a ross-tech cable, so that i know.
 

mustangmarty

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Central Texas
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1996 Passat Wagon TDI
I did not move the IP since I used the lock pin. There are small air bubbles in the fuel line going to the pump. I did bring the IP head out and back in with the criss-cross pattern to maintain pump head alignment. I also made sure the cam was fully extended to keep full tension on the head. I cleaned the intake ports with walnut shell blasting one port at a time with both valves fully closed and the other ports sealed so nothing would get in them. I made sure to get all the media out of each port before moving on to the next. I also have an open downpipe at the moment if that makes a difference.
 

Mongler98

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COLORADO (SE of Denver)
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98 Jetta TDI AHU 1.9L (944 TDI swap in progress) I moved so now i got nothing but an AHU in a garage on a pallet.
small air bubbles are normal in the clear section, ditzle mod or nictane kit fixes this if you want but its normal otherwise. a set of self made plastic scrapers from dinner ware is best, with a shop vac and some brake cleaner is best to clean the head when still on the block. if you were careful like i was, im sure what you did was fine. when cold, the QA should be 6 ish and when warm, 2.5ish
make sure your electrical connections are solid, i made that mistake before, the IP was not fully clipped in on the 12 pin.

probably air though. run it for a few minutes and if it does not clear up, hammer mod a few more points on the QA. sounds like your timing belt job was fine. i personally would have not used walnut shell, soda blasting would have been better!
 

mustangmarty

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Central Texas
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1996 Passat Wagon TDI
Never heard of soda blasting. Looks like it’ll be awhile before I can afford a Ross Tech cable. Muffler shop just hit me with $200 to weld in a new exhaust flex pipe. And I already had the flex pipe!
 

iluvmydiesels

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I did not move the IP since I used the lock pin. There are small air bubbles in the fuel line going to the pump.
the small bubbles i think can be an indication of a leak anywhere either in/@ pump, or fuel line/system. as you just replaced seals id start there. one way to to try is use spray to find a leak, if it seals(temporarily as you spray right in leaking area) engine will run better. i doubt in this case you use brake cleaner, perhaps wd40, or similar, something not -very combustible and mild. in this case not necessarily it will either (temp)seal leak, or you will get a report that you will notice, ie a smoother running motor, perhaps worth a try.
when you change a timing belt the pump timing doesnt stay where it was at prev belt. almost always it needs to be adjusted(VCDS, or vag-com), 100% of the time it needs to be checked(again its VCDS). in the old mechanical diesels you could get away, if you were really good, at 'hill-billy' timing. however even here the pump timing will almost certainly need to be adjusted, and to stress that proper static/mechanical timing steps using *all TDC marks is the best method. and will cause the least chance of problems, and if you do it correct you know your timing is right.
 

iluvmydiesels

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as you just replaced seals id start there. one way to to try is use spray to find a leak, if it seals(temporarily as you spray right in leaking area) engine will run better. i doubt in this case you use brake cleaner, perhaps wd40, or similar, something not -very combustible and mild.
(*bulb)-idea, put diesel or fuel conditioner in a spray bottle and try this.
 

mustangmarty

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Central Texas
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1996 Passat Wagon TDI
I had all TDC marks spot on. Fly wheel, injection pump, and camshaft. In fact before I even started, the camshaft was one tooth off, which I corrected when I put the new timing belt on. I’ve been letting it idle till full operations temp and kept it running another half hour. No difference.

I’m gonna do a compression test later today too.
 
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Mongler98

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Mar 23, 2011
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COLORADO (SE of Denver)
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98 Jetta TDI AHU 1.9L (944 TDI swap in progress) I moved so now i got nothing but an AHU in a garage on a pallet.
i can send you my vag-com cable, for loan, you pay shipping and ill send it to you, provided you send it back lol. PM me
 

iluvmydiesels

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phila area
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so you removed the camshaft gear off of the camshaft when you started timing job, correct?
'one tooth' off @cam gear is a lot, valves get really close to pistons, they do anyway, much closer in this case. on the other hand it sounds like youve run the motor quite *-long enough, youd have had a valve 'hang up' and lose it by now.
sounds like your re-sealing job has air leaking. most likely case, air in the clear fuel line seems to point to that. or when you were working on it you jostled fuel line or connection and its leaking. most likely your seal job, check it out.
 
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mustangmarty

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1996 Passat Wagon TDI
Yes. I loosened the camshaft from the cam gear in order to line up the cam locking plate.

Thank you Mongler! I sent you a PM.
 

Abacus

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Relocated from Maine to Dewey, AZ
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Yes, I have seen lumpy running at IQ's that low. With the engine running, I would loosen the QA bolts and tap the head towards the passenger side. I like them running around 3-4 for stock injectors and 4-6 for upgraded injectors, adjusting for smoke. The timing will come into play with the IQ, so you want a slightly more advanced timing with lower IQ number (indicating more fuel). I also tighten the top bolts with the engine running since how you tighten them can swing the IQ one way or the other. Just make sure not to overtighten them, which most people do.

The air bubbles are probably from resealing the IP. Small ones won't affect how the car runs. I have seen quite a few as the result of the o-ring on the fuel pump needing just a little grease to seal better. Over time the o-ring and thermostatic-T can get worn and create occasional air bubbles.
 
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mustangmarty

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1996 Passat Wagon TDI
I loosened the QA bolts slightly and tapped it toward the passenger side until I reached 4 and then tightened it down at which point it changed to 5.

I did a compression test. They are at 450, 470, 450, & 450. So compression is good.

I read something about “limp mode” somewhere not too long ago. Could that be it? Reason I ask is because it has no guts whatsoever. Barely gets up a hill in second gear.
 

Mongler98

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Mar 23, 2011
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COLORADO (SE of Denver)
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98 Jetta TDI AHU 1.9L (944 TDI swap in progress) I moved so now i got nothing but an AHU in a garage on a pallet.
next time, when it happens, turn it off and back on again as your driving, if it goes good for a few minutes, Limp mode 100%
 

mustangmarty

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Good idea Mongler.

But before I try that, I had another thought. Before I changed the timing belt, the motor was running smoothly. Then when I was about to change the timing belt, I noticed that the camshaft was cock-eyed enough that the camshaft locking tool wouldn’t even come close to fitting into the camshaft slot while the crankshaft was dead nuts on TDC and the locking pin was in the injection pump pulley. This is before I removed the old timing belt.

Next I removed the timing belt and cracked loose the cam sprocket to put the camshaft back into the correct TDC position with the cylinder 1 camshaft lobes at 10:00 and 2:00 pointing up and the camshaft locking tool in place and tightened the cam sprocket back down. Now I have true TDC at all three points. Cam, Crank, and IP.

However, I have not moved the IP whatsoever. Am I correct in thinking that since I moved the camshaft without adjusting the IP to match, that my IP is now putting fuel into the cylinders at the incorrect time in relation to the cam timing? And will this cause it to feel like it’s running on three cylinders and is very low on power?

Next question... If this is the case, could I loosen the IP and adjust it by ear just to see if it helps smooth out the idle? And then whenever I get a VCDS cable, I could fine tune it more at that time?
 
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turbodieseldyke

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I don't know how much you can ear-tune it. The only time(s) I did that, was after a TB change and the IP was too far off to start the car. I would "ear" it til it started and ran, then immediately Vagcommed it to get it right.

Good luck though.
 

mustangmarty

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1996 Passat Wagon TDI
Recheck your physical cam and pump timing. Is the engine smoking or making noise?
Finally got a VCDS cable and checked it out. Cam, crank, and IP are all timed spot on. I adjusted the IP timing today. It was pretty close to the red line on the bottom of the VCDS graph and I adjusted it to a little above the blue line on the same graph. Took the car for a run and it still runs like poop. I don’t feel anything from the turbo at all.

Engine isn’t smoking at all. And it’s not making any strange noises other than sounding and feeling like it’s running on three cylinders. What are the chances one of my injectors have stopped working?

I haven’t tried turning the engine off and turning it back on again while driving down the road. Mainly because my tags and state inspection are expired.
 
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KLXD

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'98, '2 Jettas
Look at the idle balance. Block 11 maybe? Three numbers between maybe -2.8 and 2.8.
 

mustangmarty

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1996 Passat Wagon TDI
next time, when it happens, turn it off and back on again as your driving, if it goes good for a few minutes, Limp mode 100%
Tried this, and it doesnt make any difference. Still runs rough with no guts at all.

How do I test the injection pump for air leaks?
 

Mongler98

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COLORADO (SE of Denver)
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98 Jetta TDI AHU 1.9L (944 TDI swap in progress) I moved so now i got nothing but an AHU in a garage on a pallet.
IP is not the area to check, check the fuel lines and check valves at the tank. you might have a fuel starve from a cracked fuel line or something.
 

mustangmarty

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1996 Passat Wagon TDI
I can see that it’s getting plenty of fuel. So far I’ve replaced the N75 valve and MAF. I’ve removed the intake manifold and cleaned all the carbon out of it as well as the intake runners in the head. I’ve cracked open and retightened each of the injectors one at time, and the engine slows down a bit for each one. Next I’m going to replace all the vacuum lines to see if that helps.
 
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mustangmarty

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1996 Passat Wagon TDI
While researching vacuum line sizes, I came across a post about a possible plugged vacuum line or a stuck wastegate. Well, I blew compressed air through that line and some oil came out. Then I hooked it back up to the wastegate and put my mightvac hand pump on the other end of the line. And nothing. The wastegate rod didn’t move at all. So will a stuck wastegate cause the problems I’m having? I also noticed that I have an aweful lot of blowby, even at idle.
 
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Mongler98

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Mar 23, 2011
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COLORADO (SE of Denver)
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98 Jetta TDI AHU 1.9L (944 TDI swap in progress) I moved so now i got nothing but an AHU in a garage on a pallet.
yes, as we have stated, your actuator is mostly cause of concern.
 

mustangmarty

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Thanks, guess I missed that statement somehow. Wish I would have thought to check that while I had the turbo out when I was cleaning the intake manifold and runners.
 

mustangmarty

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1996 Passat Wagon TDI
Well, that might explain why the actuator rod didn’t move when I tried to activate it with the mightyvac.
 
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mustangmarty

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Ok, I hooked a bicycle tire pump up to the hose that goes from the N75 down to the actuator, and the actuator rod moved like it should. From what I understand, the pressure supply for the N75 comes from the turbo itself via the hose that comes off the banjo fitting on the pressure side of the turbo. How much pressure should I be getting out of that hose at idle? How much at different RPM’s?

At idle I don’t see any pressure at all. At around 3,000 rmp I’m getting 8-10 psi.

I then hooked the turbo pressure hose back up to the N75 and checked the pressure coming out of the nipple that goes to the actuator. I get no pressure at all at that nipple no matter what the rpm’s are. But when I unplug the electrical harness from it, I then get pressure at the nipple that goes to the actuator.
 
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