Can't rev after a Tbelt/head replacement

Well I am just about done with this head replacement and new Tbelt for my 02 ALH engine. Got it running after quite a bit of cranking to get things primed, and it idles fairly well. Problem I am running into is it won't rev much past idle. It starts and idles fine now, but when I hit the accel pedal, the rpms go up to maybe 1000 or so and then stop there. Even with the pedal floored. Returns to idle just fine, but won't go to higher revs. One other thing, it does smoke a lot, really alot at idle.

So I am guessing that my timing is off. I have a VAGCOM, but one is supposed to run it until it gets to >180F to do the timing adjustment. That could take forever at idle, to say nothing about smoking up the garage and lower level of the house.

So my question is, if I were to "adjust" the timing a bit without the benefit of the VAGCOM, which way should I try, a bit more advanced or retarded? Or is there some other problem I should check out first?

Thoughts?

I would not run the engine until you verify that the static timing was maintained during the TB change. Did you follow the procedure and use all of the correct tools for the job?

Thanks Sailor. I did use the correct timing belt tools, and am pretty sure the static timing was set right. I did about 8 revs with the glow plugs out (so that there would be no compression and I could easily feel any parts touching) and all was fine. And yes, the tools did go back in afterwards and all aligned again.

Some new info, while waiting for an answer, I decided to put the VAGCOM on it even though it wasn't up to temp. Saw only a vertical line (too advanced). Made some adjustments and got it to the middle line of the graph for this engine at the lower temps.

That seemed to help some (less smoke), and it will now rev off of idle to say 1200, but no more. When I do press on the go pedal, there seems to be more smoke than at idle. I also notice that after attempting to rev it, if I pull the engine codes, a 17656 shows up intermittently (which is odd because the timing is now in the middle of the range, at least for the fuel temp at hand). I also noticed in the vagcom timing app, that when showed the scatter plot, the dots covered quite a vertical range, all still in spec but still it was bouncing around some.

I'm trying to think of what else might be the problem here. I did turn the crank over again with the GPs in place, and there seems to be even compression at all cylinders (I know not a real compression test, but at least no dead or very weak cylinders).

Seems it might be fuel supply related (yes/no?). I did not change the fuel filter, but it was a very new one prior to the head work. And when I was priming the IP with a vacuum pump, it pulled fuel through the filter with no problem. Unfortunately this engine has black rubber fuel lines, so I can't see if there are bubbles in the incoming fuel.

Anything else I should look for?

Have you checked the asv is wide open? No cloths etc left in the pipe work? Vac pipes all the correct way round?

Maybe take off the elbow pipe at the manifold, check the asv is wide open then see if it revs at all. If it does then there must be something blocking the air.

Why did you replace the head in the first place?

I seem to recall a bouncing timing graph like that could indicate a bad injection pump.

http://wiki.ross-tech.com/wiki/index.php/17656/P1248/004680

Did you see this? Check fuse 34?

just because it's not warm doesn't mean you cant check it to make sure it's not super off. you will still need it warm for you to fine tune the timing though.

Well tried a few more things, mostly poking around with a vagcom and testing a few things people suggested.

1. With the engine idling, I pulled the rubber elbow right before the ASV. Did not make much if any diff. Still would not rev up. No paper towel remnants (thankfully). And the ASV was wide open.

2. Checked underneath while idling, and it appears that the turbo actuator does move down while the engine is running (just guessing from remembered positions as I am working alone and so have to get up and turn the key off and slide back under).

3. Tried idling with the air filter cover propped open, just to see if the air filter might be restricting things. Again no diff.

4. Got something perhaps interesting in vagcom grp 003. It read: 903 rpm 810mg/R spec intake 460mg/R actual intake and 19.9% ERG. Looks like the engine is not getting near the amount of air it thinks it should. I am wondering what might cause this (other than the obvious paper towel stuck in a tube somewhere or other intake restriction). How is the ECU measuring the actual air charge, MAF sensor? I am at high altitude (8300' elevation) but the ECU is supposed to compensate for that, no? Does the Turbo play any role in moving air at idle? Suggestions here?

5. On vagcom grp 013, read the following: -0.35 -0.64 +0.68 +0.38 I am not that familiar with these readings, but it seems odd that some are + and some -. I that normal? Significance?

6. To answer Yblocker, I replaced the head (had it rebuilt) because a lifter and cam lobe had been wearing away at each other. No dropped valves or other major damage. Checked the oil pump (replaced with pickup), and bearings (all seemed good). The only other factor which may be significant here is that I took a long time in getting the parts back on (about 2 years). So the injectors and IP sat, sealed and indoors but still sat for a while. So I may be dealing with gum or deposits in the injectors or IP. Just a consideration.

Any other thoughts of things to look at? From what I've seen so far, looks like air restriction may be a prime suspect. Probably worth my time to remove and look for obstructions and the like (Although I was pretty careful when putting things back together, and every air pipe was cleaned and/or blown out before going in).

If it is sticky whatever in the fuel system, are there alternatives to a full IP and injector rebuild? Something like running from a bottle of fuel with some cleaner additive, piped directly to the fuel filter?

Other thoughts?

TIA

make sure your turbo spins freely ... you can check the fuel control ring for sticking by removing the top cover and manually sweeping the qa arm with your fingers ....it should sweep freely under spring tension and snap back without resistance

on #2: The actuator is fully up when the engine is off. When you start the engine, the actuator moves all the way down. This can be tested with VagCom/VCDS.
With the engine running, in VAG-COM go to Group 011. Down in the lower left of that VAG-COM page is "basic settings." Click this on. The N75 cycles fully on then fully off every couple of seconds. As the N75 cycles, you'll see the VNT actuator rod move up and down, about 3/4" each way. If this test is ok, you can assume that the N75 is working ok.

on #5: Normal. At idle, the ECU seeks to make every injection event equal in strength to make the idle smooth and quiet. Two injectors are being given a bit of extra fuel, two a bit less - that's what the plus and minus mean.

Check MAF requested and MAF actual
I think your static timing is not correct

Pull the elbow to the EGR and see if it gets any better. Seems like there is a rag got left in there somewhere.
And what everyone else said. It's probably something simple

runonbeer said:

Pull the elbow to the EGR and see if it gets any better. Seems like there is a rag got left in there somewhere.
And what everyone else said. It's probably something simple

Click to expand...

I think he said that was checked.

Steve777 said:

1. With the engine idling, I pulled the rubber elbow right before the ASV. Did not make much if any diff. Still would not rev up. No paper towel remnants (thankfully). And the ASV was wide open.

Click to expand...

Dimitri16V said:

Check MAF requested and MAF actual
I think your static timing is not correct

Click to expand...

Steve777 said:

4. Got something perhaps interesting in vagcom grp 003. It read:
903 rpm
810mg/R spec intake
460mg/R actual intake and
19.9% ERG.

Looks like the engine is not getting near the amount of air it thinks it should. I am wondering what might cause this (other than the obvious paper towel stuck in a tube somewhere or other intake restriction). How is the ECU measuring the actual air charge, MAF sensor? I am at high altitude (8300' elevation) but the ECU is supposed to compensate for that, no? Does the Turbo play any role in moving air at idle? Suggestions here?

Click to expand...

Try this test recommended by RacerTodd

RacerTodd said:

With the engine running, in VAG-COM go to Group 011. Down in the lower left of that VAG-COM page is "basic settings." Click this on. The N75 cycles fully on then fully off every couple of seconds. As the N75 cycles, you'll see the VNT actuator rod move up and down, about 3/4" each way. If this test is ok, you can assume that the N75 is working ok.

Click to expand...

Have you made double-super-duper sure that vacuum lines are connected properly... like you don't have EGR and Turbo actuator lines reversed?

Well, it got warm enough to open the garage and do some more testing so I tried a few more things. But still no success:

1. Pulled all the intake tubing and checked for blocks (rags, mouse nests etc). All clean. Also was able to see the top and bottom of the intercooler and all clear there too. Turbo spins freely by hand, several revolutions so no binding anywhere.

2. Ran the N75 test (grp 011 basic settings). The vacuum arm on the turbo did move up/down in cycles. So that appears to be working. The total travel was maybe 1/2" or so vertically (just guessing from finger position as I could not see, just feel it move), is that a normal travel?

3. Checked the throttle position reading in VAGCOM, and it changes as I push down on the throttle pedal, and seems stable and at the right percentage. So it looks like that is OK.

4. Double checked the vacuum lines. They seem a bit "weird" in that they do not conform to the diagrams I found on this site. This is an auto, so perhaps that is why it is different, but this car appears to have doubled the check valves going to the two solenoids. Seems like the vacuum into the solenoids is doubled/redundant. Don't know that hurts, but it seems weird. However both solenoids (erg and turbo) are connected up correctly and from the N75 test, appears to be working...

5. Had a chance to poke at a working 01 ALH. I felt the exhaust at idle, and it has a similar flow to the subject engine (just rough feel judging). I also put my VAGCOM on it and in grp 003 got similar numbers at idle, 900rpm 690 reguested, 440 actual air. Only significant diff was that the requested was way lower on this working engine, if that means anything.

6. Stills start right up, and still smoke a lot. Won't rev past 1100 or so. One other point which might say something, it seems that the engine stumbles every 5-10 secs. The RPMs go down for a moment and then it recovers and continues idling normally again (except for the smoke). This repeats almost all the time, does it mean anything???

7. In general, it feels like all cylinders are firing (from engine smoothness and exhaust feel), except of course at the stumbles.

So not sure what else to test/try here. I plan on picking up some LiquiMoly Diesel Purge and running it directly into the IP for a while (a can or two), to see if perhaps there are stuck or dribbling injectors or IP at fault here. One other thing may be a blocked exhaust, which doesn't show at idle but does for higher rpms???

Seems it is either the IP overfueling (or injectors leaking), or not enough air getting into the cylinders. One possibility I suppose is that the head rebuild was flawed and the intake valves are not opening enough (although the work was done by a reputable shop so that seems unlikely).

Any other things to try here? I am open to suggestions...

Are you sure the cam is not timed 180 degrees out? When you installed the TB, the intake and exhaust lobes for cylinder #1 (closest to the TB) should form a shallow yet upward "V".

I don't know for sure if it would even start if it was 180 degrees out, but you have checked all the low hanging fruit already.

I'm sure the cam, is not 180* out. The lobes were up when I first put the Tbelt on, and afterwards when I checked the alignment after a few revs. So unless it has skipped quite a few teeth, no way its that far off.

I have considered that perhaps it is a tooth or two off. Not enough to make contact mechanically, but enough to throw the valve timing way off and not let enough air in. But there really wasn't anytime that the tbelt was loose enough for that to happen. But if the diesel purge doesn't do anything, It's probably worth checking since there won't be much else...

Well, a partial success. Went and bought the LiquiMoly Diesel Purge and the fittings. Setup the direct feed to the IP and ran it.

After ~15 mins at idle (that was all the RPMs I could do) tried rev'ing it and it could go to 1800rpm, no problems. After some more time it was steady at 2000 rpms. And would rev up to 3000, but wasn't steady at that speed.

So looks like it was deposits on the injectors or in the IP. Smoke is way down, and engine runs smoothly.

I'm letting it sit for a few hours with the purge in the system then will run the rest thru. Maybe too soon to declare victory, but it seems this is on the right track.

Do you have any type of filter in-line with your diesel purge setup?
If not you might want to toss one in there just in case you break some gunk loose.

#2 - I measured travel on a new VNT15 turbo and got around 5/8" or so. 1/2" is fine. And if the lever was moving up and down, then the N75 valve is doing what it should.

#4 - Vacuum hose routing is the same for auto and manual, AFAIK. If you didn't disturb any hoses and the car ran fine before the belt job, I'd say it's unlikely that vacuum hoses are an issue.

You know, I did have one of those plastic fuel filters inline at first, but I had real problems priming/using the thing. Even when I sucked purge thru it it just would not flow. Perhaps a fault of the IP being gunked up, but that was my experience. Even with just a plastic tube on the input I could not get the IP to self prime. I had to use my Mity-vac to suck purge thru the line and then plug it into the IP, then it would fire.

I was wondering, because all the youtube vids for the purge show their IP just sucking the purge up thru the tubes, no priming. That was not what I saw. Another difference was my IP was not sending any fuel back thru the return line, at least not for the first 15 mins or so, til it was rev'ed up to 2K, then the return line started flowing.

I was concerned about not using the filter, and have been keeping an eye on the contents in the jar (using an old canning jar as a container so I can see it). So far nothing in the way of visible particles, just some purge with a line of very fine bubbles returning.

I had not changed any of the vacuum tubing (except to replace it with silicone, but that was before the head came off, and it was running OK with what it had. It does seem odd, whomever plumbed in a second one way valve and vacuum line to the ERG solenoid, they seem to be connected too. For now I'll leave this, but it seems more complicated than it needs to be. But at some point I will get an 02 auto vacuum diagram and make it right.

Steve777 said:

The only other factor which may be significant here is that I took a long time in getting the parts back on (about 2 years).

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I just saw this statement. Can't find the exact thread on the site, but I believe injectors should be stored with the tips immersed in diesel. Otherwise they are prone to gumming up. Don't know if the IP is subject to the same issue or not.

If they sat for 2 years, you may have just had injectors that were seriously gummed up and not properly atomizing the fuel. Maybe some time on the road (if it'll run under a load) and another Diesel Purge treatment would get them back to normal?