Sluggish ALH - Looking for direction (logs)

Backstory
I'm working on a 2002 Jetta with the ALH & 02J that I purchased from jwp175 last summer. At the time, it needed some TLC (namely addressing that it was low on power and needed some front end work). Unfortunately, I didn't have the time to really dig into the issues, so I took the car to a local mechanic in the fall (recommended on this forum) - he fiddled with it off and on for a couple of weeks, but eventually gave up on it. He did put a new MAF sensor on it (old one was topping out in the 750-850 range if I remember correctly), but it still didn't have the power it should have.

After I got it back from the shop, I put a set of cheap nozzles in as a trial and it seemed to gain some power and the (white) smoke was abated when accelerating. I've only driven one other ALH and this one doesn't seem to have anywhere near the low-end power the other had (can't say for sure if the other one was stock or not, but it was AFAIK).


Car
2002 Jetta Sedan
234,000 miles
ALH Engine
02J 5-Speed Transmission


Issue
The car doesn't seem to have the low-end 'oomph' I expect it to have, even in low gears. The other car I've driven/ridden in could chirp the tires in 1st from a start if you really pushed it...this one would be very hard pressed to spin the tires on wet asphalt! It seems to have a bit of power once you get up to 2-2.5k RPM, but I'm not sure it has all that it should.


What's Been Tried
Between the mechanic and I the car has had the following done:

• Cleaned intake
• Chemical cleaning of turbo
• Cat removed
• New MAF sensor
• New air filter
• New fuel filter
• Cleaned in-tank pickup
• Physical timing checked
• Timing checked in VCDS
• Snow screen cleaned
• New nozzles - not tested/balanced (no way to justify the cost for this car)
• Likely a few other things I've forgotten, and anything the mechanic did that we didn’t discuss...

Logs
I'm hoping that those of you more experience with well-running ALHs will be able to provide some insight given these logs - I can speculate, but really have no idea what a 'good' log looks like. All of these were logged based on the instructions from Malone with 3rd gear runs from ~1500 RPM to WOT. Maybe I'm just expecting too much? (I will add that flat roads are hard to find, so take driving on a slight incline/decline into consideration)

Group 1


Group 3


Group 4


Group 8


Group 11


Group 15



The logs raise a few questions in my mind - some general, some more specific:

1. What does Mod Piston indicate?
2. Is the slight lag in requested vs actual injection timing to be expected?
3. Why do the Torque Limitation and Smoke Limitation fall below the Torque Request?
4. What does the lag and the overshoot in Boost Actual mean? I assume these should fall more closely in line, I believe they do on my BEW.
5. Why does Injected Quantity actual lag behind (and never reach) Injected Quantity Requested? How big a deal is the 5-6 mg/str difference? Also, why does the Injected Quantity actual fall away towards the higher RPMs while the Injected Quantity Requested not?

Thanks in advance for your help! I'm eager to learn more about the VE engines and get this Jetta running well.

If blue is actual and red is requested I am wondering if it is short on air. I have never done graphing and am curious. Someone will look at and explain. Did you run a check on the n75 duty cycle?

I know somebody that did a straight pipe and found that the cat was needed for back pressure... he was getting a check engine code. His car is a 02 Jetta ALH 5-speed.

Did you set IQ? Any smoke? What color? Unplug MAF?

Thank you for the detailed post! Here's the boost graph as a log
http://log.malonetuning.com/chart/230131

you can pull all the characters out of the end of the log that follow the chart #, unless the graph has been modified like so http://log.malonetuning.com/chart/2...ORmXDpcO+w6U7wrzDmMKTwrXDnn8Aw4R6B3XCuwAAAA==

Blue is request, red is actual, and yellow is N75 behavior. The sudden drop at 4K RPM is a bit odd, and you're over-boosting by a fair amount at low RPMs. Does the actuator move smoothly on the turbo? it is over by .5 bar, and your data log suggests that the tune is stock. Boost request from a tune should be 18 psi (1.2 bar), stock is 1 bar/14.5-15 psi. MAF is working well too. What is your altitude? log suggests close to sea level.

If you plug your ECU part # into the search option in the log viewer, you can see all other logs from the same part #

038906012fd is yours
038906012bd
038906012gn

are more common options.

Injection quantity should be into the 40s, I'd try hammer modding down to 3-3.5 first and see how the car improves. What size nozzles are you running?

I may have posted somewhat prematurely and/or put too much faith in the TDI mechanic as I've found a few issues digging around today...but I'm still very interested in the forum's feedback.

I checked the vacuum lines and didn't find any problems, though I did find a few that were brittle which I replaced for good measure. I found that that the N75 did not hold vacuum which surprised me, but there's a thread (http://forums.tdiclub.com/showthread.php?t=435377) which indicates that this may be normal behavior. I was doubtful though, so I swapped swapped N18 and N75 to see what happens. FYI, N75 lost 15 in Hg of vacuum on the "Vac" port with "Out" and the vent plugged in around 6 seconds while N18 took at least twice as long to lose the same amount of vacuum. With these valves swapped, I logged the following Group 11 (boost) values:



Interestingly, the overboost seems to have been reduced and the actual boost (red) follows the Charge Pressure (%, yellow) far more accurately. I'm curious to hear what those more experienced think of this - is my N75 actually bad?

I applied vacuum to the actuator directly and I'm pretty sure there's still an issue with the VNT vanes sticking even after a couple of chemical cleanings. I'll give this a shot a few more times and/or take it apart and clean it. I believe I know someone with a couple of VNT15s sitting on a shelf that need cleaning, so I may just clean one of those and swap the turbo out at some point.

jmodge said:

If blue is actual and red is requested I am wondering if it is short on air. I have never done graphing and am curious. Someone will look at and explain. Did you run a check on the n75 duty cycle?

Click to expand...

Blue is requested, Red is actual - if you click on the graph there should be a chart with more detail on this.

I did run a test on N75 based on your comment and I did seem to get decent travel from the actuator, although I did not think it was as smooth/fast as it should be. Here's a video:
https://imgur.com/a/BT3X8

malibuz16 said:

I know somebody that did a straight pipe and found that the cat was needed for back pressure... he was getting a check engine code. His car is a 02 Jetta ALH 5-speed.

Click to expand...

I'm not opposed to considering this, but without a CEL and with the problem occurring before the CAT was removed I'm skeptical that's the cause of this problem. Something to keep in mind though!

jmodge said:

Did you set IQ? Any smoke? What color? Unplug MAF?

Click to expand...

IQ is set around 3 (varied from 2.6 to 3.8 when I checked it).

No smoke - I'd actually feel better if there was some visible (black) smoke at WOT as I'd know there was (more than) adequate fueling at that point.

I have not unplugged the MAF recently but I don't have any reason to doubt it given the performance in the charts and that it's new (and good quality). Please let me know if I'm missing something here.

Owain@malonetuning said:

Thank you for the detailed post! Here's the boost graph as a log
http://log.malonetuning.com/chart/230131

you can pull all the characters out of the end of the log that follow the chart #, unless the graph has been modified like so http://log.malonetuning.com/chart/23...XCuwAAAA==

Blue is request, red is actual, and yellow is N75 behavior. The sudden drop at 4K RPM is a bit odd, and you're over-boosting by a fair amount at low RPMs. Does the actuator move smoothly on the turbo? it is over by .5 bar, and your data log suggests that the tune is stock. Boost request from a tune should be 18 psi (1.2 bar), stock is 1 bar/14.5-15 psi. MAF is working well too. What is your altitude? log suggests close to sea level.

If you plug your ECU part # into the search option in the log viewer, you can see all other logs from the same part #

038906012fd is yours
038906012bd
038906012gn

are more common options.

Injection quantity should be into the 40s, I'd try hammer modding down to 3-3.5 first and see how the car improves. What size nozzles are you running?

Click to expand...

Owain - first, thanks for the nifty graphing utility on the Malone site!

Tune is stock and I'm at around 1,000 ft above sea level...so nothing special there. I haven't pulled the actuator off the lever yet to move it by hand, but from applying vacuum with a MityVac-style tool I did notice the movement is not as smooth as I think it should be (and I can here some faint scraping). I'm going to have to dig into that further - I assumed this would be one of the first things the mechanic checked, but it may not have been checked/addressed. (I'll give him the benefit of the doubt as it's been sitting for a few months.)

The injection quantity at idle averages around 3 mg/str, which surprised me - I was hoping I could hammer mod it down and give the QA more room to move (if I understand it's functionality), but don't want to take it too low. Should I hammer mod lower and see if the pump is able to get to over 40 mg/str? Last thing I want to do is put a significant amount of time or money in the turbo and find out I need an IP as well. Nozzles are .205.

Thanks for your help!

My muffler and cat are deleted and my ALH runs great. No codes.

Thought you had a stage 1 on it, so IQ should be normal. Pump voltage looks fine too, this is about what you can expect from a stock vehicle, likely over-fueling a little at lower RPM which is resulting in part of that boost spike.

You can do a 10-20 minute driving log with varying conditions and plot it on the site, if the file is too large feel free to email it to us and I'll send you a link. If boost request was bumped .2 bar with a tune and lower RPM fueling adjusted that'd probably sort some of it out, only thing that looks out of place is that N75 nosedive around 4 grand when request/actual look okay.

Did you check your VNT actuator manually? You should be able, with firm thumb pressure, move it at least 3/4 of an inch, freely (without squeaking or crunchy noises. Your boost is taking forever to rise which suggest to me this could be the problem. Either an actuator with failed vacuum pot, vacuum leak, or stuck/frozen turbine VNT ring assembly.

There were a few ghetto mods popular in the early Tdi years that seemed to result in this frequently, especially when paired with other fueling mods.

I don't want to derail, but what do you need tool or instrument wise to get these results from your car? Vag-com? Thanks, jeff

Yes, VCDS will do the trick. Lemur bluedriver works fairly well too if you work on domestics and want a cheaper bluetooth dongle with gauges on your phone.

nicklockard said:

Did you check your VNT actuator manually? You should be able, with firm thumb pressure, move it at least 3/4 of an inch, freely (without squeaking or crunchy noises. Your boost is taking forever to rise which suggest to me this could be the problem. Either an actuator with failed vacuum pot, vacuum leak, or stuck/frozen turbine VNT ring assembly.
There were a few ghetto mods popular in the early Tdi years that seemed to result in this frequently, especially when paired with other fueling mods.

Click to expand...

The actuator was a bit 'crunchy' even after multiple chemical cleanings, so I ended up replacing the turbo with a rebuilt unit - at the mileage, I figured the original turbo might not hold up too much longer, especially with the history of overboosting.

Here's a log with the replacement turbo - the car drives better (more consistent power), but the boost still seems lazy to me. I did look at logs from a few other cars on the Malone site and they seemed to show requested vs actual intersect around 2000 RPM - mine are not until nearly 2700 RPM. I did check actuator movement with a MityVac before installation on the car. Any ideas on what to try next, or am I expecting too much of this car?

This looks a lot better. About as good as a stock car is going to get, they only made 90hp.

Your rod actuator length was checked since the new turbo installed? Also check the vacuum system for leakdown. There's a plastic J-shaped tube from the main vacuum housing that likes to have a hidden crack and it can cause funny issues.

Plus, get ready to install upgraded injectors and a tune. That'll wake it up.