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Discussion Starter #1
Ok, another limp home story....

1999 New Beetle TDI purchased in, 1999. I am the original owner and It currently has 190,000 miles on it. In 2005 an Upsolute chip was added by Bahn Brenner, the local Upsolute representative. I am in the Cascadian region of the planet.

My spouse is the regular driver, me rarely. Up until this month I had experienced Warp Field Collapse only twice (in 6 years). I really did not think to much about it. I was beating it when it happened.

Now, I find myself driving over the local pass from Western Washington to Eastern Washington on a regular basis. To make this drive you have to go over one big mountain (Stevens Pass) and one smaller one. Now we have repeatable verifable high boost induced limp home mode. And funny, memory serves, the two previous failures were on every large hills while being beaten.

Regardless, I started following the well know and documented repair proceedures to fix the problem.

1. Verified that every inch of the intake system was in proper working order.
The entire intake system was removed and cleaned including the screen, intercooler, and EGR system. The intake manifold was replaced with a new one. The air filter was replaced.
2. I added a McNally boost gauge with EGT read out. The pressure sensor is in the intake manifold just after the EGR valve. I have issues threading holes into plastic as recommend by the manufacturer. (:) The EGT sensor is in the exhaust manifold with the thermocouple placed to the drivers side of the turbo.
3. Every inch of vacuum tubing was replaced with properly sized VW factory tubing.
4. Vag-Com testing showed fault with the N75 device. That was replaced
5. The VNT acutator arm was cycled and no binding or rough operation was noted.
6. The VNT vacuum diaphram was tested, works like a charm.
7. For fun the Injectors were replaced because, why not. We had a little more smoke than we like. (The smoke is gone now) (:)
8. No leakes are dectable in the intake or vacuum system.


Ok, the scary part.

Climbing the pass is obviously a high load event for the engine. I like to pass cars up hill. On the four lane sections you try to at least go the limit. I like to run the cruise control when I can too. Now that I have a boost sensor, I have found that the boost gauge regularly spikes (and the spikes are slow) reads in excess of 25 PSI. Usually the pressure slowiy drops to 14 PSI and no problem other than fear. If I am trying to "maneuver", flooring the throttle when the boost is already that 20+ PSI leads to a rapid jump to 30+ PSI. This pegs the meter and ocassionally after a few long moments, limp home mode. Restarting resets the programing.

When 30 PSI is noted, the EGT spikes to 1,000 degrees F + or - a few.

I am guessing that 30+ PSI is a little steep and that 1,000 deg F EGT is high? WE know limp home is not correct.

Regardless, since the N75 was replaced the VAG-Com tests are not regestering any failures. Also, other than the high load limp home epsides and scary scary high boost readings this car runs like a champ. No smoke, no starting issues, excellent fuel economy, zips around fine. Love the Upsolute chip (I think).

So evidently measuring blocks and such need to be verified, glad I have VAG-Com. Maybe as I have read, I need a parallel mechanical boost regulator? Wish I would have installed a boost gauge before I had the Upsolute chip soldered in. Really, soldered in.

Regardless, more parts are in my future. Oh joy, more parts.


Suggestions/comments accepted gracefully.
 

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The upsolute chip might do funny things like change the MAF reading, I don't know how they are set up for power. When you tested the VNT actuator, did you vacuum test it or only see if it moves? It's important to vac test it.

A brief spike to 23 psi isn't horrible but not sustained. 30 psi is a little high. Try downshifting. The design of the turbo are such that when you are high altitude (thin air), the turbo has to work harder to turbo normalize the engine and I think I recall seeing the flow chart, thin air can put you over the surge line when lugging the engine w/high load.

Re: 1. Verified that every inch of the intake system was in proper working order.

How was this done? A visual inspection can miss small leaks, a boost pressure leak test is best.

Also, since this is pretty technical for an intro, post moved to mk4 section.
 

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it obviously sounds like it has something to do with the boost control system
like stuck veins
bad actuator
or a bad sensor somewhere

that chip sounds fishy also
did it limp before the installation of the chip ever?

another idea-
has the vein actuator linkage been adjusted?
if so, i believe that would give you an over-boost or an under-boost depending on which way you turn it. I'm not saying you adjusted it, it may have been turned by whoever installed the chip.. unless YOU soldered the chip in.
It sounds like a quick and easy power mod though.. more boost = more power right??
well sorta..
as you know, too much boost is a badd baaaadddd thing :D

even if it hasn't been adjusted, it seems like adjusting it to create less boost could be your solution... but I don't know enough about it to advise for or nor...
obviously, its always best to find the source of the problem :thumbsup
 

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Discussion Starter #4
Sorry for anything negative regarding Upsolute

Thanks for responding guys. :).

I could go into detail regarding al of the checks I made. Suffice to say that I missed one thing when verifying that everything was ok.

When I checked the VNT actuator I just used my vacuum pump and verified operation. Mistake. retraction began at 1 to 2 inch HG, should have been 3 to 5. Final reading was @14 inches HG instead of 20 plus or minus HG. I figured since it was working, no problem etc. The actuator had never been adjusted since new.

All wrong. After a little thought, and rereading the posts on the actuator I figured the actuator was out of spec. I purchased a new actuator, adjusted the rod to the same length as the old rod, installed and then checked with a vacuum pump. I had the same issues with retract beginning early and reaching full stop at 14 inches HG.

The simple solution, was to increase the length of the rod until proper vacuum readings coincide with the actuator movement. As fate would have increasing the rod length a few turns total made the new actuator operate with in specification (Begin movement @ 3 to 5 inches HG and reach the stop at 20 inches HG.

I verified that the boost pressures were tracking with the expected pressures utilizing the VAG com software. All is fixed finally. Yes we have the standard initial boost spike, etc excepting as noted below.

A note about the Up Solute chip.

I did not verify this on on my NB but I believe that the factory boost setting is 14 PSI. The Up solute chip runs the pressure @ 18. When the initial pressure spike hits, the top of the spike is more rounded than the spike graphs I have seen posted on this page. Also, After the spike the boost falls to 14 PSI then slowly builds with RPM until 18 PSI is reached. At that point the pressure stays stable until the operator does something.

I have no idea why the two actuators were operating differently. The original actuator still had the factory torque striping on the rod adjuster nut and was tight. I am guessing here, but the spring on the original piece was weaker at the beginning of the stroke than the new one. I am guessing a spring gone bad. I am also making note that setting the new rod length to the length on the original piece is inadequate. The actual function of the actuator must be checked after installation. The new actuator had to have a different rod length to operate properly. The old actuator may actually operate properly, if readjusted but I am not going to test it.
the
 
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