collective wisdom needed (re: 1Z+low smoke chip) ...

MJSfoto1956

Well-known member
Joined
Mar 19, 1999
Location
Marshfield MA
TDI
1996 Passat TDI
Dear list,

As many of you know I sport an UpSolute low-smoke-chipped 1.9L 1Z motor (from a 1997 90hp Jetta/Vento) installed in my 1987 VW Syncro Westfalia camper (5000lbs fully loaded). This past week we traveled throughout the Pennsylvania hills and I noticed some undesired behavior:

Specifically, at approx 2500-3000rpms under extreme load (meaning up hills at approx 70mph) if I "floored it" I got VERY high EGTs and quite a bit of smoke out the tailpipe (also bad fuel mileage). However, if I backed off to approx 3/4-7/8 accelerator pedal position, the EGTs dropped 200 deg F and no smoke (and much better fuel mileage). What's more, the amout of horsepower seemed to increase -- meaning I could accelerate slowly up the hill. This was NOT true if I floored it -- the van would decelerate up the same kind of hill.

Now remember that this is an "older" 1Z motor with the Garrett GT15 turbo and the UpSolute low-smoke chip. It seems to me that the engine UNDER EXTREME LOAD is starved for air at those rpms. I think this makes sense as the UpSolute chip was probably optimized for the VNT turbo which "supposedly" can pump out more air under the same conditions -- right?

If so, how can I increase the amount of air the motor gets? NOTE: I already run a Pipercross, 2 1/4" custom intake pipes and a Spearco air/water intercooler -- so I've already "maxed out" the intake. Current max boost appears to be about 16lbs with occasional spikes to 20lbs. Would "upping" the boost to 18lbs help here? I assume the only way to do that with my motor/turbo combo is the bleed trick -- right?

What about bolting on a T3 (non-VNT) turbo? Especially a water cooled one? (not sure I want to retrofit a VNT to my motor at this time -- too much time, costs, and uncertainty for now)

Or is it simply hopeless -- meaning that I will have to continue to "baby" the motor while driving in mountain areas??? This makes me sad, for my wife will never drive the van under these conditions...


Any insight greatly appreciated.

Michael Sullivan
 

TDIMeister

Phd of TDIClub Enthusiast, Moderator at Large
Joined
May 1, 1999
Location
Canada
TDI
TDI
Increasing the boost will indeed aid in bringing the EGTs down. I am running more than sufficient amount of boost on my car, for the express purpose of minimizing the smoke output. However, with the boost levels I'm running, the stock intercooler is being overwhelmed, and I'm rigging up a water injection system to increase the charge density to alleviate the smoking problem and also control piston temperatures and EGTs. Increase the boost in 1 PSI increments and observe if there is any difference, but the consensus here is to not exceed 18 PSI or so...

The sudden smoke and EGT increase you describe at high load, and significant reduction in both with 3/4 - 7/8 throttle is a function of two things: too much overall fuelling, putting you over the top past the smoke limit for the amount of air the engine is taking in, as well as the injection duration being longer than stock. I have the exact same smoking problem as well with right foot to floor, and it's quite simply because the engine is plentifully-fuelled (I'll come short of saying over-fuelled and because the injection duration is longer.

One other thing to try: If you have VAG-COM, also check to see what your full-load injection timing is like under these high EGT and high smoke conditions, and compare it to the conditions at the same RPM but reduced load that does not exhibit the EGT and smoke problem. Retarded timing would explain what's happening, but if this is the case, something is causing the timing to be retarded, it should not be inherent in the ECU programming.
 

MJSfoto1956

Well-known member
Joined
Mar 19, 1999
Location
Marshfield MA
TDI
1996 Passat TDI
thanx -- when I get back from my travels I'll check it out with Vag-Com.

Two things though:

- I increase boost by using the "bleed method" with my non-VNT turbo -- right?

- Would ditching the chip and going to .205 injectors be a better solution for my application?

MJS
 

TDIMeister

Phd of TDIClub Enthusiast, Moderator at Large
Joined
May 1, 1999
Location
Canada
TDI
TDI
Originally posted by hsdesign:
- I increase boost by using the "bleed method" with my non-VNT turbo -- right?
<font size="2" face="Verdana, Helvetica, sans-serif">Correct.

Originally posted by hsdesign:
Would ditching the chip and going to .205 injectors be a better solution for my application?
<font size="2" face="Verdana, Helvetica, sans-serif">In theory, most definitely to reduce smoke and EGTs. That's why VW installed larger orifice injectors rather than lengthening the injection duration to get more fuel and hence more power. In the development of the race TDI, VW Racing couldn't keep smoke at reasonable levels by simply turning up the fuelling by lengthening the injection duration. With .260 mm injectors (yes, that's the number they quoted), they got 2.5 Bosch smoke numbers at rated power compared to 5.3.

At the most simplistic level, EGTs would be lower because fuel injected late into the expansion stroke burns at less than ideal conditions (local oxygen has already been consumed in the earlier fuel burn, and temperatures are very high which promotes cracking of the fuel molecules and breeding conditions for soot formation.
 

TDIMeister

Phd of TDIClub Enthusiast, Moderator at Large
Joined
May 1, 1999
Location
Canada
TDI
TDI
For your application, I think GoFaster has the winning solution: .216 injectors from a European 150hp 5-cylinder TDI Transporter van with stock chip, but to get a bit more out of it (but less than having a chip or tuning box), he rigged together a homemade box whose complexity lies somewhere between the Evry resistor mod and a bonafide tuning box. Smoke is at pretty low levels, and he routinely pulls a 1500 pound trailer loaded with motorcycles and tools.
 
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