1Z/AHU stumbling under part load

Abacus

That helpful B4 guy
Joined
Nov 10, 2007
Location
Relocated from Maine to Dewey, AZ
TDI
Only the B4V left
The FA is just fine and identical to the GQ except the chips. Swap those or get tuned ones and you're golden.

The issue is with the PID feedback (response/feedback corrections) in the programming since the pump electrical signal isn't correct while it's chattering. I have two that do it, both with different tunes. I leave them off unless I want to use the cruise above 2k rpm.

I do not know the correct programming for the chips, I just know the issue since I deal with it at my job in water treatment.
 

wyopel

Veteran Member
Joined
Nov 24, 2014
Location
WA
TDI
1996 B4V-270k, 1998 Jetta-140k
I'm guessing you used a standard Bosch style relay? Is the wiring below, correct?

85 ground
86 12v trigger from cruise stalk
87 one side of VSS wire
30 other side of VSS wire
I may try to get this done this weekend. Excuse my ignorance but cutting wires behind fuse panel makes me a bit nervous because I have already had a few electrical "gremlins" with this car. So a couple of questions...

Where does the other end of the cruise trigger go? If you cut it...one end goes form cruise switch to 86, but where does the other end go? Any hints on identifying wires. I can figure out the VSS from previous posts, but what about the others? Anybody with a diagram or picture? Thanks.
 

wyopel

Veteran Member
Joined
Nov 24, 2014
Location
WA
TDI
1996 B4V-270k, 1998 Jetta-140k
Thanks Todd,

So if you connect cruise switch wire to 86 on the relay, where/how did you connect the remaining cruise to ECU connection? Does that go to the 87a terminal? Sorry I am just not understanding how you used the cruise switch to switch both the VSS and the cruise?
 

ToddA1

Top Post Dawg
Joined
Aug 3, 2011
Location
NJ 08002
TDI
'96 B4V, '97 B4 (sold), '97 Jetta (scrapped)
I have not done this modification, so ymmv.

The way I envision it, do not cut/break the cruise trigger; simply tap into it.

-Todd
 

wyopel

Veteran Member
Joined
Nov 24, 2014
Location
WA
TDI
1996 B4V-270k, 1998 Jetta-140k
Anybody that has done this mod want to chime in? Is simply tapping into the cruise trigger the way to go?
 

wyopel

Veteran Member
Joined
Nov 24, 2014
Location
WA
TDI
1996 B4V-270k, 1998 Jetta-140k
So after thinking about this a little bit this is what make sense to me:


86 12v trigger from cruise stalk
85 cruise to ECU
87 one side of VSS wire
30 other side of VSS wire

So when 85 and 86 are connected via the cruise switch...that should engergize the relay and connect the VSS via 87 and 30. 87a is not used because that is the "off" position/default if the relay is not energized.

Can anyone smarter than me (probably most of you) confirm this set up.
 

goose737700

Active member
Joined
May 10, 2010
Location
arizona
TDI
2013 tdi golf DSG. 1995 EVC AHU Tdi, Dsla 1019 injectors, Vnt15.
What worked for me.

I've been meaning to post my reply to this thread for a while now, but i haven't had the time. So I had a significant stumble problem with my Van conversion since the first day I drove it. I scoured the threads and posts here to find a solution, so I pretty much tried them all. The vibration/stumble would come on (or be more apparent) at higher speeds and higher gears between 2500-2900 rpm. I tried axle shafts, the VSS to ecu delete (which did in fact work), injector cleaner, timing adjustments etc. I finally decided to pull out the injectors and sent them back to Frank to be checked out. Sure enough 2 of the 4 were way off in flow and he cleaned and reset all 4 for me. I put them back in, readjusted the IQ, and its running great, the stumble is gone for good, even with the VSS signal reattached to T28. works great in cruise and the all around drive ability has vastly improved. I would have to say the problem originated from using an old engine that had been sitting for a couple of years and neglecting to flush the injection pump before connecting the injectors. stupid mistake on my part.
 

B5.5wagonguy

New member
Joined
Jul 21, 2018
Location
Lancaster pa
TDI
96 passat wagon tdi
Just to help out anyone else trying to wire this up on a b4 Passat, I was able to locate the 12v cruise control signal wire by removing the steering wheel clamshell. Once you remove it you can see the black flat 4 wire connector to the left, it is the black wire that you want. I just traced it down to above the pedals and used a wire tap to get the signal wire for the relay. For your ground there is a brown plastic ground junction to the left of the fuse box with male spade terminals so you can just slide a female spade on and run the wire for your ground on the relay. Then the u2/02 is easy to locate on the back of the fuse box and cut then connect one side to each relay terminal. It seems to have eliminated my cruise stumble as well with the cruise switch in the off position, the throttle is a lot more touchy/responsive to quick changes.
 
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