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Wed Mar 27, 2019 8:04 am

Toobigtofail wrote: Hello,

I also have an ABA swapped (50 degree) Westy. I'm currently experiencing an issue with a surging idle, have you experienced this at all? It's fine until the engine warms up, then the idle surges up and down. Other than that the engine drives pretty perfectly.

Thanks very much,

Nick

I personally have not, but it sounds like an air leak to me.

Neil and the other guys here might have some additional insight.

Wed Mar 27, 2019 8:41 am

h00drat wrote:

I personally have not, but it sounds like an air leak to me.

Yup, check all of your vacuum lines. I'll bet one's disconnected.

Wed Mar 27, 2019 8:50 am

Toobigtofail wrote: Hello,

I also have an ABA swapped (50 degree) Westy. I'm currently experiencing an issue with a surging idle, have you experienced this at all? It's fine until the engine warms up, then the idle surges up and down. Other than that the engine drives pretty perfectly.

Thanks very much,

Nick

Does the idle ever stabilize after it surges? Would suggest cleaning the ISV first. There is a note in the A3 Bentley manual about cleaning that valve. Issue might also be due to a vacuum leak.

I had a similar issue. Turned the B+ "constant positive" wire to ECU was not connected (I'd done the harness work). IIRC, it goes to ECU 54. Without that wire connected to ECU, engine warm, especially on a hot day, when the engine was restarted the idle would go up/down then finally settle in. That "constant positive" enables the ECU to "remember" settings like ISV position, OBD stuff etc. The idle control system is "adaptive" as are other aspects of the engine management.

Neil.

Tue Apr 23, 2019 1:51 pm

Not sure if you guys resolved anything on surging idle, but here is where my van stands...

On cold start (or I guess "first" start) - regardless of outside temperature - I do have a surging idle down in the 800 rpm range. After about 30 seconds, idle stabilizes and smooths out around 1k RPM's which is where it almost always sits. I believe my high idle is because of the chipped ECU from TTT.

Hasn't been an issue because it always starts, but not really sure what is causing the idle surge when cold.

Maying that ECU 54 you are referring to Neil, or perhaps I need to clean the ISV again.

Wed Apr 24, 2019 10:45 am

Hey Tyler.

Assuming your harness was done correctly, with battery disconnected, then ECU connector removed, then battery reconnected, it's easy to measure if B+ is present at "54 Battery Power". That test is shown in the Bentley manual.

Does your van have an active VSS sensor?

Your idle issue is likely not relevant to mine but some questions, comments I posted about idle stabilization under OBD1:

https://www.thesamba.com/vw/forum/viewtopic.php?t=717664

If a recent cleaning of your ISV showed clean fluid, its likely still clean.

What is the Ohm spec of your ISV? Bentley suggests tapping on the unit while measuring resistance to see if that spec fluctuates. (they assume test connections to it are stable)

My 15º ABA swap has been idling fine for some miles now. At first start it's a little "rough" but smooths out in about 8". In that regard, my 50º ABA behaves in exactly the same manner but has an intermittent idle issue.

I plan to disable the VSS on my 15º ABA and see if that affects idle.

On my 50º ABA, which does NOT have a VSS sensor, I again monitored IAC duty cycle, adaptation other inputs with Ross-tech. Ironically, idle issue did not show up. Duty cycle remained at about 50% engine cold, warm, PS used and of course no "vehicle speed" showed up.

The idle on the 50º ABA has always dipped pretty low, then returned, when dumping clutch coming to a stop. Recently, while driving more in "big city" traffic, the idle up-down surge started happening after dumping clutch while coming to a normal stop; it would dive then surge up/down for about 6 cycles then usually smooth out. Ambient temp, engine heat, time, might be factors in that; it wasn't happening over winter months.

This is partly (or mostly?) speculation but.....

Some ABA "tuners" or "swappers" may see the ISV and VSS as nuisance items to be deleted. Yes the engine will run w/o VSS but does that affect the finer points of drivability? Maybe so. And, IF the ECU can be reprogrammed to ignore the VSS, and/or ISV, does that affect finer points of drivability? e.g. while driving at parking lot speeds over speed bumps?

I'm curious if the Bentley manual statement about the idle control system being "adaptive" applies to OBD1 as well as OBD2 (the latter has a different means of stabilizing idle). I bet it does and if so, is that aspect exacerbated by a lack of VSS input and in your case, also by an automatic transmission. e.g. when you take your foot off the off gas at, say, 30 MPH, does the engine always return to idle or does it turn slightly higher than idle?

There's at least one 2.2 Suby OBD1 swap post regarding the VSS and idle. Yes that engine management is obviously different but it does use blink codes and similar or same amount of inputs to ECU as does Motronic 2.9 OBD1 so......

Neil.

edited.

Wed Apr 24, 2019 1:38 pm

Interesting point. I do not, as far as I know, have VSS wired in. I would have to review my wiring documentation.

Incredible that this motor has been in my van for a year already, but funny how many things I can forget in 12 months :roll:

Wed Apr 24, 2019 4:08 pm

This thread is lacking a whole lot of aba swap info.

https://forums.vwvortex.com/showthread.php?4773933...nfo-thread

vss work arounds, what pulleys to use and belt sizes, easy ways to wire everything up, etc.

Wed Apr 24, 2019 6:50 pm

h00drat wrote: Interesting point. I do not, as far as I know, have VSS wired in. I would have to review my wiring documentation.

Incredible that this motor has been in my van for a year already, but funny how many things I can forget in 12 months :roll:

Congrats on your ABA year anniversary.

Ya, I ran my 15º ABA today with the VSS at speedo disconnected. No discernible difference in terms of idle or anything else.

I dunno. < shrugs > ;) Maybe it truly isn't needed under OBD1 anyways.

It's just one way to install a VSS but the actual VW part installed at speedo should be enough for ECU to use as vehicle speed. IOW I haven't gotten any DTC's for that sensor since installing it. Pretty sure you'd recall if you had to install and or interface to that hall pickup at cluster if you'd installed the VW part at speedometer.

Neil.

pic of that hall in my 15º 1892 diesel cluster. I soldered a generic 3 wire connector to it. Hall came out of a Mk2 VW.

Wed May 01, 2019 2:28 pm

Vanagon Nut wrote:
Congrats on your ABA year anniversary.

Thanks!

Okay, if it requires connecting something to the speedometer, then no, I definitely do not have VSS connected.

What is most odd is that this is a pretty new issue. Like, since my transmission rebuild new.

The only other thing I changed over that time period was that I moved my air filter from in front of the LEFT tail light, to in front of the RIGHT tail light, creating a much longer run from the MAF & Air Filter to the throttle body. I suppose this could play a role here.

I also went from a cone filter to a more enclosed air filter housing from a Jaguar.

Regardless, it only does it for about 30 seconds on cold start, then it's fine, so not a major concern at this point in time.

Wed May 01, 2019 5:38 pm

h00drat wrote:

Okay, if it requires connecting something to the speedometer, then no, I definitely do not have VSS connected.

What is most odd is that this is a pretty new issue. Like, since my transmission rebuild new.

The only other thing I changed over that time period was that I moved my air filter from in front of the LEFT tail light, to in front of the RIGHT tail light, creating a much longer run from the MAF & Air Filter to the throttle body. I suppose this could play a role here.

Ya I really don't think the engine management "misses" the VSS.

Now you got me thinking, again, about that long pipe from passenger side to intake as I have the same in mild steel. In that past I'd wondered if that pipe would pick up engine heat, especially in slow stop and go traffic. And if so, would it affect the idle stabilization system or push the IAT sensor out of range. I really doubt it though.

Separate issue but thanks for that "reminder".

Neil.

Thu May 02, 2019 2:55 pm

Vanagon Nut wrote:
Now you got me thinking, again, about that long pipe from passenger side to intake as I have the same in mild steel. In that past I'd wondered if that pipe would pick up engine heat, especially in slow stop and go traffic. And if so, would it affect the idle stabilization system or push the IAT sensor out of range. I really doubt it though.

Separate issue but thanks for that "reminder".

Neil.

I had wondered about the heat to that pipe as well. I haven't gotten this far, but I planned on hitting it with an IR heat gun after a long day of driving just to see what the temp of the pipe was, sitting above my exhaust. Like I said, haven't gotten that far.

As you say, probably completely unrelated to the cold idle issue, but something I've been wondering about.

Thu Aug 19, 2021 3:34 pm

Note sure where to put it but this seems ok.

Was inquiring to Techtonics Tuning about their recommendations for an ABA in a heavy bus, looking more for lower torque, and they recommended the 260 degree cam.

https://techtonicstuning.com/main/index.php?main_p...ts_id=2407

Thu Aug 19, 2021 5:17 pm

i had a ABA 'tall block' swap in my jetta coupe with that cam. coupled with an adjustable sprocket set to full advance the low end was great.

i was running a counterflow head in that with tuned CIS and nitrous. lot's of work done to the lower end....knife edged crank etc etc etc.

that thing rev'ed like a chain saw and would boil the 17" tires off the wheels if you let the clutch out and matted the throttle.

anyway, you'll like the cam but get the gear to take full advantage of it

Thu Aug 19, 2021 10:02 pm

nemobuscaptain wrote: Note sure where to put it but this seems ok.

Was inquiring to Techtonics Tuning about their recommendations for an ABA in a heavy bus, looking more for lower torque, and they recommended the 260 degree cam.

https://techtonicstuning.com/main/index.php?main_p...ts_id=2407

Hmm, that's interesting.
It's been a minute since I was doing "research" for the cam selection in my ABA but it seemed that the 266 (AKA 270) cam made more power and torque on the top without losing any of the low end that the 260 has.

I would have to dig a lot more to sort out where I got that info from but I believe there were even dyno sheets to prove it.

Thu Aug 19, 2021 11:29 pm

nemobuscaptain wrote: Note sure where to put it but this seems ok.

Was inquiring to Techtonics Tuning about their recommendations for an ABA in a heavy bus, looking more for lower torque, and they recommended the 260 degree cam.

https://techtonicstuning.com/main/index.php?main_p...ts_id=2407

From what little I know, or think I know, one major area of potential compromise is the exhaust design, particularly the downpipe(s) design.

I'd think that to take advantage of that or similar cam, you'd need ~ 32" (?) per pipe of dual downpipe to collector pre cat.

The tricky part, in my limited experience, assuming the exhaust is mounted off the engine like the diesel Vanagons, is making a "tight" set of appropriately long dual down pipes. Pipes that don't cantilever too far out. And that takes real skills or money.

Personally, I'd take a shorter simpler longer lasting (presumably) exhaust system over some added torque at lower RPM. Not saying one can't have both. Just saying that adding complexity to the exhaust usually means more risk of exhaust system cracks or failures unless it's done really right.

Neil.

Sun Jan 05, 2025 3:39 pm

h00drat wrote: Way back on page 15 I asked about external gauges...then the conversation went down this OBDII dongle tangent which I just sort of set aside for a while.

Well, my wiring harness came with an OBDII port on it, even though it's an OBDI motor. Based on our conversation on page 15, it was my hope that I could get a bluetooth dongle and get some basic readings from the motor. Water temp, oil temp, etc.

Unfortunately, it looks like this isn't the case. I tried two dongles with no luck. Then I asked Dave (the wiring harness builder) and he said that it wouldn't work with a dongle, but only an authentic VAGCOM reader.

After re-reading page 15, maybe I mis-read. Are there certain OBD dongles that are OBDI compatible, and some that are not? The dongle was powered, but would not communicate with my iPhone app. I don't have a PC.

OBDI is some dinosaur stuff. Many of the cheap "hud gauges" found on evay will talk to dlc for basic info- refresh rate is slow so tac is pretty useless.
Its real old protocol, i have used some of the old ebay scan gauges on tico swaps and they would get me temp and rpm...slow but worked

I push everyone to obd2 as its sooooo much better and now i offer all new harnesses so cores are not even needed. ( tdc-shop.com )

My advice- cheap 30$ ebay gauge- extende rhw dlc forward to run gauge up front or mount in back where you can peak at it if your concerned tour cluster is lying...hope that helps