TheSamba.com :: View topic - What could cause a TS II to fail prematurely?

Wed Nov 12, 2025 10:37 pm

KTPhil wrote: I have talked about this, but not yet done it...

I want to make up an "emergency TS" which is a fixed resistor representing the warm R value, compete with a connector and a grounding lug, so that should the TS or wiring fail, I can limp home with a reasonable A/F ratio.

I just haven't found the right resistor yet.

So is this “emergency TS” permanently attached to the engine so if the main TS2 craps out you can hit a switch to the “emergency TS2?” This would be a universal solution for cars that use a TS2? KTPhil is thinking of using this to limp home. I’m talking about using a new TS2 to keep on traveling. A new TS2 in a Bay window bus takes 15 minutes to replace. If it’s a pita in a type 3 then it’s probably a topic best in the “Type 3” forum.

Thu Nov 13, 2025 8:59 am

No switches (more chances to fail!). Upon suspected failure, my plan is to substitute the fixed resistor for TS2 by plugging into the harness after disconnecting the pigtail to TS2. Easy access, on top of the motor and tin. 200 ohms is close enough to drive long stances, not just limp.

Apologies for putting Type 3 specific info in this thread. But I guess anyone searching for TS2 may find this thread.

On Buses, is there a handy T1 connector that the TS2 pigtail connects to on top of the motor (like the Type 3 has)? Likely easier than getting out a special socket and fiddling getting it properly and safely torqued while on the side of the road.

Sorry for the detour... here is a pic of the T3 engine bay. You can see the plastic T1 connector just in front of the coil... easy-peasy to swap. (ignore the red circle, I stole this pic from a different thread)

I presume there is a similar T1 connector in about the same location on the T4 motors?

Of course, this post might be relevant for the madman that came up with this Type 3 solution... woo-hoo!!

Thu Nov 13, 2025 12:19 pm

Xevin said:

Quote: So is this “emergency TS” permanently attached to the engine so if the main TS2 craps out you can hit a switch to the “emergency TS2?” This would be a universal solution for cars that use a TS2? KTPhil is thinking of using this to limp home. I’m talking about using a new TS2 to keep on traveling. A new TS2 in a Bay window bus takes 15 minutes to replace.

Yes, its that quick...about 10-15 minutes as you note... on any of the type 4 engines in any of the cars and buses as well.

The problem...and why we are approaching alternate methods...is WHERE are you getting brand new Bosch, quality TS-2?
They quit producing them and most of the repproduction out there either work, don't work or work for a short period and short out. Thats a pretty wide range of un-reliability.

It would be really easy to do what KTPhil is suggesting as an emergenecy limp home...OR...as a permanent fixture under the hood....in several ways. This is one below.

You could put the fixed emergency resistor in place under the hood. Its already connected to a ground lug/spade terminal. Its positive end goes to a simple board or even a bus bar like this. The board stays plugged into your TS-2 all the time just like normal.

At the first sign of trouble, simply swap one wire to the other male tab and you are now running on either a fixed resistor or a variable resistor and bypassing the TS-2

This would be interesting even for a bus...what KTPhil is suggesting. Type 3 is only difficult because is hard to see. But sure....type 3 aside....

KTPhil said:

Quote: I want to make up an "emergency TS" which is a fixed resistor representing the warm R value, compete with a connector and a grounding lug, so that should the TS or wiring fail, I can limp home with a reasonable A/F ratio.

I just haven't found the right resistor yet.

See, thats what I am saying. You do not need to find a single, fixed value resistor. Buy a variable resistor. You are looking for what is called a "ceramet" resistor...ceramic/metallic.

You can buy one with virtually 0-2500 ohms....each rotation of the adjusting screw is a set amount of resistance change. Put you volt meter on it, dial it down to your hot setting. Mark it. Then dial it up one revolution at a time to say 6-8 ranges between hot setting and stone cold. Write those down and toss that in the glove box. Then set the variable resistor back to your hot setting and leave it that way.

If it ever stops on you when fully wramed up...just plug it in and you are running again. If for instance though your bus will not start when its stone cold and you check your TS-2 and its crapped....just turn the screw X number of turns listed on your cheat sheet to correspond to stone cold and start it. Warm it up 2 minutes and dial is back a couple of revs on the screw. Repeat until fully warmed up and you are good to go.

KTPhil said:

Quote: Is there a wattage rating we should consider a minimum for a fixed resistor?

I am not sure it matters that much unlesss its wattage handling ability is too LOW. I did not even think about that back in the early 00's when I did this and the one I picked up did just fine.

But....typically in something like an ignition ballast resistor is selected to be 40-50 watts.
You look at it like...P=V x I (Watts = volts x Amps).
You have 12 volts (you should probably read that with a meter) and probably no more than a few amps...so maybe 50 watts or less?

The little circuit board level variable resistors can be had in sooooo many shapes, sizes and brands. You will also find these in every fomrat from rheostats to potentiometers and all can work. Its just resistance.

They are heap enough that you can buy a few different ones and play with them.

Ray

Thu Nov 13, 2025 1:53 pm

For the fixed alternative, I was thinking of something like this:
https://www.digikey.com/en/products/detail/koa-spe...J0QAvD_BwE

The ECU used 1/4 watt resistors for most parts, didn't they?

In that case, despite being installed externally, I would think that would suffice for this use. I think TS2 is part of the pulse width modification circuitry, and not part of the injector driver circuits, so it isn't carrying much current. It's been a while since I studied the schematics copied here:
https://www.sw-em.com/bosch_d-jetronic_injection.htm

My thought was to encapsulate it into a T1 type connector housing:
https://vwispwest.com/connector-p-spade-connector-1-1-p-111937077/

Maybe pot it for moisture protection. One lead goes to a round lug to screw to the generator ground lug, the other to the ECU harness.

Like with your suggestion, it could be left in the engine bay, and then upon suspected failure, I just swap the ECU wire from the TS2 T1 connector to this one. Might be handy when checking other FI adjustments, so it holds TS2 at a constant, reducing the variables as you tweak idle speed, MPS settings, etc.

Thu Nov 13, 2025 2:39 pm

KTPhil wrote: I hate replacing that thing on a cool engine in the garage. On the side of the road, hot? Yikes!

I was confused because my experience replacing a TS2 in a Bay is not like what is described in KTPhil’s post. I didn’t know he was talking about a type 3 car at the time. It was in the Bay Window forum. Even a bandaid Uro (EMPI of Porsche parts) brand replacement TS2 would keep you going for a few hundred miles, not limping home.

Then you two start going on a tangent about Type 3 and 4 cars without explanation.

Now I get it. And seems like a neat idea for a Bay Window bus. I’ve seen the Vespa gimmick but will you two map out a schematic for a type2 alternative solution? Please.

Thu Nov 13, 2025 3:08 pm

Does someone have a photo of the Bay engine compartment showing the connector that the TS2 pigtail plugs into? I tried search but came up empty.

Thu Nov 13, 2025 3:50 pm

Xevin wrote: KTPhil wrote: I hate replacing that thing on a cool engine in the garage. On the side of the road, hot? Yikes!

I was confused because my experience replacing a TS2 in a Bay is not like what is described in KTPhil’s post. I didn’t know he was talking about a type 3 car at the time. It was in the Bay Window forum. Even a bandaid Uro (EMPI of Porsche parts) brand replacement TS2 would keep you going for a few hundred miles, not limping home.

Then you two start going on a tangent about Type 3 and 4 cars without explanation.

Now I get it. And seems like a neat idea for a Bay Window bus. I’ve seen the Vespa gimmick but will you two map out a schematic for a type2 alternative solution? Please.

Ah great! You get what we are talking about. The TS-2 are all the same....yes a couple different part numbers with a little more resistance for cold climates in some other cars but all will work in any of the cars mentioned here in this thread. Same form, same resistance etc.

Someone just recently posted that they had bad running with the Vespa part.....but considering that I think its low end is 200 ohms....iirc.....it should work. I questioned whether he had other fuel related issues before blaming the Vespa part totally.

When you dig around not just in bus, but 411/412/type 3 and 914 forums....and on other sites for other cars....all of which use the same part number TS-2 as the bus.....you find a lot of reports of the Uro part being REALLY spotty. Too many that have ohms all over the place through the midrange or work for a short while .....just too much stuff.

For many years a lot of other people in other cars running D and L jet have been working with solutions for TS-2 for various issues.....fuel mixture tuning....better cold starts...better hot starts....and now....lack of reliable parts. So, this conversation is not new.

KTPHIL.....yes....inside the ECU most of those resistors on the board are 1/4 watt. But for what we will be using this resistor for ....just resistance to ground, I don't think it matters. It only really matters when you are trying to put more current through a resistor than what it is rated. This application, even if the resistor is rated for 120 volts and 1000 watts.....its not going to matter. Ray

Thu Nov 13, 2025 8:51 pm

The “Vespa gimmick” is not a gimmick. It’s just a replacement TS2 that happens to be used on a Vespa scooter. Replace the sensor, and it works. I have one installed as a quick backup outside the tin in a tapped hole next to #3 intake. I can’t tell any difference in drivability. It’s also cheaper and has a more robust connection point, a potted male spade connector on top.

Thu Nov 13, 2025 9:28 pm

Bnanwel wrote: The “Vespa gimmick” is not a gimmick. It’s just a replacement TS2 that happens to be used on a Vespa scooter. Replace the sensor, and it works. I have one installed as a quick backup outside the tin in a tapped hole next to #3 intake. I can’t tell any difference in drivability. It’s also cheaper and has a more robust connection point, a potted male spade connector on top.

I thought maybe Volkswagen might consider the OEM TS2 being replaced by an Italian Vespa scooter part on a car they designed a “Gimmick.” I stand corrected :wink: :D I never said it didn’t work.

Sat Nov 15, 2025 8:00 am

Good point, Xevin. For the record, that idea was not mine.

Sat Nov 15, 2025 11:40 am

Just thought I'd provide an update.....

Check the TSII for cold resistance, and it measured ok (2.9k at abt 60 degrees). Wiggled the sensor wire around with the meter on it, and it seemed fine, did the same with the FI harness wire, and it seemed fine too; both had continuity. Made me think it was a ground issue.

Took out the TSII and put high temp copper anti seize (that's what Oreilly had in stock) put it back in and tightened it back up. It seemed to have fixed it...took it on a 20 minute highway run.

Does anyone know the torque spec for the TSII?

Sun Nov 16, 2025 6:11 am

TrollFromDownBelow wrote: Just thought I'd provide an update.....

Check the TSII for cold resistance, and it measured ok (2.9k at abt 60 degrees). Wiggled the sensor wire around with the meter on it, and it seemed fine, did the same with the FI harness wire, and it seemed fine too; both had continuity. Made me think it was a ground issue.

Took out the TSII and put high temp copper anti seize (that's what Oreilly had in stock) put it back in and tightened it back up. It seemed to have fixed it...took it on a 20 minute highway run.

Does anyone know the torque spec for the TSII?

A word about the copper anti-seize. If you are going to use that, about every other year, unscrew the TS-2 and spray it off with carbs cleaner, cir with cleaner or something fast evaporating like that and clean out the threads in the head too. Reapply and re-install.

When you see the anti-seize turning very dark or powdery black its becoming oxidized and very non-conductive. Ray

Sun Nov 16, 2025 3:50 pm

pair of two position switches or a three position selector switch.

If a pair of two position switches - one is stock TSII or second switch. 2nd switch selects average resistance when bus is hot, the other position is a slightly richer position for starting or enriched mixture climbing long grades.

If selector switch, position one is stock TSII, position 2 is average resistance, and position 3 is enriched mixture for starting cold or climbing long grades.

I bought a bunch of genuine Bosch TSII before they went NLA so I am covered but the switches will work for someone who is concerned about TSII failures. There are other threads where people have even put in dial a resistance to change the resistance at will. Adding a couple switches or selector in the cockpit area would be easy to do. Just run two high-quality low-resistance wires back to the original TSII position to keep its curve the same and put the switches or selector near the driver.

Sun Nov 16, 2025 3:53 pm

raygreenwood wrote:
A word about the copper anti-seize. If you are going to use that, about every other year, unscrew the TS-2 and spray it off with carbs cleaner, cir with cleaner or something fast evaporating like that and clean out the threads in the head too. Reapply and re-install.

When you see the anti-seize turning very dark or powdery black its becoming oxidized and very non-conductive. Ray

The copper was a quick fix to see if it fixed it. I ordered nickel anti-sieze off of Amazon today. I bought one of those TS II 'kits' off the Samba classified, once I build it, I'll swap it out and use the Nickel.

Tue Nov 18, 2025 11:08 am

SGKent wrote: There are other threads where people have even put in dial a resistance to change the resistance at will. Adding a couple switches or selector in the cockpit area would be easy to do. Just run two high-quality low-resistance wires back to the original TSII position to keep its curve the same and put the switches or selector near the driver.

This works well and is nice if you want to be able to dial in your mixture while driving. IE climbing a long hill at full throttle? Give it more fuel and watch your CHT's drop, flip back over to 'stock' using the TSII once you crest and keep rocking.