Need some help: FI hard start, dies on idle

[furgo]

Some progress, but slow going. Most of the time I could actually spend at the bus was employed trying to remove that wretched TS2 sensor thread.

I had a go with the thread extractor, but it didn't work out. The reason being, the actual variable resistor inside the bolt housing is secured in place between two metal caps: the one at the top has a spring, and the one at the bottom is solid –the thread extractor hits that one at some point. Then it can't go further: on the next turn the carved incisions from the extractor slip and carve new ones over, and there is no grip anymore.

So I conclude that the TS2 remains cannot be extracted without drilling the bolt through or breaking the bottom thermistor cap.

In the end, I decided to not spend more time on it and leave it for later. Instead, I focused on fabricating the sensor bypass workaround with a potentiometer and moving forward:

It's essentially a 5KOhm linear potentiometer in a metal box with an automotive connector for easy removal. The scale is in °C, but essentially you can see two of the key points highlighted: 20°C (68 F) is room temp, and 80° C (176 F) is when VW/Bosch considered the motor being warm.

I calibrated the scale with these two points, the data on the AFC manual, and Telford Dorr's thermistor curve.

Operating it is easy, as indicated on the scale:

- Turn the knob clockwise to enrichen the mixture (trick the ECU into thinking the engine temp is decreasing => needs more fuel)
- Turn the knob counter clockwise to lean the mixture (trick the ECU into thinking the engine temp is increasing => needs less fuel).

The figures on the scale indicate roughly the temperature the thermistor value fed into the ECU correlates to.

In hindsight, I should have bought a logarithmic potentiometer, which would have made the scale more intuitive to read and the knob easier to operate. Right now, it's way too sensitive at the hot end of the scale. Then again, I don't know how granular are the temperature switch points read by the ECU.

I'm building the mounting bracket for the dash next, and I'll then route the wire from the driver's seat to the engine compartment. I got 8 m (ca. 26 ft) of wire, which I think should be enough.

I see this a temporary workaround until I can finally fully remove the TS2 remains: I don't have an O2 sensor and I've got a Federal '79 ECU, so any changes that I do to the sensor output are effectively an open loop with no feedback. I guess I'll have to develop a feel for at which rate the engine's temp increases and replicate that by operating the bypass knob!

Other than that...

I started going through the vacuum hoses (again) and replacing them.

I cleaned up/refreshed some FI parts as I was re-testing some of them.

_________________
'79 Westy, P22 interior, FI 2.0 l Federal, GE engine (hydraulic lifters)

Decode your M-Plate

[furgo]

Thanks for the replies, excellent guidance from everyone.

@ROCKOROD71: I've got a very similar set of extractor bits to the one on your picture.

I'm not at the bus atm, and I won't have time to work on it today. In any case, I'll be preparing what I need:

• The length of the sensor thread is about 9 mm. However, the end cap of the thermistor still seats at its bottom (it can be seen on the previous pictures). That might mean that if the hole is not deep enough for the extractor, I might have to either try to remove that cap or drill through after all.
• The hole that originally allocated the termistor is about 4.5 mm
• With that in mind, I'll use the 1/4" extractor bit, which is 0.130" at the tip
• The square end of the extractor is ca. 5 mm. I don't have a 12-point socket that small to drive it, so I might have to get creative there.

Btw, unrelated to the sensor, great tip on putting the bed down to have more space to lie down facing the engine compartment, I don't know why I hadn't thought of it before

[ROCKOROD71]

Try the extractor. It is tight in there and not sure what kind of extractor you have, but forget using a drill on it. Probably not enough room to use the t-handle those sets typically come with. This came out of my pickup truck recently, something I had never seen before:

Turns out these spark plugs were original to the car, the nut on the plug you use to turn it out was completely rusted through and disintegrated when trying to remove the plugs, then the ceramic portion of the plug pulled right out, leaving the threads and end diode in the cylinder. Was really hesitant to use the EZ Out since dropping any metal in the cylinder meant pulling the head off, but as you can see in the picture it worked out. The threaded portion actually came right out once something solid was gripping it. You may experience the same thing since the sensor came apart like it did, there was probably never enough torque to the threads to break them loose. If you look at the extractor in my picture you can see it has a square end. This end is not conveniently 1/2 or 3/8 drive size, but instead we used an appropriately sized 12 point short socket that would fit around it on the end of a ratchet and extension. You could even use a swivel joint in the bus situation. Put your westy bed down and lay above the engine compartment and slowly work the extractor until it grips the hole squarely and try and ratchet it out. Use the biggest extractor you can that will fit in that sensor hole. Spray with penetrating oil before hand. It's gonna be a bitch but once it catches I think it will come out. Also in you favor is the fact that the sensor just goes into the meat of the head, not into the cylinder, there is no real danger of you messing up anything more critical to the operation of the engine.
If you do get it out you are going to want to get a bottle brush or similar and clean out those threads and use anti-seize with a new sensor, maybe try running a bolt the same size in and out of the threads a few times to clean them up and make sure your new sensor is not going to have issues installing.
_________________
1971 STD BEETLE- DD-1st car, 1st love. keepin' it stock! 1600DP, Solex 34-3 Mexi Bosch SVDA Dist NOW w/POINTS
1977 WESTY "KrustyKamper" 2L FI

[Wildthings]

Much easier to start from scratch and drill and tap the equivalent hole on the #4 cylinder. It will work just as well.

[Tcash]

Keep soaking it, doesn't even look wet.
By the looks of it, you would not need to drill the center out. It already has a hole in it. Soaking, tapping the edge of the sensor, until it takes penetrating oil, candle wax and an extractor you should be able to get it out.
Good luck
Tcash

[furgo]

[KentABQ]

If you want to get it up-and-running quickly, you might consider doing this as an interim fix: https://www.thesamba.com/vw/forum/viewtopic.php?t=248511&highlight=temp%2A+sensor
_________________
-Kent-
1976 Riviera, 1.8l FI chrome yellow VAN - "Chloe"

"I must say, how can you be in a bad mood driving this vehicle full of vibrant color.
Cars of today are so bland in comparison. It's like driving a celebration!" ---WildIdea

Bus ownership via emoticons:
---williamM

[furgo]

Another update, and unfortunately, I cannot report success.

After having removed the surface rust, then nearly a week of soaking it in penetrating oil, trying ice shock rust remover, carefully hitting it with a punch and tightening/untightening with the wrench and the special 13 mm socket... it went like Marie Antoniette.

At some point it started moving on tightening, and also on untightening. I thought it was about ready to go and I could remove it, but essentially it was the cylindrical thread starting to detach from the head... until it broke.

Although it was extremely rusty on the surface (really heavy pitting), I'm not sure if the thread is being held by rust. It might have been overtorqued from the start.

Needless to say, it's been extremely frustrating. Tinkering with the TS2 (which I'm pretty sure wasn't the cause of the FI issue -the engine would die with it shorted to ground-) has set me back one week and I'm now worse than I was before.

On the other hand, at some point in the future the sensor was going to fail of age, so better now near home than in the middle of a trip. Don't despair, focus.

Constraints

As mentioned earlier on the thread, I can't do much where the bus is parked right now. Even towing it might be a challenge. I realize that dropping the engine and redrilling the hole is probably and clearly the best option, but not a possible one at the moment. I'm mentioning this so that it's clear from the start.

With that said, I'm evaluating the other options I have...

Temporary fix

I think, but I'm not certain, that the other 3 possible locations for the sensor are not drilled to accommodate it (on the outer side of each air intake runner, next to their top studs). From the pictures I've seen, the diameter of the holes other than cylinder #3 were smaller. Also, that would require cutting a hole in the tin.

Thus I think I could:

• Simply ground the TS2 input to the ECU. Start will probably be more difficult, but I know the engine started at least once with it grounded. Or,
• Route 2 wires to from the engine compartment to the dash and use a 3k Ohm potentiometer. Regulate it during the start phase and dial it to 0 Ohm once the engine seems to be warm. Or,
• I have a good sensor and I'd like to explore the possibility to use it temporarily, even if not properly attached. There must be a way of attaching and getting it to sense the head temperature by surface contact. I'm open to "creative" workarounds here. Suggestions?

Proper fix, but DIY?

If I can manage to start the engine and it does not die, I can then take it to a shop and ask them to remove the rest of the thread for me.

But I'm also wondering which options I have to do it myself. I've been lucky not to have to use them before, but I could probably use a screw extractor/left hand drill

Pros:
• As the thread is essentially a cylinder that originally contained the thermistor, it's already center-drilled. A left hand drill might work

Cons:
• Space is tight. A power drill can't get in there. Maybe a Dremel?
_________________
'79 Westy, P22 interior, FI 2.0 l Federal, GE engine (hydraulic lifters)

Decode your M-Plate

[furgo]

[airschooled]

I took a small bath in penetrating PB blaster spray this morning. That stuff is amazing for tearing apart a rusted engine in half an hour flat. It gets in the same way moisture and oxygen get in.. Vibration helps speed the process.

As far as what the TS2 does to the fuel map, it richens the mixture by varying pulse width, not timing or frequency, doesn't it?

Robbie
_________________
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[Wildthings]

If you are living in a place that uses road salts go to your local hardware store and buy a stainless steel washer to use under the sensor. The sensor receives its heat from the metal of the head via the threads, the washer isn't important to the operation beyond holding the tin in place and giving the sensor something to tighten against.

[ROCKOROD71]

The last two posts here I haven't read, its early here, but I DID read your post regarding removing the sensor. Good job making that tool btw, that should work, although the real tool is a deeper socket.
Before I got that tool I literally was spraying that sensor every night and tapping on it with a closed end box wrench and a small hammer. It is close quarters for sure. I removed the spark plug wire and any hoses that were in the way. You can only get small swings of the hammer accomplished there but the goal is not to turn or remove the nut with the hammer but to "shock" the fused rust loose. I would spray the sensor down, wait 15 minutes, and start tapping, intermittently trying to turn the wrench with hand strength, then back to tapping. Maybe 5 minutes of this, then soak the sensor again, and walk away to try another day. Letting it soak overnight helps. Also, with hand pressure, turn it to TIGHTEN it intermittently. Eventually you start to feel a little movement. Even with this movement I was still spraying and tapping, but not getting anywhere. Once I used that tool the sensor came right out with just hand strength (this is a good spot to mention that I am a weak little bitch).

ALSO of note: I too had a steel washer between the copper crush washer and the engine tin, and it was rusted, neigh, ROTTED to hell. I wondered then as now, if this changes the resistance to the sensor? Especially if run of the mill anti-seize and not the nickel stuff was applied to the threads, I assume that thick rust doesn't pass electrons so well. I re-installed a new (used) sensor without the steel washer. If that steel washer is needed please let me know, I can add it back. I haven't had a chance to get back to my FI issue or test drive the bus, with some other car repair issues on my other vehicles taking preference.
ALSO ALSO of note: I didn't try yet but the copper washer on the sensor looks VERY close to a crush washer found in a type 1 oil change kit, the ones that go on the acorn nuts. Someone correct me if I am wrong, but I think that would work, and I have a ton of those....
_________________
1971 STD BEETLE- DD-1st car, 1st love. keepin' it stock! 1600DP, Solex 34-3 Mexi Bosch SVDA Dist NOW w/POINTS
1977 WESTY "KrustyKamper" 2L FI

[furgo]

It seems the thread is quite prone to being hijacked, but hey, nevermind. We're all on the same boat

[Abscate]

I doubt anyone has ECU source code, but has anyone figured out how the injection times varies with TSI reading?

Probably one needs to look at the pulse signal on an oscope to do this.

Does it add a Multiplier to the pulse length, how many steps are there, etc.
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[furgo]

[busdaddy]

If I was up against a rusted in mess like yours I'd find a deep socket or shortish length of small pipe that just fit over the raised middle of the TS2 where the wire emerges. Then I'd tuck the wire up into the socket (or pipe) and seat it against the flat area between the hex and the raised nipple (where the part number is) and give it a few solid whacks to dislodge the grip that iron oxide has on those threads. If it still put up a fight I'd repeat or weld the pipe to a chisel bit that fit into an air hammer for a vigourous massage. The objective is to crush that copper washer a bit and move the threads into the hole slightly creating a microscopic gap.

If all else fails there's 3 more places to mount that sensor if you F it up beyond use. Some sideways bashes flat against the hexes with a flat drift might help too.
I don't think the big washer was put there by VW, but I have seen more than one installed to keep mangled tin down in place were it belongs, likely not the best way to fix the problem.

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[Hoppy Camper]

Thanks furgo, your analysis of my post was spot-on. The ohm's were set at 200K, it was showing 9.5 and I was grounded on the terminal of the tsii. I figured my readings were too high. This is a brand new tsii! Dammit, I'll keep checking it but it did not work when I had it installed and the old one fixed the hiccup.

[Wildthings]

Kind of hard to picture, but it is possible to get a nice big dose of spray penetrant onto the threads of the TSII sensor. Measure directly up from the center of the TSII sensor 1 inch and drill a 1/4" hole in the tin. Now using a spray can with a straw on it, spray directly downward through the hole towards the TSII sensor. Repeat the spraying a couple of times over a few days until the sensor decides to yield and unscrew.

If you beat too hard on the TSII with a hammer and chisel you may break the fin the TSII screws into right off, use care.

As far as I know there is just supposed to be one washer under the TSII sensor, it gives something for the sensor to seat against and also holds the tin in place. Use never seize or dielectric grease on the threads of the sensor to prevent corrosion.

[furgo]

[Tcash]

The crush washer should make the TS2 airtight/oilproof, correct?
If it was air tight it would not be rusted.

Some taps on the TS2 with a punch or dull chisel to break the rust ring will help.
Heat it up with a torch and Melt some candle wax into the joint as well.

Good luck
Tcash