Need some help: FI hard start, dies on idle

[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
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-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]

[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

[Wildthings]

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

[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.
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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]

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

[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.

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

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