My newest Type 4 acquisition

[19super73]

I have this posted over on The Samba but as STF has a bit of a healthier Type 4 section at times, I thought I would post it here as well.

I bought this 1974 Variant off of another Samba member very late last year. I have been reviewing the work my '73 needs, just in body work and came to the conclusion that fiscally, finding a sound bodied car that runs and drives was a much smarter decision than trying to resurrect the '73.

Well, onto the pictures. Here is the car as I met the shipper in Sweetgrass MT just before Christmas. I crossed the border with it, and it was surprisingly easy. Just have your papers lined up and you're gold.






And after a bit of a bath.




After a little work.





So far I have been doing mostly clean up and small things on the car. It quit running on me the other day after starting to develop a rough idle, a backfire and then finally quitting. The battery never had a chance to gain a good charge during the winter so I will be trickle charging it (in hopes that a nearly dead battery has something to do with it), in addition to swapping in the correct AFM. The one in it is not the right one, and I luckily have a parts car that can donate. I also found an NOS one on-line in case the parts car replacement is either incorrect or bad.

[19super73]

Interesting new development. After about 5-8 minutes of running, the car starts to run rough, smell a little rich and then finally quit. Goosing the gas causes huge stumbling. I know that the AFM on it currently might be for a 914... I am hoping that maybe putting the correct AFM back in the car will help solve this.

[Piledriver]

Nice T4!

Check the CHT sensors resistance.

Better idea: Install a new one, find, clean and reinstall or redo the ends on all your grounds with waterproof loop crimps, done with proper crimpers, and put them on freshly wirebrushed aluminum smothered in vaseline or dielectric grease.

Then and only then start troubleshooting--- There is no need to throw parts at it, a decent voltmeter and a mityvac will pretty much ring out everything on DJet.
(If LJet the meter alone will do)

[19super73]

Nice T4!

Check the CHT sensors resistance.

Better idea: Install a new one, find, clean and reinstall or redo the ends on all your grounds with waterproof loop crimps, done with proper crimpers, and put them on freshly wirebrushed aluminum smothered in vaseline or dielectric grease.

Then and only then start troubleshooting--- There is no need to throw parts at it, a decent voltmeter and a mityvac will pretty much ring out everything on DJet.
(If LJet the meter alone will do)

It's an L-jet. I was going to check them CHT sensor and also the TTS to see what resistances I got.

[MGVWfan]

Grounds, yes, always rework those till they are pristine first. Gotta go from a solid baseline.

However, if that does not cure the problem...

I had the WILDEST time when trying to get my D-Jet running right, and it came down to the CHT sensor being intermittent...it would suddenly jump up in resistance by 4-500 Ohms, then drop to reality while warming up. Once at temp, it was pretty solid. A new CHT fixed the problem.

I tore the CHT apart to figure out what the heck was causing the strange resistance jumps...the thermistor "pill" is metallized on both sides, and held to the bottom of the cavity in the sensor with a spring, which is also the contact conductor for the "hot" end of the sensor. It seems the end of the spring was getting corroded, probably from the damp climate here in Houston (it is NOT hermetically sealed), and until things expanded to full warmed-up state, the corrosion was causing an intermittent additional resistance.

So, bottom line, the sensor can be flaky as it warms up, at cold temps only maybe, or at warm temps only maybe...put an analog Ohmmeter on it, warm it up (slowly) in a pan of hot veggie oil to around 250 deg F, and see if that's causing your strange FI woes. If so, replace.

[Piledriver]

I think of those CHT sensors ~like spark plugs...a consumable... but even less reliable...
Always carry a spare and replace at first sign of hiccups.

If I had to run LJet or DJet I would find a suitable thermistor and make a sealed/potted unit.

[19super73]

Piledriver, I have the same view as you. They should most likely be changed on a semi-regular basis especially now that it seems they fail more often. I just went through the same thing with my '75 Super Beetle. It would backfire, stumble etc. and quit at idle. I pulled the TSII and just replaced it without testing it. It's only about $20 so no big deal. Cleared up the issues right away.

[19super73]

While the TSII change did help, the fix was a new coil. The old one was rattling around in the bracket, beat up and a screw that was in the bracket to hold it tight, actually punctured it. It got bad enough that the car wouldn't even fire and ended up pumping fuel into the oil from the cranking. New epoxy filled Bosch coil, black rubber band cushion around it and nestled back in the bracket solved all.

[19super73]

Well, the fix was temporary. I am back to the same issues and I think it's the TTS. I have a wonderful Type 4 troubleshooting guide that points to this. I sent a scanned copy to The Samba and it's up in the tech area for all you L-jet type 4 guys.

[Piledriver]

Might want to install a potentiometer on the dash as a temp fix/diagnostic and tuning aid...
You can make a simple replacement bolt-on TS2 replacment if you can source the right resistor.
(I forget what the temp coefficient specs are, at least the cal #s are built into TunerStudio)

(from TunerStudio is built in/supported sensor)
LJet Cylinder Head sensor II
-13.888 C 11,600 ohms
53.888C 703 ohms
95.555 C 207 ohms

If all else fails you should be able to calculate the coefficient and find a compatible resistor, and JBWeld it into a large copper crimp, and bolt it to the head with a pigtail attached.
Should be ~infinitely more reliable than factory done well.


Wait--- TTS=thermo-time switch? Gotcha, should be able to simply bypass to troubleshoot.
(I would say disconnect but I'd have to look at the schematic to be sure, has been ages since i looked at an LJet setup. disconnecting the cold start injector should do, I'd consider putting it on a manual switch anyway, that way you have a "smart" controller ...
(at least if you have had your AM caffeine fix .)

If unplugging the injector doesn't work, == leaky/stuck cold start injector.

Here's the link: (its perfectly OK if its relevant information)
http://www.thesamba.com/vw/archives/man ... typeiv.php

[raygreenwood]

I should have answered here a week or so ago. In a pinch ...and if you know the weather is cold enough to need the cold start injector. ...you can wimply run a switch to the power. Like a manual choke. Flil the switch... start, stabilize rpm and turn it off. Nice car! Ray