L-Jet Injectors Aren't Getting Ground, L-Jet Injectors Options

[Superhawk996]

Yes I can use a voltmeter and I have a list of tests to do later today after work.

(IMG:style_emoticons/default/smilie_pokal.gif) You’re off to a good start.

[nmkimosabe]

Also check the o-ring on the oil filler cap. A failure destroys the vacuum, vital for L-jets.
Probably/maybe not the cause, but simple to check and cheap to fix. Sometimes the cork gasket under the oil filler housing fails, too. Again, easy and cheap.

Thanks, and when I got the car last Spring, I did replace the cork gasket at the oil filler cap with a rubber gasket.

[nmkimosabe]

Check your main grounds around the engine bay/ and the ground strap from Transaxle top-to-stud just under your trunk. Cleanliness + tightness at grounds are your buddies.

These were checked and cleaned last week by the mechanic, but I may recheck the one under the trunk. Thanks.

[nmkimosabe]

Well 2 weeks and learning a lot about L-jet injection systems the problem appears solved. Per the recommendations from many qualified contributors, I did a comprehensive check of the AFM sensor / plug, fuel pressure, fuel rails, injector voltage, injectors, cold start valve, cylinder head temp sensor, fuel pressure regulator, spark, fuel pump, ground wires, coil, harness wires, dual relay, resistor pack and more importantly the ECU itself. By swapping out an ECU with a friend the car seemed to start and run better but still for a limited time. Thus, it was determined that the cylinder head temp sensor was faulty as it ran fine when we manually operated the throttle and got the car warm. I'm still not sure which was a bigger issue, the ECU or the cylinder head temp sensor.

Next, I have to replace the cylinder head temp sensor which is somewhat challenging on a 1.8L as the sensor is hidden under the intake runner at the #3 cylinder. It could also be a broken wire in the harness but it's hard to get to it because of the runner location. If anyone out there has any suggestions to make this easier as it will be greatly appreciated. My mechanical and voltmeter skills have greatly increase as a result of this frustrating yet worthwhile learning experience. I THANK ALL THAT HAVE CONTRIBUTED!

[TRP]

great job at debugging the issue! I have so many fears about getting my ljet back up and running when I get the motor back from the builder. (IMG:style_emoticons/default/blink.gif)

[Rob-O]

The head sensor isn’t terribly difficult. Take off the runner and get a proper socket (or modify your own) to get the old sensor out and the new sensor in. Don’t overtighten that sensor! Repairing stripped threads is not a fun job.

[nmkimosabe]

The head sensor isn’t terribly difficult. Take off the runner and get a proper socket (or modify your own) to get the old sensor out and the new sensor in. Don’t overtighten that sensor! Repairing stripped threads is not a fun job.

I assume the injectors will have to be removed too. Will I need new gaskets for the runners and new seals for the injectors? Are those rubber/cloth sleeves on the runners hard to remove? Appreciate your feedback.

[Rob-O]

For gaskets it depends. The injectors could be left in the runner and just the fuel lines could be pulled off each end of the injector rail. For the runners there should be a phenolic spacer about 7mm thick or so between the runner and the head. Inspect it and replace if needed. I’ve heard different accounts on if there are paper gaskets between the head and the spacer and the spacer runner. If there are no gaskets there I’d purchase some or seal that with your choice of liquid gasket/sealant. Personally I think the traditional fiber gaskets make more sense so there isn’t the possibility that excess sealer squeezes into the intake area. The rubber boots from the runner to the plenum could be reused if inspected and they’re okay.

[Geezer914]

If it's running like crap, it may be a vacuum leak. Do a smoke test.

[nmkimosabe]

Can someone please tell me if I should use a crush ring on the new CHT sensor? The one I removed had one but I'm getting conflicting information as to whether one goes on or not. Thanks a bunch, as I'm waiting to install it.

[fiacra]

Can someone please tell me if I should use a crush ring on the new CHT sensor? The one I removed had one but I'm getting conflicting information as to whether one goes on or not. Thanks a bunch, as I'm waiting to install it.

Here's pics of a Bosch NOS CHT sensor from my parts stockpile. It clearly has a copper crush washer on it. New, never installed, part #0280130012. Hope that helps.

[nmkimosabe]

Can someone please tell me if I should use a crush ring on the new CHT sensor? The one I removed had one but I'm getting conflicting information as to whether one goes on or not. Thanks a bunch, as I'm waiting to install it.

Here's pics of a Bosch NOS CHT sensor from my parts stockpile. It clearly has a copper crush washer on it. New, never installed, part #0280130012. Hope that helps.

Thanks for the email. Any interest in selling? :-)

[nmkimosabe]

Can someone please tell me if I should use a crush ring on the new CHT sensor? The one I removed had one but I'm getting conflicting information as to whether one goes on or not. Thanks a bunch, as I'm waiting to install it.

Here's pics of a Bosch NOS CHT sensor from my parts stockpile. It clearly has a copper crush washer on it. New, never installed, part #0280130012. Hope that helps.

@fiacra
Any interest in selling this sensor? Thanks.

[fiacra]

@nmkimosabe

That one is not for sale. Original Bosch NOS sensors are almost impossible to find. However, 914Rubber (and a few other vendors) sells an aftermarket replacement:

https://914rubber.com/cylinder-head-temperature-sensor

Also, not sure if this is the correct one for your L-Jet system. I see conflicting information on-line. Is yours original? Look for the part number on the flat surface of the head of the CHT sensor. If it is 0280130003 (listed as being for a 1.7) then I do have an NOS Bosch CHT sensor that I would be willing to sell (picture below). If it is 0280130012 I also have a Bosch CHT sensor that was sold to me as NOS (but shows wear that is consistent with it having been installed) that I would be willing to sell. However that one is in a box of NOS parts that I lent to a friend in case he needed them while troubleshooting his car and I won't get that back until 4/25 when we meet up at the Red Barn. That's probably too long for you to wait. Although preferable to get a good Bosch sensor the 914Rubber part should be fine. I used one on a 1979 Super Beetle with L-Jet and it worked without any problem.

[nmkimosabe]

@fiacra
My part # appears to be 032.096.041 which according to AI is an older part # but now is 311.906.041. I did buy the sensor from 914 rubber last week, but it came without a crush washer and Dr.914 told me to use a crush washer and the part I took off had one too. Right now, I'm trying to just find a crush washer so I can install the CHT and get my car back together. It's little things like this that drive you crazy with old cars! Also, what gap do you use for your spark plugs as I'm replacing mine as they are pretty fouled. I plan to use 0.6 /0.024 but let me know what you think. Best to you on Sunday.

[Superhawk996]

[fiacra]

@fiacra
My part # appears to be 032.096.041 which according to AI is an older part # but now is 311.906.041. I did buy the sensor from 914 rubber last week, but it came without a crush washer and Dr.914 told me to use a crush washer and the part I took off had one too. Right now, I'm trying to just find a crush washer so I can install the CHT and get my car back together. It's little things like this that drive you crazy with old cars! Also, what gap do you use for your spark plugs as I'm replacing mine as they are pretty fouled. I plan to use 0.6 /0.024 but let me know what you think. Best to you on Sunday.

That is the correct gap. Should be an easily available copper washer. My local hardware store (not Home Depot/Lowes, etc.) has a good selection. Bring the sensor to a good hardware or auto parts store and they should have it. Superhawk already pointed out you can get an assortment from HF. You can anneal and use the old washer if you wish (heat to red hot, rapid cool in water), but I always try to use a new one. You can order them from Belmetric:

https://belmetric.com/washers/solid-crush-gaskets/

I have some extras so if you are desperate then PM me your address and I'll put one in the mail tomorrow.

[Rob-O]

They’re available from Porsche again, I believe.

[nmkimosabe]

@fiacra
My part # appears to be 032.096.041 which according to AI is an older part # but now is 311.906.041. I did buy the sensor from 914 rubber last week, but it came without a crush washer and Dr.914 told me to use a crush washer and the part I took off had one too. Right now, I'm trying to just find a crush washer so I can install the CHT and get my car back together. It's little things like this that drive you crazy with old cars! Also, what gap do you use for your spark plugs as I'm replacing mine as they are pretty fouled. I plan to use 0.6 /0.024 but let me know what you think. Best to you on Sunday.

That is the correct gap. Should be an easily available copper washer. My local hardware store (not Home Depot/Lowes, etc.) has a good selection. Bring the sensor to a good hardware or auto parts store and they should have it. Superhawk already pointed out you can get an assortment from HF. You can anneal and use the old washer if you wish (heat to red hot, rapid cool in water), but I always try to use a new one. You can order them from Belmetric:

I just got back from the local hardware store and found one slightly larger on the inside diameter. Will this be a problem for the sensor to properly function?

https://belmetric.com/washers/solid-crush-gaskets/

I have some extras so if you are desperate then PM me your address and I'll put one in the mail tomorrow.