Wagon progress update…getting closer!

[Pepperbilly]

A HUGE DAY! All the hard work, long hours, and anticipation resulted in success. First I cranked the engine without the ECU connected to build oil pressure. Connected everything up and started her. Took a fair amount of cranking to build fuel pressure and then she fired off. After a few minutes all the smoke cleared. Shut her back down and checked fot leaks or anything abnormal. All good!

Started her up again and adjusted all the basics. After a few minutes she settled into a nice idle…sounds so good! I also tried adjusting the knob on the computer and the idle responded to each click like I haver never seen before…thats a good thing in my book! Went ahead and topped off the automatic trans. Shifted through all the gears and it seemed to respond normally. Shut her back down and went on to finish air intake and fresh air hoses for a couple of hours.

After that started her up again with no problem. Only now my idle was not smooth, not like before. It was like it was dropping injectors…hmmm. I had a feeling about the head temp sensor…it’s an old one. Got the ohm meter out and found OPEN circuit. Looks like I need to try another sensor.

Enough for today. I feel really lucky so far. I am working with very old fuel injection components and a rebuilt original fuel pump. There are so many things that can be wrong. This is all part of the journey. This is to be expected. I take it as a big victory for now.

Bill

[Lars S]

[KTPhil]

Yes, an open reads as infinite resistance, so the ECU richens it up and this kills the engine.

Just be sure to disconnect it to measure its resistance.
It might be just a cleaning of threads and tightening down.
Or a broken wire inside.

[vwfye]

Congradulations!
_________________
64 No'back Speedster "Pearl"
1980s Sand Dragster "The Plunger"
LME "Little Giant Killer 3"

[Pepperbilly]

The engine started right up today but the idle is not smooth and the exhaust smells pretty rich. Took multiple readings of the head temp sensor and I was getting crazy ohm results all over the place! Some open, some correct, and even these negative readings. Hmmm... Pulled the sensor and found the sealing washer all screwed up. I dont even think the sensor was fully seated.

In the photo mine is on the left. I compared it to an old broken one I had which is on the right. The old one has what looks like a proper captured copper washer...it will not fall off. I think mine is all wrong. The washer is not captured and it is not copper. Gonna need a new sensor and need to match it to my computer? What do you guys think?

Bill

[raygreenwood]

[Lars S]

[Pepperbilly]

[Lars S]

Yes Bill you will for sure get wrong and funny values if you measure the sensor resistance with the sensor still connected to the harness.
Tecnically you are measuring the sensor and the sensor port in the ECU in parallell to ground...and in addition to that, if you measure with the engine running the ECU will put a voltage at the sensor wich fools the meters own restistance measuring voltage.

Thats why one can not measure the connected sensor resistance.

_Lars S
_________________
Porsche 914 -72, Bahia Red daily driver
VW411 2-d -70, White, sold
VW412 4-d, -73, Gold Metallic, daily driver
Suzuki T500, -69, Candy Gold, sold
Suzuki K50, -77, Black, daily driver
BMW R69S -69, White, sold
Husqvarna 118cc, -47, Black, Sold

[Pepperbilly]

[Pepperbilly]

Have not attempted a road test yet because I am still working the running problems out. No half shafts or brakes installed anyway.

The engine does some things well but not everything like I expected right away LOL. Here we go...
Installed a different head temp sensor with the proper washer. Got it to seat well. The cold starting is really immediate, like I remember it when it was virtually a new car. The idle is good as it warms up and the AAR is reacting correctly, but the exhaust smells pretty rich. After maybe 8 to 10 minutes of warmup the idle is very good but still very rich. I can even adjust the computer (ECU) knob and get very good responses for the idle. The big problem is the throttle response. The response is immediate but in that transition there is an unbalanced shake or shudder to about 2500 rpms, like injectors not firing. After about 2500 rpms the engine smooths out and feels normal. No amount of adjusting helped. At idle I do have a really strong response from the idle screw, so it appears to be ok. (I can actually stall the engine when adjusting all the way closed...great response!). I pulled the spark plugs to get a reading. #1 Normal #2 sooty black #3 sooty black #4 normal. Enough for tonite.

This morning another day. Time to check basics, cold engine:

Checked valve adjustment and all good at .006"
Head sensor at 3,700 ohms 51 degrees ambient air temp.
Start engine:
Fuel pressure is 28 to 29 psi and rock steady at all rpms
Timing at factory suggested 27 BTDC AT 3500 rpms both hoses off.
48 degrees dwell and very steady
Alternator charging at 13.96 volts
WR7CC Bosch plugs at .032.

I let it run for about 20 minutes and it was running the same as described above, really rich. Pulled the plugs again and same readings as above.
Any ideas where to go from here?

Bill

[Lars S]

Bill, as for the rich running have you checked the MPS for holding vaccum? Can be done with your mouth,.

As for the shudder when reving up, have you tried to run the engine without the throttle switch plugged in? It is amazing how well the engine can run without the switch plugged in. It will be a bit more hesitating when reving up since it lacks the extra injector pulses ("accelerator pump function") but if it stops shuddering the error might wery well be in the switch, dirty/worn contact trace, fingers etc...


///Lars S
_________________
Porsche 914 -72, Bahia Red daily driver
VW411 2-d -70, White, sold
VW412 4-d, -73, Gold Metallic, daily driver
Suzuki T500, -69, Candy Gold, sold
Suzuki K50, -77, Black, daily driver
BMW R69S -69, White, sold
Husqvarna 118cc, -47, Black, Sold

[KTPhil]

[raygreenwood]

A few things to think about or try:

Lars Said:

[Pepperbilly]

Ray and Lars S,

First of all I need to pickup a hand held vacuum pump. About time I had one. I gag too easily trying to hold vacuum with my mouth . I did pinch off the MPS line while running and the engine wanted to stall. So it may be ok but need better testing here.
Disconnecting the Throttle Switch made no difference…still the off idle shudder.

I am running the Duralast ignition wires with the W. German connectors that I thought were good. Yes, I am running Resistor plugs because that is what a local VW shop had. I can change that. I do have the Bosch points with same brand cap and rotor and the original stock coil.

Today was a jekyll and hyde running situation. I saw alot of crazy running conditions. Starting cold was great and quick. Off the bat though the idle was lumpy. I pinched off the AAR hose and the idle improved alot…so I let it run thru it’s warm up period like this. After that the idle settled in nicely and was very smooth. I could dial it in at 950 to 1000 rpms and even the shuddering when tipping the throttle went away! It was a short lived situation though. The idle became erratic as the engine temp increased and very uneven and tried to stall out. I never got it to run smoothly again.
I again checked Head Temp Sensor, engine off, warm and disconnected. INTERESTING READINGS. Most of the readings were around 150 to 160 ohms but a couple of times readings shot up to 3,000 ohms! Wow! I dont trust this old sensor which was a spare in my stash. New one on the way for sure.

I’ll methodically test every component to the best of my abilities. It’s a slow process. Yes, my problem could be the fuel injection harness. It is the original. But I thought before I replace the harness I would make a damn concerted effort with the stuff I have. I’m a doggone stubborn kraut

Bill

[raygreenwood]

I have a long detailed reply that I actually started yesterday. I saved that and replied to some of the new answers today.

I will post the long detailed the reply tomorrow. It gets into the MPS relationship and the knob on the EcU and the idle air bypass.

Ray

[Pepperbilly]

I went ahead and made more checks today. Warm compression revealed good results for a newly rebuilt engine with only under an hour of running time. Each cylinder cranked out 90 psi on the First stroke then second stroke went to 120 psi…all the same. At least it shows even.

I plugged off the vacuum line to the trans modulator valve. I also removed the cold start injector from the plenum but left the fuel lines on. I sealed the plenum holes to prevent any vacuum leaks. Ran the engine with really the same results as before. So no change. The cold start injector does not leak. Not even a drip so that is good news.

The head temp sensor showed good readings today. I pulled the plugs again and found the same results. 1 and 4 look pretty normal. 2 and 3 are all black and sooty again. It is a very dry soot, not wet at all. I thought if I have a rich condition they would be wet? Included a closeup photo.

I also pulled the distributor to check the trigger points. The plate looked normal but it was oily. Cleaned that with electrical spray. What tests on the bench can I make on the trigger points? That is as far as I went today.

Bill

[Pepperbilly]

Samba friends,

Ready to get back to it. Was gone for a month with my wife trailering it thru BC Canada, the Yukon, and Alaska. What a wonderful trip! If you ever want to get away from it all and see lots of wildlife, beautiful mountains, and NO traffic, this is for you.

First thing I did when we got back is purchase a nice Mityvac vacuum pump set. Can’t be without this when trying to diagnose fuel injection problems.
I first tested the Manifold pressure sensor. Bingo, found it not holding any vacuum at all… ruptured diaphram. I went ahead and tested my original pressure sensor I had stored away and it held pressure. Not sure why I replaced it back in the ‘90s, but I had.

I followed Brad Anders D-Jet Pages. What a wealth of D-Jet information. Now I know for sure that first pressure sensor is no good. My original sensor that I had stored away held vacuum for a 5 minute test but did slowly bleed down to 7 Hg. So it has a slow leak. I did an ohm test on terminals 7 and 15 and 8 and 10 on the sensor and those figures were spot on.

This could possibly explain the running condition of the engine. At the very first few minutes it ran perfectly…I was able to dial everything in for a nice idle. But after about a half an hour the engine displayed very erratic behavior and was never good from that point on. I am thinking the manifold pressure sensor’s diaphram then ruptured.

I have not run the engine with my original pressure sensor yet. I am waiting for my non resistor plugs and new head temp. sensor to arrive. May be a few days before I can run the engine again… hate the wait!

Bill

[raygreenwood]

Just do not get rid of the one with the ruptured diphragm. It could also be the o-ring but you can buy new diaphragm kits now.

I am as we speak...kind of...working on a "how to" to adjust the MPS for KTPhil...and the MPS SHOULD be adjusted to run better...because nothing these days on these engines 50 years down the line including the gasoline....is the same as it was. All of it affects vacuum signature.

I am in the process of sorting out a "black screen of death" failure on my laptop from yesterday.

Ray

[Pepperbilly]

Ray,

Don't worry. I keep everything down to tattered old carpeting!

Bill