I Need Help with L-Jet / AFC Fuel Injection Topic

Randy in Maine · Posted: Sat May 12, 2012 4:37 pm Post subject:

Troubleshoot the double relay would be my suggestion....find where the voltage come in and does not come out.

http://www.itinerant-air-cooled.com/viewtopic.php?f=50&t=5459

MadFrankie · Posted: Sun May 13, 2012 12:39 am Post subject:

Hi,

Thanks, tried all that already and it all seems fine. Voltage in and out where expected.

Think I've narrowed it down the either the wire from replay to pump, the pump itself or connections between the two. Can I shove a test light on the power wire going into the pump to test that wire?

Randy in Maine · Posted: Sun May 13, 2012 6:57 am Post subject:

Sure. Report back your findings.

pgtips · Posted: Sun May 13, 2012 10:32 am Post subject:

a test light connected at each end of the wire might not show much as you need power, i.e a test light on each end of the earth for example might not show much depending what sort of test light you have

Do you have a continuity/voltmeter (they are quite cheap and well worth owning one), in fact i'd say its essential as wires get brittle and crack with age.

You are looking for something called an open circuit which basically means the two ends don't join up.

good for getting it narrowed down, you have almost cracked it.

TGOT · Posted: Mon May 21, 2012 4:38 pm Post subject:

Im working on a 81 vanagon. Its a california fi model but has a points distributor put in. And I am quite stumped with this one. The 3-4 cylinders are not firing at all. That side of the engine doesnt even heat up the exhaust pipe. 1 and 2 are running seemingly well. The van idles ok but is obviously underpowered and drives poorly.

I have 100% verified ignition. I've swapped plugs, wires, points, condensors etc. It has spark. The firing order is correct. However when you pull the wire off the plug on either or both of the 3-4 cylinders it does not affect the idle. If you pull the plugs on the 1-2 side idle speed suffers.

The 3-4 injectors getting electrical signals. Pulled the injectors off of the 3-4 side and they both squirt appropriately.

Compression is as follows after checking the valve adjustment:
#1 - 105
#2 - 105
#3 - 80
#4 - 100

Obviously not ideal but it should work right?

So I was unable to make the 3-4 bank fire until by chance I started it with the AFM disconnected. The problem appeared to swap sides. The idle was longer affected by pulling the 1-2 plugs and the 3-4 side was now firing. Pulling the 3-4 plugs affected the idle and exhaust started to heat up.

Plugged the AFM back in and it swapped banks back. Unplug and restart it swaps again. Thinking I found an electrical fault I run through the harness checking continuity between the ecu plug and the injector plugs as well as seeing if any of the AFM wires are shorting to the injector wires and everything is fine. Since the series resistors are in the ECU on this model I swapped out the ECU also from a california vanagon and it does not solve the problem.

I think I have an intermittent problem in the harness but I do not have a spare one to swap in and I have not been able to verify it. I went through the AFC manual and came up with nothing wiggeling the harness attempting to get it to malfunction. Nothing I do allows all 4 to fire at the same time.

Is there any other test I can do to see if the harness is at fault?
Is there anything else I might be missing?
Do you think it is the harness?
How the heck does the AFM plug cause such a problem but not show up testing the wiring?
_________________
71 Super Sold
76 Westy Sold
99 Beetle TDI Sold
81 Rabbit Diesel Sold
79 Sunroof Bus Sold

I miss all of them but I still have a

76 Adventurewagen Hightop FI

SGKent · Posted: Mon May 21, 2012 4:51 pm Post subject:

On a 1979 - 1982 California the wiring is different than other bays so you need to look here towards the end on page 42. 1 & 2 share a connector. 3 is on its own and 4 is on its own.

http://www.thesamba.com/vw/archives/manuals/afc_fi...Manual.pdf
_________________
Steve aka Merlin the Wrench

formerly Steve's Racing and Engine Blueprinting. Wrenching since 1967.

bdamico on GF wrote

TGOT · Posted: Mon May 21, 2012 5:35 pm Post subject:

I need to see if the wires from the double relay to the injectors are some how compromised, or possibly the double relay connector. I didn't realize how the injectors were powered directly from the double relay.

Although I was getting a steady 12ish volts from the injector connectors so it would seem they are not the issue (unless the there is an unfound break in the harness).

I need to get back out there with my volt meter and make sure I didnt confuse the federal wiring and the 79+ california when I was doing my checks.

Thanks SGKent, let you know how it goes in a few hours.
_________________
71 Super Sold
76 Westy Sold
99 Beetle TDI Sold
81 Rabbit Diesel Sold
79 Sunroof Bus Sold

I miss all of them but I still have a

76 Adventurewagen Hightop FI

tootype2crazy · Posted: Wed May 23, 2012 10:44 am Post subject: AAR hose

Hi folks, I've been running FI on my 2.0L since the winter and it is great. The only problem I'm having is upon starting up the idle will go up and down and up and down for a couple minutes. Once it warms up it is fine. I think I've narrowed it down to the hose connecting the AAR to the throttle body. The one I have on there is just a piece of oil hose from the FLAPS. I think what is happening is the vacuum is pinching it and then releasing over and over during the warm up causing the idle to surge up and down. I don't have the original molded hose. Any suggestions on a piece of hose to put in there that won't pinch? Thanks in advance.
_________________
1979 Sunroof Deluxe Bus with the sunroof and its parts sitting in my closet and a westy pop-top to cover the hole. Lower 1/5 of the body is gone from rust. Freshly rebuilt 2.0 with Federal FI and newly restored heat exchangers.

Randy in Maine · Posted: Wed May 23, 2012 12:17 pm Post subject:

There should be no connection from the AAR to the throttle body.

Image may have been reduced in size. Click image to view fullscreen.

If you are referring to "F" or "G" here....I think I got my 13mm and 14mm hose from German Supply....

Image may have been reduced in size. Click image to view fullscreen.

tootype2crazy · Posted: Wed May 23, 2012 12:42 pm Post subject:

Woops i meant the plenum. I only got a few hours sleep last night and so I'm only firing on 2 cylinders, forgive me please. It would be hose G in the above pic.
_________________
1979 Sunroof Deluxe Bus with the sunroof and its parts sitting in my closet and a westy pop-top to cover the hole. Lower 1/5 of the body is gone from rust. Freshly rebuilt 2.0 with Federal FI and newly restored heat exchangers.

Randy in Maine · Posted: Wed May 23, 2012 12:44 pm Post subject:

While you are in there, look at the 90º boot with the steel sleeve in it at the AAR-S Boot line to see if is is split.

tootype2crazy · Posted: Wed May 23, 2012 12:45 pm Post subject:

Yeah I just put the whole thing together a few months ago and it was fine then, but I will check it out though.
_________________
1979 Sunroof Deluxe Bus with the sunroof and its parts sitting in my closet and a westy pop-top to cover the hole. Lower 1/5 of the body is gone from rust. Freshly rebuilt 2.0 with Federal FI and newly restored heat exchangers.

tootype2crazy · Posted: Wed May 23, 2012 6:33 pm Post subject:

Well I figured it out on my own. I cut a 1/2" piece off of the hard plastic brake booster tube, labeled A above, and slipped it inside of the middle of the offending AAR to plenum makeshift hose. Now the middle of the hose can no longer collapse under vacuum pressure and the idle doesn't surge anymore. Thanks everyone for all the copious help.
_________________
1979 Sunroof Deluxe Bus with the sunroof and its parts sitting in my closet and a westy pop-top to cover the hole. Lower 1/5 of the body is gone from rust. Freshly rebuilt 2.0 with Federal FI and newly restored heat exchangers.

Randy in Maine · Posted: Wed May 23, 2012 7:14 pm Post subject:

A spring will also work.

Sawspa · Samba Member Joined: May 12, 2012 Posts: 55

Hi all,
I've read through this thread and am having some similar problems. I have to pick up a fuel pressure gauge tonight, but I also might have some vacuum problems. A few of you posted that it is possible to use a propane torch( unlit of course ) to find leaks. It sounds kinda sketchy. Can u give me any insure to this? I assume the motor picks up immediately. Has anyone ever had the propane ignite in the motor bay? I have tested for power at the fuel pump and got 11v. It's possible I wasn't getting a good connection though. Almost forgot, I have a 78 westy with a pertronix 2.0L

Sawspa · Samba Member Joined: May 12, 2012 Posts: 55

Also would a corroded transmission ground strap factor into the symptoms somehow?

Randy in Maine · Posted: Fri May 25, 2012 11:54 am Post subject:

Sawspa · Samba Member Joined: May 12, 2012 Posts: 55

Hooked up a vacuum gauge. I was reading steady idle on a cold engine at 39. When I would rev the motor it would go to just above 50. I can't find what it should be in the Bentley or here, maybe I'm overlooking something. Are my pressures acceptable. I'm moving on to fuel pressure next. Sorry I don't want to hijack the thread, should I start another?

Randy in Maine · Posted: Fri May 25, 2012 3:55 pm Post subject:

Where is the gauge hooked up? Is that in inches of Hg?

TGOT · Posted: Fri May 25, 2012 10:35 pm Post subject:

An update to my issue with the 81 Vanagon with Cali FI:

I have determined whatever is going on is affected by the mixture and probably not an electrical fault like I previously was thinking. Last time I was tinkering I realized it wasn't directly the AFM being disconnected that caused the apparent cylinder bank swapping. If you richen the mixture by holding the AFM arm open with the throttle closed the 3-4 sides starts to do work but the 1-2 side appear to stop. Lean it out the same way and it goes back. Disconnecting the AFM would make it run rich right?

I attempted to see if I could find a balance and even it out but was unsuccessful. I was waiting until I could try an unmolested AFM and see what happened before I posted. I suspect not only the set screw on the AFM arm was touched at some point but also the spring tension. i got my chance tonight and it did not solve the problems but it seemed to make the engine run better. Throttle response seemed better. This engine is a can of worms so who knows.

I dont believe the mixture is the root cause, but I wanted to rule out an unknown variable before I went further. I also have no idea how the combustion is so unbalanced.

At this point I cannot find any fault in the FI or ignition systems. The results of the compression test were not stellar but it should still run decently. I am at a loss. Like usual. Strange FI problems (or other issues that seem FI related) find me.

After talking with the owner and asking the right questions we determined that this has been an intermittent problem. Some days it will be perfectly fine and go up hills, some days no power at all. He feels it has also progressively gotten worse. The frequency of occurring, the duration, and the severity of the power loss. Before I was called he was driving South on I-5 from Portland and had made it as far as Grants Pass when he could no longer make it up a hill. He pulled the plug wires to see if the idle speed would be affected and found that 3-4 had no bearing. He then pulled the plug on #4 and it was cold, even though he had just been on a sustained highway run.

Any thoughts?
_________________
71 Super Sold
76 Westy Sold
99 Beetle TDI Sold
81 Rabbit Diesel Sold
79 Sunroof Bus Sold

I miss all of them but I still have a

76 Adventurewagen Hightop FI

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I Need Help with L-Jet / AFC Fuel Injection Topic
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