Update on my post about the BENT AFM. FYI prior to the bending, the car was running great as my daily driver.

I now have a 75 7-pin AFM found on San Diego Craigslist and shipped to TN. I have verified all the proper ohm readings on the connector, fuel pump contacts especially. The flap has full range of motion and the PCB track looks similar to the AFM I removed.

The replacement unit is installed as received and the car will only run (and poorly I may add) if I mash the accel pedal to get about 3000 rpms.

I had planned to go thru the Itinerant ( http://www.itinerant-air-cooled.com/viewtopic.php?t=7761)process today, but I can't get it to idle. I only got as far as setting the MIXTURE screw to the 4-1/2 turn spot.

I do have the new intake elbow on and have tight vacuum line fittings. No vacuum lines appear to be a problem. Triple checking now.

Just tinkering around, I opened the idle screw on the TB, but that did not help.

What do you think? What is next?

Clark

Open the relay board and look at the 4 spade connector in the lower left corner. Ground the spade in the upper left corner. It's designated III in the diagram.
When you key the ignition, the fuel pump will run without having to rely on the dual relay.
If the engine runs then you have a connection issue at the dual relay

No change at all. It will fire up quickly, But takes some accel pedal pumping to get the revs up, then is controlled with the pedal at 2000- 3000.

Remove my foot and drops to a sputter and I turn the key off.

Disconnect the fuel line and check for flow - carefully....A permanent fuel pressure gauge mounted in line is a great diagnostic tool.

I have an in-line fuel press guage. Plenty of pressure.
Here is a shot of the residual pressure after my current shut down. small, fuzzy photo, but it is @ 35 psi.

Click to view attachment

Not knowing anything about this afm, could the spring tension be tight? The seller said it came out of a 75 914. It seems to have a delayed reaction to the pedal.

I gotta get a helper to crank while i watch.

Before adjusting the air flow meter, you should double check the basics. Start with making sure that your valve lash is perfect and not too tight, especially the intake valves. This could of been the reason to why the car backfired.

Next, do a compression test on each cylinder. Then post some pictures of the spark plugs. After that, get the car started, manipulate the throttle linkage so that the car stays running. Then remove one fuel injector connector and make sure you hear the engine stumble. Do this for each injector.

It would be nice to verify timing, but this may be hard to do if your car doesn't want to run anything less than 3k rpm.

Next, I would assume your car is inside a warm garage? If so, remove the hoses leading to the aux air valve, temporarily cap at the rubber S boot and cap at the plenum. Do the same for the decel valve. These two items are not critical for the engine to run and would be two less variables to worry about.

Then, read that manual about adjusting the AFM. You really need to borrow your friends air/fuel ratio gauge meter thing to adjust it correctly.

And : Be sure the resistor pack does not have a broken wire; and check the harness ground is attached tot he spade on the motor

Thanks gentlemen. Gives me plenty of things to check. Man do i hate checking the valves. I'll add the results as I get them.

I am curious about the PCB differences. They don't look different but the have different part #s on them. The current one has 7805 then 1 288 310 021.

The former one has 9006 then 1 288 310 021. I wondered if they could send different signals.

To quote my father "What was the last thing you F_cked with!"

The description of your problem reeks of false air (air that does not go through the air flow meter on the way into the engine).

Check all the hosts, especially the ones from the AFM to the throttle body. You probably knocked off a line somewhere. No L-Jet car ever built will run with an open hole downstream of the air flow meter. It leans out sooo far that there is just not enough fuel to run.

I would bet on the hose to the aux air regulator or the decel valve.

I will go thru all the vac hoses once again this evening. (procrastinate before I get to Tim's list)

In post 5 above I added a photo of my fuel press gauge. You can see the DECEL vac line folded, plugged and wire tied. I have not had a DECEL valve in operation in 3 years... since the beginning.

I hope you are correct about a vac leak, Tim has been saying the same thing. If there is one, it is not very obvious. I guess I should just remove everything and re-seat the hoses.

A few months back, I seem to remember accidently not replacing the DECEL hose from the air distributor for some reason.... and the car did act very similar to the way it is acting now.

Thanks to all for your input.

Check to make sure the hose from the AFM to the throttle body is still connected on the throttle body end. If it gets disconnected accidentally, it usually opens up a gap on the bottom where you can't see it.

I paid for a factory L-Jet class about 28 years ago. That is probably the most useful factory training I ever got.

Unless you can see that gauge when sitting in the drivers seat it isn't worth a pinch of dog poo.
Did you have the tank out, a pinched/kinked line at the tank will drive you bat shit.

Oh I disagree on the gauge.... Anytime I have issues, someone always asks about the fuel pressure. And it would take time to install one, every time someone asks, or I want to know. Really it is for troubleshooting.

The tank has not been out since 2012. But being a 75 the pump is in the front and a couple months ago I pulled the pump and the filter out from under the tank to verify operation and kink-less hoses. For now it is just lying in the trunk, lazy-ness on my part. So I believe the hoses are still not kinked.

BTW: I had to work on the Volvo last night and tonight I am going to the Ryman to see Robert Earl Keen So the 914 has taken a back seat 'til Thurs or Fri. More to come soon tho. Not switching to carbs just yet.

The AFM could be bad or maladjusted as well. Fuel Injection Corp rebuilds them. I've used a bunch of them. It's great peace-of-mind to know it's fresh and calibrated correctly.

So when you install them.... the car starts right up?

I wondered about the condition of this one, being used and previously rebuilt by out-of-business PYTHON.

Is there any way to further test the operation? Physically the flap opens smoothly, the track has marks, but is not worn thru, neither was my BENT one. I have done the ohms tests on all the connections, verified and cleaned up the FP contacts and the swivel contact on top of the swiper, what else is there to verify?

I would think I would get varying readings as the arm moves (flap opens), right. I have not done that yet, but don't know the spec per degree of motion.

I saw a test on the samba about a 60 gram weight on the flapper, have not read completely thru that yet. At this point, I am praying for a vacuum leak.

I hate it when my paying job gets in the way of fixing this car!!!

Perhaps you could borrow a known "good" AFM and swap it in- that will tell you more?

Yup, plugged in and fired up.

I don't know of any reliable tests, but I take a much more quantitative approach then most. If I were setting up to test an AFM, I would want to graph airflow vs. signal output across a range. Then compare to a known good baseline. But in shop time that's $1,000,000. So just replacing it with a rebuilt and calibrated unit, to me, is a 'shortcut'.

You may have a vacuum leak, and the AFM may be fine - So I'm not suggesting a new AFM will cure your issue. But just sharing my perspective that I hate dealing with unknowns and I find it worthwhile to simply pay a little extra and at least know what I'm starting with.

I have been offered one to test.... I hate the thought of BENDING someone else's $300 part.

I will go thru all the suggestions here by the weekend, I hope. They should remove all other doubt. Then check and see if the offer to loan is still good. And then I may have to breakout the checkbook on a freshly re-built, known good one.

Thanks again.

I have a factory calibration tool for the AFM in my toolbox.

It is not easy to use, and it requires patience. But it can be done.

I also have about 30 old AFMs. Some are bent, some are completely scrap and some work. The factory L-jet tester I have only partially works because it got immersed in water at some time in the past.

Simpler to use a volt meter.

BACK TO 914 TROUBLESHOOTING: I finally carved out some time to dig into this problem. Before I got to Tim's list of goodies, I decided to dive into vacuum leak detection.

I felt like my hoses and intake boot were tight. Everything was new. I checked a few other hoses.

DECEL: As stated earlier, the decel has been removed. I capped and folded the large hose securely. However, it easily slipped off of the connector on the Air Distribution box.

I have never been positive that #3 intake was perfect. The pipes just don't line up. #3 is on the left below. They are also too far apart to use the pretty cloth hose. I bought a radiator hose and cut it. Might have still been too short. Notice the curve. When mounted one edge was lifted up.

Click to view attachment

Click to view attachment

3/4 side INTAKE: Again as I removed these hoses, they slide off fairly easily. During this tedious removal, I noticed that the phenolic block was cracked in between the ports. Another find.... The nuts holding the intake to the head required very little effort to break the torque. Not loose but just better than "hand tight". The paper on the phenolic was brittle, cracked and delaminating from the block.

Click to view attachment

During removal, I realized that maybe I did some OVER INSTALLING of the seal kit. Probably a bad time to ask, but does anyone use the metal seals with the phenolic block on FI installs?

About 30,000 miles on all this. I plan on purchasing new hoses and intake seals today. I also plan on NOT using metal seals under and over the phenolic block.

Please chime in, could the cracked block and easily removable (not snug) hoses be the trouble?

I have never seen those metal gaskets used before?

Could they be for Carb intakes?

Clark -
Offer is still good to borrow mine, just keep in mind it is in the same uh, "patina'd" condition as my throttle body. Just let me know.

Just the phenolic block. The metal seals are indeed for carb motors (busses).

HEY HEY, I am back. Spent the last 2 weeks working on a VOLVO. Damn I hate that car.

Ok, I have gone thru my books... Haynes, Climer and Tom Wilson looking for intake runner torque settings.

Haynes said "4.35 lb f ft" on page 39. what the hell is that? My wrench is not gonna read that low if it is FT-LB.

Tom Wilson said 14 ft-lb on page 154 but that was in a table for type 1-3. just under that table are the torque settings for the type 4, but there is no mention of the intake manifold in the Tiv table.

Tom (page 153) also says "Use new gaskets on both sides, then lay the spacers on their studs. Using gasket sealer doesn't hurt, but isn't mandatory."

Is the gasket and the spacer the same? Climer has a nice exploded view drawing. #2 is the spacer, but there are no gaskets included. would both sides mean "of the engine" or both sides "of the spacer"?

Anyone use gasket sealer here? and where? on the head, on the top of the spacer, or both sides of the spacer?

What torque setting for #4?

Click to view attachment

The spacer should have paper on both sides of it. I remember the part coming with those already glued to it.

Torque for an M6 bolt into aluminum is on the order of 10 lb-ft. Use anything between 5 and 10, or just get it "a bit tight."

--DD

These are Victor-Rienz. Looks like paper on each side. Tuff to tell. The edges are shiny and i see what looks like glue on the edge. the mating surfaces are not shiny, probably paper.

On the torque, i figured i'd compare intake to exhaust, which would be a bolt. The intake is a nut on a stud. Seems to me that setup might handle more since the stud is not being torqued.

May be opposite tho.

Morning

So I've been fighting with a very similar problem with my L-Jet. For months....

However, I had just installed my L-Jet after removing the single carb setup. Almost everything was checked before being installed on the car (more on that later) or new (i.e. vacuum hoses, dual relay, TB rebuilt, etc.). I timed the car (multiple times) and installed a Pertronix.

I checked and rechecked everything, including the CHT. The resistance readings on the CHT were very close to expect4ed values published on the 'net (I checked it installed on the car, so it was difficult to get the readings at the exact temperatures that are called out for the CHT).

My symptoms were similar to yours, although not exactly the same. My car idled poorly and ran poorly. In checking the CHT, if I unplugged it from the harness while the car was running, the engine died. It started right up again when I plugged the CHT back in. I thought vacuum leak as well so put clamps around any of the new hoses that weren't on their respective parts as tight as I thought they should be. This included anything downstream of the AFM. As in, the hookup of the AAV to the plenum and the line that runs from the large rubber elbow to the oil fill housing. The small metal sleeve on the rubber elbow between the AFM and TB was pulled out and I could never get it back in. But even when I pulled the hose off the elbow and plugged the hole I still had poor running/driving. Last week I even purchased a new elbow from 914Rubber (it is awesome, BTW). Installing it didn't help. I also had purchased a new CHT from 914Rubber. I tried to pull the old CHT out of the head and had trouble doing that. It unscrewed about a turn and a half and then stops. But then I got the bright idea that the CHT is using the head as a ground and that if I grounded the new CHT and hooked it up to the FI harness, it should be getting the same reading as if it was hooked up to the engine when the engine is cold. I did that little experiment. Car started right up and idea was rock steady at 1000 rpm. I adjusted down to 850 or so. Took it for a very short drive and the car runs 90% better. Didn't want to go too far with the CHT just sitting in the engine bay getting erroneous temperature readings and using those readings to richen or lean out the mixture.

I had opened my AFM cap as well and marked the position of the spring. I adjusted it tighter and looser and neither had an effect. Probably shouldn't have opened the cap to begin with.

So, I know that's a long story, but my point is, after you get your vacuum leak project completed, check your CHT. As cheap as they are at 914Rubber you might want to pick one up anyways. Just to have one on hand. You could always do what I did, just ground it securely to something in the engine bay and plug it into the harness. You should also check to see that your current one is plugged in securely. If it isn't, that would cause a whole host of problems similar to what you're experiencing. Ask Clay, he had this issue awhile back where it took him a week or so to realize that the CHT was making a poor connection and causing poor running. If I remember correctly, it turned out that the CHT, while plugged into the small plastic sleeve, wasn't actually plugged into the male spade inside the sleeve.

According to the Anders site on D-Jet, the CHT plays a huge role in the fuel enrichment circuit. I assume that the CHT plays a similarly large role in the L-Jet system.

Sorry for the long rambling post!!!!!

I don't remember what I torqued mine to. Actually I don't think I torqued them. I just got them tight. But in reading some posts on the subject, it was mentioned (RTowle?) that he used a small amount of orange high-temp sealant on each side of the phenolic spacer/gasket. I did the same and I don't think there are any leaks there.

Sometime in the last few months, I installed the 914rubber TS2. Prior to that I ran the "INSTALLED" green line unit.... for about 3 years. The other line on this graph is from Ratwell's website as a comparison.

So the unit that made the RED line is currently in the car. I have not checked it since my AFM warped. My problem with the green line unit, was start-up idle or cold idle. The car needed my foot to stay idling at 950-ish until I got to 300*F CHT. Looking at the graph, it seems that the 914rubber unit would help. But I really did not see a difference.

BTW Thanks for the info about your test. And I also have a new 914 rubber 1975 version of the elbow with 2 large accessory outlets.

Click to view attachment

Soak your stuck sensor overnite in PB Blaster, or Sili-Kroil or WD-40 to break it loose.

I am glad to hear someone else has tried the gasket sealer, I have some and will give it a shot. I found a few more sites with FT-LB recommendations... crazy tho, some say 4 ft-lbs some say 18 ft-lbs. I think I will go with 10.

THEGOLDENBUG.COM
Torque Wrench settings
Injector/Manifold bolts to cylinder head
Lb Ft 4
Nm 5.4
mkg 0.6

TORKSPEC.COM
Intake Manifold To Cylinder Head Multi Port Fuel Injection
18 Ft-Lbs
216 In-Lbs
24.4 N-m

Intake Manifold To Cylinder Head Single Point Injection

7 Ft-Lbs
84 In-Lbs
9.49 N-m

You forgot to add the units to your graph

He did, but the title of the graph should help out there...

Only one axis can be temperature and the other axis resistance.

I figured the title would do. I never really planned on showing anyone and I know what the units are.

And now back to the subject....

This is the 1/2 side. Bottom of the intake runners. so the black stuff would be under the pipes close to the head.

Would this be considered a leak?

Click to view attachment

I would think so. Looks sooty to me but I'm not sure I would believe that much soot would be coming out of the intake area...even with the backfiring you had going on.

I think Clark did something sneaky by quickly adding that subtitle, I never saw that before

The great Captain Krusty may roll in his grave as I get ready to say this, go ahead and RTV the shit out of that gasket. Your previous threads asked the community why certain cylinders were running hotter than others. A vacuum leak will cause this, and as you have learned, a vacuum leak will also cause our Ljet's to backfire and kill the airflow meter.

I don't think you need a torque wrench for the 4 nuts on the intake manifold, just use your best judgement. Keep in mind that the steel studs are screwed into aluminum, which will strip.

Gracias Timothy,

Adding that graph was not easy, 1st I had to boil water, make a rig to hang the TS2 in the water ( need to use cooking oil next time), get a thermometer, take the measurements and make the graph.

then figure out how to save it as JPG. then make it small enough for this forum. I wish we could just copy and paste into this forum and the screen shot would be there.....and be the right size, facebook figured it out, why can't we?

anyway, I was heading in your direction Tim, but I will at least check the torque once I get a warm and fuzzy with my tightening.

I thought I had the right gasket maker, but I don't have any that will handle over 300. So I am off to the store.

I have been looking at lots of pix of vw engines online. It seems that lots of them use hose clamps on the little intake hoses. I got new ones, but I am gonna clamp them too.

During disassembly, I found lots of oily-gassy, wet spots around and under areas where stuff connects. kinda like the sooty picture above. Damn I have vacuum leaks.

Clark

As luck would have it, I got everything back together and the fuel pump is not starting up. I have 0 psi on my engine bay fuel gauge shown in previous posts.

UPDATE. bent my AFM. Got a used 7 pin one that matches, Car would start but would not idle or even run well. Air leaks seemed to be the problem.

I removed the intake tubes on both sides and found a broken spacer/seal. To remove the tubes, most of the FI stuff needed to be unplugged on the passenger side.... ECU, DUal relay, the resistor pack, the coil. And of course the FI and fuel lines were moved.

Right side needed the airbox and intake elbow removed. along with the Injectors.

OK, i got new intake spacers added 600*F RTV to both sides, new FI seals, new air distributor hoses and added hose clamps to those little hoses. Already had a new intake elbow.

Put it all back together and the starter fires, but no fuel pressure. With the key on I can open the AFM and move it and I hear what I assume is the dual relay clicking, but no fuel pump.

Click to view attachment

BROKEN WIRE.... I decided to retrace my steps and found this wire on the ignition side of the dual relay had broken. Luckily I did have some of that type of connectors with the tab to insert into the block.

once fuel pressure built up the car started..... problem is still there. Ruff starting and even ruff running. I can hold the pedal at about 2500 rpm for 4 seconds, then the car starts to die on it's own.

I think I am back to the culprit being the USED and unknown condition AFM I bought for $150, I think it was. Well at least that is what some of the core charges were on freshly rebuilt ones.

Back to the drawing board.

I am searching for a 7 pin AFM. I saw on a post that Fuel Injection Corp sells them. Their website says they have zero in stock. I will call them tomorrow.

I also see that AA has them $300 includes $100 core charge.

Anyone have another vendor they have used? Or a 75 7-pin that they will loan me for troubleshooting? I have one lead here in town, but I am not yet sure that it is 7-pin.

Anyone know what the difference in part #'s might be?

is a 7-pin the same? I see that lots of VWs had L-jet with a 7-pin AFM.

I am moving slowly on this problem.

I never heard from anyone that had a 7-pin known good AFM. So I purchased what I thought was a rebuilt one from EUROCARS9101. They had one they called REMAN! with a warranty etc....

It will be here Friday. I got tired of waiting and I have the BENT AFM that ran in my car for 25K miles and the OLD tired one that I bought from San Diego that could be bad cause my car won't run with it installed.

I took out the guts of the bent one, everything but the big gear and the spring. Cleaned things up and installed them in the San Diego unit that is not bent.

I was able to move the PCB about 1mm so the sweep arm is hitting a fresh track.....

I am now on my way to install it.

Those that pray, please say one for me.... Back in about 20.

God could not help either. Pretty much the same problem. It struggles to start unless I use the gas pedal, then it will not idle.

If I get the revs to 2000 with the pedal, it will stay there, but it is stumbling slightly. Let off the pedal and it dies.

SO now with the guts of an AFM that I know were good, I basically get the same result.

The only thing I did not transfer was the gear and the spring. Could the spring be too tight not allowing the flap to move enough at idle?

I will have a 3rd unit to try tomorrow, so maybe the pray-ers should give me one more days worth.

A vacuum tester is an excellent way to ensure there are no leaks in any components. Can’t count how many times I heard of someone chasing a K-Jet or L-Jet running problem only to find out the can on the dual vac dist. Leaked or something similar. It still sounds like a vac leak to me or something in the valve train system. Have you done a leak down? A burned intake valve might now show telling results on a compression test, but often show on a leakdown.

Keep at it, you'll get it figured out.

a vacuum tester sounds AWESOME. How does it work, can you buy one, or do I make one?

I got my nice clean REMAN! eurocars9101 ebay AFM today. Installed it.... and you guessed it: very little change.

It started a little quicker and ran a bit smoother (forced by the acell pedal). But it started and was slower to die. Gave me enough time to jump out of the seat and reach in for the throttle body and control the engine.

Again, it ran very ruff, even at 2500 to 3000 RPM, and will not idle, but is slower to die.

I'll get a video in the morning.

My plan is to go thru all the Trouble Shooting tips here once again. I will crawl under and do the HATED valve check. Probably will do the compression test 1st.

I pulled the resistor pack and checked the condition of the wires. everything looked good. It seems that the 4 tubes are connected at the bottom and wired to the 5th tab. I checked continuity from the 5th tab to each remaining tab. Is there a bench test for that thing?

I am going to be back at it in the AM, chime in with anything that we have missed so far. Disty vacuum can is a new one, so I will be on that for sure!

Vacuum tester

No tool box is complete without one.

I hope it comes with some instructions.... I have quite a few Harbor Freight tools. I can't believe I never ran into this one while shopping.

I will make a point to get one.

I started the car this morning, messed with the disty and the button. checked the Ohms on the coil. Bypassed the TS2 and saw no improvement.

And now I remember why I hate dealing with the valves.... I need to back-date my exhaust. Valves and ALT work require the exhaust to be removed on a 75.

I did compression tests today and checked the valves on one side before it became MILLER TIME.

I am concerned about the compression I thought it should be more like #4:

#1 95
#2 100
#3 75
#4 110

I wish I had done a comp test right after the cam break in, then I would have a base-line, oh well. What do you guys think?

1/2 valves checked out. I have chromoly pushrods and 911 swivel feet, so I just check the swivel foot for spin. All 4 on the drivers side would spin and the rockers only clicked just a bit, so I have 0 lash.

3/4 exhaust comes off tomorrow.

If your valves check out, you may want to look into borrowing a smoke tester machine.

They work sorta like a vacuum tester, but in reverse. You hook the machine up to your throttle body or to a port on the intake manifold, and then it pumps smoke into your intake. If there's a leak, you'll see a stream of smoke from the leak. They work well and can save a lot of time looking for a vacuum leak. The big drawback is they are quite pricey -- I did a quick look on Amazon, and the decent-looking machines start at ~$800 and go up (that's why I suggested trying to borrow one).

BACK TO BUSINESS..... I have finally checked, adjusted and re-checked my valves. Each cyl at TDC, I set the corresponding valves to zero lash. My chromoly push-rods were spinning, my swivel feet were spinning, wiggle the rocker and I got no clicking.

I re-checked compression, hoping to see a GRAND improvement.... I did not. All cylinders were within 5 psi of the pre-valve adjustment check. Except #3. It has now risen to 95.

#1 95
#2 100
#3 95
#4 110

I plan on putting the car back together this evening and returning to FI troubleshooting and air leak hunting.

any other suggestions?