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busdaddy Thu Oct 27, 2011 7:44 pm

mikewire wrote: tootype2crazy wrote: When I stick a test light in the injector connector and crank it over the light just stays on constantly. That would indicate the computer isn't pulsing the signal right?

It should pulse from what I understand - I used a DMM, not a test light and got varied readings.

This sounds very reminiscent of my problem...you read my build thread, the parts about where I found two connectors that I had mistakenly grounded, that grounded out the entire FI system, right?
If the test light is connected between the terminals in an injector plug then it sure sounds like it could be, or possibly a bad ECU but that's really rare.

SGKent Thu Oct 27, 2011 8:24 pm

tootype2crazy, you've made a lot of headway and are close to a solution. It is easy to feel frustrated but really you are doing well. I think you understand the process but I would like to restate it to be sure, and for future readers.

Each injector has two wires. One wire goes back to a common connection with a similar wire from the other 3 injectors. Those 4 wires from the four injectors are hooked together and then one wire goes from there back to the ECU.

The other wire on each injector goes back to the ballast plug where each injector has a seperate resistor dedicated to it. 12V+ leaves the double relay when the key is on and flows through the resistors to each injector. 12V+ is provided by the double relay through the resistors and ground is provided by the ECU (1979 lacks the ballast resistors I think but it works the same).

Each injector is a magnetic coil like a doorbell. When the circuit is complete the magnetism opens the pintle and fuel under pressure escapes. It acts just like the doorbell when the doorbell button is pushed only the doorbell button is electronics in the ECU. 12V+ is ALWAYS on the injectors when the key is on and the double relay energized. This means that if you (discconect the distributor so not to damage the points) turned the key on and measured voltage at the injector the voltage should ALWAYS be there. The test light should be on. This is true regardless of which side of the injector you are on - either wire. Now, when the ECU "pushes the doorbell button" it grounds all 4 injectors at once so they open for that moment. If you are measuring voltage on the 12V side the light may not change much, however if you are on the other side wire of an injector which goes back to where all 4 injectors tie together and go to the ECU, then the circuit will be grounded off and on as the engine cranks.

So if you don't get flashing on one side of the injector, move to the wire on the other side. If both sides are on all the time when the engine is cranking then the ground is not being made inside the ECU or a wire is not connected properly to the ECU (power or ground).

Last - make sure you have 12V at the positive side of the coil when the ignition is on and that cranking the engine causes a spark. If that 12V voltage is missing then the ECU has no signal at all to know when to turn on or off. It relies on the coil primary pulses to know when to fire the injectors. This means that the points also have to open and close properly or the ECU will not know to flash. How often the points open and close is the signal that tells the ECU the baseline amount of fuel to deliver before it adds extra for cold temperatures and load. If anything in this statement confuses you please PM me with a phone number and I will call and explain it and answer questions. It is late, a Friday for me and my brain isn't working well tonight.

borninabus Thu Oct 27, 2011 8:26 pm

if you "think" the injectors are not firing then pull one out and reconnect it; then crank the engine.

that will take you from "thinking" about what the injectors are doing to "knowing" what the injectors are doing.

keep at it, man.
we're here to help :)

tootype2crazy Fri Oct 28, 2011 4:39 pm

Success!!! I got it running beautifully. I noticed that when the cold start valve was disconnected it would try to fire on some cylinders but just couldn't start. So I re-cleaned all the ground connections. The one for the double relay, under the plenum, the negative battery cable to body connection, and the transmission ground strap. I even took a bit of emery cloth and a pick and cleaned in the wire spades themselves. After this I noticed it would fire powerfully on a few cylinders but still wouldn't start. So I decided to start back at the basics. I took the hydraulic lifters out, pumped them up, reinstalled them, and then adjusted the valves. I turned the key and bam, it started right up and runs beautifully. Now I just have to get it off the jack stands and see how it drives!

mikewire Fri Oct 28, 2011 7:55 pm

Nice!! :D Glad to hear good progress.

tootype2crazy Sat Oct 29, 2011 10:04 am

Ok I have it driving around. It idles great, but when it's time to drive it, it seems to be lacking in power a great deal. It definitely has a lack of power in the mid range, say from 1500-2500 RPM. I'm thinking the original problem of my low fuel pressure could be at fault here. I'm planning on getting a different gauge to see if it really has low pressure. Any thoughts on which one I should get or how to proceed? The gauge mounts directly to the rail where the nipple would normally be.

mikewire Sat Oct 29, 2011 10:24 pm

I picked mine up at my local Napa, along with a brass 90 deg fitting on the back so it would face the rear of the bus when testing. A couple of German clamps and some proper fuel line:


SGKent Sun Oct 30, 2011 7:16 pm

tootype2crazy wrote: Ok I have it driving around. It idles great, but when it's time to drive it, it seems to be lacking in power a great deal. It definitely has a lack of power in the mid range, say from 1500-2500 RPM. I'm thinking the original problem of my low fuel pressure could be at fault here. I'm planning on getting a different gauge to see if it really has low pressure. Any thoughts on which one I should get or how to proceed? The gauge mounts directly to the rail where the nipple would normally be.

you might try putting a few drops of oil on the wick under the rotor in the distributor and also a drop or two on each weight pivot. You may have a sticky set of weights. The other thing I would look at would be your timing when you are done with the oil. Make sure it is 28 - 30 degrees BTDC with the hoses off at 3500 RPM.

TGOT Fri Nov 04, 2011 9:30 pm

79 federal setup with an intermittent problem. I have a gate that needs to be opened and closed when leaving the house. Car starts fine and idles well. When I drive to the gate and get out to close it sometimes it idles really low and dies if it was a cold start. It is almost impossible to restart. By tricking the cold start injector to squirt fuel (running the starter for sec but not letting then engine catch a few times) I can get it to run very poorly by flooring the throttle. Sometimes a few of these rounds goes by and the poor running turns into a good strong rev and I am good to go.

This is never a problem after it has warmed up. If I dont stop at that gate and just hit the road again no problems at idle but somtimes I get a stumble or miss at speed.

The poor running almost sounds like its firing on less than four and lots of white smoke from the tailpipe. I have had similar symptoms on another van but it was the points burning because of a bad plug wire. On that one the problem went away after I replaced the ignition parts. I really feel like this is a ignition problem but Ive gone through that system with twice. Once looking for suspects then just swapped everything from a known good van including distibutors.

If I leave it be when it acts up and come back it sometimes it starts right up, sometimes it needs to be babied.

I began with basics by adjusting valves and the ignition system. I checked the fuel pressure and it sets at about 35 psi at idle even when the problem occurs. Replaced fuel filter anyway. Tested fuel regulator and it responds as it should. Put a spare on for fun. Put a different coil and swapped doulbe relay for a known good. Took off every vacuum hose and inspected and tested big ones but just replaced the small ones. Swapped s boots known good van. Plugged brake booster line to rule it out. Took a propane torch and went over the whole engine, nothing changed. Temp sensor 2 test ok but also swapped it from a good running bus too. AFM is not sticking when problem occurs and the contacts look really clean. AAR closes as it should and opens when cold. The wire that goes from ecu to negative side of coil has continuity even when problem occurs. Injectors squirt when attempting to start when problem occurs. Verfied cold start valve operates and doesnt leak. Wiggling harness when engine runs ok doesn't replicate problem and wiggling when problem occurs doesnt make any difference. Compression is about 115 give or take for all 4 with the lowest reading on #4 of 110 ish.

So, any ideas? I have been pulling my hair out trying to make this a perfect bus but this seems to be one tack that won't come out of my rear! Thanks for reading.

SGKent Fri Nov 04, 2011 11:39 pm

I have two suggestions - kiddingly - don't stop at the gate. :)

I would sniff the engine when it is warm to be sure the AFM is adjusted properly. You may have a tiny change in air to fuel ratios since it was new and it may be a little lean now - due to anything from a small vacuum leak to aging or even alcohol in the fuel. The engine was not meant to be left idling after starting it until it was warmed up. Start and drive away.

When the engine starts it knows it needs extra fuel because it is cold so the cold start valve injects a little fuel and that helps it start cold. That burns off quickly. The TS2 (temperature sensor 2) tells the ECU (electronic control unit) that the engine hasn't warmed up and it needs extra fuel. The AAR (aux air regulator) opens up when cold and acts as an idle bypass to speed the idle up. Once it warms up and closes the idle drops to the normal circuit. If your mixture is a little off or the idle speed too slow, then the engine dies on you at the gate because it is just a wee bit too cold still to operate properly cold. If you drive it off it warms up and then it is inside that window where it can operate. If you sniff it then you will know if the mixture is set correctly. One area where vacuum can leak is that the injector seals get old and dry out. If you haven't replaced them and the fuel lines, it would be good to replace them and all the fuel lines before you sniff it. If the mixture turned out to be way off then you might want to do more service on the FI - replace the hoses, service the distributor etc but my guess is that the dying is normal because the car just needs the idle mixture tweaked to factory settings. At least that is my guess.

TGOT Sat Nov 05, 2011 12:01 am

SGKent wrote: I have two suggestions - kiddingly - don't stop at the gate. .

Everyone says that but I just have to or the horses could get out LOL! It wouldnt be such a big deal if it would fire right back up but it is quite the annoyance.

Checking the mix is exactly the kind of thing I didnt think to do, now to find an exhaust sniffer.

borninabus Sat Nov 05, 2011 5:35 pm

make sure you rule out ANY other possible causes first.

you shouldn't automatically assume your FI is at fault.
these aren't T3s :lol:

if it feels like it's only hitting on 3 then that's where i would start.

is this a new problem or has it always been this way?

TGOT Sat Nov 05, 2011 7:25 pm

This is a new to me bus, only had him a month. PO was a vanagon and subaru mechanic who took ownership when the previous owners got fed up. He said it seemed like a point issue but he really didn't give a damn about aircooled and was just looking to unload it. It was good price and the parts alone on the sunroof will cover the cost of it if there was serious issues. I drove it home and realized what a gem the car was if only I could get the bus to run well.

I just don't know what basics I'm missing. Ive swapped the entire ignition system (distributor to plugs) from a running bus. I did the compression test when bought it and at a buddy's with his tester to confirm the readings. I've confirmed fuel pressure even when its acting up. Cleaned the grounds under #3 and by the double relay. I've been swapping parts from a good running bus and nothing I've swapped has affected the running of the good bus or improved the problem.

I don't know if running on 3 cylinders is the description to use, more like it idles so low is it shakes like its missing. Also it doesn't just die it starts, runs fine and revs strong, drives good, then you stop and it slowly idles lower and lower until it dies even if you hold the throttle open once it begins its gradually downhill. I will say with the way the temperature dropped the last two days the bus is staying running shorter before it dies and is much harder to start. Today while driving I got really bad hiccups from the engine but it didn't quit on me. First thin I did was check the dwell and it was right where I left it at 45 degrees. Points has a small gray spot so I sanded them, put it back in, checked dwell and timing, thinking all was well then set off but the hiccuping continued. Got home dwell wasn't changed and couldn't see anything on the points.

I took SGKents advice and swapped out the injector seals, I had already swapped all the fuel line about a week after I bought it. No change. I attempted to richen the mix with out a sniffer to see if the problem improved. I turned the AFM screw clockwise/in about 3 full turns before it bottomed out and tried to start it at half turn intervals while it was dieing. with no improvement. I set it back to the original setting.

busdaddy Sat Nov 05, 2011 8:38 pm

If it's been half as cool and damp in Oregon as it's been here I'd be looking at plug wires and other ignition components myself, once it warms up and dries out it likely works fine :wink:

TGOT Sat Nov 05, 2011 8:53 pm

The bus I swapped ignition systems with hasn't been affected though. Maybe tomorrow Ill swap it all back.

SGKent Sun Nov 06, 2011 12:58 pm

if richening the mixture didn't affect it then I doubt if it is FI related unless the pump is dying for some reason under those circumstances. You should have seen some change. Tell me - is there anything unusual about where the gate is - unlevel ground where the bus sits at an unusal angle or up hill, downhill etc? If you start the bus say in a parking lot in a shopping center, drive it the same distance as to the gate and let it idle the same - does it die there as well. I am wondering if you have moisture in your fuel that is getting picked up when you are at the gate if you are on an angle or something like that. You say you have already monitored fuel pressure when this happens?

Also - please don't double post on this. Make an entry in the other thread you have going on this to use this thread exclusively so we don't have to chase all over trying to see what your answers are.

TGOT Sun Nov 06, 2011 3:03 pm

SGKent wrote: if richening the mixture didn't affect it then I doubt if it is FI related unless the pump is dying for some reason under those circumstances. You should have seen some change. Tell me - is there anything unusual about where the gate is - unlevel ground where the bus sits at an unusal angle or up hill, downhill etc? If you start the bus say in a parking lot in a shopping center, drive it the same distance as to the gate and let it idle the same - does it die there as well. I am wondering if you have moisture in your fuel that is getting picked up when you are at the gate if you are on an angle or something like that. You say you have already monitored fuel pressure when this happens?

Also - please don't double post on this. Make an entry in the other thread you have going on this to use this thread exclusively so we don't have to chase all over trying to see what your answers are.

Sorry I just thought if it wasnt FI related it shouldnt go here anymore. Westfabulous just started having me try stuff and I went with it. How should I consolidate? Just link to this thread in the other one? Maybe copy and paste what was said too? I did make a mess of things. Thank you for the help and patience.

The gate is level ground and I could try a parking lot but Id have to leave it there for a while because this only occurs after a cold start. I have tried driving around the house and stopping and it just dies as well with no restart. I have left my fuel pressure gauge attached so I can read what happens when it dies and I keep fairly consistent 35 psi.

SGKent Sun Nov 06, 2011 3:29 pm

if the fuel pressure is a consistent 35 psi +/- then it is unlikely to be a supply problem.

Gotta think about this one.

SGKent Sun Nov 06, 2011 3:56 pm

Quote: lso it doesn't just die it starts, runs fine and revs strong, drives good, then you stop and it slowly idles lower and lower until it dies even if you hold the throttle open once it begins its gradually downhill.

What about compression WHEN it is doing this? You say it is a 1979. That probably has hydraulic lifters. Oil has a different thickness when it is cold. Maybe there is a problem with the lifters being out of adjustment or a valve is sinking. That might only show up when the oil is thick enough not to allow the lifters to bleed down. If you had a valve sinking the lifter might be holding it open when the lifter is unable to bleed down because the oil is thick. At RPM a slight valve being open would not be as noticed and the engine oil would warm pretty fast to where the oil would thin out and allow the lifters to bleed down quicker. Once the problem starts I can see where fouled plugs etc would not be easy to get rid of just by opening the throttle. Also if it is an intake it would affect other cylinders too.

Nect check the ground straps and battery cables. Measure voltage at the battery when this is happening to be sure we aren't experiencing a voltage drop. The battery is most likely to be at its lowest voltage when cold, when the engine has just been started and when the engine is running slow. My 1995 Acura, now totaled, was maybe 10% slower cranking one morning so I replaced the battery. The bass in the sound system came back when the new battery was installed. On late Acura RL's some owners for example get weird things like computers lose their memory etc even though the car starts fine - it is a symptom of the battery getting weak. Electronics do weird things when battery voltages drop. So try to rule that out as a possible cause. This includes the igntion switch which can do weird things as well when it wears out - which they frequently do in buses. I carry a spare TSII and spare ignition switch the failures are frequent enough.

Next if you have a spare ECU, swap it. One thing it could be is a bad ECU. Rule out the ECU. That is an easy swap.

As BusDaddy said - now would be a good time for fresh plugs, wires, cap and rotor if the PO didn't already swap them. They do weird things when old and damp. You could have a cap that has carbon tracks in it or a rotor that is so worn the voltage isn't jumping from it when it is cold.

TGOT Sun Nov 06, 2011 5:06 pm

Unfortunatly I dont think I can swap ecus, my other FI is an 76. Ill have to ask some friends if they have a 79 I can borrow.

Thats a new theory about the valves. I only ever did compression while the engine was warm. Ill try that if it acts up tonight. Would a decent test also be to set the lash to .006 like one was attempting to bleed it up? This would be sure to close the valves all the way and if it dies then I could rule out stuck open valve twice with the compression test.

I had the same idea on the battery voltage being screwy, but I have been swappinh batterys with the good bus and the poor running bus because of all the fruitless starting to keep it all charged up. Lowest voltage I pulled from a battery when swapping it was 12.2 ish. It has done this with both batterys in it. That should rule out poor battery right?

I know when the engine is running I get 13.6 to 14 at the coil so the alternator and VR are putting out. The coil when not running doesn't get to much of a voltage drop, maybe .3 volts. I should have mentioned I cleaned up the battery cables at the posts, at the starter, at the negative to body, and the trans ground with a steel bristle brush when I was going through this on my own. Ive done so much I lost track of that!

Ill buy some new ignition stuff on Monday and try it out, worst case Ill have nice new
stuff.

Also in case anyone is readint this though for their own problem solving here is a link to a thread I created to try to solve if it wasnt a FI issue:

http://www.thesamba.com/vw/forum/viewtopic.php?p=5663009#5663009



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