1)From what I can see, all hoses are connected. 2) The decel valve is definitely functioning. Tested an alternative way and still shows as working. 3) AAR elbow hose is not split. Cracking, but not split enough to matter. 4) One-way brake servo hose valve is working. Checked that. The timing appeared slightly out (by one degree) and I have altered the idle speed as it has always been a bit high. Interestingly, and I don't know if it matters, but when the bus is started from cold, the idle speed is fine. It's only after the accelerator has been touched for the first time that the high idle speed starts. My next step is to test the ECU wiring with a multimeter.
Sounds like the 5th injector isn’t cutting out, just unplug the electrical connector from it, see if it makes any difference?
Done a few more "tests" this morning. 1) Fifth injector - Removed the plug to this before start up. Took longer to crank over and fire up, and then a few more seconds to get to a reasonable idle. So it appears that this is working as required on start up. 2) AAR hose - For the first 30-45 seconds, it idled reasonably. I clamped the AAR hose and the idle DID drop. Once I removed the clamp, the idle returned to normal. 3) Fifth injector - After about 45 seconds, the idle started to creep up. I removed the fifth injector plug to see if this was continueing to fire unneccessarily. The idle remained high. So it appears the fifth injector is stopping when needed. 4) AAR hose - With the idle high, I clamped the AAR hose once more. This had NO effect on the RPM. I have to go out in the bus now, for a reasonably long drive, so we shall see how she fairs. On my return, I will be sitting down with the FI manual and a multimeter and testing the FI electronics side of things.
I have found a post I wrote in May 2018, where I mentioned a slight "popping" on deceleration. I think popping is an overstatement. I can bearly hear it. It's more like a dull thud. Probably just linked to the reduced back pressure on the Vintage Speed ehaust. In this post, I was advised to replace the smaller vacuum hoses. I was advised to use 3mm silicon hose which would stretch nicely over the 5mm fittings. I can't find what it is that I bought, but I suspect I did buy 3mm hose. Is it possible that the 3mm hose is restricting it somehow? I will probably replace it to 5mm, as that's what it should be. Off to test the electronics now.....
Well, testing the ECU was a failure! I hate having this '79 CA FI bus. Everything is different! The usual L-Jet diagnostic manual wasn't of use. The pins appear to be different on a '79 CA bus. I found another diagram specific for a '79 CA bus, and a different diagnostic guide, but still no luck! Was getting no readings at all on the pin pairings. https://www.thesamba.com/vw/archive...al/AFC_FI_Training_Troubleshooting_Manual.pdf https://www.thesamba.com/vw/gallery/pix/1719886.jpg I am going to give it a break for a few days whilst I wait to get some 5mm silicon hoses, and report back!
5mm vacuum hose came. Have replaced about 10 pieces of hose, and appears to have made no difference. What I have noticed, however, is that there appears to be a reasonable amount of suction on the oil filler tube. Is that normal? The revs also appear to drop a little when the cap is removed.
Well, I appear to have found the "temporary solution" to the problem, and in turn, hopefully we can ID the source of the problem, and a permanent fix. High cold idle is still a proble, but, if I pump on the brake pedal about 5-10 times, it goes down! The video link shows the problem and solution from start to finish. https://www.dropbox.com/s/8a85hrggatrjvs3/Video 18-09-2018, 17 06 25.mov?dl=0 Any ideas? Presumably something to do with the brake servo and associated hoses?
I did the “brake booster test”. Pumped brake pedal with engine off. Went “hard”. Started engine. Pedal went down a little. So appears brake booster itself is working, right?
Did you try plugging the hose as above? Plug the hose after the check valve (engine side) then drive it. If it is normal, plug the hose at the servo end and try again. If the check valve tested OK then it will be the long hose or the servo itself leaking down.
I did do it, but I think I might need to go back and re-test. I've now worked out that it takes about 2 minutes from cold for the high idle to occur. Cheers
Check the oil breather at the front of the engine, it may need a clean out. Also check the seal around the throttle body to inlet plenum
Finally found a spare 5 minutes to look at this! Oil breather is fine. Clean as a whistle. Throttle body seal looks fine. Gone back to testing the decel valve. When it is plumbed is as usual, it revs high. See video. https://www.dropbox.com/s/jm9mb1li24q9zoe/Video 10-10-2018, 16 01 39.mov?dl=0 However, when I remove the hose and plug the end, the revs return to normal. https://www.dropbox.com/s/d0mkliyhrlbbcec/Video 10-10-2018, 16 02 51.mov?dl=0 Is this a sign of the decel valve being faulty?
Well typically, after not doing anything to it, I have driven the bus this morning and not had any issues! First time in 6 months! Fingers crossed!
You could still have a reasonable hole in the brake servo pipework , so the servo works still, but a few mm hole woiuld provide the equivalent of the AAR being stuck on.. The other fault might still be the 5th injector but stuck open mechanically so pulling the wire does not stop it. Or its just gunge making a mostly working valve fail to close properly..
Bus is having some welding work done at the moment. When I pick it up on Friday, I will see how it runs, and take it from there. Fingers crossed!
