[T3] Mysteries and FI Parts

[Jeremy Menzies]

Whoops, sorry for the huge run on sentence.  A combination of thinking I could 'make it quick' by making a huge list and an excessive amount of coffee are to blame for that one...  Thanks for weeding through it anyway.
Intake: I do have the plastic spacers in there and I put paper gaskets on after reading about how the metal ones are wrong for the FI intake runners.  When I pulled it apart, there were actually no gaskets at all and after putting some on, the idle was a whole lot smoother, so I think there was something in that.
Trigger Points: Interesting about the dwell drifting.  The guy I'm working with said he had a couple of sets from a good 914 that I could try out, so I think I'll check those out and see what happens and if it's no dice then it's quite possible I'll be sending them your way ($10 sure beats the $114 for a new set!)  I've actually debated getting a Bosch machine out of curiosity and a desire to be able to do quick tests all at once but I'm concerned about blowing cash on a dud unit...
Injectors: Do you mean the pins in the body of the injector that the plug slips onto?  I didn't tighten these up and I'm not sure how.  I carefully pulled the female 'faston' terminals out of the plastic plug housing and cleaned and tightened up the curled ends and the crimp on the wire.
AAR: It's quite possible that I just haven't run it long enough for the oil to get hot enough to close the regulator.  After my 2+ mile drive it felt like it was sucking as strongly as when I first started and when I plug it the idle drops considerably (I'd say down to 850 or so plugged from 1600+ open). I did pull it out and take it apart to free things up and lubricated with some clean oil.  I also tested it with some heated oil in the kitchen, slowly heating and checking to see if and when it closed.  It snapped fully closed at around 150F, maybe a little hotter but it doesn't seem to close like that in the car.  I left the adjustment on the spring where it was set (all the way to the '+' side of the scale) but I'm not sure what the + and - are supposed to indicate exactly.
TVS: I'd like to take a look at your write up on this.  I've read a few different long threads discussing the variations and methods for testing this over on the samba forum but frankly all the back and forth arguments can get in the way of getting a straightforward testing method.  I think I need to have the part in front of me, too.  I'm skeptical that this is the problem but I haven't tried unplugging and driving it, so I'll have to do that once I get the brakes back together.

Timing:  I have set it to what I think is 0 TDC using the diagram in the Bentley (looks like: |   | | |  the first line to the left being 0 deg then 5, 7.5, and 10?)  Set with both a static light and then rechecked and adjusted with a strobe.  I had the idle set at 850 with the strobe.  When I open the throttle, I can see the marks move left of the pointer on the fan housing (marks go this way facing engine <---- ) so I assume that means it is advancing.  Plus the vacuum chamber moves the breaker plate and holds a vac. and the centrifugal weights are moving freely, so I assume they're working OK.  I haven't done anything to check how far it's advancing but it moves past the right most mark (is this 10deg BTDC?).  I used the 0deg. mark prior to when the problem cropped up and the engine ran fine as far as I could tell, so I assumed it was correct.  There are some other cast marks on the pulley that are further to the left that are not illustrated in the Bentley, though so perhaps I'm not timing it to the correct one.
Voltage: I have yet to check from the fuse block or the voltage regulator, so I will do that and report my findings.
Ignition Switching Clicks: I definitely hear one and the whirr of the fuel pump, I'll have to stick my head down there again and listen more carefully for two.  I'm pretty sure there's two, though.  I assume this is the pump relay clicking?
FI Components: I've been skeptical of the FI system, too, especially after doing multiple tests with positive results.  After going through all the things I have, I thought that maybe something was amiss with a component and my tests weren't revealing it, so trying other units might reveal something.  One reason I wanted to find parts was so that I'd have some on hand just in case there was a complete failure of one sometime down the road.  Another thought I had was maybe some water got into the ECU because the problem cropped up after the car sat in the rain for a few days and it happened briefly once before during a heavy rain.  Although, when I looked at it it didn't look like it had leaked and the car ran fine in between the first time and the current extended issues.
Wiring Harness: The shop who used to work on the car before I bought it butchered the wiring harness at some point, either when they put the rebuilt engine in or 'fixing' ends by just cutting them and butt splicing back together.  Every wire has been cut and spliced with cheap pre-insulated splicers and all the wires have pretty brittle, cracking insulation.   Although my testing showed little to no resistance in them, I'd like to get ahold of a harness that I can rebuild to have solid clean connections.  Either way, let me know what you'd be willing to part with, even if the FI is OK, at some point I feel I should get ahold of some good spares.
Thanks for the pointers, hope this is more coherent.
-Jeremy

> From: jadney at vwtype3.org
> To: type3 at vwtype3.org
> Date: Tue, 9 Aug 2011 21:49:15 -0500
> Subject: Re: [T3] Mysteries and FI Parts
> 
> Whoa, Jeremy, take a breath.  ;-)
> 
> Make some paragraphs (leave a blank line.) That will make your stuff 
> lots easier to follow. 
> 
> Read on below.
> 
> On 9 Aug 2011 at 16:18, Jeremy Menzies wrote:
> 
> > I've been chasing a mystery engine problem for a few months now on my
> > '71 Squareback (MT, FI, rebuilt stock 1600 w/a '69 case) 
> 
> > In short, I've gone through everything that I and the guy I've started
> > working with can think of: set all the basic settings (timing, points,
> > valves, etc); replaced all the vacuum (even the charcoal canister) and
> > 99% of fuel hoses (not the ring main yet, it's not too old); good
> > rebuilt fuel pump and filter; removed, cleaned and replaced gaskets on
> > the intake manifolds and intake air distributor;
> 
> Do you have the special Type 3 FI bakelite insulator gaskets between 
> the intake air runners and the heads?
> 
> > replaced head temp sensor (it was iffy); checked ohm and volt values on
> > air temp, TVS, MPS, Injectors, Trigger points (all within spec from
> > what I can tell and what the Bentley says).  I tested then pulled the
> > trigger points and cleaned and bench tested them (ohms are 0 on one
> > side and maybe .5-.6 on the other, openign and closing properly in
> > car); 
> 
> You can do basic trigger point tests with an ohmmeter, but the 
> rubbing block wears (slowly!) changing the dwell. This can lead to 
> eventual running problems. I reset them when I rebuild a distributor 
> ($50) or I can just do the trigger points ($10.) This is not 
> something you can check yourself unless you have the Bosch D-Jet 
> tester; you'll have to send them to me.
> 
> > pulled the plug to the brain and checked continuity to all end points
> > (either 0 or at most .2); pulled all sensor plugs and cleaned and
> > tightened up all internal contacts; made separate grounds from batt to
> > case ground and both FI and fuel pump relays; 
> 
> Did you tighten up the connector pins that connect to each injector? 
> These sometimes get loose and make intermittent contact.
> 
> > pulled a vacuum on MPS
> > (holds at +15"hg); compression good (140 on 1&2, 145 on 3&4); fuel
> > pressure set and holds at 28.5psi when engine is running; hooked a
> > smoke machine up to the intake (small leak around TVS but none others
> > spotted); pulled, cleaned, lubed and checked Aux. air regulator
> > (closes around 150F out of car but seems to stay open in car after 1-2
> > miles of city driving); new spark plugs; new plug wires; tried both
> > good coil and condenser (from well running cars); checked charging
> > voltage at generator (haven't yet from regulator), 12.6-13.6 at idle,
> > 14-15 at 2200; isolated generator from coil, no change in problem. 
> 
> This all sounds fine. The AAR is probably fine, it's just confusing 
> you because you feel vacuum when you put your thumb over the hose. 
> The test is to see if the idle changes when you close the hose with 
> your thumb. It never makes a perfect seal, it's just good enough to 
> make no change in the idle.
> 
> > Trans mount looks original but no cracks, tears, not loose, feels
> > solid; pulled, cleaned and lubed rubbing block in the TVS then
> > adjusted as per Bentley 'click' test (haven't rechecked with ohm
> > meter). 
> 
> The TVS check is a continuing problem. The click test is only valid 
> on 68-9 cars. You need to use an ohmmeter or the Bosch tester to set 
> the later TVS's. I have a writeup on this if you want it. It calls 
> out all the versions of the TVS, of which there were more than 5.
> 
> If you think the TVS might be the problem, just unplug it as a test. 
> Your car might be a tiny bit more sluggish, but if your same old 
> problems are still there, the TVS is not the cause.  
> 
> > Checked ignition oddities by pulling plug wires at idle to note
> > changes, no one cyl. acts vastly different from the next; tried a
> > different set of plugs, no change.  Pulled injectors to test spray,
> > cleaned and bench tested, checked ohms (spray looks pretty fine and
> > conical, sparkling clean, tips snap in and out on bench, ran some
> > alcohol through to get any grime out, ohms are within Bentley specs). 
> 
> All sounds fine.
> 
> > So, the mystery is: 
> 
> > Pt. 1- Runs OK at idle set to 850 (way too high with aux. air reg. left
> > open, like 1600 so I plug it) but something sounds amiss.  It's kinda
> > like a misfire but it's very subtle and doesn't isolate to one cylinder
> > through ignition wire pulling.
> 
> What happens if you leave the AAR connected and let the engine warm 
> up. Does the idle come down? If not, maybe it really is stuck. Yours 
> can be taken apart carefully and freed up. If yours is broken, I have 
> good ones.
> 
> > Pt. 2- When driving, no matter the speed of the car, the gear, or RPMs,
> > the whole car lurches and bucks, especially at lower RPMs (like in the
> > bottom of gears or under load).  It's as if you had a switch on it and
> > were flicking it off and on, comes in and out of power, off and on with
> > smooth RPMs.  It doesn't seem to do it in a pattern either, kind of
> > when ever, randomly coming off and on while going.  It's hard to
> > describe.
> 
> Are you setting the timing to TDC at about 900 rpm? With the timing 
> light, can you see the timing advance as you open the throttle and 
> let the rpms climb up?
> 
> > Pt 3- This happened once the other day and I haven't duplicated it yet.
> >  I took it out for a test spin, trying to get it more warmed up to see
> > if the AAR closed and see what generally happens when it's warmer.  I
> > got maybe 1.5-2 miles from home (in rush hour city traffic, so it warms
> > up quickly) and all of the sudden the idle just dropped out and it
> > would putter at idle, kinda stumbling and low but not stalling (sounded
> > like those low revving race engines, sputtering and grumbling). 
> > Shortly thereafter, I pulled in to get gas (only had about 1/2 gal) and
> > the gas pedal would not respond at all for 10-20 seconds, not with
> > pumping or holding or gentle persuasion, nada.  And then boom, on all
> > of a sudden, high revs and going.  Got gas, checked AAR (still wasn't
> > closed) and exhaust was very sooty black, bumped up idle screw with no
> > difference.  The gas pedal remained unresponsive every time I let off
> > and came into a stop then tried to go again, so I wound up laying it on
> > thicker and made it home.  Like I said, I haven't duplicated the
> > non-existent gas pedal symptom, but I haven't driven it much at all 
> > aside from around the block on test runs.
> 
> Possible reasons for running rich: system voltage too low. Connect a 
> voltmeter to the fuse box and watch the voltage while you're driving. 
> Check it when the engine starts to falter. Does the voltage still 
> come up around 14 V or so if the rpms are above 2000?
> 
> > Pt. 4- It smells like it's way too rich (gas smell but no leaks), the
> > plugs get coal black instantly, and the exhaust looks black but
> > according to an emissions tester, it shows up lean. 
> 
> Get in the driver's seat and turn the key ON. You should hear a relay 
> click and then a second click about 1 second later. Do you hear both 
> clicks?
> 
> > Conclusions thus far: I'm pretty stumped!  Everything tests within
> > specs and technically is functioning properly and or good but it still
> > won't drive right (it used to!).  Next step: Start trying to swap out
> > other components and see what happens, if anything.  
> 
> While anything's possible, my bet is that it's not a problem with a 
> defective FI part. The brains are almost always okay. The 70-1 
> pressure sensors fail occasionally, but you did the right test and 
> yours passed.
> 
> > These would be things I'd like to try first:1. ECU- 311 906 021D (I
> > have black sticker, not sure if it matters)  side note: I saw a
> > rebuilt unit with 021DX as the end in the part #, anyone know if this
> > would work? (I imagine the X indicates remanufactured) anyone have
> > luck with remans?2. Aux. Air Regulator- not sure on the # but it's not
> > the electric version (mine seems to not close properly when it's in
> > the car, so...)3. Wiring Harness or master plug to ECU & end plugs for
> > Mar. '71 production (I want to rebuild mine but don't want to pull it
> > all apart to do so. I'd rather get one with as many of the connectors
> > as possible and redo the wiring and boots then install it)4. Manifold
> > Pressure Sensor- 311 906 051C5. Throttle Valve Switch- 311 906 111C 
> 
> It's almost certainly none of those parts. I have all of them if you 
> really wanted them, but it would just be a waste of your time and 
> money.
> 
> Let us know what you find when you do the extra tests above. Consider 
> sending me your distributor or just the trigger points.
> 
> -- 
> *******************************
> Jim Adney, jadney at vwtype3.org
> Madison, Wisconsin, USA
> *******************************
> 
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