All Things V6...

[CitroJim]

That's very true Simon, it does look increasingly like a fuel delivery issue...

Always good to know how the Jetronic woks and its weak areas though for the inevitable problems that will occur with it later

Given the car has been laid-up for a while it could be down to muck and gum from old, stale petrol becoming dislodged and bunging things up... Fresh petrol is an excellent solvent for such deposits...

I'm thinking that if there is starvation arising from any cause then the initial strong enrichment (by opening the injectors for longer) will allow a start but as soon as the mixture strength is wound back after a successful start - and it does happen quite rapidly on an Jetronic system - then the mix is too weak to sustain running even though the ECU believes the mix is 'right' for the prevailing conditions...

I take it the fuel filter has been absolved of guilt? That will easily get blocked by old fuel residues...


Mike, the problem with the AFM is often intermittent contact with the cermet track so your advice is good... There is a test you can do involving a 9v PP3 battery and a meter to ensure the track is good across the range. It should rise and fall linearly...

The other problem with the AFM is the spring goes weak and this causes the engine to run rich across the range...

[Mandrake]

It would also be worth monitoring the output voltage of the AFM (preferably with an analogue meter or oscilloscope) to check that it is not too noisy.

Good idea - I've never worked on a car with the old vane and potentiometer MAF sensors but it looks like the potentiometer inside is very similar to the fuel float gauge types and can probably suffer from the same problems, but is probably repairable if it can be opened up.

That would certainly screw things up if the wiper on the MAF sensor was intermittently losing contact... I'm not sure David has a scope but I have one if he gets stuck.

[CitroJim]

In the absence of a 'scope an analogue voltmeter will do...

Digital ones are no good at all for such a test... Unless they have a pseudo-analogue bar display to show trends...

[Mandrake]

Nah, you can't beat a scope for detecting noisy potentiometers An analog meter is a distant second and a digital meter even with pseudo-analog bars need not apply.

The problem with an analogue meter is it is too slow, and these type of problems sometimes only happen if the potentiometer is moved quickly - for example in testing a TPS you might only get it to play up if you snap the throttle open and closed quickly. Moving it slowly and gently from one end to the other so the analogue meter can keep up may not provoke the fault.

[CitroJim]

The AFM is heavily damped Simon so the flap does not move that quickly... If it did the mixture would be all over the place and there would be lots of overshoot and fluttering.

It's both damped by a big clock spring (which weakens over time) and an air chamber...

Think of the damping on a height corrector for a rough sort of analogy...

Agreed a 'scope is best but in the absence of such a meter is better than nothing at all...

A bit OT but these fully digital 'scopes now available. Do they show any delay or are they as quick to respond as a proper traditional CRT analogue scope? I only have experience of the traditional type...

[Mandrake]

A bit OT but these fully digital 'scopes now available. Do they show any delay or are they as quick to respond as a proper traditional CRT analogue scope? I only have experience of the traditional type...

Depends how much you pay!

Mine is only a cheap little £100 digital scope the size of a pack of cigarettes, and for "audio" frequencies like this its more than fast enough. I haven't used it for a while, but from memory it goes up to about 2Mhz, and there is no noticeable lag between applying an input like touching the probe on a signal to seeing the response. (I'm sure there must be a small amount of digital delay but it must be only a few milliseconds)

I'd like to get a better one so I can get back into electronics a bit more - you can get a really decent portable digital bench scope that is good to a few hundred Mhz with 4 inputs and lots of functionality for around £300 these days that would put my big old 100Mhz analogue CRT scope I left behind in NZ to shame!

The specs on some of the modern digital scopes these days are pretty amazing and for not a lot of money.

[CitroJim]

Gosh, that's good value for such a powerful 'scope Simon... I've got three. All are old. The one I use all the time for my vintage wireless activities is a good 45 years old and my best one must be knocking on at least 20! I also have a portable one that runs on rechargeable batteries and that one is a good age too. It has a tiny CRT in it and is perfect for general automotive use, especially checking hydractive electrovalve waveforms...

I also use a traditional Avometer rather that digital meters of which I have several. One quite scruffy one for automotive use... A do have a couple of digital meters but much prefer the traditional ones..

When it comes to electronics I'm very old-school...

[DHallworth]

Well the handy thing about having a couple of projects on the go at once, is when one pisses you off you can go and do another...

Last Thursday I collected a 1954 Ferguson TE20 with the 4 cylinder Standard Motors diesel engine in it.

One of these was the first thing on 4 wheels that I drove as a kid and I was gutted when my dad sold the one we had. Ever since I was a teenager I swore I'd have my own.

When I collected the tractor most of the tin work was solid although the rear wings were missing.

I told myself I was going to keep it in original condition however have started restoring it fully at the moment.



I knew the gear selectors were seized when I got it so I had to do some dismantling to sort that out:



Tonight I spent an evening without even thinking about the CX whilst wire brushing and painting some of the tractor parts in primer.



I'll spend another couple of evenings tinkering with the tractor and then come the weekend I'll have another look at the CX with a set of fresh eyes and hopefully something will become apparent.

David.

[Stickyfinger]

TrackORS !!!!!

[CitroJim]

TrackORS !!!!!

Ohh Arrr And a diesel one too...

Will run very well on veg

I hope you're not painting it red David Grey is the only colour for a TE20!

[DHallworth]

I'm not, Jim

2 tins of Fergy grey sitting here. That's just a red primer that I'm applying before the top coat It'll also run very well on red diesel which we've got a tank of for the JCB and other tractors Much less agro then veg!

David.

[CitroJim]

I'm not, Jim

Thank goodness for that David!!!

They really don't look right in any other colour but Fergy Grey...

One of my cousins has a TE20 that runs on TVO... I believe their engines were a derivative of that used in the Standard Vanguard...

[DHallworth]

They were indeed. My Grandad had a TVO model that we've still got, the TEF Diesel engine was sourced from the Standard Motor Company. I believe it was used in Triumphs IIRC.

David.

[Mandrake]

It seems to run very well, I've changed the oil in it once and will do it again before I start using it regularly. It was a but spluttery when I first started to ask it for power but that cleared very quickly and when I planted it in 2nd it came on boost very aggressively and took off. It surprised me how quick it actually is!!

I hope you won't be following this guys example once you have it fixed and on the road:



Can't tell exactly what speed that might be but it looks like he has the speedo wound off the end near the middle of the video.

Edit: just noticed in the comments the poster claims he's getting 220 HP from it with the turbo boost upped to 1 bar...

Also don't do this:



(same guy)

[hattershaun]

David,
Check the wiring harness connector plugs near the back of the engine.
When accelerating the engine rocks and pulls the connector block, so you get a poor connection, no electricity flowing and momentary lots of power, felt as a jolt or hesitation or stalling.
I've experienced this on more than one T2.

In fact, you would be wise to pull apart all the engine bay connectors, clean & lube etc.
CXs are terrible for getting corrosion in the connectors, due to the cheap components and poor location of relays and wiring routes. Who would put a bank of relays behind the headlight, so all the crud from airflow hits them.
Compared to other cars of the era, where all the fuses and relays are in a sealed box, behind a second bulkhead all safe, dry and warm.