Club 80-90 Forums

Hi All

So this is my first post, been using the forum and website extensively, and I'ev already tried to search for a simmilar issue to no avail, so please excuse me if this type of thing has been covered alredy.

So anyway, I collected my Grandad's '86 T25 (2.1 DJ) from the south of France after it became a bit too much for him to use any more. Went down in April '13 and drove back to London, took it for a few camping camping holiday around UK and back to France (Le Mans) with no problem.

This year on my Annual trip to LeMans the camper over heated and broke down, which is in hand and getting sorted. However whilst problem solving the over heating problem, I came across a little electical box that had been disconnected. I took a note of it's part number (251906 083A ) and quickly google-ing it, turns out to be a 'Digital Idle Stabilizer Control Unit' according to go-westy - as per this link (http://www.gowesty.com/ec_view_details.php?id=3826" onclick="window.open(this.href);return false;)
Bit more googleying and it looks like it control the idle speed using various sensors - fine and no bother, understand that. However the van has no problem idling without (this one at least) connected.

Can anyone shed some light as to whether this should be connected or whether there is a 'mod' to bypass this control unit for any reason.

Thanks

Chris

They are usually disconnected when something doesn't work in the idle sysytem including the unit itself, or has been left bypassed by whoever checked the timing last - what happens if you plug it in ?
I have to admit I don't exactly understand what this control unit (only on DijiJet) does that the other idle control unit that is behind the rear lights doesn't do - in the Digifant 2.1 there is just the one behind the lights and the rest of the control is done by the ecu, which in the MV also controls the timing advance so I guess it's something like an additional idle timing control that smooths the timing at 850rpm better than the disi can do on it's own mechanically and with vacuum advance

I had a look last night and noticed that the plugs that look like they go to the control unit are just plugged straight into one another, I didn't have time to play too much and was on an eber diagnosis mission so didn't try to plug in the control unit. I will do that tonight and see what happens..

Would this have a relating factor to an somewhat instant stall immediately when I turn the engine on with no throttle applied? Basically (I've accepted it as a 30 year old van issue) when I start the van from cold, if I don't apply any rev's the engine will conk out. Start again with some revs for a few seconds and it idles fine. Like I said never been a problem, just to it down to being oldish

One school of thought is that they cause more problems than they solve and it's best to leave them disconnected. When they work they have a slight benefit on idle running. When they are bad they cause a lot more running issues. When I had my petrol I couldn't detect much of a difference either with it or without so I just left it bypassed (ie like yours is with the plugs connected together)

Aidan wrote:I have to admit I don't exactly understand what this control unit (only on DijiJet) does that the other idle control unit that is behind the rear lights doesn't do - in the Digifant 2.1 there is just the one behind the lights and the rest of the control is done by the ecu, which in the MV also controls the timing advance so I guess it's something like an additional idle timing control that smooths the timing at 850rpm better than the disi can do on it's own mechanically and with vacuum advance

Yep, AIUI, that's basically it. The main idle control box manages the idle speed via the idle air valve. This little doofer does a bit of fine-control via adding a bit of a dela...y to the ignition timing to smooth it all out, since ignition and injection are totally separate on the DJ's Digijet.

McNab - GoWesty are in the US, where all vehicles needed cats WAAAAY before ours here - so all their info relates to US-spec vehicles (same for the otherwise excellent Bentley manual). To translate US-to-Europe for injection trouble-shooting, you need to think of your DJ as a 1.9, not a 2.1. All their 1.9s had the Digijet yours has, all their 2.1s had the more advanced Digifant Aidan mentions. The only real other difference is that their Digijet included a cat, so lambda input - yours doesn't.