Zaky31

Zaky31

Active Member
Hi all. Any ideas??
1995 D1 V8i 3.9

When I startup i have to sit on the throttle keeping the revs up otherwise it dies.
It will stay like this until it's warm (usually after 1 minute or so) then I can take foot off gas and it'll run fine without stalling.

It does this only on petrol. When I startup on LPG it runs fine??

Any ideas???
 
Does the stepper motor make adjustments to idle speed to compensate for heavy load

ie when you switch on air con, put in drive if auto, put load on alternator
 
Gave it a go today. Stepper motor doesn't seam to affect it. Turned on lights, fans heaters A/C etc. no affect.

Have noticed though the middle silencer on exhaust has a hole in the side. Could this cause it?

It still starts up first time no problems. As soon as it fires the Revs shoot up. Then as it drops down it drops well below 300rpm then dies if I don't give it a steady throttle. But after about 30 - 40 seconds once warm it'll sit comfortably at 1000rpm????
 
That's high a 1000rpm 650 to 750rpm is the band it should be in. I would check the base idle, a simple 5 min job first, plus the usual suspects in the engine bay.
 
I think I might have set the idle high to prevent it cutting out a few weeks ago. (Idle adjust where cable meets carb)
I'll set they back down. But What else can I check to see why my disco is hunting on startup??
 
Tightening the throttle cable does not raise the idle. It actually holds the throttle position above idle. The ECU gets a reading from the throttle position sensor telling it so. The stepper motor will not make correct adjustments if not idling.
Idle adjustment Allen screw behind throttle butterfly. You need to nip the hose to the stepper motor and adjust to correct rpm using a tachometer.

This is assuming you have efi which you should on 95 3.9.

As for the cause, you need to check a few things with a multimeter. I'd start with air AFM and temp sensors.

Specs can be found at http://www.actproducts.co.uk/2011/lucas-14cux-fuel-injection-system-–-installation-and-diagnostic-notes/
 
So I took out the stepper and gave it a good old clean. It was carbed up. Replaced but no change to the warm up hunting problem.
I did notice that stepper motor 'pin' (whatever it's called) didn't move when I pushed it. Should it freely move when I push/pull??????

Will it only move when commanded by ECU?

Can I run engine without stepper in but plugged in so I can see if it moves or not?
 
So turned out the problem was ........ An underpowered battery. I left the disco standing for a few weeks and when I came back the battery had drained. I took the battery out and sat it on a charger for a couple of days soon as I put it back in and fired the beast Up it ticked over nice and smooth no Rev bounce and no cutting out
 
Zaky31 said:
So turned out the problem was ........ An underpowered battery. I left the disco standing for a few weeks and when I came back the battery had drained. I took the battery out and sat it on a charger for a couple of days soon as I put it back in and fired the beast Up it ticked over nice and smooth no Rev bounce and no cutting out
Click to expand...

As you originally could start the engine your battery was ok, remember the alternator takes over as soon as the engine is started.
So your issue at the start of this thread has now disappeared, sometimes they do, hopefully it won't return.:)
 
I only use my disco at the weekend and more than a few times I don't, and so I have found out that the old saying "use it or loose it" can be true, no major issues but things don't work on the 'disco' as they should first time. :D
 
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