Starting sequence?

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skysurfin09
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Starting sequence?

Post by skysurfin09 »

What tells the fuel injection system to switch to idle mode after initially firing on turn of the key. I'm trying to fault find this starting problem and as I don't know the sequence of start up I'm chasing my tail. Erm1e sent me a copy of the Vanagon T2 Digijet Fuel Injection System VW handbook but, I need to know the order the signals are sent and to where. Can anyone help out as I'm being driven to distraction by my lack of ability to nail this fault down please.....Thanks Rob
'89 2.1 injected (Digijet)...travelling in hope over adversity

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skysurfin09
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Re: Starting sequence?

Post by skysurfin09 »

I've proved out the ignition switch by doing as Mocki said, i.e taking a live feed prom the live post in the rear fuse box and connecting it to the live side of the coil and the fault remains i, e fires on the key and immediately dies, I've reset the ignition timing by eye and by slightly advancing and retarding the distributor (trial an error) had the engine briefly trying to run on. However, in the meantime I've had to put the battery back on charge tonight with a view of trying again tomorrow. Thanks Mocki and Erm1e for your advice it is much appreciated...Rob
'89 2.1 injected (Digijet)...travelling in hope over adversity

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Re: Starting sequence?

Post by Aidan »

when you start the van the starter trigger signal is also sent to the ecu to say we are starting use default start map, once you release the starter that signal is lost to the ecu so the ecu knows it is running map according to temp sensors, load (hall signal) and if at idle the idle control circuit is running the engine, so is the micro switch on the bottom of the throttle body working correctly, if it is then it's likely there's an issue with the idle control, it just wants to run at 850rpm and will alter the fuelling and the air mix by the bypass valve to do that, if it can't then either it's getting an erroneous signal, fuel pressure is low or the timing is so far out that it can't get a burn cold. If the microswitch isn't switching then the ecu is trying to run the engine at idle without the benefit of idle control, ie no air bypass valve. If the bypass valve isn't working then the idle control unit will struggle to run the engine.
Do you still have the cream plastic idle signal amplifier thing in the system and connected ? That seems to be the least reliable element and is often bypassed and then the throttle body idle turned as open as possible to get DJs to idle when cold, they then idle fast hot. I haven't run a DJ myself so have never got to understand what that plastic box does, on the MV it's function along with the vacuum advance is integrated into the ECU which makes for more reliable engine generally.
Temp2 signal is important for the engine to run so check that the cvalues you are seeing at the sender are correct for the temp compared to the graph in the manual, temp 1 rarely fails.

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skysurfin09
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Re: Starting sequence?

Post by skysurfin09 »

Aidan thank you for your post it will then give me some guidance as to the next link in the chain. It would appear that it's possible that there were two faults, of which a dead hall sensor was but one. Thanks again for the advice ....Rob :ok
'89 2.1 injected (Digijet)...travelling in hope over adversity

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Re: Starting sequence?

Post by skysurfin09 »

Aiden, the Idle signal amplifier had been by-passed previously. I checked a video on Ytube on how to test the two switches you mentioned and there is a corresponding click at the upper and lower throttle positions, i don't have the knowledge to check values unfortunately, but thank you for the help given...Regards Rob
'89 2.1 injected (Digijet)...travelling in hope over adversity

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Re: Starting sequence?

Post by skysurfin09 »

: I've now changed the coil and changed the dizzy, reset the timing and she fired on the key. I revved the engine twice and she then died not to restart. I give up .......The indication is no spark at the plugs as I pulled them and they were wet I don't have enough years left to wait for them to dry out and attempt to restart her. I admit it I've no idea where to go next. :( :( :( :( :(
'89 2.1 injected (Digijet)...travelling in hope over adversity

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skysurfin09
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Re: Starting sequence?

Post by skysurfin09 »

anyone?
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Aidan
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Re: Starting sequence?

Post by Aidan »

ok so she's dried out and sat for a day will she start and if she will, will she run on idle steadily and start to come up to temp, don't give it any throttle for a few minutes and then just gently increase the revs then drop back to idle

double check before starting that AFM and temp 2 are plugged in

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skysurfin09
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Re: Starting sequence?

Post by skysurfin09 »

Thanks Aidan, will do mate...Rob :ok
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Re: Starting sequence?

Post by tonytech »

Not sure if it helps, but...
I used to have a DJ, on a number of occasions (cos I'm a numpty) I left accidentaly left the air flow sensor disconected after some maintenance.
Turn key, engine starts, but dies imediately unless I reved the nuts off it. I'd be looking at the connections around this area.
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skysurfin09
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Re: Starting sequence?

Post by skysurfin09 »

Okay joke over, plenty of fuel going to cylinders, plenty of spark at the coil, plenty of spark at the head, plugs wet. Engine just turns over with no attempt to fire....Ideas most welcome please....Regards Rob
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Aidan
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Re: Starting sequence?

Post by Aidan »

has the timing moved, was the clamp tight ?

maybe go back to initial setting try putting disi rotor back to the mark on the top edge side of the disi body with engine at tdc on number 1, rotor arm will be pointing roughly at the rear stud on the top of the engine where the cover plate is

unless you can do static timing in which case do that it will be more accurate

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skysurfin09
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Re: Starting sequence?

Post by skysurfin09 »

Aiden, I had tried to fit several times different Dizzys and a coil given by Em1re, in the doing so I had set the timing up 180* out. As soon as I realised this and reset the timing she fired up lovely. I think that I had trouble with the plug from the Hall sender and once I'd sorted that out and the timing all was as it should be ...Please accept my thanks for you advice and please see my post in General chat as you qualify in spades....Thanks Rob

:ok
'89 2.1 injected (Digijet)...travelling in hope over adversity

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