2.1DJ idle and smells too rich.

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josephcarey1
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2.1DJ idle and smells too rich.

Post by josephcarey1 »

Hi guys,

I’ve recently got my 2.1DJ rebuilt engine running. The old engine was poorly looked after and ended up with a cracked head and leaking gaskets. This new DJ I have built from scratch with minimal reuse of old parts from the original engine.

I’ve searched the forum and wiki, but nothing is really standing out.

It runs, but it really smells of a lot of petrol. It’s worse when it’s cold and does improve when it gets warmed up, but I still don’t want to be standing behind it! It’s running a bit too rich and it hunts on idle or runs too quickly on idle.

Temp sensor on the side of the thermostat housing has been replaced, idle valve is good and working. The black box behind the drivers side rear light appears to be good. I opened it up and it’s like new inside. The contacts and the socket it plugs into was a bit poor so I cleaned them up. I’ve cleaned all the earth points up, put new HT leads on, new rotor arm, new vacuum pipes for the distributor.
I’m concerned about the air flow meter; someone has opened it up before. I have a feeling it’s been messed with.
How does one test the air flow meter?
I was suspecting my distributor to maybe be contributing to the unstable idle. Possibly the vacuum part of it not working correctly.

What else might be causing this?

The throttle switch appears to be good. I can hear it click on and off

All help and advice is highly appreciated.

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Mocki
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Re: 2.1DJ idle and smells too rich.

Post by Mocki »

Injectors worn ?
mine was the same when I first picked it up , ran well,  it stank of petrol , especially when cold .
That was ten years ago , I weighed up the cost of new injectors, of refurbing them , and  junked the injection system , switched over to a DG carb and converted it to lpg 

Now days there is a place over in Hull that refurbs them, resonalble priced, and excellent reputation.
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josephcarey1
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Re: 2.1DJ idle and smells too rich.

Post by josephcarey1 »

Mocki wrote: 18 Mar 2021, 22:04 Injectors worn ?
mine was the same when I first picked it up , ran well,  it stank of petrol , especially when cold .
That was ten years ago , I weighed up the cost of new injectors, of refurbing them , and  junked the injection system , switched over to a DG carb and converted it to lpg 

Now days there is a place over in Hull that refurbs them, resonalble priced, and excellent reputation.

I suppose it could be a possibility. It smelt bad with the original engine but much worse where water was leaking into the cylinders and you ended up with watery petrol smell.

I’ve considered a few times going carb.

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Re: 2.1DJ idle and smells too rich.

Post by scotttie »

So two things here which might not be related:

1. Running rich: An injector being stuck open will cause rich running. There is a procedure for checking injectors amongst other digijet components in the workshop manual (http://syncrosport.com/info/manual/VW_T ... nj_Ign.pdf). Have you tried adjusting the AFM screw to see if it makes a difference? Count the number of turns you make so you can get it back to where you started in case it doesn't help. Is the timing correct for the petrol you're using? 

2. Hunting idle: With the idle control system functional it should sit pretty much bang on 800 rpm. Check the throttle switch with a multimeter to confirm it's definitely working. Have you given the idle control valve a good clean with brake cleaner? Even if it is buzzing it can still be a bit gunked up.
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Re: 2.1DJ idle and smells too rich.

Post by josephcarey1 »

scotttie wrote: 19 Mar 2021, 07:16 So two things here which might not be related:

1. Running rich: An injector being stuck open will cause rich running. There is a procedure for checking injectors amongst other digijet components in the workshop manual (http://syncrosport.com/info/manual/VW_T ... nj_Ign.pdf). Have you tried adjusting the AFM screw to see if it makes a difference? Count the number of turns you make so you can get it back to where you started in case it doesn't help. Is the timing correct for the petrol you're using? 

2. Hunting idle: With the idle control system functional it should sit pretty much bang on 800 rpm. Check the throttle switch with a multimeter to confirm it's definitely working. Have you given the idle control valve a good clean with brake cleaner? Even if it is buzzing it can still be a bit gunked up.
Hey Scotttie,
I've not tried adjusting the CO mixture. I can give it a go. Where is it located on the AFM? I have a hole near where the rubber pipe to the throttle body goes, it has a hex screw inside of it. Maybe that's it?

At the moment my idle is around the 1k mark, sometimes slightly higher. I'm using normal unleaded fuel. I've read a few things about the timing. Some say time up at TDC, others say time it at 5 degrees Before TDC and then there is a GoWesty video that marks 35degrees before TDC at 3k rpm. I'm sure their video is most likely for a digifant though and not a digijet. No idea if it makes a difference or not.
When I have done the timing, I've disconnected the vacuum pipes on the distributor, I've unplugged the green wire and then I've disconnected the two connectors to the white box in between the coil and ignition amplifier and connected them together. My timing actually fluctuates a little and never stays right on the point where I've set it.

As for the Idle control valve, I've cleaned this with brake cleaner a few nights ago. it wasn't too bad. I've also made sure that the clips on the rubber pipe and the 4 pipes for the inlet (2 on each side) are good by replacing them. The rubber pipe was checked as well for splits and is all good. the same for the pipe from the idle valve and breather pipes. They have all been replaced and have had new clips to avoid any unmetered air getting it.

The idle switch on the throttle is good. I connected my meter to it and can see it open and close. I'm a bit concerned about the AFM though. Someone has been inside it before. It could be something innocent as cleaning the carbon track or it could be something like someone decided to adjust the clock spring and messed the calibration up.  

the distributor, the drive, AFM, Injectors and inlet are all from the old engine. The rockers, pushrods, valve springs and collets are all from the old engine. Everything else is brand new such as crank, connecting rods, bearings, pistons, liners, brand new heads, new valves, oil pump, etc. Everything inside of the case is new except the distributor drive. That was from the old engine.

Thanks for the help so far guys! These old fuel injection systems I find are a bit confusing.



 

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scotttie
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Re: 2.1DJ idle and smells too rich.

Post by scotttie »

Yes it's the allen head screw in the hole.

What do you have the timing set to? By normal fuel I guess you mean 95 RON? in which case your timing should be 5 degrees BTDC. Yes go westy video is for a MV (digifant) engine. The manual I provided the link for on syncrosport is what you should follow for timing setting procedure (digijet section). I had a rich running problem which turned out to be my timing slightly out, so best to make sure it is set up correctly. Worth having a read of this which describes the issue I had with rich running and timing: viewtopic.php?f=37&t=173318

Have you put a multimeter on the temp 2 sender? I've heard of people having problems with them even after replacement so worth checking it is giving the correct reading. If it's telling the ECU the engine is cold when it's actually up to temperature you will be running rich.

With the AFM, it could be giving a false reading telling the ECU more air is entering than actually is, and in which case the ECU will deliver more fuel making it run rich. If you can get hold of/borrow a spare AFM in working order to try in place of yours that is the easiest way of checking if the AFM is at fault.

Can't really comment on how your engine rebuild (what is new vs reused) could have an impact on the running issues you have as it's beyond my knowledge!

Try not to give up on the fuel injection! It is a pain to fault find but when it's working it's great  :D
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Re: 2.1DJ idle and smells too rich.

Post by josephcarey1 »

Hey Scotttie,
Thanks for the link. I will have a look at this tomorrow.
I will check my timing again tomorrow and also do a full check on the electronics using that digijet manual.

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Re: 2.1DJ idle and smells too rich.

Post by bigherb »

Before you start mucking about with it, you need to check the injector switching time, that will tell you where the fault most likely is. Use a multi meter that measures dwell angle. Connect across an injector plug cables, with a warm engine you should read around 3 deg at idle. If it is correct, then the problem is a leaky injector or too high fuel pressure. Incorrect reading would be control problem faulty sensor etc.
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Re: 2.1DJ idle and smells too rich.

Post by ajsimmo »

Fuel pressure regulator is also a possibility. Is the vac hose connected, and good? Can you hear the engine tone change when disconnected? There should be a pressure test point in the fuel hose at the front of the engine, to the right of the dizzy.

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Re: 2.1DJ idle and smells too rich.

Post by josephcarey1 »

ajsimmo wrote: 20 Mar 2021, 08:21 Fuel pressure regulator is also a possibility. Is the vac hose connected, and good? Can you hear the engine tone change when disconnected? There should be a pressure test point in the fuel hose at the front of the engine, to the right of the dizzy.

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Hi ajsimmo,
The vacuum pipes are new. If I disconnect then you can hear the engine tone change. The previous owner didn’t have the pipe connected to the retard part of the distributor. They just connected the advanced to where that goes, connected the one on the fuel regulator to the other part of the plenum and the retard on the distributor was left disconnected. I have since corrected all of this.

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Re: 2.1DJ idle and smells too rich.

Post by josephcarey1 »

I readjusted the timing today and things seem to be a bit better. I took it for a road test and it run well. Plenty of torque as well. The engine is way better now it’s new than the terrible mess it was before.

I’ll run it tomorrow when it’s completely cold and see what happens as that’s when it was at its worst.

I shall let you know. Thanks everyone for the help.

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