Engine running problems

Does anyone know what is or could be causing this problem. All connectors and pipes have been checked and replaced if needed. Any help would be fantastic or any local mechanics who knows there way around a MK1. 

Reading your post I don't think anyone could solve this unless they have a crystal ball as there's not much information on what's wrong, what been replaced, what car or engine you have etc…  

mark1gls said

Reading your post I don't think anyone could solve this unless they have a crystal ball as there's not much information on what's wrong, what been replaced, what car or engine you have etc…  

I thought this was the Psychic Friends Car forum……
make model engine, fuel type………

While I am not Claire Vorant.


I do see further assistance in your future as long as there is a tad more detail in your post.

Sorry I have been trying to add a small video, I thought I'd cracked it but obviously not. I'll try again but if not I'll try and explain what is going on. 

So we know that you have a Digifant Injection system that was indicative to later Cabriolets 90-93.

You didn't state the Year, or Model.
But we can gather the fuel type.

Explain what you have done to the engine lately.
Explain what the engine is doing,  Videos have to be hosted on a hosting site, then upload the link to here.

Please read my How as a First timer should open a thread.

Attention First time posters or folks that need to set your profile. | Page 2 | VW Vortex - Volkswagen Forum

So it’s 1991 left hand drive 1.8 injection petrol with I think a digifant11 H2 engine.
the fault is an ongoing fault which I have had for around 8 years but I have decided to try and sort it, rather than living with it.

recently I have just replaced the exhaust manifold with a new one as the old one had a split in it.

cleaned inlet manifold and pipes to make sure no blockages.

checked all wiring best I can as not really sure what most of it does, but no brakes or corrosion visible.

start the engine cold (starts fine) but touch the accelerator and it coughs and splutters till the temperature gets to a certain point.

once warm if driven at 30 she’s fine but try to accelerate there’s nothing there, it is like it’s just trying to suck air and you get a few pops I think from the air intake box.

 

Check for Vacuum Leaks on the rubber hoses.
If the Idle by-pass screw on the back of the throttle body is finger tight that is you can adjust it with your fingers the o-ring is bad.  

Count the number of turns it takes to remove it write that number down. Take it to a hardware store of your choice and get a new one.  
Return it to the Count that you removed usually requires a 7mm spanner.  Also Wrap the threads and threads only with PTFE (Teflon Tape).

Start the car.
Remove the blue connector on the water outlet flange better/worse…. no change it is BAD.

Remove the o2 connector on the back side of the valve cover right rear cover 4 wires better/worse . No change the o2 sensor is probably bad.

While you are at it, if the battery cables (specially the Ground) is still OEM, I would replace it from battery to frame and frame to engine.

Clean as many grounds as you can find, if you click on the link in my signature there are a plethora of things you can do yourself, and they all relate to a 90ish RHD Cabriolet.  

Might want to read how to improve your grounds, and the Electrical PRIMER in the Electrical section…

Get  a Digital Volt Ohm Meter, you will be needing it as there is a good way to statically check your timing,

Static Ignition Timing on VW A1 and A2 DigiFant Engines.

You don't need to start the car but the key is in and in the run position.

www.cabby-info.com has a pictorial on how to set your static time…Or where your timing marks are.

Thank you for that, i will work my way through your list, i will let you know how i get on.

Right latest update.

Changed all the ground leads under the bonnet, changed the live lead from battery to starter.

Checked all timing marks everything correct there. Bought a timing light to set the dizzy that all lined up now.

fit new o-ring to idle by-pass screw although think they gave me the wrong size, so waiting for another through post.

checked blue connector that seems to be working fine.

checked the o2 connector and nothing seems to change when u disconnect the leads, is there a way to check it before I go looking for a new one to buy.

on the air intake does anybody know what the factory position is for the Allen key screw.


 

That is the co mix, and usually isn't messed with, without a co2 tester. Should of been sealed with a lead cover.  

If you disconnect the o2 and te idle on a warm car should change, no change means usually to me that it isn't working, and Yes you can buy a Generic replacement over the 140 dollar Bosch one.  The Generic just needs to be soldered and heat shrunk. the 4 wires are white to white it doesn't matter which is which only the Black one matters as it is the Sense, the 2 white are for the heating element, and are non-polarized.

You can also use the single wire (black) generic sensor and they are even more cost effective.  

Once I have replaced the lambda sensor would a co tester set up the air flow, 
 

Final update.
Car finally fixed, turns out the ECU I had fitted a copy of years ago was the wrong one for my car. Took the car to a specialist who's had to order the right one from Germany.

wow, what was the pn of your old one vs the new one…. curious minds want to know?

pn ???
having a thick moment lol

Part number   not sure because the labels have fell off the old one.