Injectors misbehaving but trying to understand the numbers

[KennyW]

My Q3 is supposed to have a height level sensor which alters the height of the headlights. This is missing but the associated wiring is also missing.

I'm going to have a good look around the FNS wheel arch and under the bonnet.

Q3 has audi's quattro system so is ideal for me where I stay on a farm in a rural location.

Kenny

[darbuck]

I get you, maybe it was never fitted Kenny. Hopefully you find it.

I cleaned and recut the injector ports and seats and cranked it over. It turns over nice seems to be generating a bit of compression with the injectors out so I think the engine is good. I have a bit more tidying up to do and give it a service and then see if it will start and run
I live in the middle of the bog of Allen here so I get why you want the four wheel drive. It can be very helpful. I don't have it but plan to buy a 4wd in a year or two.

[KennyW]

I thought I would take a chance on this one due to it being Cat N insurance damage. I am to try and find out exactly what the damage was but susppect front end.

According to the build codes it does and the diagnostics say no comms to control. The control is behind the glovebox, I've comfirmed it is there along with the wiring plug.

Will find out later.

Kenny

[darbuck]

Ah well then it has it . It may have been chopped off on the front end during the smack it could be just a case of go to a scrapper and get the front loom out of one that still has it. I would imagine it is common enough on them.

[darbuck]

Ok so I have the tested injectors in and cranked it over but wouldn't start. No fault codes. I have cam crank synchronization.Tried it with easy start and she fired up ran ok for a couple of seconds so it can run which means I have a fueling issue. I haven't coded injectors yet so will do that in the morning. I think there might be air in the pipework but can't be sure. Any other suggested checks

[darbuck]

Ok got it running on it's own. It was air locked I disconnected the injectors electrically and mechanically and now it runs rough and the engine bounces a good bit. I can't get it to accelerate above 1200 1500 rpm and it sounds really clunky if I do so I don't want to do it much. I tried disconnecting the Flexi behind the maf and it shuts off straight away. This tells me I have a fuel delivery problem to the injectors, I still have to code them and I need to plug it in for codes but getting it to start is good start for my sanity. The laptop is charging away so I'm hoping to plug it in tomorrow.

[darbuck]

There are no codes, Ok so I plugged it in and the reference rail pressure is 349 and the actual is 322. The regulator is showing as regulated and 37% open. That means it is 27 bar or 391psi of a difference . According to info Marc gave me in a different thread at idle it should be about 230 bar and There should be a maximum of 250-300 psi difference so I think the regulator I put in 2023 is either a dud or I fried it when I had the plugs for it and the exhaust temperature sensor reversed or something. Unless of course it damaged the driver in the ECU. I replaced it at the time because the car was slow to start and I had it out for testing anyway. I think I will throw the old one back in and see if it makes a difference.This is my theory at present. Can anyone suggest another reason for high fuel pressure.

If it is it explains the rough idle. Unfortunately I think I changed a perfectly good engine unnecessarily . I do have two cars with that engine now so no harm to have a spare if the unthinkable happens.

[darbuck]

Ok so programmed in injectors and runs better and revs up. Engine still jumping a bit but no where near as bad as it was.The fuel rail pressure has eased off after I discovered a kink in the return line it was very slight but enough to cause an issue apparently. I have a temporary fix done on it for now. I have a coolant and I think a boost leak at the back of the engine. I have had a look at the injectors on diagbox and 2 are showing 146ms and the other two are saying -147ms. I'm not sure what this means. I know I'm nearly there but something is not quite right with the fuel system I think I'm still questioning the regulator. I am getting a lot of water coming out of the exhaust but this could be still from when I cleaned the Dpf I used a hell of a lot of water to clean it and they have a huge surface area for water to hide. The boost leak sounds like it might be at the cat egr or the exhaust but I can't see enough to tell. It will probably be after Christmas before I get at it again.

[KennyW]

Darren,

Giant step forward with engine running. Keep it up you are almost there. Sorry, can't think what could be causing the 'lumpy' running.
I'm thinking is the ecu an exact match as we know slight differences can cause major problems.

Kenny

[darbuck]

Hi Kenny it's the original ECU so I don't think it's a match issue but it could be a control issue. I'm not sure what it is but I think it is still fuel/air ratio related I a few bits I need to do.at the back of the engine which I am not relishing doing given my experience with the back of the engine.
As you say it still isn't too bad as I have it running and it's not smoking so some progress at least as you say. The sensors all are off the original engine so the only differences would be mechanical and the injectors. I need to find the leaks first anyway. They could be partial culprits. I will post up when I know more. How did you get on with the Audi.

[darbuck]

Hi all I think I am chasing the wrong problem here. I think it might be an air leak rather than a fueling issue and it might be to do with my pipe work. It is exhibiting the behaviour of a petrol with a vacuum leak. I know stociometric is higher in a diesel and mostly airleaks are ignored but they can still cause problems. I'm going to smoke test it today to see if I can find the a leak when herself isn't looking. I have all the Christmas stuff under control at this stage so I will have time on my hands.

[darbuck]

I have smoke tested the engine and the egr to intake flange is leaking and it is leaking at the egr pipe clamp as well. It's also leaking from the lower plastic turbo to intercooler pipe. Im not sure it would be enough to cause it to idle erratically though. I have also found a coolant leak at the rear of the engine that can't be accessed with the engine in the car so I am now back to having to pull the bloody engine again!!!. There is a pipe clamp off a main feed hose that I missed needed. So not a happy camper. The unmetered air could theoretically cause poor idling I will also test the regulator when I have the engine out. I just keep telling myself the engine runs so its worth a shot I think.

[myglaren]

I think that you deserve the 2024 percywhatsit award.

[darbuck]

I don't know what that means but ok, if it's for stupidity and determination I probably do.

[darbuck]

It's the rear of this pipe that is leaking I'm going to try to fix it in situ