UR Quattro 20v Injectors

[predding]

Thanks for the info - good to know on the inserts. After polishing and some careful easing, all injectors now fitted into rail. Its quite a job and no way could it be done with injectors fitted into the head as you need to ease the rings into the cups then press down with a flat bladed screwdriver on the grooves in the injector plastic body. I am sure there would have been a dedicated press tool for this in the factory. It needs alot of pressure and a final check to made sure they are all fully bedded and the grooves are at the same level. Will now refit the assy after lunch. Thanks for all your support

[newsh]

Pretty much how I've always done mine.

Nice job on the rail refurb

[predding]

Pretty much how I've always done mine.

Nice job on the rail refurb

Thanks so much, being stuck out here in the back of beyond is tough going. Its all re-assembled, I also got a brand new Varta battery too and she fired up well and idled smoothly but - same old same old. Under pressing the throttle quickly it gulps and splutters and pops and just wont pick up. If I do it, slowly its fine

Its almost like a vacuum leak issue but she runs smooth under low or zero load

I am at my wits end now, I have cleaned all the MAF and intake sensors and they were showing the correct resistance. Back when I started there were error codes on the OBD so maybe I will dig out my notes in the morning. Getting pretty tired of it all now...

[newsh]

Have you done a proper boost leak test?

[newsh]

Which part of back of beyond are you in?

[predding]

Have you done a proper boost leak test?

No as it dont know how to do that - can you give me any pointers. I had planned to drop the valance covers today and check all the turbo hosing for leaks. I am in SW France about 1 hour from Toulouse - it's like North Yorkshire :-)

[newsh]

Ok there are various how-to's on here but basically..
You need to make a bung for the MAF hose, you might find a plastic plumbing cap that fits or some kind of lid, I've even used a circle of plywood cut to size with a hole saw. Drill a hole in the middle and fit a schraeder valve (tyre valve) a tyre shop will sell you one for like 1 or 2 EU.
Pull the hose off at the MAF and cover the MAF with rags so you don't damage the screen or remove the top of the airbox to get some room to work. Plug the MAF hose with your test bung.

Now you need to pressurise the inlet tract with an air line, don't go over 1 bar like this as the PCV system (engine breather pipes) are still connected, these really only ever see vacuum on the atmospheric side of the turbo, you can isolate these by disconnecting the 20mm breather pipe at the MAF hose and plugging the MAF hose so the test still works.
If it won't hold any pressure (which I suspect) you've got a leak to find, as it's stumbling and stalling off idle it's likely a big one.
When you've found one leak and fixed it, retest and you'll find more smaller ones.
A lot of us have ended up replacing all the old rubber hoses with silicon including all the old cotton braided vac lines which also have to deal with boost pressure.

Many years ago in another life I had a girlfriend in Toulouse and we did some touring around that area and over into the Pyrenees, beautiful.

[predding]

This is great - thanks SO much again as this has given me a procedure to follow. Have printed it all out for the file :-)
I did call Pete at the White House garage yesterday and he also mentiuoned that he uses a pressuretest on the system so again, thanks so much for your help in explaining how to do it. I am time rich but knowledge poor ;-)

I did wonder about age deterioration on the hoses and will look at replacing them all since after 32 years there is bound to be some leakage due to material degradation, nothing lasts forever

I am also cleaning the MAF head (terminals not the wire) and was wondering what people use as a contact cleaner. Will then test again as I have the procedure from a specialist in Norfolk that tests and services the same Bosch unit for Porsche 928 cars. I will also check (again) the resistance and voltages across the terminals as per his instructions

I did make up a rudimentary test lamp ~ 3 years ago for the OBD and counted the (morse code) flashes to get the fail codes and it did suggest a mixture problem but again, I didnt have the knowledge to resolve it

I guess I should really start a new thread now we have moved onto misfiring issues...

Paul

PS We can see the Pyrenees from our house, best on a clear winter day with snow against the blue skies...

[predding]

Have found the perfect jar lid to fit internally into the MAF hose so just sourcing a Schraeder valve now

One quick question. Do you know how I could test the O2 sensor (electrically?) and generally how long they last? I have owned the car 30 years ie the sensor is original. Thanks

[predding]

Have now sourced Schraeder and attached electric pump - it wont pressurise any higher than 0.5 bar and immediately after switching off, there is a massive sigh of air as it escapes somewhere. So sounds like a joint isnt tight or a massive crack. Time to start dismantling and test, Cheers

[Dynasty]

Use soapy water to check for air leaks. The O2 sensors can i.e. be checked with a scope.

How to check for leaks:

https://www.s2forum.com/forum/techni...-testing-draft

[predding]

Use soapy water to check for air leaks. The O2 sensors can i.e. be checked with a scope.

How to check for leaks:

https://www.s2forum.com/forum/techni...-testing-draft

Thanks Dynasty - I have printed all that out and am following methodically (being abit slow I didnt realise I needed to make the required blockages) I have now pressure tested 2 of the 3x hose assemblies with plugs and the Schroeder; the Michelin hose is in fine fettle. The complex one is today. I will then refit them all using a light sealant on the large diameter conns and then block as per the diagram and test. Its a very draining exercise I have to say cos you dont know what the problem is/you are looking for an I am not an expert / have reduced confidence in what I used to do. And if it is all OK and leaves me with the MAF, which is giving correct readings on the MM, am starting to get a bit stuck The other area I will test is the accelerator pump while I have the long metal inlet duct off that runs parallel to the head as I did buy a vacuum gauge/tool some months back. I really want to find the problem as all the parts are in good nick and something has caused this due to it being standing for over 2 years albeit in a cold garage

[predding]

Small update - I have now tested all the hoses and no leaks at all, anywhere. Have checked thoroughly in side the Michelin one too with the steel ring supports and all good (it actually inflated slightly). I did find one of the intercooler rubber mounts sheared where the rubber meets the metal so it would have been relying on the hose connection for strength on that side but the other two mounts were strong so there was a tiny, tiny possibility there could have been a leak but unlikely. Just sourcing a new mount now and will then rebuild it all and move back onto testing the MAF.

[newsh]

URS4Boy's how-to post is very good for testing individual parts but in the end it's over complicated.
The system should hold 1 Bar with JUST THE BUNG IN THE MAF HOSE. This tests not just all the big hoses and pipes and the intercooler but also the PCV system and the Diverter Valve. You should also check the DV diaphragm by applying vacuum (sucking) on the small actuator hoe which runs to the valve fro the inlet manifold.

Did you test all the small bore vac tubes running from the back corner of the inlet manifold?
There's one to the DV, one to the ECU and one to the fuel pressure regulator, if they are original cotton braided pipes they will be rotten.

[predding]

Thanks newsh. I have just printed this last page and will use it as a check procedure when I have it all reconnected. I have some new small bore tubing so will replace the cotton braided pipes. Sorry to be dim, and I did search on here, but where is the ECU located on the RR 20v?

I have also now checked the MAF using the test procedure here https://forums.quattroworld.com/s4s6/msgs/20442.phtml ie

"Re-connect the MAF sensor harness connector. Peel back the rubber boot on the connector to expose the terminals. Switch the DMM to 20 VDC. Connect the DMM to the back side of Terminals 1 and 3. Turn the ignition switch to "ON" (run) but don't start the engine. Should be 1.2 to 1.5 Volts. Start the engine and let idle. Voltage reading should now be 2.5 volts. Increase the engine speed briefly (manually move the throttle position to more open). Voltage should increase to 3.0 to 5.0 volts (depending on engine speed). All the of the specified voltages must be obtained. If NO = replace MAF."

The original MAF is showing OK on the Ohms BUT there is NO volts between Terminals 1 and 3. I had bought a replacement copy/pattern MAF a couple of years ago and it made no difference just fitting it BUT this time it has registered 1.5 Volts which is in line with the procedure. I double checked the original MAF and nothing again. I havent check with the engine running yet as the pipework is off but will do so again and see what the OEM and replacement MAF show

I had been using the JDS Porsche test and either I must have missed this or maybe took the static test to be OK but this alternative test may reveal something.

I read somewhere that the pattern Chinese MAFs are no good and on the 20v RR it needs to be an OEM Bosch unit.

Anyway - I have found something...

Cheers