My S2 coupe bit of a rebuild and repair thread.

[K Simmonds]

Good idea to at least get a set of terminals as spares, they're pretty easy to replace.

I know it's yet more expense but perhaps investing in a can of Deoxit D5 would be a good idea for ensuring good continuity between connections, I'm yet to use it on anything automotive but it works wonders of Hifi electronics. A 5oz tin will probably last you for life.

[B5NUT]

Thanks will take a look at the pins again. As they look plated I don't want to clean them as it were. Will take a look at ekta and see what type they are and get some ordered.

[K Simmonds]

Indeed those MAF connections can be highly problematic, I twist mine ever so slightly with some fine nosed pliers or a pick to ensure good contact. I dare say a squirt of Deoxit D5 wouldn't go amiss as well, will be doing that as well from now on.

[newsh]

Excellent news!

MAF pins certainly look ok, but then they always do. The tiniest bit of corrosion, just where the pin makes contact and passes the current, adds a little resistance which can screw the air mass reading. Just bear it in mind if you get any mixture adaptation codes, or the car starts feeling a bit limp and using more fuel.

[psiconauta911]

Once again sorry B5NUT for posting on your thread about something that dosen´t relate to your car but as a conclusion to my AC problems. Last friday I removed my condenser and took it to a repair shop, it was ready yesterday, 3 leaks found and repaired, instaled it today morning and got it regassed and it is now working.

By the way great job you´ve done, you should be proud after so many hours and sore knuckles to be able to drive such an awsome motor.

[B5NUT]

Received the Bosch Lambda sensor this morning, so cracked on removing the old one. It put up a hell of a fight. My lambda removal tool would not touch it. It just started spreading apart at the bottom of the socket and slipping on the nut. Thankfully found a more heavy duty removal tool at Machine Mart that did the trick.

Does not look in the best of condition and 2 out of the 3 holes were almost blocked.
1-lambda.jpg

If I'm reading this right it was manufactured week 51 1994 so the original sensor for the car.
2-lambda.jpg

Went back to the garage that tested the car and now the emissions excellent and well below the limit. He was surprised by how much the car has improved.

I'm stilling to looking at changing all the rubber the vacuum lines and pressure test the boost hoses. However it does not look to be the cause of my issues as along with the improvement on emissions the fuel economy has also improved and it's back to normal if not better.

[K Simmonds]

Well in my opinion anyone who has a '(not at all) Superchips' set up on their car deserves slating. Has to be the worst aftermarket set up I've seen by some considerable margin. You could probably trick one into making as much power with a £20 bleed valve.

Sent from my SM-A115F using Tapatalk

[B5NUT]

No idea if the last owner is has been or has registered on the forum. I hope not has I have slated him enough

I did not mind the NGK sensor but preferred the Bosch one. It was also cheaper as well.

[K Simmonds]

Yeah they do look good, nice and clean as well as tight. I can't recall if their Gold plated as stock (I think they are) but we did a at least one group buy of replacement Gold plated terminals on here a good many years ago as I can remember doing mine. Was the previous owner on here?

Bosch senders are a better job so perhaps that's worked out for the best, though I'm not going to start slating NGK's stuff, as rule they're pretty good quality.

[B5NUT]

Well the NGK Lambda did not arrive at the parts supplier. So have 2 Bosch sensors on order from different suppliers that should arrive tomorrow.

In respect to the pins on the MAF connector they all look in very good condition, they look like they are gold plated...
connectors.jpg

[newsh]

If the vac line to the Fuel Pressure Reg is leaking a little it can cause rich running off boost and lean running on boost. A bigger IM leak can cause the reverse! Everything from the MAF onwards needs to be super airtight.

Your mileage is pretty good but might get better yet

Clean or replace the pins in your MAF connector if you haven’t done so yet.

[B5NUT]

Thanks John, The sensor I was able to next next day was an NGK one and it's from an Alliance Automotive group factors so it should be a good one. I would have rather have a Bosch sensor but that was all that's available in the short term, and NGK are a good brand and they are the only ones that do the plugs for the cars these days. However I will source a Bosch sensor as a backup.

There is insulation on the downpipe but that's about it. It could be the cats were not fully up to temperature. Tomorrow when I replace the sensor I'm going back to the garage as he said would keep checking the emissions until it's fixed. He known's what I'm like with my cars they have to be right.

Just had a quick look at the history of the car and there has been nothing there about emissions, But I guess a pass is a pass regardless of how close it is to the limit line.
mot history.jpg

[johne]

The new lambda sensor needs to be genuine Bosch, lambdas are one of the worst areas for cheap copies that don't work well, should cost you around £60.

You can read your lambda values in VagCom if you have that or you can buy a cheap narrowband gauge for £15 to read the values. Using a DVM to do it really isn't that easy - should be around 0.5 volt BTW.

Your MPG figures sound reasonable for around town driving, you need motorway cruise to see the 30's.

Our cars are hard to get the cats up to temperature for the MOT emission test especially if you have no insulation around the pipes between the turbo and the cats.

Your "high emissions" may be no more than the combination of poor aftermarket cats and them not being hot enough to work properly for the test. How many times did the tester have to run the test to get the machine to pass you?

and do make sure all your small vacuum pipes are in good order......

[B5NUT]

Thanks for the information. The engine is my next study program as it were. I just need to find a good service manual on the ABY engine.

Just after I put the post about the rich running of the engine I did a search and a forum member PM'd me with a few fault finding idea's. One of them is the coolant temperature sensor. With the initial over heating problems I was having with the car about 6/7 months ago I purchased every temperature sensor on the car, but I never got around to replacing that sensor. So this afternoon I have replaced the coolant sensor on the back of the block.

I've also ordered a new Lambda sensor and that should be with me on Monday morning so it will be replaced then regardless. I've Just seen how to test a lambda sensor, and wondered if it can be done with the sensor on the car. So I just set the meter to read DC voltage, connect the positive lead to the black wire on the sensor and the negative lead to the harness on the car and then start the engine. From what I understand a good Lambda will generate about 1 volt. Or is it best to remove the sensor off the car and do the blowtorch test?

Had a look for the part number on that BMW hose and after a quick google search it's only coming up with search results from the US. Need to see if I can find something from the UK.

Currently my DIS is reporting MPG of around 26-28MPG. However I think it's dropped a little over the last week or so to around 24MPG. Not a massive drop but a drop. Out of curiosity is my mpg good bad or just plain ugly? Note it's standard ABY S2 not mapped in any way.

Also this is the first time I've put the car through the MOT. So I have no idea what the previous reading were. Also the last MOT was not worth the paper it was printed on there were so my issues on the car it should have never passed an MOT. The last tester must have got a hell of a back hander to pass that car with no advisories!

The vacuum lines on the car don't look the best and some to appear to be a little lose it be the fact the ear clamps have badly rusted and not gripping the pipe very well. So I will have to replace them regardless. Just need the pipe and some correct size ear clamps.

[Lago Blue]

Re: Running rich

While waiting for a new lambda sensor, know that they can be tested in situ. for function (w/ a good automotive DMM), and that the following may be much cheaper and help prolong downstream component life.

If those exhaust readings/smell check are taken at idle, it may be that the FPR is either not receiving, or capable of holding full warm engine vacuum, which should be 18 to 19 inches of water column at idle. As you may know, full vac. is required to both reduce fuel pressure at idle, and to also have that fuel pressure ramp up when not, as the ECU is expecting to have use of that full range of fuel delivery pressures (from fully reduced, to full) during those rapid transitions both to and from idle. What this does is balance fuel pressure to the instantaneous (and quickly varying) manifold vacuum, to achieve close to correct fuel delivery, such that the O2 sensor et al; can then possibly manage the last little adjustment.

From the Audi 20v Turbo training manual:

"The pressure regulator maintains
the fuel pressure at approximately 3 bar (43.5 psi)
above intake manifold pressure."

"At idle, only a small quantity of fuel is needed to
maintain engine operation. Vacuum from the intake
manifold is applied to the diaphragm and spring in
the pressure regulator which allows more fuel to
return to the fuel tank to maintain correct fuel
pressure."

Even though there is a dedicated vac. line directly from the I/M to the FPR, the I/M itself may not ever contain full engine vacuum for use if there are leaks out in any of the various branches of the vac. system. Typically, it's the hard plastic and soft rubber vacuum plumbing that becomes defective first, but the FPR diaphram can leak also (can create a kind of 6th injector effect!). One can do vac leak-down tests over time for the entire vac. system, branch by branch (all the way back to the rear. diff actuator on a Cq) to check for leak locations.

If less than current century thick-walled proper synthetic small-bore vac. hose is used (the now less than current BMW dealer issue smooth exterior black hose is very good and has correct ID for tight connections on our existing Audi vac plumbing), under-spec hose can partially (with heat and/or hose bends) or fully collapse in use, impeding vac. delivery.



BMW vac hose Screen Shot 2022-05-28 at 10.13.50.png image_85212.png