Engine cut-off.. speed sensor fault?

[audi660]

I've just done the 1.8T coil mod on my S6 and the car is pulling very strong! Only problem is that the engine seems to cut off for a split second or so and the car does a nose dive. I'm getting engine speed sensor intermittent signal when VAG is plugged in.
This morning the VAG was plugged in while the engine was running, then the car just died and the codes were engine speed sensor and flywheel reference pin. I cleared the codes and started up the engine again.
Can anyone help me with this please...

[urquattro-island]

maybe

you should change the speed sender, this seems to be your problem. Have changed a few of these in my time as a mech...

[audi660]

Found the problem
It was a bad connection on the common power supply to the coils..
Thanx

[A80Avant]

are the 1.8T coils better than the S2/RS2 ones?

[audi660]

Yeah they are, making loads more power and car is very smooth now.
That cut-out prob has come back and dont know what it is..
anyone know what the voltage on the wires going to the 2 pos units to supply power is?

[ezveedub]

Yeah they are, making loads more power and car is very smooth now.
That cut-out prob has come back and dont know what it is..
anyone know what the voltage on the wires going to the 2 pos units to supply power is?

I had the same issue. I changed the CPS, but still had issue. I believe its the POS on the driver's side of the bracket (runs Cyl 1,2 & 3). Try swapping them and apply good thermal paste to the back of them. See if you know get a possible flat spot around 4K RPM. Thats what mine did, so I changed it out the passenger side POS (swapped from driver's side). I haven't seen an issue since last week. I believe since it may have an issue cutting out it will affect Cyl 1 timing, some the G28 references with.
Regards,
Ernest

[UrS4boy]

Yeah they are, making loads more power and car is very smooth now.
That cut-out prob has come back and dont know what it is..
anyone know what the voltage on the wires going to the 2 pos units to supply power is?

Did you use the DIY instructions that I wrote? As far as I remember, the switching voltage to the POS units (either the stand alone OEM ones or the internal POSs in the 1.8t coil packs) comes from the ECU at 5 V. The power to the coils should be 12 V and comes off two fire wall plugs (at least for an UrS4).

Do you happen to know Rudi D. in SA? He did a conversion on his 92 S4 and may be able to help you.

At this point, I suspect a bad connection somewhere.

Dave F.

[audi660]

Getting power to coils from the power wires that give power to the 2 original pos. Did the mod on another S2 and having the same issues.

[UrS4boy]

Other than a bad connection in your DIY coilpack conversion, I have to think that it is the engine speed sensor and/or crank position sensor (twins) located on the intake side of the engine near the bell housing. Clean and/or replace. Crank position pins have been known to fall off the flywheel (assuming you have an OEM flywheel). IF you have an aftermarket flywheel, the steel pins in the aluminium flywheels sometimes are too far away from the crank position sensor, causing the ECU to lose track of where the engine is in its rotation - so it shuts the engine down.

HTH

Dave F.

[macspring]

Too many questions ???

Hi,

I have similarish problem with a 1995 standard ABY Avant, on which the VAG codes indicate the engine speed sensor, G28, as being faulty. The sympton is that the car is slighty reluctant to start, two seconds longer than it used to. It idles rough and has difficulty pulling away cold, especially going uphill, (extra weight rather than the angle of the car). It behaves like a small cold engine carburettor'd car when the choke has not been pulled. Also when driving along at say a steady speed, 40mph or 60mph, it is every couple of seconds, doing the opposite of surging forward. Minor hesitancy.

It is like the electrics are being reduced rather than being cut off completly, as the effect is not dramatic, but can be sensed none the less. It also feels like it has less power than normal, but will redline and "go" if forced, but you know you are forcing the engine rather that its previous/usual willingness to rev. A new engine speed sensor is on VOR and I should have it fitted by Monday evening 21/08/06. So I'll let you know if this cures it, but in the meantime, if anyone has any comments please share your experience or opinion.

After the problem above is cured, I am also going to fit a new fuel pressure regulator on the end of the fuel rail, a new N75 solenoid valve, and a new lamda probe, one after another to see if there is any advantage to be had. The car has done 110K and is standard apart from a new S3 recirculation valve.

Has anyone had a genuine fault with one of these items and what were the symptoms before finding the cure?

Is the fuel filter replacemnet as awkward as I think it is going to be? Any gottcha's to be aware of?

Thank you.

[mastermind]

I think if you check with VAG while the engine is not running, it should give you a speed sensor problem.
I seem to be getting the same problem, noticed it on track day a month ago but doesnt happen on normal daily use. I havent changed coils or POS yet.
I noticed that a faulty Lambda sensor I had, causes a flat spot under light acceleration especially when the engine's cold.

[audi660]

I have replaced the lambda, ignition point sensor and also speed sensor. The car gives no fault codes and then all of a sudden comes up with internal memory error code, which points to an earth problem.
When this code comes up, the car starts with its "engine cut off" problems and also get very bad backfire now and then.
The car also starts smoking alot when the pos connector is sometimes moved round..
Hve just changed back knock sensor but no luck yet.
When wiggling the pos connector (coil 4 & 5) around, the problem seems to get either worse or a little better.
Maybe intermittent brake in a wire in the wiring harness??

[UrS4boy]

Maybe intermittent break in a wire in the wiring harness??

I think you found your problem: The POS or the POS connection serving 4 and 5. If you haven't already replaced the POS, do so. (You can use the V6 POS - brown by Hitachi - if you are strapped for cash). But maybe, first, pull the connector cable off, pull back the rubber boot and look for a broken wire or a bad pin connection.

Dave F.

[audi660]

Think ive found the problem.. A faulty TPS!!!
When measuring the ohms across pin 2 & 3 from closed to WOT, The reading is 950ohms to 2400ohms. Between 1200ohms & 1500ohms & also at WOT there is an intermittent break and I get an open circuit.
Does anyone know what the values should be from closed to WOT?
How do I repair the TPS?

[martinjs]

0.75 - 1.3k ohm at idle position.
3.6k ohm maximum at WOT