Engine Cut Out Around 4500 RPM

[gmac78]

Are they TS tuning chips? Sounds very similar to a problem i had. If they are TS chips they store 100's of fault codes once powered up for the first time. Once the codes are cleared the issues will disappear. Mine used to rev to a similar rpm then hard cut, and rpm needle used to bounce of zero.

If i rem correctly it took a few attempts to get vcds to connect to the ecu, but once it did connect it connected first time every time there after.

Cheers

[gmac78]

Also if it is TS chips, it takes a min or so for VCDS to retrieve them all as theres so many initially. Good luck fella.

[steverrquattro]

Also if it is TS chips, it takes a min or so for VCDS to retrieve them all as theres so many initially. Good luck fella.

Yes I believe it is the TS chips. Can't wait to get it sorted.

[gmac78]

My monies on all the hundreds of fault codes that first show up. Had me stumped for a while as no codes were coming up when I first scanned, however after a wee while a list will appear. Darn good chips these TS ones!!

[steverrquattro]

My monies on all the hundreds of fault codes that first show up. Had me stumped for a while as no codes were coming up when I first scanned, however after a wee while a list will appear. Darn good chips these TS ones!!

I did the scan and nothing showed up. So do I just leave it plugged in and for how long?

[gmac78]

Does the scan complete and come back with zero codes or do you initiate the scan then it kind of hangs for a while?

I can't rem exactly how long it took but it was long enough for me to think it wasn't working and abort the search. Try Initiating the scan and leave it for a couple of minutes.

[Cordoba16vt]

Are you sure ECU reads vehicle speed ? if not you are in limp mode

[steverrquattro]

A very interesting day and a big thanks to AndyP and Mac2226 for coming along and helping.

Here's how it went:

Connected the laptop via the OBDII setup to the blue and black connectors dangling down beneath the glove box. Nothing on Andy's laptop as it failed to connect as it did to my ebay scanner.

Removed centre console, glove box and section under the steering wheel so that the ECU can be brought out so that the green and red wire can be checked back to Pin 55 for continuity. Unfortunately there was no connection, so the correct wire was found and wired into the blue connector.

Still not reading, so checking the wiring and one wire was missing which was dangling nearby with a different type of metal connector fitted? This was wired into the blue connector and then there was a connection with the laptop and also the code reader with some 200+ codes stored. These were then cleared and the car test driven.

Meanwhile. Mike with his smoke machine had checked all pipes for leaks and everything was tight as it should be. In other words, no boost leaks.

After the car was test driven, the codes subsequently pulled with just x4 faults showing, I think? Altitude sensor, throttle potentiometer, speed sensor + one other I can't remember. One thing to note that during the test drive there was no boost but it did not cut out. That said I found a loose jubilee clip the day before which I re-tightened.

The TDC sensor and speed sensor on the bell housing were found to be very loose and tightened.

I've since measured the voltage on the throttle potentiometer and this was 0.2V closed and 4.8V on WOT. For resistance checks it was just under 1000 ohms and 2530 ohms at WOT although SJMautotechnik say I should be looking for 2800 ohms.

I removed the altitude sensor just to visually check it over and re-fitted.

A further test drive and two codes are now left:

00281 Road speed signal. Is this the same as the RPM sensor, the one that had just been tightened? Note that I am using analogue clocks, so I use the mechanical cable arrangement straight out of the 5 speed gearbox, but I thought that this sensor is different from the speed one (G66).

00528 Altitude sensor. How can I test this? BOSCH part number is 0280101001

So, apart from my car looking like it did three years ago, I believe we are making progress.

[AndyP]

Still no boost I'm guessing?

Some info here for testing the altitude sensor:-

https://www.s2forum.com/forum/techni...ude-sensor-f96

00281 is the VSS signal which on the S2 comes from the hall sensor on the front left gearbox output flange, not sure where this is going to come from on your car as you have a mechanical speedo??

[steverrquattro]

I've done some reading and here is what I found in relation to the altitude sensor:

Resistance

Pins 1-2 1.03K ohms
Pins 1-3 2.54K ohms
Pins 2-3 2.41K ohms

Voltage ref SJMautotechnik http://www.sjmautotechnik.com/troubl...ng/20valt.html

Pins 2-3 Expected 5V, measured 4.96 (Pin 2 is +ve supplied from ECU and pin 3 is ground)
Pins 1-3 Expected 4.1, measured 4.96 (Output voltage at an elevation between 600-800 feet. Actual is approximately 62 feet in sunny Doncaster)

Any comments?

[Cordoba16vt]

does ECU read road speed ?

[prj]

If ECU does not read road speed and the chips you have my LC in it, then there's the reason for your cutout.

[AndyP]

If ECU does not read road speed and the chips you have my LC in it, then there's the reason for your cutout.

The chips are not yours, they're TS Tuning

[prj]

Well then that's solved at least.

[steverrquattro]

Looking at the effects of the code 00281 which we know points to the G68 Road Speed Signal, in the table it references 'possible effects'.

-A/C compressor does not cut out

in 1st gear at full load

-Engine speed briefly drops below

idling speed when disengaging clutch

in overrun phase

-Engine speed limited to 5300rpm

(only with USA coding)

I presume that this problem will not effect, or be the cause of a lack of boost. I have also assumed that the Altitude Sensor readings that I have taken are also OK as they are similar to others. I will however swap the one from the RR at the weekend to see if this helps.

As a double check this evening I will have a look at the N75 and air circulation valve to make sure they are working and they are plumbed in correctly.