No boost after engine/turbo upgrade

[gmac78]

Cheers for that Paul, yeh hoping something is a miss inside the ECU connector, these wires felt quite stretched when i was putting it back together. It certainly didn't go back together as neat as it was when i first opened it.

[UrS4boy]

Removing Pins From the T55 ECU connector (for future reference)

Cheers for that Paul, yeh hoping something is a miss inside the ECU connector, these wires felt quite stretched when i was putting it back together. It certainly didn't go back together as neat as it was when i first opened it.

Not sure if this is going to help or not:

Removing Pins From the T55 ECU connector (for future reference):

http://forums.quattroworld.com/s4s6/msgs/212815.phtml

[gmac78]

Alright troops.

Not really getting a chance to get near the S2 this time home, kids taking up all my time. All i've done really is to open up the ECU harness and inspect the wiring for anything obvious. Nothing found (ish). Pins 44 and 30 for IAT have been checked for continuity against all the other pins in the harness and there seems to be no short between them. However, whilst inspecting in and around the ECU connector i somehow blew one of the Moteur fuses. I inspected the ECU connector harness again and couldn't see what caused the short but something i touched obviously shorted out. Fitted a new fuse and gave the ECU harness a good wiggle but couldn't get it to blow another fuse.

Swapped RS2 V stream chips for the TS Tuning ones i had which made no difference, still IAT temps slowly rising to 97- 100 degC.

I'm thinking whether right or wrong, if ECU pins 44 and 30 are not shorting against any others in the ECU connector, then you would think the issue would be further back within the ECU itself?

Do you think that if pins were inserted incorrectly elsewhere in the harness, they would cause the IAT to rise even although currently pins 44 and 30 are open circuit as not connected to the sensor?

Hope that makes sense?

To cheer myself up and get my 5 Pot fix, i bought myself a 2007 Volvo S60 2.4D and a DTUK tuning box. All i can say is this thing is a hoot to drive, what a difference the tuning box makes, very un-diesel like power delivery, loves to be revved and lovely sounding vocal engine. Just can't stop smiling when driving it, loads of grunt!!

Anyhow, what i really want is to sample RS2 power!! I think i'l need to try another ECU if anyone has one they will sell?

Cheers

[UrS4boy]

Pin T55/30 is just a common grounding point for seven ECU-related devices:

The seven devices are, left to right,

1. G61 knock sensor, 2. G66 knock sensor, 3. Idle switch/throttle potentiometer, 4. F96 Altitude sensor, 5. G62 engine coolant temp sensor, 6. G42 Intake air temp sensor and 7. Coding card for trip computer (probably regardless of whether the trip computer is installed or not).

AAN ECU schematic



ABY/ADU ECU schematic:



Pin T55/44 is the G42 IAT signal to the ECU

2322 (Blink Fault Code), 00523 VAG1551/2 Fault Code Number
Inlet air temp sensor (G42)
Open or short circuit, Defective sensor or wiring
Symptom: Slight power loss, Increase in fuel consumption
(Reference SJM Autotechnik)

The G42 IAT is connected to the ECU via pin T55/44 (with a blue striped brown wire (BR/BL) for an AAN). A digital multimeter can be used to measure the resistance of the two-pin device G42 intake air sensor with the connector harness removed. With the engine OFF long enough to cool sufficiently, at an ambient air temperature of 20 degrees, a value of 450-650 ohms should be measured across G42.

From Audi, via SJM Autotechnik:



REFERENCE:

G42 Intake Air Temp sensor info:

http://forums.quattroworld.com/s4s6/msgs/20996.phtml

[gmac78]

Evening all,

The last couple of days i've managed to trace all the wiring from the ECU to their relevant connections checking for continuity, grounds etc with nothing untoward found. All ECU pins were inserted correctly and in the right designation. I was kind off disheartened as i was hoping i would find something but everything checked out good and was done correctly as per the 3B to ABY conversion.

So, i went for a start just to make sure i had refitted all the connections correctly, she fired up no bother and let her tick over on idle. Something was bothering me with the high IAT temps i had been observing previously so whilst the car was idling with VCDS connected i decided to pull the connection of the coolant temp sensor G62 just to see what would happen. Other than a change in idle, i noticed the reading on VCDS jump from 33 deg to 66 deg?? EH???? Reconnected plug, idle went back to normal and the reading on VCDS returned to around 34 degC. This is when the penny dropped!!

After all this hassle, going through all the wiring etc i had been looking at the wrong temp on VCDS all the time, i never noticed the IAT temp reading which was on measuring block 2 or 3, can't remember now. How on earth did i miss that?!!!!n Aaargh i'm so annoyed with myself!!

Anyhow, i guess that proves that my ECU is ok now as the correct IAT of between 20 and 30degC was observed during my wee blast out on the road.

However i'm still not getting full boost, max i saw was 1.6 bar with a hesitation in the higher revs. Once i got back to base i scanned for codes and
00515 Hall sensor Intermittent code was present.

As previously discovered, with the car idling, if i alter the dizzy one way or another i can get these fault codes to illuminate the blink light on the dash so is there an exact sweet spot where the dizzy needs to be? Or can it be a wee bit off either way and still work spot on?

With the car running the dizzy can be moved quite some way in either direction and still remain running. I'm just not convinced it's in the exact right spot at the moment.

Come on 3B owners, what can i be doing wrong with regards to the dizzy setting.

Cheers
Gordon

[LHD_Kid]

Mine never seemed that sensitive to the position of the dizzy. I always set everything on the marks at TDC then the dizzy on its mark and no issues...

I'm sure you're fully aware of all the marks, but you should see a dimple on the lower cam cover lines up with a line on the crank pulley, the cam pulley lines up with the notch on the cam cover. (Also I think there is a line on the rear of the cam pulley). An "0" on the flywheel visible through the little window and finally the rotor arm in the dizzy.

With the cam cover off you would see two "0"s facing each other on the camshaft cogs...

Edit: is there any play in your dizzy - it has the correct narrow tipped rotor arm?

[UrS4boy]

With the cam cover off you would see two "0"s facing each other on the camshaft cogs...

Something like this?

[Error404]

My guess is the ABY/RS2 ECU uses the hall sensor slightly differently.
In the Pico link Robin posted there was some really useful info in there about the relationship between crank reference and cam position. I think you really need to make sure this is bang on. A cheap scope could save you a lot of time & effort

[twoqu]

I guess the sweet spot is going to be where ever the dizzy position does not throw any cam sensor fault!

[gmac78]

Evening gents,

I've finally managed to get the car running without any dizzy codes been thrown so happy with that. The sweet spot wasn't too far away from what it was set at so one to remember for future reference. However i still can not get full boost, max around 1.6 bar. I checked my F96 Altitude sensor and across pins 1 and 2 it was showing 490ohms, quite some way off from the 1200ohms it should be at sea level. Quickly tweaked it so it was showing 1200ohms and off for another spin.

I was sure that was going to be the root cause of my boost issue but strangely it did not really alter max boost, so i'm back to square one again. All timing marks are spot on, they we're double and triple checked when putting everything back together so no issues there.

About the only thing that i haven't replaced on this car is the boost recirculating valve, however i did check it with a midivac before refitting it to the car and was holding a vacuum no problem. Is this enough of a check to confirm it is ok?

I've not tried the TS tuning chips yet so think that might be the next port of call.

Any other good ideas for me to try?

[twoqu]

If the valve is original then its going to sub optimal at 25 years old plus!
Although you have tested the integrity of the diaphram, its not really a test of the spring.
Might be worth a punt as others have restored stock cars performance with a replacement.

[UrS4boy]

About the only thing that i haven't replaced on this car is the boost recirculating valve, however i did check it with a midivac before refitting it to the car and was holding a vacuum no problem. Is this enough of a check to confirm it is ok?

By-pass valve info (at one point the 710N was the "hot" replacement for stock)

http://forums.quattroworld.com/s4s6/msgs/20994.phtml

[gmac78]

Tonights i fiddled with the F96 trying different resistance readings across pins 1 and 2, varying from 600 ohms to 1500 ohms, again no difference to boost so put it back to 1200ohms.

I decided to try the TS Tuning chips for the first time so got them fitted and went for a blast. At first i took a slow spin round the local roads just to get a feel for them, then slowly applied boost making sure AFR's were safe. All seemed good so went for a proper WOT spin, defo pulling harder than the homefry up to around 1.5 - 1.6 bar where i encountered an all mighty bang between 5-6k rpm!!! Oh ****** i thought i had blown the engine, however it was still running spot on. What the hell happened there i was thinking? Carried on for a bit then applied boost again up to 1.5-1.6 bar and when the revs reached around 5.5k, the bang happened again and i was kind off thrown forward, the rev counter needle flicked back to almost zero then back up the rev range.

Drove home to scan for codes but none present.

Is this sudden loss of power some kind of boost cut?? Never experienced that before and the homefry chips didn't do it.

Anyhow the car drives spot on up until 5-6k but still only geting 1.5-1.6 bar boost. My boost gauge back lighting is goosed and it was starting to get dark so couldn't get an accurate reading but certainly not getting the 1.9 bar i should be wth these chips either.

These things are sent to test us eh!!

Any thoughts gents?

[UrS4boy]

Ha Ha. Classic. Boy gets new chips. Drives the bag off the car and discovers that he has a hidden boost leak.

Time for a boost leak test.

http://www.s2forum.com/forum/showthread.php?t=63974&highlight=ABY+boost+leak

One of the usual ABY/ADU suspects:

[gmac78]

I pressure tested to 2bar and no leaks, this was a couple of weeks ago but worth checking again perhaps. Not convinced this is a boost leak issue but you never know.