WOT Fault Resolved

[Greg_S]

Paul, mihnea can you confirm this one im confused now too.

Greg

[porkkis]

On 3B S2 it's certainly 0.6bar.

[porkkis]

Uh. I checked my altitude sensor. It showed 744ohms between 1 and 2 at ambient 1025mbar. I opened and twisted it 'til I got the reading of 1200ohms. 1-3 and 2-3 are both ~1100ohms. WTF?
I hope this unit is not supposed to be so sensitive that 1025mbar should give 744... I even might replace the whole thing with few resistors.

And afterall this procedure didn't change anything. It still boosts 1.6 = too much.

One thing I dont get. How is it even possible for the ecu to tell the n75 to raise boost over 1.5 as I have a 2.5 bar MAP.

[porkkis]

I'll continue my monologue. The problem is solved. Boost gauge to wg hose and the discovery was that everything is fine until WOT. Running on WOT there is absolutely no boost control. I've already ditched those chips.

[Martynf]

Another set of figures to throw into the mix:

Todays Barometric pressure is 1029.6 (UK south east and VERY sunny for once!)

Old barometric sensor on car:
1+2= 500 ohms
1+3= 2000 ohms
2+3= 2000 ohms (measured this many times, its correct?!)

New barometric sensor:
1+2= 900 ohms
1+3= 2300 ohms
2+3= 2000 ohms

Notes:
My ANALOGUE multimeter is old! I am pretty sure my ohm readings are about 100-200 ohms lower than they should be as the meter will not zero correctly, it is always about 100-200 ohms less than zero to start.

The vacuum pipes to the vapour trap: one of them goes through a 180 degree bend then to the green solid vacuum piping, this hose was not running smoothly through the 180 bend, it is folded over tightly and crushing the vacuum pipe! cannot be good!! will replace.

Martyn

[Martynf]

Verdict after a short drive, there is slightly more boost available now. I gotta get me a boost gauge! :-)

[porkkis]

Problem solved, again.

I'd recommend you not to trust any of the above mentioned resistance values as they're irrelevant.

Measure voltage over pins 1 and 3 when the unit is connected and ignition is turned on. I presume it should give 4.0 volts at 1000mbar as my friend's one gave 4,03 at around 1010mbar.

I twisted the thing back. It's only pretty damn hard to calibrate, took maaany iterations.

So ignore those resistance readings as they may vary depending on the internal design of the unit. I don't think they used the absolutely same part for over 20 years.

[Paulm]

Still no overboost

Old

1-2 1.183
1-3 2.74
2-3 2.42

New

1-2 .81, yes .81
1-3 2.27
2-3 2.41
any ideas

Paul

[ericd]

Sometimes they come back, this problem originally described and detailed by Jim on his car 4 years ago is still evident today, Looked at Irvin's car today (Jims old car)

528 - Barometric pressure (Altitude) Sensor (F96)
Open or Short to B+

This suggests that the sensor (f96) has failed within a 4 year timeframe, anybody got similar experience, towards the end of the thread they're seemed to b a bit of debate over the relevancy of actual measurements found on these sensors, can anybody reclarify specs for this sensor ?

[T2Andy]

Any one had any results lately by changing the f96 ,

[avants2turbo]

i know this thread is old, but i thought id test the 3 i have
1 2 3
1-2 1.3 0.72 0.74
1-3 2.66 2.29 2.24
2-3 2.41 2.41 2.41

The first one is off my coupe, and the other 2 are from avants, all 3 are ABY engined

Any ideas on this? Dont know what the air pressure is outside but im in tonbridge kent, its over cast and very windy, about 10-12 oC