I have been suffering from poor performance on my Aero for a few years now, with the boost gauge generally only going to the middle of the yellow, but occasionally going further to the right to remind me of how life used to be.
Earlier this year I invested in a hand held ODB reader and carried out some tests with a passenger looking at the live data to see if I could identify if the issue was lack of boost or ignition being retarded. I concluded that the issue was boost and after reading around (again) picked up on the failure of the one way check valves on the EVAP system as being lthe likely cause.
This was confirmed by blocking the relevant pipes and doing a test drive with the dealer with his Tech II connected. The readings from Tech II and the ODB reader were consistent. MAP values were as follows:
Original: maximum around 148kpa
Pipe blocked: maximum around 204kpa
After the long preamble, here's my question. Does anybody know what the correct value should be ?
I'm delighted the car will be back as she used to be when the valves are replaced but the MAP value seems higher than I was expecting & I would like to be sure that the boost levels are not too high which is masking another problem.
Thanks
I can't tell you the exact value but I'm fairly sure that around 200 is somewhere around "correct" remember that the car will adapt back after a while to be whatever specification is. As it couldn't reach target boost pressure it may be going a bit higher for now but the car should pull it back after a while, simply put get the valves replaced and see what happens!
AIUI there isn't a specific value mapped (unlike T5) because the ECU requests a certain air mass, not a boost pressure. It achieves the required figure by a combination of throttle position and boost pressure- if it can't get enough air from throttle position alone, it ups the boost pressure.
The cheap and nasty fix for the failed valve is to disconnect the R pipe from the APC solenoid and leave it plugged with a bolt or similar.
That's what I believe is correct, I think it will put on a CEL above certain values though, somewhere around 200 seems familiar but that may be after ripping a car to bits and putting it back together... but I think that they may settle down to ~180kpa.
Thanks guys - good answers, quickly just like the old place. :)
I'll wait until the one way valves are installed and take the readings again & post here.
If the "right" answer is 180-200 kpa, that's higher than I thought as I believed that even the Aero only ran about 0.65 bar boost, so would have expected 165-170 kpa as a test value
If you think back to the 9000, which had similar output, peak boost for an Aero was over 1 bar relative to atmospheric (>200kpa absolute). So 200kpa seems the right sort of range.
Not sure about absolute boost levels but if the air mass (which at WOT is analagous to boost) exceeds the requested amount then a DTC is generated.
WIS only gives a pressure/voltage chart. This only goes up to 175KPa with 100KPa being atmospheric.
Well, I've had my Aero back to normal for a couple of weeks now and am still enjoying it !
As promised I'm posting back with my MAP values so others can compare:
Checked it about a dozen times last weekend. Generally showed 190-195 kPa at around 3000 rpm. A couple of times I saw more than 200kPa with a "best" of 212kPa, which I guess when it was on overboost.
In everyday language it looks like normal boost is 0.9 bar with overboost perhaps allowing up to 1.1 bar.
It would be nice for others (with ODB readers) to post their results