Member Since: 20 Jul 2015
Location: Here
Posts: 575
Those two should track together - I can't see what is causing a drop though, unless there is an overboost?
Maybe the turbo is spooling up too quickly? Which would indicate exhaust back pressure is the cause, but why all of a sudden?
I know you've done a pressure hold test, but could there be a leak that only shows at higher pressures? are there any signs (oily / sooty deposits) of charge air leakage around the inlet manifolds?
30th Sep 2022 10:54 pm
johnhorgan
Member Since: 23 Sep 2019
Location: Richmond
Posts: 117
I was accelerating quite steadily in the graph, maybe the reason it dropped suddenly was because it had reached its peak ?
There are no signs of any leaks or residues, I have sprayed soapy water sprays and easy start all over the place without any signs.
1st Oct 2022 7:26 pm
johnhorgan
Member Since: 23 Sep 2019
Location: Richmond
Posts: 117
I noticed that the fault P132B and the warning "engine fault" on the dashboard only occur after turning the car off and then on again.
As soon as I restart the engine the fault is back on the iid tool. If I just cycle the ignition after a test drive (having cleared the fault prior to the test) no fault is present. As soon as the engine is running the fault is shown.
1st Oct 2022 7:32 pm
Flatlander
Member Since: 20 Jul 2015
Location: Here
Posts: 575
Then it's a pressure measurement that doesn't agree with the mapping or commanded position. The end-to-end movement of the turbo actuator is OK - that bit of info you provided narrows it down quite a bit, i'd still try restricting the exhaust gas flow - BTW, are your EGR valves blanked?
ETA - you might have mentioned it previously, do the barometric pressure and the boost pressure give (very) similar readings with the ignition on but the engine at standstill? Also, does the intake (not ambient) air temperature read broadly correct - it will read high if the ignition is on but the engine not running. Is the charge air temperature sensor value plausible?
ETA2 - the drops in boost, did they coincide with gearchange? if not, they should be tailing off as the requested torque drops but not falling off a cliff!
1st Oct 2022 8:29 pm
johnhorgan
Member Since: 23 Sep 2019
Location: Richmond
Posts: 117
End to end movement of the turbo actuator is ok.
I tried blocking one side of the the exhaust but still the same fault code appeared when I ran the engine.
Egr valves are removed and blanked off.
Barometric and boost pressure readings are very similar 14.1psi and 14.5psi.
Intake (not ambient) air temperature is correct as is charge area temperature.
The drops shown on the graph were not manifold boost, but manifold boost pressure adjustment bank zero and boost pressure adjustment at full PID.
Manifold pressure dropped slightly, but this coincided with a drop in accelerator pedal voltage (slightly easing off the accelerator pedal).
I also tried another MAP sensor that had a big build up of soot all over it, but it read similar to the clean one I removed.
2nd Oct 2022 2:27 am
Flatlander
Member Since: 20 Jul 2015
Location: Here
Posts: 575
When you say EGR blanked and removed, are they also removed in the software? I wonder if that is the root cause?
To be honest, I'm running out of steam on this one...
3rd Oct 2022 3:28 pm
johnhorgan
Member Since: 23 Sep 2019
Location: Richmond
Posts: 117
I dont think it matters on a 2005 model.
I have been using this vehicle regularly without fault, I shall continue and see how it goes.
Thanks for your help, if you have any more thoughts let me know.
3rd Oct 2022 7:36 pm
Flatlander
Member Since: 20 Jul 2015
Location: Here
Posts: 575
It doesn't matter on that MY, I just wondered if you'd had any software mods done.
It's going to niggle me, I've got 2 weeks holidays coming up - wild camping without any comms, so I'll have plenty of time to ruminate over it! - expect some questions / suggestions when I get back.
3rd Oct 2022 8:06 pm
johnhorgan
Member Since: 23 Sep 2019
Location: Richmond
Posts: 117
3rd Oct 2022 9:56 pm
johnhorgan
Member Since: 23 Sep 2019
Location: Richmond
Posts: 117
Got the limp mode and message special functions not available today (for the first time), whilst accelerating briskly uphill.
I pulled over, turned the engine off and back on again, continued my journey (50 mile round trip) with the vehicle running normally.
When I got back I checked the fault codes again, this time a new code added to the list.
I now have P132B-00 (6C) and P0046-00 (68)
Vehicle is still running normally.
7th Oct 2022 9:06 am
johnhorgan
Member Since: 23 Sep 2019
Location: Richmond
Posts: 117
My understanding is, out of range boost, signal, or wiring.
Not sure which one though !
7th Oct 2022 7:24 pm
gstuart
Member Since: 21 Oct 2016
Location: kent
Posts: 13635
Hiya
Hope I’m not stepping on anyone’s toes but saw ur thread and had something similar
For me I had air leaks on the intercooler hoses , egr pipes where they met the throttle body and turbo actuator arm sticking , so fitted all new silicone hoses , T bolt clamps , greased actuator and freed off , plus put some cleaner into the fuel tank , new MAP sensor
Smoke tested after to ensure all the air leaks were fixed
Found using the iid when turning the ign on and off u can watch the travel of the actuator arm , ref Boost pressure adjustment - bank O
Member Since: 23 Sep 2019
Location: Richmond
Posts: 117
Thanks for your input, but I have tested for boost leaks and the actuator seems to be functioning normally.
Here is a shot of the readings when the limp mode, no special functions cut in whilst accelerating uphill on a cold morning.
43 psi manifold air pressure at the peak.
Blue Boost pressure adjustment bank 0
Green Boost pressure adjustment at full PID
Brown Manifold air pressure
Purple Mass air flow sensor A signal frequency
8th Oct 2022 10:38 pm
bigjc
Member Since: 24 Nov 2011
Location: Cheshire
Posts: 81
Did you ever get to the bottom of this?D3 G4 Selections car ‘08
L322 G4 2003 Event car ‘03
110 G4 Event car ‘03 and ‘06
Series 2a ‘68
25th Nov 2023 10:41 am
johnhorgan
Member Since: 23 Sep 2019
Location: Richmond
Posts: 117
No, but a friend of mine borrowed the vehicle and the turbo blew its load whilst he was accelerating uphill.
I told him it was overboosting and to not drive it with his foot to the floor, never mind.
I have not investigated much yet, but I did notice the actuator arm adjustment bolt has fallen out.
Maybe it rattled loose and affected the amount of boost.
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