MultiECUscan to assess VNT functioning - Alfa Romeo Forum
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MultiECUscan to assess VNT functioning

Recently I had a MM issue, and after reading the MM with MultiECUscan the error code was P0238, turbo pressure too high. For me the suspect is a clogged up VNT, so now I want to evaluate the VNT functioning by recording various parameters while driving.

The big question is: what parameters should I record and what should I look for in the recorded values? I am not limited to only 4 parameters btw, so I -could- just record them all...

I was expecting to find a big 'MultiECUscan' thread or something, too bad there isnīt one yet

Alfa 156SW 20v 2.4JTD
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requested and measured boost, rpm, VNT%

the more items you log, the slower it goes and the worse the result is.
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Had the exact same fault today.....I was going to see if the turbo actuator was free to move first.

I'm thinking of pulling the exhaust pipe off the turbo and trying the oven cleaner trick.....but I'm driving to Disneyland Paris on Friday!!!

I might see if the guys at AHM can have a quick look tomorrow!
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Done some digging and found that the turbo solenoid crops up alot on the Fiat sites because they keep failing when they get wet!!! and seen as the 159 one is located at the front of the bonnet/engine bay area it might be knackered.

Anyway, I disconnected the vac line to the turbo and gave it a good old suck and with a torch and mirror I could see that the actuator is working and pulling the mechanism a good amount. There is a filter in the turbo solenoid which I'll have a look at tomorrow and if messing around with the solenoid makes a difference I'll change it.

FYI 1.9JTDm solenoid P/n is 55203202 and is priced approx Ģ100ish.

I'll post my results....
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Theres been a few issues on here lately with solenoid potential issues, i wonder if once the weather turns wet then cold the solenoid gets sticky or the vent filter blinds.
Your right on issues on fiat especially stilos.
On my jtdm the solenoid is sitting on the lower member same height as radiator bottom , alongside the bottom of the air box, it was a fit fix later to move them up and bolt alongside the battery.
When i did fmic i cut a piece out of front to clear pipework but made a good job of patching hole and sealing it for this very reason.
Ive left mine where it is as always looks clean and dry under there when i change air filter.
Im sure ive seen threads on stripping and lubing valve but may need epoxy to rebuild.
Im sure a squirt of wd40 into ports and clean and dry vent filter wouldnt do any harm, if your thinking of changing it anyway.
You may need some vac pipe off ebay also as pipe seems to age harden /split
I think its inner dia 3mm or 4mm silicone vac pipe thats recomended,
I have a meter of both waiting for that day when i need to do mine.
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I braved the weather last night and disconnected the vac pipes from the solenoid and using a syringe I operated the solenoid. Drove it this morning and it seemed to make an improvement, but not cured, so I've bought a solenoid and will replace it. The car pulled slightly better and when the turbo was holding max boost it didn't go into Limp mode like it did over the weekend.
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OK, after cleaning the MAF and MAP I decided to take a punt and ordered a vac solenoid. Replaced it and the car is now driving a lot better, the turbo in the low rev range pics up a lot better and I also notice that when you do a moderate acceleration you feel the push in the seat. So I carried on and did an oil and filter change and a quick clean of the air filter.

I'll post a little update after the trip to Disneyland Paris. Hoping for some good MPG.

Cheers
Dave
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Might be worth resetting learned parameters in multiscan , with all that done and a nice long trip to relearn.
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I've read on a forum that the turbo vac solenoid might need to be calibrated!!! Would resetting the learned parameters do this?????
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Ive not heard of a calibration as such for that solenoid, but whenever i clean map maf filters or injector cleaner etc i always do a reset learned parameters, as far as i know its more for smooth idle and engine noise.
The only thing ive heard gets calibrated when fitted is swirl flap actuator.
I think the boost solenoid is simply pwm control and at idle only opens enough to control vac to 75% from ecu map, this should be around -600mbar vac at the actuator and be enough to pull the actuator to the stop screw, but there is no feed back signal to know where actuator is so i cant see it calibrating itself.
Its still worth resetting parameters, with any change to control or sensor side.
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UPDATE: After replacing the vac solenoid, a long drive from Basingstoke to Disneyland Paris and back......I can say that the car is 100% fixed. Plenty of low down torque and no sign of an engine management light.
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