P0234 again

82053 Views 33 Replies 18 Participants Last post by Carol1982, Jan 17, 2022

esh

Discussion Starter · Dec 12, 2017

So I took my '14 2.0 AWD in last winter for the P0234 overboost DTC. Dealer refused to repair under warranty with 48K on the odometer. I couldn't use another dealer as one company now owns all the dealers in the state and the others are 6+ hours away.

So I paid to have the boost solenoid replaced. It fixed the problem until it started giving me the same error this winter and about 15K miles later. Runs fine, watching the boost gauge on my OBDII interface shows nothing unusual or crazy amounts of boost.

My question...are these wastegate solenoids really crappy and prone to break easily? Anyone had to replace more than one? Has anyone ran into bad or sticking wastegates on their turbo so far? I'm at 62000 miles now so I'm doing it myself this time. I've found the part here and there online for $18-30 or so.

1 - 20 of 34 Posts

atlcarl69

· #2 · Dec 12, 2017

You have a 24 month Ford warranty with unlimited miles on all Ford Parts: FordParts.com

johngriggs

· #3 · Dec 12, 2017

Not likely maybe, but there's a sensor for boost pressure that could be giving you fits as well I suppose.

esh

Discussion Starter · #4 · Jan 23, 2018

Atlcarl- I'm not dealing with that dealership again.

So I changed the solenoid and the code came back again. Watching my boost gauge via OBD2/Torque app, I don't see anything out of the ordinary when it happens.

I can see two MAP sensors...one on the cooler, top of pipe, right side front. The other is on the front of the manifold. Does anyone know which provides information for/to what? Ex-is one for fueling and the other just to compare readings to detect leaks? I'm wondering if one is reading faulty but I would think I would see boost issues on the app as well if that's the case.

waverunner10

· #5 · Jan 23, 2018

You have a 5 year 60,000 mile drive train warranty!!!!
Why are you paying anything??????????
Call Ford Motor Company!!!!!!!
This is all covered on the drive train warranty!!!!!!

esh

Discussion Starter · #6 · Jan 23, 2018

Thanks for the help. The warranty is expired had you read the whole post.

The previous repair was not covered under warranty.

Let's get away from warranty and try to focus on the question I asked.

Reactions: 3

esh

Discussion Starter · #7 · Jan 24, 2018

So I did some reading and datalogging and I think I have some things figured out.

The code is being set due to the difference between commanded boost and pressure measured before the throttle plate. I thought it would command and reference boost at the MAP but that doesn't seem to be the case.

At WOT, the commanded, pre-throttle, and MAP are all very close, about a 1 PSI spread.
At half throttle, well, see the attached screenshots. Commanded will be 21.6, pre is 28.8, and MAP is 18.6 PSI. (Subtract the baro reading of 14.4) This short bit of acceleration from a stop set the MIL at half throttle today.

I understand at part throttle the pressure will be higher upstream of the throttle, thats why even at idle there is a little bit of positive pressure in the system.

Possibly the pressure sensor on top of the intercooler outlet is bad? Any other ideas? Anyone else have similar datalogs I can compare with? Also, this only occurs in the winter or late fall. I considered water/oil sludge in my intercooler but the pressure sensor is on the wrong end for that to be a problem i think.

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johngriggs

· #8 · Jan 24, 2018

esh said:
So I did some reading and datalogging and I think I have some things figured out.

The code is being set due to the difference between commanded boost and pressure measured before the throttle plate. I thought it would command and reference boost at the MAP but that doesn't seem to be the case.

At WOT, the commanded, pre-throttle, and MAP are all very close, about a 1 PSI spread.
At half throttle, well, see the attached screenshots. Commanded will be 21.6, pre is 28.8, and MAP is 18.6 PSI. (Subtract the baro reading of 14.4) This short bit of acceleration from a stop set the MIL at half throttle today.

I understand at part throttle the pressure will be higher upstream of the throttle, thats why even at idle there is a little bit of positive pressure in the system.

Possibly the pressure sensor on top of the intercooler outlet is bad? Any other ideas? Anyone else have similar datalogs I can compare with? Also, this only occurs in the winter or late fall. I considered water/oil sludge in my intercooler but the pressure sensor is on the wrong end for that to be a problem i think.

I suspected boost pressure regulation.

But, all your sensors are tracking each other dynamically, which makes it hard to say which is right or wrong per-se. At least for me, lol. Something is working, but sending an offset or improperly scaled reading... or worse, it's being misinterpreted by the PCM which would suck if that's bad.

It would be instructive to see a known good system. Know anyone with another vehicle like yours that is operating properly? Might give you some insight.

esh

Discussion Starter · #9 · Jan 27, 2018

It was over boosting, not a bad sensor.

I drove around in the freezing cold with the windows down so I could hear what was going on. I could hear and after that I could then feel compressor surge.

I changed the solenoid, replaced the hose clamps, and pressure tested all the hoses. I also pressure tested the wastegate and it worked fine. Last, I put a new turbosmart dual port in for fun.

Before, the pre throttle pressure was high and the wastegate duty cycle was lazy...usually 15-20% up to low 30%. Sometimes it was zero as it was overboosting! Rolling on the throttle the boost would spike 6psi+ over ecu commanded boost.

Now the wastegate duty cycle is more active and up to 56%. It controls boost way better and it's within about 2.5-3 psi of commanded boost, and quickly evens out to dead on.

Maybe the solenoid, maybe a leaking line connection...probably both. I'm happy I have my car back. Fingers crossed she stays happy.

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Reactions: 1

Ozekuga

· #10 · Jan 28, 2018

Very good detective work, thanks for taking the time to explain your findings and solution.

Reactions: 2

Rocko

· #11 · Feb 6, 2018

waverunner10 said:
You have a 5 year 60,000 mile drive train warranty!!!!
Why are you paying anything??????????
Call Ford Motor Company!!!!!!!
This is all covered on the drive train warranty!!!!!!

Which covers internally lubricated parts...

KYrust

· #12 · Nov 14, 2018

Check Engine code P0234

Any suggestions? The code came up the other day. I drove for a few days light went off, drove for a few more and it came back on. It says engine miss fire or over boost condition.

KYrust

· #13 · Nov 14, 2018

Here is the printout from the code

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Gryffindor101

· #14 · Nov 15, 2018

KYrust said:
Any suggestions? The code came up the other day. I drove for a few days light went off, drove for a few more and it came back on. It says engine miss fire or over boost condition.

My first suggestion is to search the forum as there is some existing information that will help you. Like this thread I merged your thread with.

KYrust

· #15 · Nov 15, 2018

Thanks.

jimmythecheese

· #16 · Dec 2, 2018

p0234 overboost

My experience with this code: 2013 Escape 2.0 There are 2 turbo solenoids, one on top of the engine, very easy to change and one on the turbocharger which is a little more difficult. What confused me initially was the parts have different numbers. The reason why i found out because the bottom solenoid is sold with the vacuum tubes.
This is the part no. BL3Z-9K378-A . It costs approx $30. so change both. To change the bottom solenoid, jack up passenger side,
remove tire. You have to work around the strut, pull small wire clip off electrical connection and remove, then pull three hoses off solenoid and slide off
the bracket. Reset code and hopefully it works for you also.

waverunner10

· #17 · Dec 2, 2018

Your drive train warranty will cover this
5 years or 60,000 miles!
Take it to another dealer!
also call Ford motor company!!!

Sheepish

· #18 · Dec 3, 2018

jimmythecheese said:
My experience with this code: 2013 Escape 2.0 There are 2 turbo solenoids, one on top of the engine, very easy to change and one on the turbocharger which is a little more difficult. What confused me initially was the parts have different numbers. The reason why i found out because the bottom solenoid is sold with the vacuum tubes.
This is the part no. BL3Z-9K378-A . It costs approx $30. so change both. To change the bottom solenoid, jack up passenger side,
remove tire. You have to work around the strut, pull small wire clip off electrical connection and remove, then pull three hoses off solenoid and slide off
the bracket. Reset code and hopefully it works for you also.

so if Im' reading you right, it's the same solenoid, they just charge more for the bottom because they include the lines? so you can just change both without having to change those lines?

jimmythecheese

· #19 · Dec 4, 2018

p0234 overboost

Sheepish said:
so if Im' reading you right, it's the same solenoid, they just charge more for the bottom because they include the lines? so you can just change both without having to change those lines?

Thats what I believe because I could not find the bottom solenoid sold separately anywhere, and it cleared the code for me.

jimmythecheese

· #20 · Dec 4, 2018

I have 120000 miles on mine so not gonna happen.

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