P0234 and poor fuel mileage, please read.

[SRubenstein]

Hello community, I keep reading about how common this p0234 code is w/ a tuner but something has changed in this truck. I've had a P. O. S. Superchips flashpaq in this thing for a couple of years and never had this problem the first year after installing it. It seems for the last 6-9 months that this code will pop up after the slightest bit of throttle past 1/2 way. When I first installed this tuner I could smoke the tires off it and it would not trip this code. It also appears that my fuel mileage has gone to crap as I used to average 18 mpg w/ my 4. 10's and 35" Toyos. I now average 14-15 and if anything I've toned down my driving style due to the code that keeps showing up and of course the obvious fuel prices. Ithought my fuel mileage would be going up as the engine continues to break in (now at 83k) The performance on the truck is decent but I've really backed off it, trying not to throw this code. Any ideas what may have changed? A good friend of mine w/ a completely stock truck has been throwing this code for about 75k. Maybe a waste gate isssue? Any ideas appreciated.

 

[p-Bar]

Could be the sensor for the OBDII which I think get the MAP to decide what to do for boost. Can you put a boost gauge on and see what happening? maybe bad MAP sensor

 

[SRubenstein]

I need some voltage specs to know what to look for. I have plenty of resources available such as Mitchell, Alldata, and I own a DRB III. I just didn't know if there is one common item that always goes hand and hand w/ this code. Just to update I did remove the Superchip program today and returned it to stock. The code came back after a short 10 mile higway run. Any ideas appreciated. I'll look at the map readings tomorrow. Thanks Scott

 

[p-Bar]

If you can PM BOB4X4 and ask him nicely he can get you a flow chart to troubleshoot this problem. He works for a dealer. Must be nice to own a DRBIII

 

[SRubenstein]

Thanks I will contact Bob4x4 and see if he has ab etter diag procedure than Mitchells has.

Just an update. I checked the wastegate mechanical activation and it moves freely other than the spring tension from the actuator pulling it back. With no superchip program I road tested it and monitored boost pressure w/ a DRB III. I hit 49. 5 lbs and the light/ code came back on again. I believe that this is a calculated reading by the map sensor, am I correct? I think it is coming down to either a bad solenoid for the wastegate actuator or a bad map sensor. Any other ideas?

 

[p-Bar]

Now remember at sea level subtract 14. 7 from your reading if it is coming from the map sensor. It's not calculated off the OBDII port unless the DRB does it . You should put an ohm meter on the soleniod and you should read 10 ohms. Curious pull fuse # 36 and see if you are getting the high boost. This is the fuse that sends 12v to the cooling fan, a/c clutch, and wastegate

 

[AllianceDiesel]

you got something reading wrong if you hitting 49 boost on a stock truck, no wonder your gettting an overboost code. ya the drb calculates the baro pressure into the boost



I'm curious where did you get your hands on a DRB? I would love to have one but they are so damn expensive.



here is the trouble shooting chart.



1. OTHER DTC'S



--------------------------------------------------------------------------------

With the scan tool, read DTCs.



Do you have additional DTC's?



Yes

Repair all other DTC's first.

Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)



No

Go To 2







2. TURBOCHARGER AND/OR WASTEGATE DAMAGE



--------------------------------------------------------------------------------

Visually inspect the turbocharger assembly for signs of damage. Pay particular attention to the Wastegate area and linkage.



Was any damage noticed?



Yes

Repair or replace the Turbocharger or Wastegate.

Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)



No

Go To 3







3. WASTEGATE



--------------------------------------------------------------------------------

Pressure the Intake air system per test *INTAKE AIR SYSTEM PRESSURE TEST.

Pay particular attention to the Wastegate signal line and the Wastegate actuator canister area for leaks.



Were any leaks detected?



Yes

Repair as necessary.

Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)



No

Go To 4







4. TURBOCHARGER



--------------------------------------------------------------------------------

Disconnect the wiring connector at the Wastegate Control Valve.

Remove the Wastegate Control Valve from the turbo.

Inspect the o-rings and the valve for damage.

Replace any damaged o-rings or a damaged valve.

Using a pressure/vacuum hand pump, apply vacuum to the tip of the Wastegate Control Valve.

Use your fingers to cover and seal the two radial holes located between the two small o-rings on the tip of the valve.

The valve should hold vacuum.



Does the Wastegate Control Valve hold vacuum?



Yes

Repair or replace the Turbocharger.

Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)



No

Replace the Wastegate Control Valve.

Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).

 

[SRubenstein]

My dad and I own an auto repair shop in the North Shore of Mass and we've had our DRB about 8 years. It definately comes in handy and makes diag much easier when you have the manufacturer specific tools. We also have a Tech 2 for Gm's and an NGS for Fords. I have seen that diag procedure in mitchells and just havent gotten to pull that solenoid off yet. I will ohm it out like p-bar said and go from there. It's tough to work on your own stuff when your busy fixing everbodyelse's all day, lol. I was hoping someone would have the actual Chrysler trouble tree but I think I have some routes to test for now. Thanks again.

 

[AllianceDiesel]

that is chryslers, strait from the website.

 

[SRubenstein]

Thanks mopartech, I guess mitchell's copied it verbatim (that's a surprise, lol). Here is where I am with this thing. I swapped out the map w/ a friends truck (a known working good one). Took it on the higway and again hit 50lbs of boost per the DRB!! Of course code came back again. I had my wife do a brake stand in it once I got home and had her watch the boost go right up to 30lbs and I watched the wastegate, never moved?? I did pull the actuator today and it does open w/ a 12v signal. It does ohm out at 11 ohms. I was brave enough (or stupid enough, you decide) to crawl under there while she was doing the brake stand and manually moved the wastegate, the boost went from 25 to 17 (good sign). So when should the solenoid be opening to move the actuator? I'm starting to understand this system better but am still limited for the specs when this thing should open and move the wastegate. Any insight is appreciated. I did pm Bob4x4 but have not heard back yet. Thanks again.

 

[SRubenstein]

I wanted to make sure this was truly fixed before I posted. It's been about 2 weeks without the code. I found the cause of the problem to be rust buildup where the actuator linkage meets the wastegate. It took near 60lbs of pressure to move the wastegate open (no good). I removed the linkage, wire wheeled off the rust, and then proceeded to open it up about 40-50 times while monitoring how much pressure it took to move. Tomorrow I will reinstall my Flashpaq and hopefully the code will stay gone. Thanks to those who chimed in with ideas. Hopefully this will be helpful to the next person who gets this annoying code. Now I can fix my friends truck.