Over boost code solution questions !!!
 

So I'm new to the hhr ss been reading a lot of forums and comments just bought the car runs great other than throwing the P0234 code, so the question when doing a tune or tuner which creates more boost you have to do wide band o2s correct ? So if I did the o2s would I still be getting the over boost codes ? And if so what are good o2s other than the Aem ??? Thanks !!

Welcome to the site! Try plugging P0234 into the search window there are many threads with solutions to your issues of overboost , most point to loose or broken wires, not the O2 sensors

P0234 Turbocharger/Supercharger 'A' Overboost Condition OBDII Engine Light Trouble Code | AutoCodes.com

Does your SS have the GMTU (GM turbo upgrade ) or Stage 1 kit as it's commonly called.
If so, check the wire splices at the upper and lower Tmap connections.

No it's completely stock with 90k miles im leaning towards the wastegate im hitting around 20lbs-23lbs what should stock be hitting ? Want to do the stage kit, would that solve the problem where I wouldn't have to change the wastegate for less boost ? Been reading also that if I do the stage kit have to have it tuned also can't just plug and play ?

20-23 lbs. sounds just like the GMTU or another tune. Any chance the former owner had it tuned but didn't pass that on when it was sold ?
If it has the GMTU, it will have a sticker inside the fuel door that says : Premium Fuel Required
The stock sticker would say : Premium Fuel Recommended
Stock numbers are generally in the 14-17 range depending on the variables such as elevation.
Mine was around 14 stock. 19 when I got the GMTU.

The GMTU kit is not a plug/play. It's just the 2 Tmap sensors and some stickers. The new tune is then downloaded by the dealer and is a VIN specific upgrade to the purchased kit.

I'll check for those ! I don't know the previous owner bought it off a lot... If it had the tune and the 2 tmap sensors it wouldn't throw a p0234 code though under full throttle right ? Where do I go from here ? What can I do to stop the code and limp mode, it's frustrating lol

Everything I have looked at looks stock and the fuel door says recommended, do you think the spring in the wastegate worn out giving me a higher boost ?

Very possible!

May be the bypass valve sticking ? Or the vacuum line to it is off or broken. Easy to pull and check. Only a spring and rubber diaphram. (honestly. It's a little tricky to get the tools to it. 10mm socket on a 1/4 inch drive setup worked for me )
Here's a link with some pics: https://www.chevyhhr.net/forums/how-...acement-43763/

Thank you ! Looks like I have some trials and errors to try and hopefully fix the issues ! Thank you everyone for the input !

Please let us know what cures the problem

So finally got around to try and fix the over posting code I changed the bypass valve to the forge replacement and now have a cool sound but still over boosting running about 20lbs for about 3-4 seconds then cuts out and goes into limp mode

If I understand it correctly, the bypass valve could cause an underboost, but not an overboost. It seems quite often the problem has been the wastegate solenoid, AKA boost control solenoid. I just went thru this myself. I had to find a solenoid, because you can't get the part as a standalone.

I got a good deal on a used turbo, with the solenoid still attached, but my backup plan was HERE look at post #8. Problem solved. Another cause that I found others had was the electrical connector for the solenoid had been heated up by engine heat and had become brittle and fell apart. The solenoid is attached to the turbo by a T30 torx screw, it has 3 vacuum(pressure) hoses and the elec. connector.

Thank you ! One more area it could be and hopefully that's the issue!

If he has a Trifecta Tune with infiniboost option boost pressures exceeding 20ish PSI with OEM senders will trigger the overboost gate stuck open code. Stocker, When you press the CC steering button, do you see Cruise Control show on the DIC? if no, You may have the same tune.
Here is what I did to live with it, picked up a Turbo smart Compaq BOV and disabled the code from appearing again(software assist), note: avoid turbo surge by adjusting the BOV to mid soft allowing the charge pressure to push the piston and allow recirculate of the gas into the turbo. you can turn the tune on and off via the CC button.

He did say it was bone stock.

Even with a bone stock SS you would not know the Trifecta tune was installed unless you were told it was. Some guys(me) bypassed the GMTU because of all the issues reported. "Stockhhr's symptoms seem to match what I saw happening. The only difference is I know I had a tune installed whereas he is not sure. A simple test of the CC button would reveal if this a Trifecta tune is installed. I believe they are the only ones with this specific feature.

So I bought the car seemed to be bone stock can't tellnof it has a tune or not but when I press the cc button nothing comes up on the dic... How would I find out if it had a tune ? Could I just do the sensors and get rid of the codes ?

Well...it's either Stealth tuned, or cruise control isn't working properly. Do you notice a difference in performance after pressing the CC button? The difference should be night and day. As far as the overboost goes, changing to 3Bar MAPS will only allow the ECM to see actual boost pressures. Trifecta has been known to work around them by using an algorithm to allow for higher than normal pressures. They make the ECM think it's seeing less boost. The problem is your ECM/tune, if it doesn't like what it's seeing...you end up with ENG PWR REDUCED.

Not to say that your tune or ecm is bad. I don't belive the sensors are going to solve your problem. Inspect all your vacuum lines carefully. There's a lot of useful info over at the cobalt forum. You could even have a "boost multiplier" I'm not sure what they actually call it but it's another way to fake the ECM. I've seen guys use .035 welding tips to restrict flow to the bypass valve, allowing higher than usual boost. Once you reach a certain point, the ECM no longer cares how hard you press the pedal or how fast you want to go. It takes care of the engine first and foremost.

Check out that boost control solenoid mounted on your turbo. Also, who was the previous owner? Or, does it seem like they'd tune it? Tuning isn't for everyone.

The Trifecta tune can be programmed to the traction control button also.

Just for clarity, which button is it? Pushing the CC button on mine (the on/off with the little light) doesn't trigger any DIC message either. Pushing the "set-" (while driving) triggers "cruise control engaged" message (or something to that effect).

I think that(TC) is the preferred button. But I'm sure any could be used. They certainly perform some ecm magic over there at Trifecta!

I'm just asking hhr5678 to clarify the procedure for stockerhhr's benefit. If stocker's (potential) Trifecta is tied to cruise control, what exactly should he do to verify. It seems the actual Cruise button may not be it, but perhaps the "set-" button. Also, what should stocker try in order to determine if it is tied to traction control button?

Actually, thinking some more, this doesn't make sense. The actual cruise control button never triggers a message in the DIC, and if it is set to the "set -" button then what, your car doesn't have cruise control anymore? It's more likely that it is, in fact, set to the actual cruise control button, and there would be no way of knowing if you had the tune, except for performance. Someone correct me if I'm wrong, please.

Would turning the cruise control off, also turn off the tune? Or does turning cruise on turn off the tune? Could that be a test for stocker, to turn off the tune and see if it still overboosts? He would also need to know what turns off the tune if tied to traction control button. I would think that if it still overboosts in all scenarios, then he does not have the Trifecta tune.

Stocker, you do know that turning the key off and then on again, gets you out of limp mode, right? And as long as you don't overboost for 3 seconds, you won't go into limp mode. 3 seconds of overboost condition triggers limp mode or 50 seconds cumulative.

If he's seeing more than 16 lbs of boost at any time it's more than likely been "modified" not necessarily tuned. As I started earlier, there are small changes you can make to the vacuum system to trick the ECM to allow more boost.

If it's the Trifecta "Stealth(on or off)" tune. I would suspect it's tied to the traction control button. I think the only way to tell is the ol' butt dyno. I've never had the Trifecta tune but as I understand when you turn on traction control it activates the tune. I'm not sure how you'd find out other than through previous owners. Which is why I asked who owned it prior.

I'm pretty certain boost tops out around 12-14psi stock. The problem may be it needs a tune. If it's been modified and not tuned the ECM is just not a happy camper.

Would you agree then, that if the problem was because of a Trifecta tune, then turning the tune off would eliminate the problem? Maybe someone who has it can chime in - Does the tune default to "off" when you start the vehicle? i.e. Do you have to push a button to turn the tune "on" each time you start the vehicle? If not, how do you turn it off?

With regards to mods, the wastegate adjustment mod is temporary, with the computer relearning back down to 260 ft lbs torque. Are these other mods permanent? I read about putting a partial obstruction in a line like you mentioned, but don't remember much else, other than it wasn't a very good idea.

I'm still leaning towards the boost control solenoid.

Here's a tutorial of sorts about the Trifecta tune , the second paragraph speaks to activation methods..,

https://www.modernperformance.com/pr...ss_electronics

Stockerhhr,
DIC Cruise control message shown under driving conditions denotes we do not have the same tune.
Either way if you are experiencing P0234 when you floor it this could be bad vacuum lines, IC coupler leaks, waste gate spring stressed, or faulty MAP. Keep in mind the stock 2PSI senders out of range at boost 20PSI, when the ECU sees that out of range value P0234 occurs. How many miles is on the vehicle?

My configuration is as follows:
1. My trifecta tune will enable/disable based on the Cruise Control Steering wheel button. When pressed CC ON the Tune is off, CC depressed off ="Tune On".
2. The Cruise control option is completely disabled with the selected tune.
3. The DIC does not report Cruise Control when button activated(lit) or not activated(not lit).
4. The TCS button has a separate function, launch, TCS active or TCS shutdown disable(tire burnout option:-) the added Tune bonus is no ECU learn down.

To recap here is my experience with the P0234:
I purchased all the tunes CJ had for the HHRSS, Infiniboost, and E85. I took his advice and recommendations for the tune activation characteristics.
Unfortunately, I have only used the infiniboost on pump gas to date. When I upgraded the IC pipe the over-boost CEL started activating, tune activated. Then it happened again with the tune deactivated, I was forced to comb through the entire system looking for leaks. Once I determined all was well, I proceeded to rectify the issue, pulled the diverter noticed no issue, checked the wastegate-no issue, then picked up several different aftermarket items Diverters/BOVs for testing, eventually choosing and loving my Turbosmart adjustable BOV. Once I had the performance I wanted, re-programing with the trifecta I chose an option to disable dependencies and P0234. To date I simply watch the RPD, set alerts, and have fun.

I hope this information helps.

For those looking for a virgin HHRSS check out this add on CL: https://phoenix.craigslist.org/evl/cto/5398214922.html

Yeah I know that turning the car in and off gets it out of limp mode just frustrating that I cant flor it, I have to watch how much boost I'm pushing then let off and get on it again... And cc button no change in power so I'm thinking that my car is stock, other than the forge bypass I just added and K&n but had the over boosting problem before and here and there I get the PO234 codes... I want to do a tune and the map sensors but want to fix this issue first.... Checked the vacuum lines and seems like no issues thought about just spending a couple bucks and replacing them and go from there...

That's a lot of awesome advice ! I'll check all my piping and see if I can find any leaks, and need to check the wastegate as well ! Thank you...

Understand, brother, I was in that exact same place less than 2 months ago. It started boosting to 20 PSI and then P0234 with no turbo (2-3PSI), not really full limp mode. But when you're trying to pass a semi truck, and all of a sudden no turbo? Not good.

In less than 2 weeks, it was slamming to 25 PSI in the blink of an eye (didn't even have to floor it anymore!), accompanied by a screech. I was trying to be careful, but old habits... I had to fix this. I replaced the solenoid, problem solved.

Unfortunately, now I have low compression in cylinder #4. It may just be coked up valves, but it could be something serious. I hope you can get yours fixed soon.

I'm not saying that the solenoid/ elec. connector is the only possible cause, But in my research, it was much more often the cause than anything else. If the elec. connector is falling apart, there's a post in that css link I provided for that too. If you haven't read those threads yet, there's good information. And after seeing some of the attitudes over at css, you'll appreciate the people here even more.:thumb:

So went through the piping no leaks... Don't know how to check the wastegate spring but also another thing is that when I hold the boost steady at 14-15psi for a few seconds it will still put into limp mode, someone told me the throttle body could be cracked... I'd rather not replace the turbo of that's not the problem also, still trying to narrow down.... Advise please !!! No vacuum leaks or IC piping leaks and now that I had the forge bov valve trying to hold any kind of boost for a little bit of time it releases pressure....

Interesting, now 14-15 psi triggers your overboost? I wouldn't have expected that. I wonder if it's because of elevation?

Yes, 3 seconds of continuous overboost or 50 seconds cumulative overboost will pretty much shut down the turbo.

Did you see the information I gave you in post #13?

Forge BPV or BOV ? BPV would be an easy bolt on swap for the stock one. Now a BOV unit requires a relocation and tune I believe.

it happened to me last night. 2009 - owned since new - had the gm stage 1 done 6 yrs ago. so gm has a tsb that states the wastegate rod is out of adjustment - - I don't believe that can be the case - I bought the car new & no one ever touched the turbo, so , how can the rod be out of adjustment on it's own? wouldn't it be out of adjustment from day 1? is it true the solenoid is not available seperatly - you have to replace the turbo just to get the solenoid?

Others have posted a replacement solenoid is available in the aftermarket, the adjustment can be considered out if the solenoid is faulty, so the computer can't read specific parameters


http://www.full-race.com/store/efr-t...ent-kit-1.html

I thought I saw a listing on either AutoZone or Advance the other day as I was racing through a drill down.

I believe it's the wastegate solenoid you can't get separately. At least I can't find one. The boost control solenoid on the intake manifold is available. I haven't figured out a way to tell which is the issue with my over boost which then triggers no boost and a low mass flow pending code. It happens rarely so its hard to troubleshoot. The maps and wiring are fine.

OB's post and link points to the WG solenoid. GM alternative is to buy a complete Turbo

The solenoid on the turbo is the boost control solenoid, controls the wastegate.

The solenoid on the intake manifold is the bypass solenoid, controls the bypass valve. Yes, it is still available from GM.
SOLENOID | Genuine GM | 12633411
Ecotec LNF Bypass Valve Solenoid 12633411

If it were a code for underboost, we would be looking at the bypass solenoid as a possible culprit.