Keep getting a P0236 on and off. Also my scan gauge has been reading 4-5lb of boost at idle and the readings dont match my gauge or seat of pants feel. Would a bad MAP be doing this or maybe PCM tables got screwed up? I have a new map ordered for tomorrow morning

 

From your description and the EC I think you are on the right track.

P0236 – Fault sets if Manifold Absolute Pressure (MAP) signal is higher than the specified pressure.

 

don't 100% trust your boost gauge, from what I understand they can be off up to 2 lbs.

The sensors are reading right, but the needle is not just 100% calibrated.

 

Well I don't know where you got your info from William but I've never heard of that before. Maybe with a cheap set of gauges, but why would a credible gauge manufacturer think it's good business to sell a boost gauge with +/- 2 psi variation??? Isn't that the entire point of putting anolog gauges into your pickup, so you can ACCURATELY monitor things like boost?




I'm having the SAME exact problem and code intermittantly. Started last week for the first time. Did it again on Friday and again this morning. Was pulling a horse trailer all 3 times, but it doesn't do it when running down the road. It's setting the CEL and code at the end of my trip, when I'm idling/coasting at the end of my driveway, right before I stop completely. So a NO boost situation. And I can have it sitting in park and idling, clear the code with my scangauge, and it'll come right back. Next time it won't do a thing. Can drive 500 hard miles pulling the entire way and it won't do it until I stop at the end. Very strange.

 

I'm at a lost on this one. The only thing I can think of is the MAP sensor is getting stressed over time. By that I mean it has a sealed diaphragm and when boots hits it, it moves inward. That movement causes some electrical components to change value and is converted to an electrical signal to the PCM. Almost sounds like it's not returning to it's full relaxed state. Guess it would not surprise me with higher boosts some are running and the age of the sensors. Nothing last forever and bet there are a ton of MAP sensors out there doing the same thing. Unless you are watching it with a real time scanner you would never know it, except maybe crappy fuel mileage.

 

I was wondering along those same lines. But it sets the "check engine light" when the code trips. So it's noticable.

Here's the kicker with mine though... with the injectors and turbo I'm running I'm already hitting 30+ psi on my in-dash gauge. So I have a MAP regulator installed between motor and sensor so the max the MAP sensor ever sees is approx. 18-20 psi which isn't enough pressure to have it "overboosted".

And I've pulled the trailer hard several times before last weekend with no issues. Then all of a sudden it decides to do it.

 

Way to just be a d-bag and attack me to start ****.

Whatever.

 

I know the super duty guys talk about this, but I've never really heard anyone talking about it for the OBS.
Neal's running one on his truck though.
One of those "can't hurt" things if you ask me.

 

You still didn't say where you got your info from. Not really an attack at all. It was merely a statement. And if you took offense to it, then maybe you should think before you type.

It's more common on the SD's to have a MAP regulator because the sensor is set to trip the CEL and code at around 23-25psi. Since they have larger injectors stock, with a chip they can set that code easily. On the OBS, the sensor is set to trip the CEL and code at closer to 30psi. So with stock injectors and a chip you'll never see it. Even with stage 1's it's hard to achieve with a stock turbo. When you get into stage 2 and larger injectors and larger turbos in the OBS, then it's a good idea to have the MAP regulator in place.

The reason for the MAP regulator is so that it only sees a max boost level UNDER where the sensor and pcm are set at. This is because once it senses boost levels at or above the "desired" maximum, it sets the CEL and de-fuels the motor, in turn decreasing performance at higher boost situations. So to "fool" the system, it keeps the boost getting to the sensor limited to under that threshold so that you have full fueling in the higher power ranges.

 

Hey Ryan, I'm a little confused where you put the map regulator at. Just in the line I assume but where and where can I get one? I've hit 33 lbs before and maybe I should have one in there. Granted I won't hit that very often at all but.......what do you think?

Sorry, don't mean to hijack the thread here

 

Put it inline between your boost gauge and the MAP sensor. You can buy them (Riffraff Diesel or ITP diesel) already rigged up and ready to rock (at least for the SD's) or you can buy an air compressor regulator some place like Home Depot and do a DIY method.

William if you thought Ryan was being a d-bag and attacking you... well I'd hate to know what you'd think when someone really laid it to you. All he did was ask where you got your info.

 

Chase is right except you install it between your MAP source (usually the little nipple on the pass side plenum if still running the stock plenums/intake runners) and the MAP sensor mounted up on the top of the heater core housing. When installing a boost gauge, most people "t" that MAP line so if you've done that, install the regulator between that "t" and the MAP sensor. Since I upgraded to the 3" plenums and am running an intercooler, I relocated my MAP line to the "hot" side right where it comes out of the turbo. My boost gauge is tapped there too.

As Chase mentioned, Riffraff and ITP, both have ready to go setups that are preset. You might have to modify the mount to work on the OBS since it's something they primarily sell for the sd's. I built my own (for more money than the pre-made ones) with a regulator from my local auto refinishing/paint store and hoses/fittings from napa. Still need to get my new mounting bracket built though.

 

I guess I should have been more clear... you put the reg. in the MAP line between the boost gauge fitting and the MAP sensor... thanks for saying what I tried to say but typed too fast Ryan

 

Alright, thanks guys. I have an IC too and have my map on the hot side also. I will check it out. I'll see what Clay has.

 

I personally don't think that 30 lbs of boost will hurt you that bad.
I hit it, travis hits it. and I'm sure others hit it. I dont' think travis runs one.

And btw, I got my info from Clay.....
The guy, you know, who sells the gauges.