Code P0236

[ronale]

While towing a trailer the MIL light (readout was P0236) appeared without no significant change in power. A few miles later while beginning uphill, almost all power were lost for a few seconds. The power has been stable since (2 months). I have checked vacum lines and the vacum is present - I cannot move the wastegate arm while idling. My only suspect is the wastegate solenoid. I hear a clicking sound, it opens/closes 2-3 times a second at idle speed. Is this right?

[moondoggie]

Good Day!

Unfortunately, my code info is only good up to 95 - OBDII began in 96 & all the codes changed.

You seem to suspect the wastegate system. The best way to troubleshoot this is to monitor boost, even temporarily. I've been temporarily monitoring the boost in my 95 pickup for over 3 years now. I put a fitting on the intake & ran a hose into the cab by the fender-door-windshield post corner, to my old vacuum/pressure gauge.

An intermittent wastegate solenoid could certainly have caused your problem, although a lot of other things could too. Monitoring your boost would/will tell you. Wastegate solenoids often fail intermittent. If yours didn't release boost as you started up the hill with the trailer, the PCM would have known that through the IM MAP sensor; the PCM would then have pulled fuel to reduce the overboost condition. On your next restart, the truck would again run nominally. (The previous is a somewhat educated guess.)

Let us know what your boost does.

Blessings!

[ronale]

Will install boost gauge and let you know readings.
Thanks.

[Robyn]

The waste gate should not be doing anything at idle. It should be shut tight and bot open untill boost reaches a pre determined upper limit and then the PCM will pulse the vacuum to allow the waste gate to slowy open some to decrease the boost or to maintain the boost level at optimum.
Check your vacuum pump and waste gate solenoid.
The vacuum should be a strong 18-20 inches or more with no wiggle of the needle.
If in doubt replace the waste gate solenoid.

[ronale]

Boost gauge are now installed and readings have been around 0,5-0,6 bars (approx. 7-8 psi) at maximum. I will keep on monitoring the boost from now on. Malfunction has not occurred since the trailer towing 3 months ago.
Thanks for your help.

[DA BIG ONE]

If I remember correctly, PO236 can be traced to the boost sensor on top of intake, looks like a MAP sensor (most probably is) has 2 wires and is pressed into the intake w/o ring type device sealing it. If I remember correctly if boost spikes it can cause the issue you described because the boost is beyond the parameters of the EMS. If the code keeps coming back then its the sensor it'self that needs replacement.

I'm thinking the stock boost sensor is only calibrated to 1 bar pressure; I'll be tinkering w/2 bar boost sensor soon to see if I can keep PO236 from showing it'self every one and awhile......

[DennisG01]

Assuming your problem was a sticking wastegate solenoid, it woldn't hurt to spray some WD-40 into the vac line at the wastegate. It will help to prolong the life of the solenoid.