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SOS Need help on road

T

TurboTahoe

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Hi Guys,
On the road with family. Suburban is throwing code-PO236. I changed air filter code went away by itself but SES is on again. Vehicle appears to have low power, but is not blowing smoke. We have mobile wi-fi and will be checking for messages. Thanks.

Rob
 
x2 on boost code, you'll have to trouble shoot your vac system, also check for cross over leaks, that can cause a low boost but is usually heard.
 
Hi Joey. No boost gauge on this rig. I just pulled over to an OReilly's and used their scan tool. Looks like it threw another Po236. I have few tools with me. I can see that the vacuum wastegate is being actuated by the controller (I see it pulling the wastegate), and I can tell there is vacuum from the vacuum pump.

Is there anything else I can do on the road or am I reduced to trying to find a dealership?

-Rob
 
tap on your wastegate solenoid to make sure it's not sticking. That may be your problem. Also check for cracked vac lines from the pump to the solenoid and from the solenoid to the wastegate actuator. See if you can find a place that will let you "rent" or borrow a vac gauge to check how much vacuum you have at both the wastegate and at the pump/solenoid.
 
Should try hooking vacuum straight to the actuator, and if power comes back then replace as much of that plastic vac line with some vacuum hose, especially crack prone corners around engine. I found that you can slip it right over the hard vac line and it works good enough.
 
Hi guys, Thanks much for the help. You guys are the best.

Had a nice chat with Tim. Just like family, as you would expect.

Bought a gauge from NAPA (needed a new one anyways). Vacuum is 15" or higher at the waste gate when solenoid is active. Waste gate actuator appears to have no problem holding the waste gate closed. My 'poor mans test' was to rev the engine (or have wifey do it) and when waste gate is closed, try and move actuator arm with small wrench to see how firmly it holds. Holds very firmly.

I also used the $20 vacuum pressure and fuel pressure gauge to test static fuel pressure. I did replace the fuel pump with a new one about 2-3 years ago (GM part) and wanted to make sure (per Tim's suggestion) that I had good pressure. (Actually, I'd like to check pressure under load, but NAPA didn't have enough adapters for me to T the line, believe it or not. So I am reduced to checking static pressure. I found around 3-4 lbs fuel pressure.

So, I'm thinking maybe a faulty boost/MAP sensor?

I did take the MAP/boost sensor off and plugged/unplugged the weatherpak connector several times in case its a corrosion issue. Did the same with the electrical connector on the wastegate solenoid.

If this keeps up, I'll take Tim's suggestion to wire the wastegate shut. I'm not towing. It's just me the family on I5 to California (the People's Republic of) to visit relatives.

Any other input or suggestions are welcome.

BIG BIG thank you to Tim for helpful suggestions. And Joey, and Buddy. You guys are really the best.

-Rob :)
 
Could be MAP sensor Rob, I'd still try the WG wired test, revving and wrenching @ idle still not gonna equal flow/back pressure as your engine @ power, safe enough test to do since you aren't running hard, if you do determine it is a sensor make sure it is the MAP(boost) and not the firewall baro, they look the same but are index keyed differently.
 
You could also have Bill drop ship a TM to where you are going, when I put one on my burb before going to ATT, I installed per his instructions recommended length, no gauges and ran with it for over a year and no issues with it.
 
3-4psi doesnt seem very good static fuel pressure, did you mean with engine off or just static as in idle?

Instead of wiring the actuator shut, just try putting the vacuum pump straight to the actuator, should do the same thing or possibly show you what the issue is.

Of course it could be that you are overboosting because it always has vacuum ;) and then it automatically defuels you while the code is set to make it run bad. You could cause this too by wiring it shut or putting vacuum straight to the actuator.

Does it perform bad right from the get go? Because if it does good for first couple minutes its because the code doesnt set until the boost is over or under the desired pressure (+/- 3psi) for at least 10 seconds straight. When code sets it cuts your peak fuel rate by 20mm3, and youre only programmed to 67mm3, which is weak to start with. When it sets for overpressure usually on a long interstate on ramp acceleration or up a hill, something that lasts 10 seconds.
 
My suspicion from our phone call Buddy is bad diaphragm leaking a little and letting the WG open just a little off it's seat under load, had it happen to me once, passed all normal "functional checks", but that is a quick way to determine if solenoid is bad.

I have done it that way only to be fooled by the bad diaphragm, which I found only after returning home and pulling a vac on it with my Mitey-vac pump, so now my preference to wiring shut at onset of issues is that it eliminates all vac system suspects at 1 time, then I work my way back up the chain from there, same end result proving the vac system out just a different starting point.

Wired shut IMO is more expedient way when having a bad 6.5 day with A a need to be some where, B a vehicle load of passengers that don't share the 6.5 passion like we enthusiasts do, or worse yet both scenario A & B happening at the same time on a hot summer day/nite :eek:
 
buddy said:
3-4psi doesnt seem very good static fuel pressure, did you mean with engine off or just static as in idle?

X2 something odd here if that is fuel @ idle


Of course it could be that you are overboosting because it always has vacuum ;) and then it automatically defuels you while the code is set to make it run bad. You could cause this too by wiring it shut or putting vacuum straight to the actuator.
Click to expand...

Buddy you may be on to something with the over boost as 0236 is a summary low or high out of range boost code, I once had a MAP that went bad high showing 35psi boost and limping me on accelerations, but that should take him to 50mm rate unfortunately he'd need a scan tool to see it, as it would reset once he shut down.

Rob how far out on the highway are you, you can get a $20 boost gauge for diagnostic purposes as well, just depends on the accommodating nature of the family I guess to take time to install it. ):h
 
If you are hurting for fuel supply then perhaps you aren't boosting enough to make PCM happy? This would explain the low power and the fact that you aren't making black smoke.

When I had a WG solonlid failure, I was puking black smoke. IF you aren't belching smoke, and throwing a boost out of range code, perhaps you don't have enough fuel to create enough boost to make PCM happy, and its showing up in Boost out of range.
 
Agreed Matt but if it were a partial opening of WG it would not puke black, as it would be getting air just not enough to meet the demand, remember the protection tier, if it has a prolonged boost error it will limp fuel, so I suspect we have real or indicated boost error combined with a fuel limp. My leaking WG diaphragm incident was not accompanied with heavy smoke either just low power.

Could be low fuel but code 236 does not happen with a low lift pressure fuel condition even with a failed lift with just the IP pulling it's own fuel he should be able to manage highway speed just have crappy acceleration.

Remember my old snot in my stocking thread at old site, that was with nearly fully blocked tank sock, max speed 20-35 mph, no boost codes there for me just crappy performance & eventual shutdown until I could blow some of the crud back off of the pickup foot, blowing air back toward the tank.
 
Turbine Doc said:
Could be low fuel but code 236 does not happen with a low lift pressure fuel condition even with a failed lift with just the IP pulling it's own fuel he should be able to manage highway speed just have crappy acceleration.
Click to expand...


Let me rephrase I should not say it does not/could not set a 0236 code, I guess it is possible, I have not seen it manifest itself with a low fuel pressure as being the prime issue, but I guess in extremes it might allow a 0236 to be set
 
Thanks Buddy and Doc for your time in helping me debug the Suburban. Symptoms are: vehicle operates normally on initial start-up and throws a code under sustained acceleration. After it throws a code, the vehicle seems to have no power and even at WOT there is no power and no smoke. I have wired the WG shut as Tim suggested. Power is back under normal cruising, but still seems to defuel when going up steep hills. We are currently just north of the California border, on our way to La La Land. Would be happy to meet a member with scanner. Thank you guys again, you're the best. :)

Sincerely,
Rob :)
 
Well, then I would say you dont have a leaking vacuum, but a constant vacuum, wastegate is staying closed and you are getting too much boost compared to crappy stock boost curve. So wiring it shut did just like expected, set you for overboosting like it was before. You can try spraying some WD40 into the boost solenoid or hitting it a few times. Its supposed to be off normally, so when truck starts it opens solenoid to allow vacuum through to close wastegate so you get boost off the line. It must have stuck open or you got the lines on backwards or something. Have you messed with the lines into the solenoid at all? I think some people have gotten them unstuck with some WD40. Otherwise its like a $25 part and 10 minute install.
 
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