[bkylecox]

This is a bit of a read, but I appreciate any help and guidance I receive. Recently my truck began having a sporadic issue. It goes to total power loss (like key turned off), backfiring, lots of white smoke, bucking, etc. It only happens at normal operating temperature and in the 2000 rpm range. It eventually clears up and runs fine. It has gotten worse as of late. I originally suspected the FICM, so I replaced with the stock unit. The hotter FICM is the only mod other than an EGR delete.
I hooked an EDGE monitor just to see what's happening when it has one of its fits. Here is the data I gathered that seems off:
*VGT% is all over the place right before, then spikes to 85%. Normally at idle is around 45%
*MAF-V normal at idle 1.5v. Drops to .3 or less when it goes into fit.
*MAF lb/hr falls out
I replaced the MAP sensor with known good unit. Do I need to try the same with MAF? What other tests or inspections need to be made? Is this a turbo issue? I originally thought fuel. Changed filters (twice). Pulled drain plug on lift pump to check for sludge, rust, water, algae. Seemed to be good. I'm just finding a lot of info and having a hard time processing it all. I had it to my mechanic. I don't remember exact code numbers but it was EGR (I assume from the delete) and MAF code. Will the MAF cause this much havoc? I feel there's something there that I'm missing.

 

[bismic]

If you own a 6.0L, then you need a good scan tool of your own.

Suggest ForScan Lite on a smartphone app for the best "value". You will also need an OBDII adapter. What kind will vary based on what phone you have. You can also put it on a tablet, or the full version on a laptop.

Please confirm, your ICP sensor is behind the turbo?

 

[bkylecox]

If you own a 6.0L, then you need a good scan tool of your own.

Suggest ForScan Lite on a smartphone app for the best "value". You will also need an OBDII adapter. What kind will vary based on what phone you have. You can also put it on a tablet, or the full version on a laptop.

Please confirm, your ICP sensor is behind the turbo?

No, I believe my ICP is on front corner. ICP value is about 650 at idle and much higher at throttle. I currently have it hooked to a CTS Edge. It's not producing any codes. My mechanic (also my father) had it hooked to a Snap-On scanner and got the aforementioned codes. My fault for not writing them down. I do most of my own work, as time allows. I was looking for advice on where to start looking for the problem.

 

[bismic]

It is not an early 04 if the ICP sensor is on the Passenger valve cover. It is the later 04.

Have you checked the EBP sensor and verified that the EBP tube is clear?

What are EBP, MAP, and Baro at KOEO?

 

[bkylecox]

I

It is not an early 04 if the ICP sensor is on the Passenger valve cover. It is the later 04.

Have you checked the EBP sensor and verified that the EBP tube is clear?

What are EBP, MAP, and Baro at KOEO?

I'll get those values tomorrow. Didn't have time to mess with it today. I'm going to check fuel pressure as well.

 

[bkylecox]

I


I'll get those values tomorrow. Didn't have time to mess with it today. I'm going to check fuel pressure as well.

So, I haven't been able to get to the EBP, MAP, and Baro readings. I did however pull EBP sensor. Tube was clear. I ran wire through it as well as compressed air. Cleaned some gunk from the sensor. Reinstalled and test drove. SSDD. Runs fine cold. As ECT, EOT reaches ~170 it has its seizures again. I can hold accelerator pedal in constant position, ICP values don't change (around 3000 psi), APP% doesn't move, IPW stays constant, FICM voltage good. Again, what goes erratic is MAF lb/hr, MAF-v, and VGT%. It's almost as it's losing fuel and the turbo is trying to compensate for lack of fuel. But why only at normal Temps and not also at cold?

 

[bismic]

Get a scan tool that reads the PIDs MAP, Baro, and EBP. Suggest ForScan (or even Torque Pro).

 

[bkylecox]

KOEO readings. EBP-14.0; MAP-14.0; Baro 28.9

 

[bismic]

What "units of measure" is the Baro in? The other two appear to be psi. Probably inches of mercury, but you need to check that. We always need units of measure with numbers.

 

[bkylecox]

Sorry. Yes. PSI on MAP & EBP. Baro was inches of mercury.

I should add, I've figured out the Edge monitor a little better. I've started monitoring other values during its fits. At normal driving speeds boost running about 8% (give or take), EBP around 12psi, MAP reading about 21 psi. Boost will fall flat to 0%, EBP falls to 1 or 2 psi, and MAP will fall to nearly nothing. It bucks, falls dead, occasionally backfires through exhaust.

 

[bismic]

Check the MAP sensor hose for rips or tears or plugging or for poor clamping onto the intake nipple. Make sure it isn't plugged also. Then check the intake manifold nipple for plugging. Then remove the EBP sensor and use a stiff weed-whacker string to check to see if the tube is plugged. If the EBP sensor itself is carboned up, you can clean it with MAF sensor cleaner or even carb cleaner and a toothbrush.

 

[bkylecox]

I've been through all those procedures. I've replaced the MAP sensor.

 

[bismic]

No leaks in CAC boots or even the CAC (intercooler) itself?

 

[bkylecox]

Not in boots. Fairly certain intercooler is fine as well. I've checked connections and pigtails to ICP, EBP, VGT solenoid, MAP, MAF. The most aggravating part is, it won't malfunction at all until the ECT is near or at 170°F. I can usually drive through the problem after some cussing and feathering of the throttle. But, as stated before, when this happens, I lose all readings for boost, EBP, and MAP. It's not a miss like it's just 1 cylinder, it's all 8. It just momentarily goes dead like the key is off. Let off Acc Pedal and it'll buck and jump a little. Belch white smoke and go again for a bit, then do it again. Turbo???

 

[bismic]

MAP and boost are essentially the same thing, just the Baro reading is added to MAP. The Accelerator pedal, MAP, and Baro all are on the same v-reference circuit (351). They also share the Signal return (internal PCM ground circuit). ICP and EBP are also fed that same v-reference voltage. I would try running with EBP and ICP disconnected. Also, monitoring the v-ref voltage might help.

The Edge is pretty good at monitoring PIDs, but not that thorough at reading codes.

 

[bkylecox]

I put it on snap-on scanner today. Only got EGR codes. It's deleted. Ref-v should be 5.0, correct?

 

[bismic]

yes .

 

[bkylecox]

Ok. So v-ref was about 3.5. I unplugged IPC and EBP. Ran like ****....but ref-v came up to normal. Plugged ICP back in, ran better, voltage maintained. None of the original symptoms reared their ugly heads. I'm supposing there's an internal short in EBP. Going to replace sensor and go from there.

 

[bismic]

Either the sensor or the connector (or less likely the wiring).