Instead of having to read 3 pages to get up to date I decided to post a summary;

I'm having intermittent power issues and if I let the truck sit for more than 3 days it is a bear to start.

When the motor is cold and sometimes warm it lacks power can't pull a hill unless in 2nd (manual transmission) and acceleration is poor below 1800 rpm and then once warm (sometimes) it runs like a scalded dog, plenty of power, easily accelerating on the same hill in 3rd.

Sometimes when I start cold I hear a hiss from the exhaust & motor area, I understand that is the EBPV restriction to help warm the truck up quicker. I've read about the mod to eliminate it in case it is malfunctioning during normal driving but I can't do it right now. I've pulled the tube and EBP sensor - tube was clear, I cleaned it though just in case... didn't make any difference in performance. Using my AE I do get a P0476 Exhaust Pressure Control Valve Range/Performance code... my exhaust back pressure at idle is 15psi. Could the sensor be bad and could it cause my intermittent power problems.

I pulled both valve covers, checked wires for chafing and rod clearance, torqued the rocker and injector bolts, and completed the 50 cent mod (harness was firmly connected before the mod). The harness on the drivers side looked new as compared to the passenger side & I had to grind more of the quarter on that side to get the valve cover clearance. All injectors looked stock (AE) but #8 had LL stamped on it, maybe a rebuild?

I cleaned and checked both air inlet tubes for holes, they are good.

Checked turbo wheel and housing - no play, freely spins, no scarring or bent fins.

Replaced the MAP sensor hose because it was repaired with a straight coupler. Now I get a P0237 Internal Control Module Sensor A Circuit Low but no CEL. I feel some cushion resistance when I plug the MAP into the harness but it does latch, is that normal, pins are straight. Trying to find a used one for troubleshooting. But still sometimes plenty of power and this morning power and accelration was terrible.

Some suggested my starting issue may be GPR & Glow Plug related, all ohms, volt checks are good and it also passed the AE test.

During a cold buzz test injectors 1 2 3 4 7 8 are all quiter than 5 6, number 4 is very faint. I'm about to pull the trigger on injectors but as I said before sometimes this motor has tons of power.

Cylinder Contribution test throws a code of P0284 Number 8 cylinder and sometimes other cylinders when cold, but always number 8. Cylinder Change rotational velocity readings are all 0 to 1.1 % except number 8 and it reads anywhere from 2.2 to 2.9 % and I understand 3 to 5 % is not good.

In 10 days we leave for a 4000 mile vacation pulling our trailer with plenty of grades to pull I'd like to find the solution before then or it may be a slow go.

I'm willing to work my **** off over the next 10 days to get it right.

 

Notwithstanding your buzz test observations, your rotational vel seems OK. Since you have an AE I suggest you monitor the ICP variables (log them) when you are having these issues, as in go drive it and log it. You may want to seriously consider temporarily disabling the EBV before you do this just to see if most of your problem goes away.

 

How do I monitor the ICP variables, this AE stuff is new to me.

 

When you are connected go to the live data tab. Select the parameters you want to log and you can watch them in near real time. I would probably go with ICP, PW, RPM, MAP and for giggles EBP. I would not log too much as the bandwidth/speed suffers. You should be able to see the live data in their own windows To record the data you need to hit the record icon on the top so do this when you are ready for the log of the problem area you have. I would be curious to see what your MAP and back pressure looks like.

Oh, might also want to log throttle as well to make sure there is a good linear signal and see how the other parameters respond. Good luck.

 

I guess I should have read a little more about data logging before I left. I started the recording at idle and then pressed f10 to stop after 20 seconds. I then pressed f11 to start as I pulled out of the driveway and then f10 after a couple of miles (truck was running terrible) at the beginning of the hill I pressed f11 to start and the truck was running terrible and after about 10 seconds I felt a change and everything was running great. I figured this is perfect I'll be able to see the data at the change. I got home pressed play, selected the parameters, and I only captured the idle data... Crap! I'm getting out the book to read up on recording right now, next data recording might not be until later tonight or tomorrow so my truck will run poor again.

 

I forgot to mention I couldn't find PW, what is that? Found it, Injector Pulse Width

 

I have some logs from Del's truck. I don't see any obvious problems as far as his ICP is concerned and it seems to respond properly to throttle input readings. I am wondering about the relationship of his exhaust back pressure and manifold pressure readings. Del does not have a boost gauge so we can only guess what boost he is actually making though the readings seem to suggest a close to 1 to 1 drive pressure ratio? Here is what I am talking about:

EBP MAP
14.86 14.3
20.34 18.1
26.8 24.4
29.4 28.4

The last one with a throttle of 53 and ICP at 2700. If I were to guess I would say he probably made about 14-17PSI there. Anyone out there with a similar setup that has logs to compare and any input it would be appreciated.

Anyway, I called Del last night after some , sorry bout that Del, and suggested he look real hard at his fuel delivery since his truck can run fine one moment then not as well the next. Also the intermittent no start could be due to fuel delivery. A piece of hose, fittings and gauge are relatively cheap to make sure that he is not running low on fuel pressure.

He is also going to go over the engine again making sure he has no boost related leaks. Again this will not affect the no start issue though.

Unfortunately none of the logs he sent were when his truck was acting up so generally they appear to look OK. Just wondering if anyone has logs of the EBP and MAP from their setup for comparison.

 

FWIW I just tried to log my truck, laptop battery is about shot, but I saw similar type number relationship of EBP and MAP. Just a bit more "boosht" on mine which was not unexpected.

 

Thank you Mike for looking at my data logs and calling the other day.

Being the impatient sort I couldn't find all the parts I needed to put a fuel pressure gauge together yesterday so after reading several posts regarding fuel pumps and how similar my issues were to others I just bought a new fuel pump. Before I installed it I blew some compressed air back into the tank in case I had somescreen blockage. I didn't notice any driving improvements or AE log data but it was worth a shot; bright side, now I have a new pump and spare.

This could still mean I may have a fuel delivery problem, maybe injectors right, or do my ICP numbers eliminate the injectors as a cause?

7 more days before we pull out for our 4,000 mile RV trip, any more ideas?

Here are a couple of data pics Before - After Pump install
Red - Throttle Pos
Green - ICP
Blue - RPM
Orange - MAP


Before Fuel Pump Install



After Fuel Pump Install

 

What do the rotational velocity numbers look like with a cold engine? (you'll need a resistor on the EOT). Did you ever clean the screens in the mixing chamber (inside the fuel tank)?

Does it act any better if you plug the truck in over night? How many miles on the engine oil, and what weight and brand are you running?

 

Could you explain how to add a resistor in the EOT system. I'm assuming that's required since the EOT on a cold engine would not be in parameters?

I have not cleaned the screens but I did blow compressed air back into the tank, I understand that would help dislodge some crud if there was a rerstriction. My tank is near full so I don't plan to drop the tank before my trip unless everything else looks perfect and that has to be the culprit.

The PO had the oil changed at a service center with 15W40 (no brand mentioned) in April, about 2,200 miles ago, he said all hwy miles. My plan was to have it changed at about 3,500 and then it would last the rest of the trip or I suppose I could change it now and then have it changed later in the trip.

I planned to drive & scan it on a cold start this morning to see if the performance has changed and then I'll plug it in overnight for a drive tomorrow morning to check any differences.

Thank you

 

I performed a buzz test this morning and #1 & #7 were very faint (inside cab, hood closed) as compared to the others.

I also have a question regarding the fuel pump. Every time I turn the key on I hear the electric fuel pump, good thing, but it does even if I just recycle the ignition is this normal? I do not have any visable leaks.

Also just a few seconds after I turn the key on or recycle it I hear a short growl or purge sound in the engine compartment. Is that a normal sound & what is it, my 97' 7.3 didn't make that noise?

What's next?

 

The compressed air will work sometimes, but is by no means fool proof. I would at least rig up a fuel pressure gauge and watch to see what's happening to fuel pressure when you're having problems. You can use one of the ports on the back side of the fuel bowl to plumb a temporary gauge in. I've seen guys duct tape a gauge to the windshield for diagnostic purposes.

For the resistor, you'll need a 5.4k ohm resistor. Bend it in a U shape, unplug the EOT sensor and stick the U-shaped resistor into the plug. When the computer reads the resistor, it will make it think the oil temp is 160 deg.

 

OK for the experts out there this may be insightful... First start/run of the day.

First picture is right out of the driveway and everything feels good. Notice the IPC is right up with the Accelerator Position - first time this has happened. To the right of the picture though it dropd off?

Second picture shows the performance as it starts up the grade, shifting from 1st, 2nd, then into 3rd. The motor never gains RPM, Boost after shifting into 3rd and ICP is falling off.

Later up the grade performance improves but ICP never mates with Accel position but I am able to gain RPM & Boost in 3rd

What happened, does this shed some light?

 

I know the answer to your problem is staring me in the face. It is just a matter of making sure I pinpoint it right. Your ICP will not stay up with the throttle on the graph because of it's value which will max at 3000. It should follow along with it which it does for the most part.

I see that the RPMs, boost and ICP fell off in that 3rd gear part. What I don't know is what you did from then on. Did you stay in the throttle all the way or did you back off and get back into it towards the end of the graph? Shift gears? Your #s go all over at the bottom of that RPM drop off.

For anyone who has stock injectors, what kind of duty cycle #s do you show at WOT under load? This truck shows 36%.

Also of interest looking at the data tables, there are times when throttle input seems to fall to idle or 11.7 when clearly it looks like your foot is in it? For whatever reason your truck does not seem to want to go over 2500RPMs. Is this correct? Have you ever had it over 2500?

I know you replaced the fuel pump but I would really like to know that your pressure is where it should be. Once we know that we can look into why that fuel is not getting into the hole like it should. During that RPM drop off portion it appears you ran out of oil as that ICP should have been commanded higher based on the throttle input. The duty cycle just goes from 36 down to 26 when it should be commanding more ICP. Then suddenly and mysteriously it finds some ICP I assume just from letting up and getting back on the throttle.

I am going to do some research and get back with you. I think we may need to log a few other things but if anyone with stock injectors has any duty cycle data that would be useful. Without reading all the way back, have you tried unplugging the ICP sensor and driving that hill in default mode?