So...
I am still trouble shooting a low power issue with my truck and I am suspecting my EBP sensor and/or tube may be partially clogged. At any rate....I was using my AE to monitor some sensors while I drove down the highway and noticed that my Fuel Pulse Width never climbs over 3 ms at WOT. I think the range of the pulse width is 1 to 6 ms so maybe something is telling the PCM to 'de-fuel'?

I checked some old posts and found a very helpful post from Justin03PSD where he posted his data log. His pulse width peaks in the nigh fours.....so I am thinking that my readings are not normal. Highest I can get is 2.85 or so....


With the engine off, the exhaust back pressure is about 1.5 psi higher than the manifold absolute pressure. They should be about the same with engine off....correct?

Am I going down the right path? My thoughts are that a partially clogged EBP sensor or tube may be causing a condition where my PCM restricts the fuel injector pulse width. Am I way off base or could this be a possibility?

I'll pull the tube and sensor this weekend unless someone thinks I am wasting my time and chasing my tail.

Any thoughts?

 

I didn't see a tuner listed in your sig, and I can't say positively on stock tuning. I've talked with my tuner before about the ebp sensor, and he said said that there isnt really much of a difference with the tuning if its stopped up, or if the sensor is unplugged or operating correctly. I do no run one on my truck and has not affected anything at all.

Like I said, it may be different with stock tuning though. Or if you have pinholes in the EBP tube, that could create a low power issue, i've seen that before.

How much of a powerloss are you feeling? What does your boost gauge needle act like when you stomp on it? and whats your max boost? are you're egt's excessive?

 

I'm running the stock tune right now, but I do have a Bully Dog Power Pup programmer...but it's not loaded right now while I diagnose this issue.

When I floor it from a dead stop...the engine falls on it's face and struggles to get across the intersection. As the boost starts to climb, the power comes back in. Max boost pressure is about 15 psi or so. The upshifts are very hard during acceleration. Not sure what that is about. I can probably accelerate just as fast by using part throttle so something is not right. Feels like an intercooler boot is missing, but my gauge takes it reading at the AIH port so there must be boost all the way up to that point.

I do not have a pyro gauge. I bought my gauges years ago and didn't want to drill and tap my turbo. Bad decision because now I really wish I had that gauge. So, I have no clue what my EGTs are.....

The feeling could also be described as if something was restricting the fuel. My AE scan tool has a pull down menu choice for fuel pressure but it reads zero so that must not work for my year. My next best thing to check was fuel pulse width so that is why I posted this question. I suspect that my pulse width readings are not normal. If this is confirmed, then I can look into the possible causes for that.


I read some posts here on FTE where owners have experienced low power and bad mileage and then cleaned their EBP sensor and tube and the power came back. So, I was sorta hoping.....

I rebuilt my own injectors last weekend. Maybe I messed something up. The truck idles quite smooth though and runs smooth, just low on power. Maybe I wasted my time and/or caused this issue with something I did? No SES light. Only code is P0541 Air Intake Heater Circuit A low. (I removed my AIH and installed a fitting to connect a hose for my boost gauge).

 

How bad, if at all, does it smoke when you stomp on it?

And the fuel pressure is not tied into the pcm at all, so you would have to have a mechanical gauge on it to tell.

What are are you ICP and % duty cycle like when you get on it?

 

No smoke at all when I stomp on it, at least not that I can see. ICP pressure is about 2990, I don't remember what the ICP DC is....I think I did a data log...darn, I can't open it (I need to learn how to use my AE more effectively..) Hard to see all the reading and still keep an eye on the road.

KOER On Demand test only returns the P0541 code and I also ran this HPOP health check
http://www.roadsidehelpnetwork.info/AE/healthck.pdf
All readings were in line....except for the exhaust back pressure. The guide said it should be between 10-15 psi. I am reading 15.5 psi at idle.

When the truck fired for the first time, I had about 1/3 quart of oil pour out of the muffler drain hole so I obviously had some oil in the exhaust from when I pulled the injectors. Because of that, I am wondering if the EBP sensor tube got some oil in it and then it got hot and gunked up and possibly causing some problems.

I am also wondering if my EBP valve might be not completely open.

 

Perfectly normal.

At 3000 psi of ICP, you can empty a stock injector in 3.5 ms. Since you are running stock tuning, 3 ms is about right.... depending on ICP pressures. The higher your ICP, the shorter the pulsewidth.

They don't always match up. So no, they won't always be the same with the engine off.

If there was an actual problem, you would have a code set for high exhaust backpressure.

 

Run AE again. This time watch the boost that AE reports, and compare it to your boost gauge. See if there is a discrepancy of more than a few psi.

 

Ok good. Thank you for the comments. Hmmm, so all things are pointing to the injector rebuild since that is all that changed. Maybe I need to pull the sticks and have them flow tested...

 

My AE does not have a choice for reading boost, but it does have Manifold Gauge Pressure. That reading seems like it would be boost and yes, it does match my mechanical boost gauge exactly. That was one of the choices I had showing on the live data meter when I was driving home last night.

So, prior to removing the injectors, the engine had a barely noticeable miss at idle but still felt like it had plenty of power. In top gear, when trying to accelerate from 45 mph there was a much more noticeable miss. Upon visual inspection, injector #7 was not discharging oil. PERDELS reading was:
Cyl 1= 0%
Cyl 2= 0%
Cyl 3= 1.4-2.5%
Cyl 4=0-1.1%
Cyl 5= 0%
Cyl 6=0%
Cyl 7=2.7%
Cyl 8=3.2%

I pulled all injectors, replaced #7 with a rebuilt unit I ordered from RiffRaff and rebuilt the remaining 7 with an Rosewood kit. After reassembly, my PERDELS are:
Cyl 1=1.1%
Cyl 2=0%
Cyl 3=2.1%
Cyl 4=1.3%
Cyl 5=1.3%
Cyl 6=0%
Cyl 7=0%
Cyl 8=3.6%

This morning I ran a buzz test on the cold engine and #3 came up with High/Low side open. I wonder if I should go ahead and get a new set of valve cover gaskets and under cover harnesses?

 

Subscribing.

I don't have anything to add to the diagnosis, but if you need more logs from me to compare against I would be glad to help.

 

Thank you very much. Are you able to read Barometric Pressure in psi with your AE? I am only able to see the volts from the sensor. I think it said something like 4.75 volts. Not sure what the range was but the bar on the bottom of the meter was orange(ish) and about 75% of total range.

 

That's a possibility. A buzz test checks the electrical side of the injectors. A chaffed harness wire or a loose connection would cause a failure when running a buzz test.

 

Justin,
Do you have a log that shows the Exhaust Back Pressure at WOT while accelerating from a dead stop? I would be very curious to see that. My exhaust back pressure climbs to the high twenties pretty quickly and settles in at 38 psi or so. I am not sure if that is normal or not.

Thanks for your help.

 

I don't have any other logs to reference, but I can take some this weekend (probably Sunday). I am assuming you want 'em taken with the stock tune.

I will PM you my email address, be sure to reply with yours so I can send you the logs.

 

I found the issue. My injectors were not holding oil pressure. They would run fine at idle pressures, but when the HPOP comes alive, the poppets couldn't hold the pressure. Here are the details.

It turns out that I messed up during the injector rebuild. The instructions said the poppet valve needed to be in the EXACT same position as it was prior to dis-assembly. So, I took one of those vibrating etching tools and made some witness marks. Upon re-assembly, I aligned the marks and then installed the armature plates.

I missed an important step designed to test if the poppet was indexed correctly. I was supposed to gently spin the armature plate 360 degrees clockwise and feel for the home position and confirm the channels in the armature plate was parallel to the magnets in the solenoid. (Thank you Jim from Rosewood for suggesting that I check the poppets...)

So, off come the valve covers and solenoids and sure enough, 5 of the 8 injectors had poppets that were not indexed correctly. I corrected the issue and now the truck runs like a top.

I hooked up my 7000lb boat and towed it around for about an hour to make sure everything was ok and didn't have any issues. So, I am satisfied that this issue is resolved.

Thanks to EVERYONE who offered their help and comments. All suggestions were welcome and helpful, gets me thinking and eventually we figured it out. You guys rock!

I have another thread that I started during my solution finding process so I'll post the same update there as well.
Thanks FTE!!!!