Tracing Down A "Lope" Or A "Miss"

I only got one good WOT run. Tunes are on tow economy and the bed was empty. I can feel the miss at cruising speed and acceleration. Not so much at WOT, but it takes quite a while to get to 60mph.

 

More Lope/Miss Info

 

Fix for AE versions that read FIPW under 0.6 while running.

1. Hook up to the truck and open the "Live Data Grid" tab.
2. Check "Fuel Injector Pulse Width" from the alphabetized list.
3. Look to the right of the Sensor Name and you will see a button marked "...".
4. Click that button and look at the "Scale Factor" window - it will have "1" in the window. Change the scale factor to 10.

Any time you get fancy with your PID settings, it's always a good idea to save the session so you can get your PID settings
loaded when connecting. Remember, it will save all PIDs with your custom settings, so set up your PID "kit" carefully for subsequent use.

 

Posting your data.

AE saves files in "CSV" format by default. For those who are curious, that means "Comma Separated Values".
The forum does not accept CSV files as an attachment, so the CSV "extension" needs to be renamed to something
the forum will accept it.



Since AE files can get pretty big, "DOC" files will allow more data to be attached. Once you've recorded your
data, follow the red round road to making your recording available on the forum.

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For those who are have trouble attaching files, it might be your IE security. The attachment screen is a pop-up.
You can circumvent the pop-up blocker for websites you trust (like FTE). Here's how you do it with IE:

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Mongo has no paper clippy thing. Mongo use chrome.

 

Chrome has nothing to do with the paper clip icon. That's a post response window here on FTE, a format that isn't affected by the different programs available to access the 'net.

You don't have a paper clip icon because you're not a paid supporter.

Being able to post attachments to a post in a thread is a benefit for paid supporters.

Stewart

 

This graph was back in may. Its a stock wot-ish run. I did a wot run this morning but I think it got overwritten by the 80e wot run, but the stock graph looked alot like this one.


[IMG][/IMG]

My reason for posting... the truck seems to fall flat when I stomp the throttle in 80e. The icp and icp dc is way out of whack. It looks to me like the hpop is getting tired and cant keep up??? But I don't Know.


[IMG][/IMG]

 

Nope. It's called trying to hit 260+ RWHP with stock injectors.

Don't waste money on a pump.

 

Thanks for the reply cleatus. So is that why the dc is so high but the pressure is low because the injectors can't get rid of the fuel fast enough? Wouldn't the pressure be increased, trying to inject fuel faster? Sorry if these are dumb questions. I'm trying to gain better understanding of the beast.

 

Not dumb questions.

It's going to sound a bit complicated but I'll start with what your data is showing me. However, I'm no longer getting into the nuts and bolts of how the PCM handles the calibration parameters because a lot of people are now doing their own tuning and since I had to learn and become proficient on my own back in early '08, I expect others to do the same - there is no free lunch. Sorry to be a stick in the mud but the 7.3L is still (and will always be) a secret squirrel club.

A lot of people will monitor commanded injection pulse width along with RPM, injection pressure, and injection pressure regulator command. You happen to have graphed mass fuel desired (which is actually a good thing, although not as telling as pulse width). Now, I'm not targeting any aftermarket tuning company in particular because EVERYONE who can or has written calibrations for one of these things MUST exceed a certain injection on-time command to extract power levels above about 260-280 RWHP when dealing with stock injectors. There is no way around that.

In the most basic of descriptions, what you're running into is a cause and effect case of what commanded pulse width does when injection pressure falls; all because the PCM feels that the mass fuel desired MUST be maintained. It's a vicious cycle that causes a downward spiral in injection pressure until the high pressure oil system and injector flow reach an agreement and level off.

 

Here's what I was looking for......

Ford Truck Enthusiasts Forums - View Single Post - DTC 1211 on stock PDS under load.

 

Low ICP/high IPR at WOT

Uh-oh... I've been dreading this one. I breezed over it, but I can see that bag lying next to the cat (as he licks his paws). Here are the symptoms that make one break out the AE in the first place:

• You stomp on the throttle and you're climbing the tachometer, but you feel like the truck is holding back at high RPMs. The next gear up takes its turn, and all of a sudden - you get a renewed rocket ride. Tach ticks up, torque tapers, and toe is tempted to tamp and twist. The next gear arrives, and here comes that surge of sass on the shift.
• The EGT gauge spins to the right a little further than you want, so you log on the forum to ask "How high should my EGTs be?" 1250 degrees F is redline. You can drive the truck with high EGTs for a short time, but it depends on how high they are. 1350 degrees? A couple of minutes. 1600 degrees? Well... assuming your gauge isn't pegged - finish your WOT run pretty soon.
• Slightly elevated boost above normal. This one's hard to spot... you have to really know your truck. I could see the boost climb a couple of PSI when the torque was fading at high RPMs. This one symptom was the most confusing because torque was fading and boost was climbing. One word - Heat. The heat of the EGTs was expanding the gasses - adding "artificial" boost.
• Coal. Soot. The black snake. We've seen the posts from the newbies: "How do I get more coal?" I am proud to say I belong to a forum where the caustic contrail is frowned upon. I'm not saying the truck would burn clean without this syndrome... but it would be far less dramatic if the syndrome didn't exist.

ICP/IPR/FIPW 101
Getting a specific quantity of fuel into the engine is a matter of xyz oil pressure pushing fuel out of the injectors for zyx time.

• Injector Control Pressure (ICP) is the pressure the High Pressure Oil Pump (HPOP) is applying... this is what actually pushes the fuel out of the injectors.
• Fuel Injector Pulse Width (FIPW) is how long (in milliseconds) that pressure is applied to each injector to push the fuel out. How long is a millisecond (ms)? There are 1000 of them in a single second. FIPW is typically from 1 to 6 ms, so we're talking some tiny times slices.
• The Injector Pressure Regulator (IPR) is a valve that closes the drain on the High Pressure Oil system. The higher the number on the IPR (in percent), the more the valve is closed in hopes of building oil pressure behind it (ICP).

Caveat to FIPW: While it's true the FIPW can get as high as 6 ms on a stock truck, I have seen the pulse width go over 3 ms on a stock truck for only two reasons: The ICP is low for the fuel quantity desired, and starting the truck. Starting has low ICP because the engine turns the HPOP.
How does ICP get low when IPR is high? Look at your FIPW on a scale of 0-6. If you have high ICP, you don't need a high FIPW, because the fuel needed will get out of the injector fast. If the FIPW is high with a high ICP command, the injector can completely drain and have nothing left - yet the FIPW keeps the oil applied. Here it comes: When the injector bottoms out, the oil drain is exposed to the High Pressure Oil. I'll emphasize that:

When the fuel is completely gone from the injector, the oil that pushed the fuel plunger down is now escaping... bleeding oil pressure. That's bleeding ICP. The IPR tries to compensate for the reduced ICP, and slowly climbs. That's one way this goes sideways. In the case of stock injectors, the big droop occurs when the FIPW climbs over 3 milliseconds. I have a graph from a run up a hill with a heavy load (not a WOT run). The EGTs would climb, the driver let up off the throttle a little and the EGTs would cool. The driver gave a little more throttle, and the EGTs would climb again. One interesting part of all of this is the IPR (Injector Control Pressure Duty Cycle) "trend" - watch how it changes, depending on the Fuel Injector Pulse Width.



Many other things can cause the ICP to dip and the IPR to climb, making the FIPW climb as well: Bad injector O-rings, low fuel supply/air in fuel, bad HPOP, internal leak, bad IPR, bad ICP sensor, and a few things I can't immediately recall. If the Mass Fuel Desired is higher than the stock injectors provide, then that is the first suspect. I have not yet research what MFD is supposed to be on the varying injectors/nozzles... but I have the data in my collection to figure it out.

 

Great info guys, thanks.

Looking at the data I see that the FIPW gets all the way up to 4.75. I thought I had the max set right on the session but I was wrong so I didn't post a graph with FIPW, but here's at screen shot.

[IMG][/IMG]

Weird how the MFD never goes over 68 in 80e but does in stock? Much more research to do.

This all tells me that you cant try to diagnose an issue in a non-stock tune unless you know all the ins and outs of the tuning.

 

Mine did that and I installed a T500. My ICP gained about 700 PSI at WOT, but that was still 500 PSI short of the target 3000 PSI and the IPR was still high. What I'm saying is the T500 improved the situation greatly, but it wasn't a fix.