Engine/Transmission (1998.5 - 2002) Gary-K7GLD and other APPS Gurus

[FLynes]

I recently had to recalibrate the APPS, after getting my P0121 code. I got the APPS back into specs, but I did NOT turn the vehicle to "On" and depress the accelerator pedal.



Here's my thought/question for you guys: Would not teaching the APPS after calibration cause MPGs to plummet?



I ask this, because no P0216 or P0215 codes have been thrown, but my mileage has just gotten terrible in the past few weeks... . terrible being from 19MPGs to 12MPGs, with no different driving habits or conditions.

 

[JLandry]

Fred,



In the absence of other things contributing to it, I can't think of any direct correlation between APPS calibration and fuel economy. The APPS merely tells the ECM where the driver has the accelerator pedal (with an "idle" and "not-idle" verification signal included as a backup).



Have you noticed any change in performance or driveability?

Have you changed your fuel and air filters recently?

What about tire air pressures?

Could your exhaust brake butterfly be stuck partially closed?



Best regards,



John L.

 

[Gary - K7GLD]

I agree with John - must be some other sensor issue, such as IAT or MAP - but you'd usually also get codes...

 

[mhenon]

Fred, I agree with the others it shouldn't have anything to do with your mileage dropping off. Mileage going south that fast makes me think of a bad load of fuel or plugging fuel filter. Don't think it's your APPS but recalibrate anyway. Then you can scratch it off your list of things to look for!

Mike

 

[FLynes]

Gentlemen,



It was a shot in the dark; I tend to agree with you all that the problem lies elsewhere.



I've not looked at the MAP or IAT sensors yet..... and to be embarrassingly honest, I don't know where they are located!!!!!



No change in performance or drivability, though when I have the cruise control set to 55MPH, it does fluctuate up and down about 1MPH... never noticed it before, but that doesn't mean that it didn't do it before.



Tire pressure is set to factory stds, and I just had the tires rotated and balanced last weekend... I do it every 6000 miles.



I just had my AirDog installed in February, so I'm pretty sure the filter is still good... it was installed at 115,000 miles and I'm now at 122,000. I've got a new Fram stock air filter in it too.



Hmmmm, never considered the Jake Brake butterfly being partially closed, but then again I would think that the noise made by partial closure would be apparently audible, and there is no noticeable difference.



My bet is that the VP44 is slowly but surely going South, but I just haven't popped any codes yet. I was thinking that maybe another option might be to check out the injectors... . I wonder if they might be crudded up. Is it easy to take them out/inspect?



I recalibrated the APPS, so we'll see if that makes a difference, then again I would think that had it not recalibrated itself by now, I would have noticed that as well.

 

[DLBurns]

Did recalibrating your APPS clear your code? I am getting the P-0122 code for mine and I want to be sure it is a goner before I throw money at a new one. This is my second APPS with a little over 40K on the odometer.

I'll be contacting Timbo if I can't clear this code.

 

[rweis]

ONE of the symptoms of a failing VP44 is fuel mileage getting worse and worse. However, on the same hand it may not be the VP44 going south.



Most times the advance piston starts to stick and not agree with the amount of advance called for and that disagreement is one of the reasons the 0216 gets generated.



There is only fuel and air. Something is up with one of them. Filters as suggested, fuel pressure / volume to the VP44, injector(s), or one of the sensors (IAP, MAP, etc). Grounds come to mind since all the sensors work off grounds and usually 5 volt supply.



I would not automatically jump to the VP44 unless you also get codes that directly point to it.



Bob Weis

 

[rweis]

DLBurns -



Have you done the manual recalibration of your dc APPS? (There is a thread on how to do the manual recalibration. You have to remove the APPS bracket and get to the actual dc APPS to rotate it) 0122 I think implies a low out of range voltage which can occur if the pin23 C3 is not close to your APPS sticker number. The dc APPS has a small amount of adjustment you can do.



Bob Weis

 

[FLynes]

ONE of the symptoms of a failing VP44 is fuel mileage getting worse and worse. However, on the same hand it may not be the VP44 going south.



Most times the advance piston starts to stick and not agree with the amount of advance called for and that disagreement is one of the reasons the 0216 gets generated.



There is only fuel and air. Something is up with one of them. Filters as suggested, fuel pressure / volume to the VP44, injector(s), or one of the sensors (IAP, MAP, etc). Grounds come to mind since all the sensors work off grounds and usually 5 volt supply.



I would not automatically jump to the VP44 unless you also get codes that directly point to it.



Bob Weis

Bob,



Is there a way to un-stick the advance piston, without tearing the VP apart?



Also, where are the IAT and MAP sensors located on this beast? I'm betting on the driver's side of the engine block, but I want to make sure, before I undo something critical. If I remember too they need two different sized wrenches to get them off.

 

[TSBrown]

the iat is at the back drivers side of the head and the map is just before the iat. The iat is 13/16 and the map is 1 1/4 deep well wrench wont fit.

 

[rweis]

You can try various lubricity additives, but generally if you have not been using them from day 1 the damage is done and can not be repaired. Tolerances are measured in 1/10,000" and it does not take much for damage to take place.



I would try a lubricity additive, can't hurt, and might help some.



Your sig has a 2001 truck. Bosch had experimented with a brass advance piston sleeve that ultimately did not hold up well. I think all the rebuilds now use the steel advance piston sleeve which holds up much better and in addition there have been several other internal improvements to the VP44 (diaphram etc).



Bob Weis

 

[FLynes]

I have used PS or Howe's since I've owned it (1 year now).



I'll pull the IAT and MAP out and inspect them today.



BTW, can you clean them both, or are they a disposable/replaceable item?



Also, how hard is it to pull the injectors and clean them?

 

[JLandry]

Also, where are the IAT and MAP sensors located on this beast?

Fred,



See the attached picture below. To orient yourself, note the fuel injector line you see in the upper right corner of the picture is the last one (cylinder 6) at the back of the engine on the driver's side. This area is basically above the lift pump.



Regards,



John L.

 

[FLynes]

John,



Great pic, thanks! Even better is that I no longer have that OE Carter POS, so access should be a breeze.



So if I pull the injectors, what's involved? This question seems to be avoided..... am I in for a treat?

 

[Gary - K7GLD]

I have used PS or Howe's since I've owned it (1 year now).



I'll pull the IAT and MAP out and inspect them today.



BTW, can you clean them both, or are they a disposable/replaceable item?



Also, how hard is it to pull the injectors and clean them?

Nothing to clean on the MAP, the IAT often gets coated with soot, especially if an exhaust brake is installed, but it can be cleaned with carburetor cleaner. It will be interesting to hear what condition you find the IAT in...

 

[FLynes]

I'm going to stop by Auto Zone, on my way home from work, to pick up a can of carb cleaner. I'll post my findings this evening.



On a happier note, since throttling back to 55MPH from 65MPH, the comp has read about 4MPG better. I've gone 115 miles since fill-up, and I'm still at the full mark... . I top off my tank; I don't stop filling, when it clicks. That may not be good, I know.

 

[JLandry]

So if I pull the injectors, what's involved? This question seems to be avoided..... am I in for a treat?

Fred,



Not avoiding here... just have never done it myself... yet.



If I thought my injectors needed cleaning, I think I would pull them out and take them (or ship them) to a reputable shop that specializes in this sort of thing to have them thoroughly cleaned, the pop-off pressure tested, and recalibrated (as needed). With the high cost of replacements, I'm not sure I'd want to start monkeying around with them too much.



Keep in mind that if you remove the injectors, you'll nee new o-rings for both the injectors and fuel connector tubes, and also new copper shim washers for under the injectors. The tightening torque of the injectors is critical to preventing hidden leaks.



John L.

 

[FLynes]

Good morning, Gentlemen,



So I didn't post yesterday evening, for a very good reason. I took the IAT sensor off... . it was a bit of a bugger, but I reached it... . don't know how the folks with all that OE fuel crap do it, LOL.



The IAT sensor was completely crudded up with black tar. I took it to my workshop and thoroughly cleaned it..... took before and after pictures too.



I put the part back on the engine and torqued it per another post's recommendation of 10lb/ft... ... ... ... and the brass fitting snapped, which is when I freaked out, because now I had the brass screw part in the motor.



I calmed down and fit my finger on the broken part and ever so gently backed it out. Got it out, went inside, cussed a bunch and started calling around. Dodge dealership was already closed... this was at 6:15PM. Called AutoZone... . special order item. Called Napa..... closed. Called O'Reilly Auto Parts..... special order item, and they didn't even know if they could get it, because there was no price listed. AutoZone wants $34. I'm calling Dodge this morning to see what their rip-off price is.



Lesson learned? The torque spec is NOT 10 lb/ft!!!!!!!!!#@$%!



Oh well.



I'll post pics when I get a new hard drive for this POS HP laptop... . keep getting the blue screen of death when I type... . four times now.

 

[FLynes]

Okay, so AutoZone can't get it till sometime next week.



Local Dodge thieves want $48 and can't get it till next week. #@$%!



Went to Mopar Parts America and have it coming tomorrow for $43 , which includes express next day shipping... . part was $23 by itself. Oo.

 

[mhenon]

These guys could probably over-nite it if you need it fast:internet specials