Sorry for the long post…

I’ll start with the diagnosis for the purpose of brevity, but would be glad to discuss how I arrived at this conclusion if desired.

After infrequent PO174’s I have concluded that I am experiencing a backflow from the intake manifold out through the EGR and dumping into the exhaust manifold. This extra air is causing the pre cat O2 sensor on bank 2 to read lean and the PCM is dumping in extra fuel on this bank, peaking the LTFT at 25% and setting the code.

Now this condition does not present itself very frequently but can be replicated with careful driving. Heading down the Interstate between 75-85 MPH (but holding a constant speed) I’m running about 1-2 inches of vacuum. The EGR duty cycle may be about 50% or so and the EGR ‘circuit’ is performing its function. Now, if I’m careful enough I can ease it into the boost 1-2 psi and the EGR duty cycle will stay above 0%.

At some point when I cross over to some ‘magical’ manifold pressure, with the EGR valve still open, the LTFT’s on bank 2 start increasing up to the maximum of 25%. If I increase boost/load ever so slightly more, the EGR duty cycle will go to zero and the bank 2 LTFT’s will retreat to a more appropriate level.

The only other factor I might add (and I have a whole lot of data) is that with the vacuum line disconnected from the EGR both bank 1 and bank 2 LTFT’s are in lock step; varying from about 1-5% positive. With the vacuum line connected, bank 2 LTFT is always about 5-7 percent higher than bank 1.

So my thoughts are why is the PCM not commanding EGR duty cycle to 0 when I approach 0 inches vacuum? My presumption is that because either the PCM is ignorant of that fact or was never accounted for in ‘the programming’.

I suppose another factor worth mention is that for the first 40K of operation I have never seen a light, this problem has only come into existence since this summer. So another question is why now?

Some folks have suggested that the EGR valve itself has a ‘weak spring’. I have wondered whether a poorly behaving DPFE is preventing the PCM from knowing and commanding EGR duty cycle to 0; however, with all of the information I have read from the Ford Service DVD I can’t determine if the DPFE has any impact on EGR duty cycle. It seems its sole function is to produce a voltage (it does, 1v with EGR duty cycle 0 and 1.2v when EGR duty cycle is anything greater than zero) that tells the PCM whether the EGR is flowing or not. Finally, I suppose there is always the possibility that the EVR is passing more vacuum than it should, holding the EGR ‘more open’ than it should. One Ford tech even thinks it could be the orifice in the EGR tube (corroded ‘more open’).

After reviewing all of the theory, concepts, and operation of the EGR system from the Ford service DVD I came up with another couple of thoughts and is why I chose to make this post here. One side of the DPFE is connected to the intake side while the other is connected to the exhaust side of the orifice. If the intake side is only expecting 22-0 inches of vacuum (sans KB unit), perhaps having a positive pressure on the intake side is having an unintended consequence (although I would think that consequence would result in an ‘Insufficient EGR flow’ DTC).

Another thought is that although there is a vacuum reservoir, under NA operating conditions ‘system vacuum’ is going to decrease as load increases. My theory is that under significant load there simply isn’t enough vacuum to even open the EGR; however, when boosted, the ‘system vacuum’ originates from the back side of the SC and although I have yet to measure it, something tells me vacuum is relatively high here even if the manifold side is +- 1-2. This high vacuum source is being passed by the EVR and is ever so slightly opening (or holding open) the EGR. Perhaps it’s a combination of some of the possibilities I listed. I though of piping manifold pressure to the EGR circuit instead of ‘system vacuum’, just as an experiment.

So I’m here to ask for your opinions. Let’s have them.

P.S. Why does the KB chip eliminate LTFT’s? With the KB chip my LTFT PIDs always register 0.

Oh, and it isn’t a Mustang, it’s a 2K Navi with the 4V motor TS5001 KB kit.

 

1-2" of vacuum during cruise is around .9 VE, and that's not normal. Are you running a boost-bypass valve?

 

Yes, and I think it is working just fine. Pushing the Navi at 80+MPH into a headwind can do that. To be more specific, calculated engine load at 'the effect point' is generally between 65 and 75%. At 90+ MPH I'm almost certainly into boost unless I'm in a tailwind. I do agree with your math; however, if I nail it, there is a LOT more motor left.

So, I'm not willing to take anything off the table just yet. Do you have something I should try?

 

I would get rid of the KB chip. Get you an xcal 2 or just a SCT chip from a very good tuner and have them turn off the EGR functions in the ECU, block off the EGR and see if that fixes the problem. If it does, then you know you have a problem with the EGR system and can go from there to determine exactly what it is and fix it. Then you can have the EGR turned back on, unless you just want to leave it off, which is fine too.

You will get more power and probably better gas milage with a SCT tune anyway. It will also fix your STFT and LTFT. I think you have a problem with the tune if one of them is always zero.


Marlon

 

The guys I know running KB's haven't had the best of luck with their chips. There's a couple things you could try, but it would require a change in your program.

Ever look into purchasing some tuning software?

 

^Yes. In the chips forum I'm looking at getting the SCT Pro Racer package. I'm just trying to figure out what I'm buying.

There's just so much hype out there.

 

If you think this one is fun, you ought to see the (perhaps silly) questions I'm raising in the 'Chips' forum.

 

You aint' lyin'!

Don't be intimidated by the Pro Racer package. It has very detailed help files that help you understand what everything does. You can also purchase the SCT Tuning Manual which has even more info, and tuning strategies...I strongly recommend getting that book and a wideband O2 (if you don't already have one). One of the nice things I like about it is how much control I have over the transmission.

The Pro Racer Package may seem like it's a bit much, but it is a very powerful tuning tool. SCT has their own forum where you can go and get updates for your software and tuning/technical help from employees and dealers.

The base file you get should be close. I know the file I got was pretty close; I just need to make some slight changes to the fuel and spark...a lot easier than starting from scratch.

Good Luck!

 

Well, I'm 90% of the way to some SCT hardware/software, but I'm just not yet clear on what I need to get to address my known (and unknown) requirements/desires. The guys at MotorHaven have certainly tried to help me out (bless them for their patience) but I feel I've still go a bit of learning to go yet.

It would be so much easier if I was doing a 2K3 Cobra, but when it comes to a Navi, there isn't that much 'common knowledge' out there.

 

hkiefus, what are your questions?

Tuning your Navigator is no different than tuning your 2003 Cobra.

 

My questions have to do with what pieces of hardware I'll ultimately have. Pro Racer software and a chip are givens. XCal2, I don't know. A WDS can do the job for me, but it can't accommodate a wideband O2. So, it seems (although I don't like the idea) that I need the XCal2 just so I can see A/F while I tune. So, I'd really like to get something more economical than an XCal2 just to read A/F.

Perhaps a Tweecer in more in order for me. I don't know. I try to be an educated consumer but neither vendor can tell me why theirs is better then the other's, in fact neither is doing a real good job and telling me what's what as it is. I've made the decision that I don't want to have to flash a tune; I want to be able to switch to stock or yank the chip entirely and not have messed with the contained PCM programming. With SCT that leads me to the Pro Racer Software, a chip, and *then I suppose a device that connects to my laptop that read/writes from/to the chip*. Nobody is telling me about this device, what it costs, whether it comes in ‘the package’ and so on.

From the Tweecer perspective, I first thought that it was simply a data logger/PCM flasher. However it seems I can use a chip with it too, they are not telling me about that otherwise unmentioned magical device that sits between the laptop and the chip. Further, it seems, but I'm not sure, that the Tweecer will accept an additional input like an LM-1. But what they don't say is what A/D device sits between the LM-1 and the laptop. Also, they claim their RT (Real Time data logging) isn't available for the Gator, yet (he) claims he can 'get it done for me' in a week after I purchase.

So that's the education I still need to work out.

Finally as far as tuning goes if it was a Cobra, there's 500 other people out there I can rely on for direct application experience. With the Navi, and I really wanted to keep this my little secret so a bunch of people don’t start asking me how, I'm trying to create multiple tunes for a switching S/C, I can run N/A, 6 psi, 9 psi, 12 psi, and 15 psi and two separate fuel systems all while running down the road. (Hence my need to switch multiple tunes while in operation.) Finally, my point is, there are probably very few Navi applications that I can rely on 'in the community' and less so with what it is that I am trying to do.

 

Three options with SCT:

1. Buy the Pro Racer with a tuner, not a chip. The tuner is the XCal2. The XCal2 plugs into your laptop via USB. The XCal2 also plugs into the computer via the OBDII port. With this, your laptop datalogs. If you have a wide band O2 sensor, it can plug into the analog input on the XCal2 and you can datalog that as well. So, need to purchase Pro Racer, XCal2 and if you want, wide band O2.

2. If you must have a chip for the "switch on the fly":
Buy the Pro Racer with a chip and a tuner, and special adapter cable. The chip is the SCT chip. The tuner is the XCal2. The XCal2 plugs into your laptop via USB. The XCal2 also plugs into the computer via the OBDII port, but with the chip installed, you also must use the special cable. With this, your laptop datalogs. If you have a wide band O2 sensor, it can plug into the analog input on the XCal2 and you can datalog that as well. Purchase Pro Racer, XCal2, chip and special adapter cable, and if you want, wide band O2.

3. If the thought of purchasing the software, XCal2 and chip doesn't suit you, we have a new SCT Raptor (datalogger interface) that we can let go cheap (SCT discontinued the product when the Xcal2 came out). So you need to get the Pro Racer software, chip and SCT Raptor. You'll also need to purchase a wide band O2 to plug into the Raptor.

The tuning on your suv is not much different than any other blown 5.4 Ford application, for the most part.

The Tweecer is not likely to support your truck. It have very little coverage for Ford trucks and SUVs, its PCM code support is spotty at best. Check them out, its pretty primitive compared to SCT's stuff.


Why is SCT better? The software is better documented and handles more functions in the PCM. The software interfaces with the XCal2, for extremely fast datalogging. They are in stock, Tweecer isn't until at least late January. The SCT is produced by a company that's going to be around to support it and the support is by a company with some of the foremost gas tuning experts in the aftermarket. The Tweecer is produced by a two man team. Naturally, we're biased.

 

Well, it looks like SCT is going to get my business. Thank you for confirming what were my suspicions relative to Tweecer. Not that they're a fly-by-night operation mind you, but I have been in the SW industry too long and know exactly is what behind those 'we can do it for you' promises.

So, do you still feel like doing some base tunes? N/A, 6 and 9 psi on 93 octane, 12 and 15 psi on 100 octane LL?

 

In case you haven't seen it yet, here is the link to the SCT website for the PRP. I think it needs to be updated though, cause I think thats the one they sold before the Xcal2 came out.

From what I understand, they sell a PRP with a chip and a chip burner with a non flashing Xcal2 for datalogging. The dataloggin Xcal2 is cheaper I think since it doesn't do any flashing. If you can buy that Raptor though, it will do the same thing I think. I have never used a Raptor, but I have heard it was the fastest datalogger around in its day. I have used the Xcal2 to datalog though and I can tell you it works great.

Also, I don't think you will need 2 seperate tunes for 6 and 9 psi, or 12 and 15. You should be able to tune at 9 psi for 93 octane and run at 6 psi or less with no problems. You should also be able to tune at 15 psi on 100 octane and run less than 15 psi with no problems.


Marlon