RBob,

Now that I have applied the HiWay SA patch to my 7747 bin, I see that AFR for OL can range upwards to 16.1:1. I also see that the ECM Constant Table contains one setting for MAX AFR in OL(Non-Idle).
Should this be set so it is consistent with the AFR invoked for HiWay SA? It originally had been set at 15:1.

 

Good question, bump this to the top. I don't think it really matter too much but I haven't had to mess with any of the highway parameters to get good gas milage. I just wish I had a wideband o2 sensor to verify the AFR's so as not to run too lean.

 

Yes, the max lean OL AFR should be matched to the hiway AFR table:

;--------------------------------------
; Max lean afr
;--------------------------------------

LD2C5: FCB 169 ; 16.9 max afr

For the '747 of course.

RBob.

 

Thanks to both of you for responding. I went and made the change so it matched the 16.1 ratio for the MAPxAFR table in the patch. Like JPrevost, I am a bit hesitant just because I don't want to poke a hole in a piston. But I have a 68mph
speed parameter and a 75sec delay programmed into the Constant Table. I've had it out on the road and it appears to run fine. I hope to put a diag tool on it this weekend.

 

Rbob,

Burned a chip with the patch incorporated into bin and made changes to the Constants Table. However, during my drive the scantool is reporting that the O2 sensor voltage is staying near the .4mv range. If I remember correctly the text from the patch suggests the ECM will go into OL and O2 voltage will drop below .1mv. The commanded AFR is 16.1 or less depending on MAP, and I have added 1d for Hiway Spark. Spark counts don't change. Does it sound like the patch is working or have I done something wrong?

 

I also did some additional scans, and the idle BLM's started climbing to 172. This happened once I raised the OL AFR threshold to 16.1 in the ECM Constant Table. I am not sure if its what I did or the patch, but I have replaced this bin file with the bin I had prior to implementing the Hiway Patch. Any suggestions or comments on what I may have done wrong?

 

I've never seen a BLM of 172, that's aweful high. You're open loop driving must be stalling or not even starting!

 

What hiway patch are you guys talking about? I thought that once your set speed and time delay were met, that the computer would ramp the afr up to the max afr @ 2C5. Adding whatever spark you may have put in your hiway sa table. Am I missing something?

 

JPrevost,

An update. I found that the pigtail from the O2 sensor had sagged to the point of resting on the collector of my TPIS headers. Needless to say, I replaced the sensor yesterday and put insulating conduit on pigtail to avoid a recurrence. I did do another scan yesterday once everything was fixed. I still find that the Hiway Patch doesn't put ECM into O/L after the prescribed time and MPH parameters are met. I do notice that the O2 sensor will meassure down to .03 but it will transition back up to .87 and the BLMs do not lock at 128. I also noticed that the BLM's in general are somewhat higher on the patched Bin File than the identical one that is not. BTW, Rbob's fix for the TCC lock works nicely.

 

Which one is that? I don't think I've come across it...

 

V8,

Its here:
https://www.thirdgen.org/techbb2/sho...hreadid=127583

Change the 007 address from 24 to 20 and now the overdrive doesn't unlock when I lift of at 80mph.
Also, addresses 567,568,569 set to 0.

BTW, any comment on my results with the Hiway SA patch so far?

 

This patch is in diy-efi/incoming: hiway747.zip. The value at 2C5 is just a limit for the open loop AFR.

RBob.

 

When in highway mode the BLM will lock at whatever value it is currently at. As for detecting when in HiWay mode I can't remember what to look for on the scan tool.

There was something that stood out. The INT should lock at 128, learn should be off and closed loop is on(?).

Also, double check the coolant threshold. The stock patch has it set to 167f, above the common 160 thermo some folks use. The other thing to check is the ESC_DONE patch. Without it the ECM needs to do the PE mode forced knock test successfully before allowing Hiway mode.

RBob.

 

RBob,

First of all, sorry about using the wrong forum name.
I had noticed the INT locking at 128. I thought the patch would cause the ECM to go O/L not C/L and so was expecting the BLM's to lock onto 128 as well. Although some O2 sensor readings did get down into the .05 range, they did not stay there. The patch I used came from V8 Astro and according to the text which you wrote, had the ESC_DONE patch as part of it. Regardless, I had implemented that patch already. But I will check bin file to make certain.
If 167F is the coolant threshold, that presents no problem since I use a 180F thermo and the motor usually runs at above that in order for OD to engage. On the coldest days, engine operates at 173-178F. At this point I have re-installed the chip with the Hiway Patch disabled. The BLM's appear to be more in line with what I expected. I am willing to try this again if you could email me a zip file with it or direct me to where I could find the patch. Currently the motor averages 23-24mpg at a 75-80mph cruise. Is the Hiway Patch worth the effort? Anybody get results that justify the changes?

 

hey guys


why are you having to add the highway mode patch to these cars my 88 TBI car( i also found out that the 88 was a sstand alone year for the ECM whne i tried to get a chip finally got a bin file for it) after reading the chip my car has highway mode already set in the chip. it will engage the highway mode patch after 52 mph. I also have had a Air?fuel guage hooked up to the o2 sensor when @ highway mode it would not light up a light @ all. the last light to light up is 16.5/1 so i guess it's around 17./1 from what i can gather.

then reason i searched this out is cause a friend told me i must havee highway mode on my car from the mileage i get around 29.2 average on trips so hhe set out and finally got a binary file for my ecm. (mark riley @ turbo tune)


i was just wondering why you guys had to patch it in. did only the fisrt yr TBI cars get it factory? i'm curious