EFIDynoTuning Forum

So I have an interesting story to share about an 87 Ford Truck. Ford put the HEGO wiring on the blower motor circuit. Because of how they wired it, the blower motor while off allows the Negative current into the Positive current..... When the blower motor is on, it causes about a .1-.2 voltage drop for the HEGOs on the 1 and 2 settings. The drop increases the higher the blower setting. This as you'd imagine really messes up the EFI because the O2s read lean so the ECM adds more fuel... O2s continue to read a lower value and you can imagine how this continues. I've never used my heater for over a decade cuz of the voltage drop. Now I have all these fancy logs I got to see it was only on one circuit, the ECM is not affected. Well... I thought so but then watchin the logs while tuning, I turned the heater on and watched the HEGOs drop.... BS!!! But ok. I've removed the blower motor off that circuit and things behave better now especially the HEGO readings. I can also use my blower motor again albeit there is still a hit to the HEGO.
Putting the blower motor on it's own Negative circuit and retain the switch/speed functions is gonna be a nightmare which requires ripping the entire dash out. So that will never happen. The impact isn't too horrible so as long as I get my tune solid, then I can live with the performance impact it will cause.

The key thing is I had to move the Positive for the blower fed directly from the battery via a fuse/relay. W/ the relay, that feedback loop can not occur ever unless I turn the blower motor on vs. w/o the relay/dedicated Positive, that feedback loop is always there. The most F'd up part is testing the current on the Positive & Negative wires for the blower motor. Key off, they register as Negative to the battery post current test. Key on... They both register as Positive. Blower Switch on, they register correctly at the motor but at the resistor pack, Positive AND Negative are present on the Negative wires and Positive wires hence why it messes up the HEGO readings.

Below is the thread I made regarding this and I'll write up another thread about the fix I did. Still this is a big cause for the fight I've had w/ tuning my MAF curve... Add all the other issues I had to and it's been a hell of a fight ;) In this case, this is literally "by design" from Ford. They fixed the issue somewhere between 87, 88, or 89 before they finished the 4th gen line of trucks too. Such a horrible gen only cuz of all the weird shyte Ford did to em.

https://www.fullsizebronco.com/threads/ ... ed.527905/



Fuel errors on 3rd MAF change since blower motor fix:

1.025
1.002
0.988
0.996
1.017
1.005
0.997
0.991
0.995
1.000
1.002
0.997
0.998
1.001
1.000
0.995
0.997
1.020
1.007

Haven't really ever had that close of #s in every row until now.

I finally have a working transmission again and holy shit is this one fast :D 0-60 in 9 seconds and she's got tuning room to grow :D <3 I also do rolling starts vs. hard starts cuz I respect my gears and gain nothing from trashing them so it's probably a second or so faster :D I built the trans myself which makes this more awesome ;) AOD w/ 4R70W gears :D <3 I can now modify it and know what I'm doin and have reasonable expectations of results. My friend put it best when he explained it to some others "He got so pissed about his transmission and getting ripped off he learned how to build it himself" and that is 100% factual ;)

My build thread on that is here if interested:
https://www.fullsizebronco.com/threads/ ... too.527188

As expected, a new transmission required a tuning adjustment. Not REQUIRED but more required because I can and have the logs and I'd never sleep if I just let it run when I know I can make it better ;)

The "wall" I've mentioned before was also the transmission as suspected but the TPS was another one. Now I've unlocked everything from the mechanical aspect especially the ability to easily run over 4K. W/ my block, it has a zero balance crank/fly wheel so I can do about 6-8K RPMs for redline (have NOT tested that out yet but hitting 6K at a stop in park since a friend asked what it sounded like was not hard and felt it had more to go).
I think there's something w/ the zero balance too cuz it's super quiet unless you put a load on it. Wonderful thing just a notable like you can't show your exhaust off in the parking lot sittin there.

So here's some log screen shots of the difference between the AOD I smoked (F' Monster Transmissions for selling me a stock AOD w/ original Ford OD for the HP/HD 3x price) vs. the new AOD w/ the 4R70W gears I heavily built.
You can see my full tear down review of the AOD Monster Transmission sold me... It's pretty horrific...
https://www.fullsizebronco.com/threads/ ... rs.527152/

Just before blowing up the AOD w/ a pretty solid tune: Blowing up the AOD because everything was working so wonderfully and some guy had to show off with an accel on the freeway so I had to show him up..... Smooth Operator :D At least the OD band didn't fail until I got off the freeway so he never saw any issues :D 2 Results after the AOD w/ 4R70W gears build I did and my first MAF table adjustment after I'll have a few more to do after to fine tune it again but now w/ the consistency w/ everything, it really should tune well. It may be a "no brainer" that a perfectly working drive train will give more consistent results to tune around but it's very different from the "awareness" vs. knowing since we have real data to see/prove things vs. "the feelz". It's def the nice thing about the entire journey I've had so far (more to go) goin from what felt great to... Holy shit! And STILL having more to go but more importantly everything in between so I really do have a good understanding of good vs. bad and so much more vs. just "the feelz" :)

I will say the best part right now is the reactions of folks when I disappear from a light. There's been several times now that everyone just sat at the light even tho it was green :D <3

Thank You again, again, again Decipha for your part in these capabilities <3

Woohoo! Thank you Decipha! Happy Thanksgiving too!

Aight I'll go with Kreuger effect plus I didn't have much time w/ the new TPS before I modified it :) FUEL_APT_LAST shows as -1 when I'm off the pedal.... Assuming that's flag you mean then it does "work" but I will say there have been plenty of times I don't think I ever saw it pop up. It goes yellow -1 on the dash so it's an obvious signal. I rarely noticed it before but I see the -1 for FUEL_APT_LAST a lot now w/ the new TPS so your point makes sense.

Tempting to go back in the logs and check that out now but meh, I believe you're right so I'm just gonna go forward and take that evidence as a notable for things to look for if a TPS is failing ;) Thank You as always!

Unfortunately his ECM doesn't have a catch code (cheap reman) but def notable, no A9L2 for him ;)
I'll look more into the A1C and the other BINs to see what will work for him. Thank You!

I see the functions for MAP but since it's not relative to me, I haven't played with those. My friend wants to tune his Speed Density setup tho.

So can I load the A9L2 up for him and tune I gather the Volumetric Efficiency / MAP stuff?

One thing I oops didn't include in that last post was I did set the TPS to 190 before fogger replied and it did improve things. It picks up noticeably sooner and more frequently. It's clearly a difference in the fueling too.

I figure the reason why is the FN331B TPREL Accel Enrichment table. When my TPS Ratch is 178 like it's always been, that means it takes 12 extra steps in AD counts/throttle travel to hit the next table of adjustment which is 452 where it reduces fueling by 25% from Stoich.

W/ the TPS ratch @ 151, it was even harder to hit that 452 adjustment point. Not like I was tryin just simply means it required more than my typical pedal travel.
After modifying the TPS so I could rotate it to sit at 190 AD counts (I had to take off a fair amount of meat) that means I'm hitting that 452 adjustment point a lot sooner and I definitely did.

So maybe not necessary to set the TPS to .95v / 190 AD (I hope I did that math right :D) but maybe it has some merit?

I will say I prefer the benefit of the accel enrichment to occur where the pedal is at NOW vs. before because it's where I'd expect it to begin picking up as is. I'd say I'm at about 25+% pedal travel when this happens now vs. before it was closer to say 33+%. This made that 33% and beyond acceleration just better over all as well. Anything below 25% has always been cruising travel speed and anything above is when I want and they do accel noticeably faster for any vehicle I owned including both Broncos so this just feels right as is.

Feel free to vote this being Logical thinking or Kreuger Effect :D

I've seen the debate sayin it doesn't matter so I let it be especially after reading the logic behind RATCH. I coulda swore I was on one of the getting started dox or whatever again and it said that was a requirement but I've been going by this statement the whole time in the Idle Air doc:
"Many used to believe the TPS had to be at 0.99 for max power, thats complete crap anyone feeds you that garbage you wrap them in the mouth as per decipha. The ecu takes the lowest tp voltage since key on (known as RATCH) and uses that as a relative position of 0 throttle which can be logged as the payload TP_REL, this is the relative throttle position the ecu uses for its calculations. TP_REL does not exist in the older foxbody ecu's."

That's why I didn't care about the TPS .90-95 voltage forever but somewhere recently re-reading everything I coulda swore I read that while I'm trying to cross off everything from the basic To Dos. Thought that was my last item :D Maybe it was on the EEC Tuning Forum then cuz they focus heavy on voltage for those tunes. I've been workin on too many things but Thank You for calling that out :D

As it stands my base tuning is FINALLY complete now that all the mechanical/sensor stuff is resolved. (NOT) Surprisingly the ability to dial things goes REALLY fast when everything is in order and it truly gives light so how precise the measurements EFI makes.

When I started all this like most folks with no knowledge of EFI so say a lil exhaust leak... Meh it won't affect anything as long as it's getting fuel, that's all that matters..... or say ACT vs. ECT fueling ratios ;) :D I've been significantly enlightened and I've really just begun ;)

I have another detour for a while to deal with but I'll keep at it ;)

I don't think I've found a TPS voltage log value for the EEC-IV, just the AD Counts. Is it just not there?
I believe 190 AD Counts in .95 volts so that works but since I replaced the TPS I'm gonna finally set the TPS to .95 ;)
I COULD probe it, but all that really matters I figure is what the ECM sees anyways.

For the record, my typical TPS ADCount was 178 w/ the mechanical idle setup. Now w/ the TPS replacement and re-adjustment to the mechanical idle to dial that back in, I'm at 151 TPS ADCounts so now it's a good idea for me to adjust since I can't get passed the 600ish TP AD Count range to hit WOT which I have set to 725 still since 730 was my average range for TP and the pedal all the way to the floor.
After I setup the TPS to .95 volts, I'll see where I'm hittin then ;)

Remember that "wall" I mentioned? I've hit it a few times and always figured it was the tuning or something else with all the other various issues.

It was the TPS! I replaced it and sure enough, things are WAY better now and no more "wall". I would have never figured this out (logically besides throwing parts at it) and with everything I've changed..... I just simply never would've figured it out in this life time :D Except..... I have LOGS!!! So here's another story BUT this unlocked the last piece to be able to properly tune this EFI setup.

Failing TPS adds Turbo and Blow Off Valve :D
Been having this issue that kept getting worse but I've made so many changes lately it was hard to really suspect what it was. I checked some stuff for the TPS before and noticed as I pressed the pedal the TPS voltage would reset momentarily then pick right back up. Didn't occur to me what this would do later and again making so many changes all while tuning the EFI.

I built a new intake that's 4" (104mm) all the way to the TB (The 302 TB is 4" or 52mm x 2). The old intake was 3" but had a 55mm MAF body which was a choke point.

I was able to accelerate NP before but w/ the new intake I could not easily accelerate after half throttle. Oddly enough that's where the TPS voltage dropped when I tested it but this is a few weeks later so I wasn't puttin them together yet. Once I got my tune in order I could haul ass but if I pressed the pedal hard at half throttle EVERY SINGLE TIME it would make this PSSSHHHHH Blow Off Valve like sound but more like vacuum. Makes sense w/ the new intake, maybe it has a leak? Nope sealed that so well I doubt I'll ever be able to dis-assemble it ever again even tho I built it to be able to break down and the issue remains.

The craziest part of the BOV sound is the next result was like a turbo spooling up and the truck really accelerated. I paniced each time and backed off cuz I knew somethin wasn't right.

In each log when the event occurs I can see the TPS dropping in/out on the hard accel and only then otherwise it always shows like it should, nice and smooth.
The air intake stayed consistent but when it'd drop out it increased and the EFI went right with it and had no problem fueling which is why it ramped up like the turbo feeling but because it chugs momentarily when the TPS drops out despite the AFR being proper still, I gather that's what gave the perception of the turbo spool feeling. I don't have a turbo so I know this is not normal ;)

After seein several logs of the TPS dropping out and given the fact the dead spot is SO consistent so as long as I slowly ramp past it, all is well OR if I work around that dead spot, all is well..... It's gotta be a damn sensor!!!!

Sure enough I turned the truck on but didn't start the engine w/ my laptop hooked up and I checked the pedal and watched the TPS meter. Sure enough it kept dropping out.

Replaced the damn TPS sensor and voila! Bonnie has balls again :D Now the entire drive train is not only leak free but fully operational ;)