Eliminating extraneous sensors (MTX)

[firebat45]

So, for the Chump Car build (and other builds) I am rewiring the engine bay to clean up unneeded things. I'm doing my best to figure out exactly what's needed and what isn't. Most of what I'm doing probably isn't practical for a street car, this isn't another one of the "Can I delete the IAC?" threads.

What's the bare minimum needed for a SHO engine to run properly (track use) on the EEC-IV?

I've deleted/looped back all the SPOUT/VIP/IDM connectors and wiring, that's all useless to me.

Do I need a BAP or no? Not doing hillclimbs, elevation will be fairly consistant.

Do I need O2 sensors? Apparently they aren't used during WOT, as the engine goes into OL. Don't need them during decel either, as the fuel gets cut. Part throttle may need them, but I only care about not running dangerously rich/lean, not about emissions.

On that note, EVAP completely deleted of course.

VSS, needed for an MTX car? I know it's used for cruise control, and that's gone, but is it necessary for anything else?

As far as the list of known needed engine wiring parts goes, so far I've got:

Crank sensor
Cam sensor
Injectors
DIS input/output wires
Fuel pump control
Fan control
ECT
ACT
MAF
IMRC
IAC (if it just did idle, it could be deleted for a track car, but it does decel bypassing as well)
Starter and ignition wires
Knock sensor

Anything else obvious that I'm missing? Obviously I could eventually figure this all out on my own, but having a discussion here may save me some time and help out other people looking at rewiring engine bays or transplanting SHOs.



I'm hoping this thread will be a discussion on the inner workings of the EEC, instead of it just being regarded as a magic box that runs the engine. I think it's useful to know the inner workings and logic behind why the EEC does what it does.

 

[Racer X]

You've deleted the one thing that you could have, although you will need to keep the solenoid.

No O2, or no BAP will throw a code and put you in a limp mode. No VSS will affect idle decay adversely.

 

[firebat45]

You've deleted the one thing that you could have, although you will need to keep the solenoid.

No O2, or no BAP will throw a code and put you in a limp mode. No VSS will affect idle decay adversely.

Purge solenoid? Why would I need to keep that? I've deleted a lot more than one thing (cruise, evap, diagnostics, IRCM, etc)

I figured that getting rid of O2 or BAP would throw a code, but does the EEV-IV actually have a "limp" mode? If limp mode just means stuck in open loop, that's fine.

 

[HotRodKid]

I dont see the reason for deleting anything really, if it runs well dont screw with it.

If you delete something like the BAP the car might run perfect or the EEC might revert to a ******** value. an example of this is the ka24e nissan motors. If the coolant temp sensor fails and goes to ground the ECU thinks its like -40F and gives the engine enough fuel for air that dense ... which just doesnt frickin work on a 100 degree summer day

 

[firebat45]

I dont see the reason for deleting anything really, if it runs well dont screw with it.

I'm not talking about stock SHOs though. For instance, the Camaro you're doing, you need to find a place to mount the BAP, make a bracket for it, extend/shorten wires, etc. Wouldn't it be easier to just delete it if it wasn't actually needed? Now add that up with all the extra stuff on the SHO engine, and it makes quite a difference when you're done. Not to mention it cleans up the engine bay, makes maintenance easier, and means less points of failure.

Now, if it does have a real purpose to the engine management, of course it needs to be kept. That's what this thread is about, separating things like cam sensors from things like evap canisters. There may not seem like much point, but for someone who wants an ultra clean engine bay for a show car, or someone who potentially needs to swap engines in the middle of a 24 hour race, etc, it matters.


Interesting point about the sensor default values. If (for instance) the BAP fails and grounds, the EEC may think the car is driving around on Everest, or maybe Death Valley. It might be completely different when the EEC receives no input from the sensor at all though.

 

[Racer X]

You need to keep the evap solenoid, otherwise the ECU will store a code for it. You can plug the ****** at the TB, but keep the solenoid.

BAP sensor? What happens to the barometer when a storm rolls into town?


Yup.

When a sensor fails or it removed, the ECU goes into a
"guesstimate" mode, where it guesses what the operating parameters should be based on a combination of the readings from the other sensors. This guesstimate is waaaaay off sometimes, and most times the car will run like poo, if at all.

We've given you the answers to your question (in so much that there aren't any "extra" sensors as far as the EEC-IV sensors), so at this point you can take that as your answer, or you can press on and learn on your own what many of us have learned already.

 

[NovaSS]

http://www.shoforum.com/showthread.php?t=115598

this thread will sho you now to wire a sho into another body.

to be honest deleting most of the stuff does not give you any real performance gains and gives you other issues that you will waste time chasing. The EEC IV is a pretty good system, Ford didnt waste money on stuff that wasnt needed.

 

[gmorrell]

Back when I was building harnesses and doing tuning for the V6 SHO motors in many a Pike's Peak Hillclimb car, I left all the engine sensors in place, including the O2's and BAP.

You have to be careful when you start removing things without fully appreciating how to properly terminate EEC inputs so EEC doesn't go off into FMEM strategies or drop some hard failure codes, which might put you into a limp home strategy.

If EEC goes into a hard failure mode, or worse, limp home, fuel economy will suffer, and this is undesirable in an endurance race like ChumpCar or Lemons.

 

[shooff82]

fab a manifold and put 3 deuces on that *****!!! AAAHAHAHAHAHAHAHA!!!!!

 

[SuperchargedSHOguy]

Back when I was building harnesses and doing tuning for the V6 SHO motors in many a Pike's Peak Hillclimb car, I left all the engine sensors in place, including the O2's and BAP.

You have to be careful when you start removing things without fully appreciating how to properly terminate EEC inputs so EEC doesn't go off into FMEM strategies or drop some hard failure codes, which might put you into a limp home strategy.

If EEC goes into a hard failure mode, or worse, limp home, fuel economy will suffer, and this is undesirable in an endurance race like ChumpCar or Lemons.

This!

I left all the sensors and underhood wiring in my RWD car. I made a custom interior harness for the bare minimum-gauge cluster and ignition/lights only.
Really, what are you looking to loose by eliminating some of the sensors (not being a smart ass)?

 

[firebat45]

Thanks for the replies so far everyone. I know that most of the sensors are needed, but I'd still like to understand more what everything does, and think it's a valuable thing to be posted on SHOForum. I wasn't aware that an MTX car needed a VSS for anything other than cruise for instance.

Really, what are you looking to loose by eliminating some of the sensors (not being a smart ass)?

I think a few people are missing my point here. I'm not trying to eliminate them to increase performance or anything, I am trying to figure out what is needed and what isn't. I would never bother going to the trouble of stripping out 2 or 3 wires and a sensor out of a normal SHO, for me this is more about engine swaps, and the associated rewiring and fabrication needed for each little thing. Again, I'm not trying to cut out things that are needed, but not everything is needed. Clutch safety switch for instance, has no impact on performance whatsoever. For my race car, I'm leaving it off (well, looping pin 30 of the EEC to pin 46).

Another thing I found today that I'm pretty sure isn't needed is the octane adjust sensor.

 

[gmorrell]

Another thing I found today that I'm pretty sure isn't needed is the octane adjust sensor.

Leave this one shorted, or jumper it to sensor ground at the EEC 60-pin if you like. If the octane adjust pin is open, EEC pulls (retards) timing 3º across the board, everywhere. This is the "I got a load of crap gas" Hail Mary

 

[SinisterSHO]

Thanks for the replies so far everyone. I know that most of the sensors are needed, but I'd still like to understand more what everything does, and think it's a valuable thing to be posted on SHOForum. I wasn't aware that an MTX car needed a VSS for anything other than cruise for instance.



I think a few people are missing my point here. I'm not trying to eliminate them to increase performance or anything, I am trying to figure out what is needed and what isn't. I would never bother going to the trouble of stripping out 2 or 3 wires and a sensor out of a normal SHO, for me this is more about engine swaps, and the associated rewiring and fabrication needed for each little thing. Again, I'm not trying to cut out things that are needed, but not everything is needed. Clutch safety switch for instance, has no impact on performance whatsoever. For my race car, I'm leaving it off (well, looping pin 30 of the EEC to pin 46).

Another thing I found today that I'm pretty sure isn't needed is the octane adjust sensor.

People called engineers did that in the 80s when the designed the car. And I think you're missing everyone elses point that there is no point in taking it out.

 

[firebat45]

People called engineers did that in the 80s when the designed the car. And I think you're missing everyone elses point that there is no point in taking it out.

What the designed the car for and what I'm talking about doing with the engine is different. That is why there are things they added that are no longer needed. You can't tell me that having EGR or cruise control is intergral to the proper operation of the SHO engine.

Maybe nobody should have ever swapped the SHO engine into anything else (Ranger, Cobra, Dune buggy, etc) because that's not what the Ford engineers designed it for? Maybe nobody should have ever put FI on their SHO, again, it wasn't designed that way, so they should have left it, right? Thanks for your input, but you're the one missing the point.

 

[Sho Amo]

BAP: I think it would be better to just relocate. If you put the Bap in the cabin it would be out of the engine bay but still give a baro reading.

O2: The o2 sensors are very integral in tuning the engine for all rpms. Just remember your gas pedal isnt an on/off switch.

VSS: This is crucial for decay. Have you ever noticed that the car wont idle at 800rpm if your cruising in neutral to a light? It will hang around 1200 or so until you stop. If you take out the VSS your decay will become erratic and can cause shifting issues (think of heel-toe downshifting and such)

Octane Adj: There is no real point to delete this since its such a small thing. It will pull 3 deg timing if its not shorted, causing a small power decrease.

ECTs: There are 3 ECT sensors. One is for the instrument cluster, which can be swapped over to an aftermarket or whatever. Second is for the eec. This will adversely effect the performance of the car. The EEC has a totally different injector offset for different coolant temps as well as timing. Third one is located in the heater hoses and is only for HVAC. I believe that one can actually be deleted if your doing away with HVAC.

ABS: can be deleted. all wiring modules lines etc.

CCRM: Can be replaced with individual solenoids.

Airbags: all can be deleted including crash sensors modules wiring etc.

A/C: can be deleted just make sure to reinforce the motor mount bracket it was located on. These have been known to break and leave you royally farked.

IMRC: make sure the butterflys are either removed or pinned open. Just deleting the wiring will leave you a very sluggish sho motor.

IAC: Necessary for idle obviously. Can cause the car to stall while downshifting or getting off the gas quickly.

IAT: This can pull or advance timing depending on intake temps. This will promote consistent power. Without it, your car will run dramatically faster or slower depending on intake temps. If you really didnt care im sure you can do the same with the BAP. Just put it in the cabin out of the way, or in front of the car somewhere hidden.

Charcoal canister purge: not necessary. It does however need to be deal with by either keeping it relocated somewhere plugged in or jumpering it at the pcm.

Clutch interlock: can be jumpered at the pcm. I have had this deleted for years. However can be a good anti theft device if you hide a switch somehwere.

 

[Sho Amo]

P.S. Do you have a schematic for the eec?


Radio noise suppressor capacitor: Is this what is bolted to the coil pack? What exactly does it do? I have had mine hangin in the engine bay since I did the COP.