Ford EEC-IV experts, code 172 (Lean) few questions related to thermactor delete

[theoldwizard]

Originally Posted by TT_Vert

I don't think they even introduced MAFs to the 460 architecture EVER and if they did it was not until the EEC-V and that may have only been in the peoples republic of California but I could be wrong, it's happened before.

Too old to remember ! All the years, engines and vehicle lines are just a blur !

Bottom line, why is it lean ?

[sibe]

off topic..

but from the gazillion snipits I have saved ingo on a 460 to MAF... they did do a MAF 96-97 EEC-5 obdII in cali as I have the tag some place but this post snip was cool.

Keep in mind, that the OBD-II MAF 460 computers are completely TFI based for fuel and spark. There are no high-tooth-count trigger wheels for 460s, so if you want to run a modern CoP ECU, you're going to have to adapt something, as I'm pretty sure they don't support TFI/PIP inputs for timing.

Also, there's another gotcha with the OBD-II 460 MAF computers - it requires a special 4 tooth trigger wheel on the crank for misfire monitoring. You will also need the front cover off a MAF 460, as the standard front covers do not have the boss to mount the crank sensor. The truck will run fine without the sensor, but you will get a check engine light unless you tune it.

Back to your lean issue...
have u doused the intake and such with some brake clean or carb clean.. to see if you get an rpm jump ..

Is TPS setting at idle OK..

My son mas Motis in his shop,, he in donner, CA til tuesday..

Do you have anything to see data or just a code reader..

[theoldwizard]

Originally Posted by sibe

Keep in mind, that the OBD-II MAF 460 computers are completely PIP/TFI based for fuel and spark. There are no high-tooth-count trigger wheels for 460s, so if you want to run a modern CoP ECU, you're going to have to adapt something, as I'm pretty sure they don't support TFI/PIP inputs for timing.

TRUE ! They have a distributor with a PIP sensor under the rotor.

Originally Posted by sibe

Also, there's another gotcha with the OBD-II 460 MAF computers - it requires a special 4 tooth trigger wheel on the crank for misfire monitoring. You will also need the front cover off a MAF 460, as the standard front covers do not have the boss to mount the crank sensor. The truck will run fine without the sensor, but you will get a check engine light unless you tune it.

I never heard of an EEC-IV/V system that used a crank mounted wheel ! The PIP sensor is electrically very different from the next generation 36 minus 1 tooth wheel (this idea was proven on engines with DISI; DISI is still used on some DIY/aftermarket EFI systems) and sensor. The PIP sensor is a Hall effect sensor and the other is a variable reluctance sensor. Signal conditioning inside the module, before it get to the processor, is very different.

Originally Posted by sibe

Back to your lean issue...
have u doused the intake and such with some brake clean or carb clean.. to see if you get an rpm jump ..

More specifically, around any mating surface between the throttle body and the intake manifold and the intake manifold and the cylinder heads.

Originally Posted by sibe

Is TPS setting at idle OK..

TPS has very little to do with any of the strategy unless it is VERY FAR out of adjustment. The software compensates for small mis-adjustments.

[TT_Vert]

Originally Posted by sibe

off topic..

but from the gazillion snipits I have saved ingo on a 460 to MAF... they did do a MAF 96-97 EEC-5 obdII in cali as I have the tag some place but this post snip was cool.

Keep in mind, that the OBD-II MAF 460 computers are completely TFI based for fuel and spark. There are no high-tooth-count trigger wheels for 460s, so if you want to run a modern CoP ECU, you're going to have to adapt something, as I'm pretty sure they don't support TFI/PIP inputs for timing.

Also, there's another gotcha with the OBD-II 460 MAF computers - it requires a special 4 tooth trigger wheel on the crank for misfire monitoring. You will also need the front cover off a MAF 460, as the standard front covers do not have the boss to mount the crank sensor. The truck will run fine without the sensor, but you will get a check engine light unless you tune it.

Back to your lean issue...
have u doused the intake and such with some brake clean or carb clean.. to see if you get an rpm jump ..

Is TPS setting at idle OK..

My son mas Motis in his shop,, he in donner, CA til tuesday..

Do you have anything to see data or just a code reader..

Thanks for the suggestions.

I haven't checked TPS voltage but I doubt that would cause a lean condition w/o causing any drivability issues. In all my years working with, racing, etc. EEC-IV I've never seen a TPS issue cause a lean code and certainly not cause any drivability issues.

Vacuum is a stable 22" at idle and I see no indications of vacuum leaks. A leak to throw it beyond adaptive fueling limits (25%) would have to be fairly large and the idle would be very high on a SD car w/ that size vacuum leak IMO. I'll use some propane or something flammable to see if I notice anything but nothing in what I've seen in this engine during my diags indicate a vacuum leak of any sort.

on SD anything that causes a vacuum leak would only raise idle, it would be compensated for by the MAF UNLESS it's the head to intake gasket perhaps but even then the intake pressure should show this and adjust.

Dave

[theoldwizard]

Originally Posted by TT_Vert

In all my years working with, racing, etc. EEC-IV I've never seen a TPS issue cause a lean code and certainly not cause any drivability issues.

That is because we learned how to deal with TPS slightly out of adjustment back in EEC-I !!!!

[TT_Vert]

Originally Posted by theoldwizard

That is because we learned how to deal with TPS slightly out of adjustment back in EEC-I !!!!

Whatever the reason for it I've never seen a TPS cause a lean issue. The TPS tolerance can be anywhere between .6V to 1.1ish volts closed throttle and really react no differently as far as fueling goes. So I suppose if it's WAY off it can cause problems but you'd certainly have indicators in drivability, especially something that puts as much load on the engine at low RPMs as these tanks do.

Dave