1997 F150, flags rich 1132/1152, P0172/P0175 (if my memory serves well, all 4 were rich codes for sure on xcal2)

At the MAF I have 12v on the red wire. (to battery & to neighboring black wire)
LB/R 1.5v @ idle. Pin # 88. I believe to be MAF Signal to PCM
T/LB 0-0.06v @ idle. Pin #36. I believe to be VREF to MAF

MAF appears to have a solitary VREF, the TPS and DPFE have solid 5.05V VREF, on a BR/W wire to pin #90

Both the PCM's I have on hand do the same thing, 0v on pin #36. Even when the wire is disconnected from the harness. What could be causing this, if I'm correct that its the VREF and I need that magic 5v.


Truck: 1997 F150 4.6 VIN:6 4R70W IMP4 Processor code? Troyer 5.4 supercharged tune on xcal2.

For the love of my sanity, I sincerely hope someone can help me.

 

The HO2S sensors must be tested thoroughly because they are at the heart of the Fuel and Catalyst monitors.

The operation of the Emissions control in OBD depends on the sensors being at proper operating temperature. Both the catalysts and the HO2S sensors need to be at several hundred degrees before they are working efficiently, so they have heaters built in (two white wires) to get them up to operating temperature as soon as possible. Because the HO2S sensors need to operate at near stoichometry they cannot be used when rich fuel/air mixtures are needed

And so, it works like this (open/closed loop), -

1. For 180 seconds from cold start the system is Open Loop - fueling is arranged as a function of temperature, (ECT, IAT) and air input (MAF) etc, with no reference to stoichometric (lamda) levels.

2. The engine is in open loop during WOT (Wide Open Throttle).

3. When the engine is in negative torque (ie overrun, engine being driven by transmission) fuel may not be delivered via the Injectors at all. During such periods fueling is in Open Loop.

You have to keep in mind w/a 97 harness, the copper, aluminum or stainless inside the insulation separates on occasion @ the bends, - specially toward the connectors. So always check the harness continuity. As much of a particular wire controlling a sensors valve or whatnot in question. On my 98, so far, the IAT wire broke inside and it fooled me for awhile until I checked continuity. There wasn't none. The wire/insulation looked fine on the outside, but had separated inside the insulation. The knock sensor did the same thing.

Since your truck was first tuned, - that was awhile ago, -it's ran on the rich side from what I recall. Very much so at one time. You have to locate the problems to eliminate the DTC's first and foremost. Also, speak with your tuner or a good tuner (with experience) to determine a tuning issue once you have exhausted any possible mechanical/wiring issues.

I suggest satisfying that before going futher.

 

P0172 System Too Rich (Bank 1)*
P0175 System Too Rich (Bank 2)**

P1132 Lack Of HO2S11 Switch - Sensor Indicates Rich*
P1152 Lack Of HO2S21 Switch - Sensor Indicates Rich**

You realize you fueling isn't mapped with these DTC's. Also realize with DTC's, the O2's are most likely toast. Any time you run rich, the O2's are compromised fairly quick. Attempt cleaning them, - if you have a compressor. Denatured Alcohol might work after soaking. With a compressor (blow gun) you can use stronger chemicals, such as carb cleaner. BUT, you have to blow it out immediately in order not to damage the sensor. That makes them possible to clean when trying to figure out a rich situation. That's also how you can service a otherwise non-serviceable part such as the IAC. Just do it quickly, then take a peak. You damage the plunger rubbers or it won't work right. Then follow up with WD40, blowing that into the IAC w/compressed air to force lubricate moving parts. I still use my original IAC.

About the O2's, -

Also keep in mind when replacing the O2's, you have to run rears up front with LT's. All 4 sensors are identical with that model. The duty changes at the connector. You order rears because you can get up to a 19" harness. With the front sensors, you don't have that option. The difference with part #'s have to do with harness length and nothing else. That said, in order to get the proper length harness for LT Headers, you have to order rears. Isn't a big deal since the important parts are all the same.

 

Hm. I found the "gambut" of tests for the MAF, will be re-running my tests.

• I remember being told my pins were in the incorrect order @ the MAF. Can anyone tell me wire orientation please?
• The MAF test's I was given today by a friend list PIN 36 (MAF RTN) and PIN 88 (MAF SIG). Can someone verify terminology for me? I have it envisioned as "SIG" is the 5v VREF. Am I backwards?

Starting to wish I had a BOB... Break out Box seems to be impossible to locate.

 

Have you ohms the wire for the 5v reference from MAF to PCM? My guess is a bad wire if PCM swapping didnt fix it.

wire 36 is return, and 88 is MAF signal according to AllData.

 

I had only tested for continuity before, I will retest the wire tomorrow before work. I was unaware of the maximum resistance the first time through, it seems 5ohm is what is maximum?

 

A good wire is about .1 - .3 Ohm resistance from my experience. 5 ohms is a lot of resistance.

You need to remove the connector from the PCM and the MAF and test the wire itself to see if its crap through the harness or possibly open.

 

I don't understand why it's so rich. I'd get that worked out. I can't believe that engine running rich again lol.

Well, don't catch the barn on fire, Mom will git after yuh.

I found your build on an old hardrive the other day. Back when the blower was still on the bench lol.

 

97 4.6L F150 READ, -


MAF


IAC


TPS

 

Spent a few minutes between bursts of rain.

No shorts from 36 to ground, vpwr or 88.
No shorts from 88 to ground, vpwr or 36

Vpwr to power ground 11.5v
Power ground to neg batt post 3.2 ohm.

36 end to end 0.3ohm
88 end to end 0.3 ohm.

More tomorrow.


I'm curious what the tan wires function actually is, where its voltage comes from etc.

 

Finished testing, came to the end of the tests with "inconclusive" everything appears to test out fine. Really confused now.

 

You always have to check the 175 Mega fuses, since they tend to just fracture at the solder bulb. You also have to check the wires/harness above the AC accumulator. The harness dip there and sinks over time. Once you loose the insulation with any of those wires there, you' ll get a magnetic interference that creates havoc with the ignition systems.

Did this happen out of the blue / all of the sudden?

 

As far as I know, I've always had a rich issue, the previous owner removed the bulb for the cel. Only became aware of it after the swap and tuning attempts.

 

I wonder if the engine ever ran right for very long? Obviously something was being missed. Perhaps something out of the ordinary, like a mistake made during the initial first tune from the 4.6L to the built 5.4L. Didn't Troyer tune it? If so, that's makes that sort of hard to believe, but not impossible. You would have to sit on a dyno with this in mind, in order to find out what's going on with the AF's.

All these years, time, effort, money spent and chumped by the tune would blow big time.

 

I'm trying to make sure I got my truck in the best condition I can get it in. Then I'm going to go visit Blue Oval since they're around 4 hours away from me. The guy I emailed, called me and we discussed the truck. Sounded confident he can tune it.

Just don't want there to be shop time on top of the dyno time.