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

[TT_Vert]

The code doesn't occurring until a good 20-40 minutes into a drive. It may not be going into closed loop before that though as I read these don't go into closed loop that often. IMO I get pretty good gas mileage out of my 32' 95 460 southwind at around 7.5 on average (While towing a car). In fact just this weekend I got 7.7mpg going through a "mountain" in Kentucky into Tennessee and i seem to have good power so I don't know that I have a fueling issue here. I'm going to throw a fuel pressure gauge on the rail to check it when I have a chance. However, I do have a few questions.
I see code 172 has multiple possible results. One says 172 is lean, one says it's just not switching. These are two very different things. I don't have the ability to easily monitor the o2 in real time on this PCM so I don't really know what the activity is (Unless I back probe the plug while driving).[/LIST]The thermactor tube on the back of the right head broke so I plugged it (it's leak free) I also unplugged the TAB/TAD valve vacuum sources so they do not open any longer since they would just be pumping air out of a hose that no longer goes anywhere. I am wondering if the PCM is looking from air from them and not seeing but but still adding fuel. If that was the case I would assume it's be reading rich.

Any input would be appreciated

Thanks
Dave

[sibe]

lean fuel.. air leak from exhaust.. goofy o2..

You can run a scanner to read live,, I have a snap on use with a 2 pin adapter into service connecter. get basics..

[TT_Vert]

There are only like 3 or 4 scanners that can read the eec iv realtime. Two of them are unobtanium (or over $400 If you can find one.) Bosch and another I can't recall can do live data. I don't feel like mortgaging my house for a snap on scanner I'll not use again.

This is speed density also so no maf to deal with


Ford plastic vacuum hoses are known to get brittle and break so last year I vacuum checked each of them. They were all still perfect and not hardened at all, shocking actually. I'm going to check for vacuum leaks again when I get a chance. I'll also check vacuum and fuel pressure at the rail again.

Any other input from anyone is appreciated

[sibe]

I have a snap on motis in the back,, I used it as a scope, old software but what it is updated with 2017 maybe it still opens.. just a nags.. I look later today..

If I have it, you can use it, I can send it.. no biggie..
I have 2 other scanners ...Versa, solis snappers and a Launch that will read my 1995 460 E350.. give me running values.

Todays new cars are a PIA.. Snappy does good on some and Launch is way better on others... I have Collision shop so it is alot of resets, brakes and body stuff sensors etc.. not alot of drive stuff except for my BMW junks I have a fetish for..

[TT_Vert]

Originally Posted by sibe

I have a snap on motis in the back,, I used it as a scope, old software but what it is updated with 2017 maybe it still opens.. just a nags.. I look later today..

If I have it, you can use it, I can send it.. no biggie..
I have 2 other scanners ...Versa, solis snappers and a Launch that will read my 1995 460 E350.. give me running values.

Todays new cars are a PIA.. Snappy does good on some and Launch is way better on others... I have Collision shop so it is alot of resets, brakes and body stuff sensors etc.. not alot of drive stuff except for my BMW junks I have a fetish for..

That'd be nice. In the meantime I'm going to continue looking for a scanner that can show me live data on our EEC-IV setups. I'm still trying to find more details on what procedure is uses and criteria that must be met to trigger a 172. Given this is MAP i doubt vacuum leaks are the issue and for the sake of argument I pulled airpump feeds to ensure a bad solenoid was allowing non requested air upstream of the o2 but i still get the 172 so that's not it.

Dave

[TT_Vert]

So at this point I'm about out of ideas w/o having some real time data to look at. I've gone through everything it could be and all it really leaves would an exhaust leak upstream of the o2 which isn't likely I'd have one large enough w/o it being obvious to do this. Here is the latest list of things I've looked into to try to determine this issue. Remember the thing runs perfectly and gets 7.5mpg towing 4300#.

• I have verified fuel pressure at load and temp. 40 w/o vacuum to FPR and 30psi w/ vacuum at idle.
• I have tried to send the engine lean by creating a huge vacuum leak (No sign of o2 going lean
• I have bench tested my o2 and while it may be a tab "slow" it is responsive enough not to do this IMO
• I have checked continuity of H02S connector to PCM
• I have checked continuity of both H02S and SIG RTN back to PCM
• I have checked short to power/ground of each and to each other
• I have verified I have good voltage at the o2 heater circuit
• I have verified EGR moves and that I get no EVP codes (indicating EGR isn't moving)
• I have 22" and steady of vacuum at idle which is great. I have verified I have vacuum to EGR and that the hose EGR solenoid to EGR is air tight
• I have vacuum checked all other vaccum hosts
• I have bypassed the air pump in case TAD/TAB were allowing non requested AIR upstream of the o2 leaning it out
• I don't appear to have any major exhaust leaks upstream of that o2
• I have verified I have a functioning MAP sensor
• I have made sure the PCV check valve was functioning as designed
• Last year I did replace the electrolytic caps in my PCM as they were starting to leak. They did no damage to any traces or the board. That cleared up what seemed like a slight miss but even then it ran perfect otherwise. Likely due to a dirty 5Vref it was getting due to bad caps.

[sibe]

Originally Posted by TT_Vert

So at this point I'm about out of ideas w/o having some real time data to look at. I've gone through everything it could be and all it really leaves would an exhaust leak upstream of the o2 which isn't likely I'd have one large enough w/o it being obvious to do this. Here is the latest list of things I've looked into to try to determine this issue. Remember the thing runs perfectly and gets 7.5mpg towing 4300#.

• I have verified fuel pressure at load and temp. 40 w/o vacuum to FPR and 30psi w/ vacuum at idle.
• I have tried to send the engine lean by creating a huge vacuum leak (No sign of o2 going lean
• I have bench tested my o2 and while it may be a tab "slow" it is responsive enough not to do this IMO
• I have checked continuity of H02S connector to PCM
• I have checked continuity of both H02S and SIG RTN back to PCM
• I have checked short to power/ground of each and to each other
• I have verified I have good voltage at the o2 heater circuit
• I have verified EGR moves and that I get no EVP codes (indicating EGR isn't moving)
• I have 22" and steady of vacuum at idle which is great. I have verified I have vacuum to EGR and that the hose EGR solenoid to EGR is air tight
• I have vacuum checked all other vaccum hosts
• I have bypassed the air pump in case TAD/TAB were allowing non requested AIR upstream of the o2 leaning it out
• I don't appear to have any major exhaust leaks upstream of that o2
• I have verified I have a functioning MAP sensor
• I have made sure the PCV check valve was functioning as designed
• Last year I did replace the electrolytic caps in my PCM as they were starting to leak. They did no damage to any traces or the board. That cleared up what seemed like a slight miss but even then it ran perfect otherwise. Likely due to a dirty 5Vref it was getting due to bad caps.

the wild goose chase continues.... You can still try a new O2, a good brand... I have had them test fine but they dont hold the range when in real world ..

the only other thing and a long shot id the fuel... it can be laced with high ethanol.. I got like 4.5 mpg, normally 7 avg..
any way I went back to that station, grabbed a few gallons ,, I tested it.. 22% ethanol.. My son filled up his old rat beater 72 ford, that same weekend there.. He said ir ran like crap..
We can argue that it is not suposed to be, but with prices and ethanol is cheaper,, I have seen this alot doing powersports stuff at my sons shop. 2 stroke meltdowns.. test fuel .. yep bad..

[TT_Vert]

Originally Posted by sibe

the wild goose chase continues.... You can still try a new O2, a good brand... I have had them test fine but they dont hold the range when in real world ..

the only other thing and a long shot id the fuel... it can be laced with high ethanol.. I got like 4.5 mpg, normally 7 avg..
any way I went back to that station, grabbed a few gallons ,, I tested it.. 22% ethanol.. My son filled up his old rat beater 72 ford, that same weekend there.. He said ir ran like crap..
We can argue that it is not suposed to be, but with prices and ethanol is cheaper,, I have seen this alot doing powersports stuff at my sons shop. 2 stroke meltdowns.. test fuel .. yep bad..

Funny you mention this. I hate being a parts changer but I did throw a Bosch sensor in it yesterday even though the stock one did bench test ok. I did see a few anomalies in the old sensor which I don't know if they would be an issue or not but I figured at $25 for a sensor there was no reason not to swap out the 60K mile one. I've filled up at stations from Tennessee to Wisconsin and most places in between and always have had this issue so while it may be the typical 10% ethanol content I don't think it's any one station and E10 is here to stay sadly so I'm stuck there. I wouldn't mind taking you up on the offer for the scanner if you are still game. I can cover shipping both ways and give you a deposit until you get it back as well.

Dave

[sibe]

Let me dig for it,, my tech said it is around... but I will be away on a trip to donner CA, so tuesday,, I will message you..

[TT_Vert]

Originally Posted by sibe

Let me dig for it,, my tech said it is around... but I will be away on a trip to donner CA, so tuesday,, I will message you..

Appreciate it. And if anyone sees anything I've missed i'm all ears!

Dave

[theoldwizard]

Originally Posted by TT_Vert

It may not be going into closed loop before that though as I read these don't go into closed loop that often.

NOT TRUE ! It goes into closed loop as soon as the engine is warm !

Originally Posted by TT_Vert

... i seem to have good power so I don't know that I have a fueling issue here. I'm going to throw a fuel pressure gauge on the rail to check it when I have a chance.

Not likely.

Originally Posted by TT_Vert

I see code 172 has multiple possible results. One says 172 is lean, one says it's just not switching. These are two very different things.

Not to the PCM !
Lean (all the time) does mean "not switching".

The strategy will try to drive it rich when it is stuck lean. If it can not, it will set the code.

Likely a vacuum leak somewhere.

[TT_Vert]

Originally Posted by theoldwizard

NOT TRUE ! It goes into closed loop as soon as the engine is warm !

Actually this doesn't appear true on these calibrations. The parameters that must be met to be in closed loop are not very often met from everything I've seen and read. I'm sure others can chime in on this but here is just one snipped of the many that have monitored open/closed loop status of their PCM on the F53 TOE0/TOE1 calibration.

On my TOE0 calibration, the diagnostic scanner shows the ECU almost never in Closed Loop. A closer investigation shows that it does go into Closed Loop, but only at very low manifold pressures (high manifold vacuum), such as when you are coasting with the throttle closed. It is also set not to enter closed loop at idle.

This has several consequences. No Closed Loop means no Adaptive control. Adaptive is the mechanism whereby the engine tunes itself to adapt to different fuels, and compensate for wear. With no Adaptive control, your engine cannot adapt to the 10% ethanol fuel now in common use in many parts of the country. On 10% ethanol, your engine is now running 4% leaner.

Originally Posted by theoldwizard

Likely a vacuum leak somewhere.

With a MAF perhaps, with a MAP not likely since it uses manifold pressure to determine load for fueling so there is no unmetered air even w/a vacuum leak. You may see a higher idle w/ a vacuum leak but you won't see a lean code. Test it by generating a large vacuum leak by pulling the PCV feed hose from back of manifold. Beyond that I see 22" of stable vacuum, you aren't going to see that on one of these engines with a vacuum leak large enough to lean it out enough to be outside of the adaptive short term fuel trim adjustment. Regardless of all of this I am 100% sure I have no vacuum leaks as I've vacuum tested each vacuum hose when I was hunting down EGR issues last year which are completely unrelated to this. My EGR system is now functioning as designed so no reason to go down that path either. I have no head to intake leaks either.

Dave

[theoldwizard]

Originally Posted by TT_Vert

With a MAF perhaps, with a MAP not likely since it uses manifold pressure to determine load for fueling so there is no unmetered air even w/a vacuum leak.

By mid-90s (IIRC) all Ford engine were MAF.

Originally Posted by TT_Vert

Beyond that I see 22" of stable vacuum, you aren't going to see that on one of these engines with a vacuum leak large enough to lean it out enough to be outside of the adaptive short term fuel trim adjustment.

Okay, then something else is causing a lean condition. Vacuum hose and junctions are NOT the only possible source of "pirate air".

Originally Posted by theoldwizard

The strategy will try to drive it rich when it is stuck lean. If it can not, it will set the code.

P.S. I actually WROTE some of the software for all EEC-IV and EEC-V PCMs.

[TT_Vert]

Originally Posted by theoldwizard

By mid-90s (IIRC) all Ford engine were MAF.

Okay, then something else is causing a lean condition. Vacuum hose and junctions are NOT the only possible source of "pirate air".



P.S. I actually WROTE some of the software for all EEC-IV and EEC-V PCMs.

Given your experience you'll know that MAF was introduced to different vehicles in different years. For example, in the fox body mustangs it was introduced in 89 for all 5L, the 86-88 were all SD. 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.

Dave