Wow... I think I'll just pull all this crap off and go with a holley 4BBL........ What does WOT mean? (and yes I really don't know....)

 

WOT - Wide Open Throttle

WFO - Old term from Wide Freaking Open


For a lot less than swapping to a carb you can do some bolt on mods that will increase your horsepower. Even staying away from the internals you can get 35-40 more horsepower and torque out of the 351. The 302 can get slightly larger gains, but after that they both fall prey to stock head and intake limitations.

Do you have any modifications at all now?

 

That's not what I'm talking about, and the ECT isn't a "feedback" sensor anyway. "Feedback" means the EEC seeing the effects of its actuators, like a DPFE showing the effects of the EVR/EGR, or the HO2S showing the feedback of the injectors. If an injector fails to open, or sticks open, the EEC will have some indication by the HO2S's feedback.

There is no feedback for the 2ndry air system on EEC-IV trucks, which is what this thread is about.

I guess I missed where you cited all your sources. Don't try to turn this into a personal attack - you post what you think, & I'll post what I think. Those who read what we write can judge for themselves, or do some research on their own. My signature links are some of what I'm citing from, but also from Haynes, Ford, code reader documentation, & more. I think you're just misunderstanding me, AND what you're seeing in those code reader books.

That's a really bad idea, for lots of reasons. But it's your truck - trash it if you want.

 

Rather than go into detailed hair splitting, the below is from Haynes, one of your sources and mine.

Courtesy of Hayes manual 36058 (880) Chapter 6, Section 8, in regards to EEC controlled bypass and diverter valve operation:

"b) Proper diverting of air to the exhaust manifold during cold start, warming, and warm start conditions or to the converter in all other conditions by the diverter valve,"

Under Troubleshooting options later on the page:

"For this reason the EEC-IV system incorporates a self check function that monitors the thermactor system during actual operating conditions."


The O2 and ECT sensors provide input the same way they would for a stuck injector or clogged injector. If outside secondary air isn't injected it would obviously affect the mixture flowing past the O2. The ECT is used on the EEC trucks to determine when to dump air at times of heavy load by sensing excess heat.


There is no personal attack involved. I simply don't agree with your statements that
and...


Both the manual and the fact that different codes exist for circuit and various pump operations tells me that there is feedback and that the statements are incorrect.

If you or anyone else has evidence to the contrary I'm all for seeing it.

 

You all have lost focus of what the original question was, all he wants to know is will disconecting the air pump mess up his computer. He already has in his mind to disable all the emission controls he can, this is his choice, the truck already has the cats removed and he wants to install headers. The answer is no, the truck will run just fine without the air pump. Back when we had emission inspection here in Fl. I had an air pump on my mustang gt that I hooked up only to pump air into the exhaust stream to help it pass, i ran empty cats to pass the visual and it was carbureted too. After that I unhooked it. So T30, the answer to your original question is, no! go ahead and disconnect the air pump if you wish, install an aluminum intake and a holley four barrel if that is what you want to do, it will not trash your truck by doing so. After all, it is your truck.

 

Good point Fatdad.

I just hate seeing someone get rid of a working injection system. Since the converter is already gone it looks like the rest of the emissions will follow anyway.

For the work involved I wouldn't go back to carbs unless I really wanted major changes. I'm curious to see what mods he already has.

 

I agree that we're straying from topic, but hey: that's why it's called a "thread". I also agree that removing ANY emissions components is categorically BAD, for several reaons, and I never encourage it. I'm only discussing how the EEC manages/monitors the 2ndry air system, and what the codes mean.

"Input" is one thing. "Feedback" is another, and that's what you don't seem to grasp. The EEC uses MANY inputs (including ECT, ACT, PIP...) to decide when & how to manage the 2ndry air system. But it has no feedback to know if any air is actually flowing anywhere, or in the correct direction, or at the right time, or anything else. The ONLY feedback it has in an EEC-IV truck is the voltage across the TAB & TAD solenoid valves' circuits. There is no pressure sensor; no flow sensor; nothing to tell the EEC if energizing the TAB or TAD has had any effect. Yes, any air that actually makes it to the upstream ports will pass the HO2Ss, but so would air from an intake leak, or air that didn't get burned because of low fuel pressure or sticking injectors or anything else that generates a lean condition. So the EEC can't interpret a lean signal from the HO2Ss as being specifically 2ndry air feedback.

This is ESPECIALLY true at cold startup, since the HO2Ss aren't hot enough to provide ANY useable signal to the EEC. Ford's documentation doesn't describe the EEC-IV Managed Thermactor Air System operation in that much detail, so I can't confirm that the Haynes description actually applies to these trucks. But I admit that I had never noticed that brief remark before. However, it's moot in this discussion because the HO2Ss can't detect that air anyway.

 

My code reader will indeed force the ECM into a diagnostic mode in which it will look for the pump input ahead of the O2 sensor & report an error if it isn't found.

In any case, this link shows how I cut the smog pump out of the circuit on a '95 F-150 351w with no ill effects on drivability (for those, like me, determined to do so). I wouldn't recommend it either. I also wouldn't recommend ever exceeding the speed limit.

http://www.supermotors.net/vehicles/...ry/16229/54839

 

OK I worded that 2nd part badly - there ARE diagnostic procedures & tools that can be used to force the 2ndry air system to run. But it's not part of the SELF-diagnostics that the EEC normally performs, or that it can be triggered to perform by a typical home mechanic.

I'm still not convinced that the system is active at cold startup, but I'm not arguing it, either.Is that a MAF engine? Do you know the code number? I'm interested to read up on it.

 

Gotcha, Steve. Greatly appreciate your thoughts & advice.

It's been a while since I pulled its britches down, but I think the code downloaded was 311, maybe 312. 3-something I'm sure. I'll check it again when it warms up a bit (it's FREEZING in Alabama!).

No, it's an SD engine. What are the implications of that? Did FoMoCo install MAF 5.8's in trucks in '95?

Thanks

JF

 

Yes, there were some MAF 5.8L trucks built in '95 w/E4OD under 8500GVWR. They'd have slightly different engine management schemes, and slightly different emissions controls.

When you get that code number, I'm also curious about your scanner brand & model. Ford's diagnostics for the low 3## codes in '94 (the OP's truck) doesn't involve triggering the air pump thru the EEC.

 

Steve,

I agree that there is no physical direct feedback, but the input from the ECT and/or O2(s) would be no different than your injector example. If the EEC tells the injector cycle to shorten, yet still reads rich past the O2, it gives possibles to troubleshoot but does not know if the injectors are stuck open of if someone is dumping fuel in the intake. Likewise, then the EEC directs upstream air and the sensor inputs don't see that change the code gives various items to check.

As for the O2s, I stated earlier that input from such would only occur once closed loop operation was taking place.

I think Haynes only gives two or three specific codes for the flow related side, and a couple for the circuits. Looking at the codes in my Actron plug in cheapy scanner book, it shows codes 311-317 all realated to the flow items. I had never noticed in the past but it also shows codes for lack of operation on both banks for trucks with two O2 sensors. Being that is that case it must use the sensors to throw those unique codes.

There is also a code (315) for inadequate flow during cold start. Where they get the input for that one I'm not sure. It might be possible that even though the O2 is still heating and not being used, it could be used to detect a very rich mixture.

If you want the full codes from my book let me know.

 

You're assuming that EVERY computer has the ability to throw EVERY code listed in your book. They don't. I have several code lists, including the Ford list specific to each year & model of vehicle, so I agree that there ARE codes that describe flow faults. But since these trucks don't have the sensors to detect them, truck EECs aren't programmed with those codes. They can't store them because they can't detect them.

And a cold HO2S (HEGO) can't tell the EEC anything. Read the caption of this diagram. It's from Ford.

 

Once again you're arguing yourself in circles, changing direction as you go.

Apparently both mine and JLFs trucks will store codes they can't possibly sense or detect. I have no idea what his was, but I know mine was a diverter code that was easily detected and didn't relate to a circuit problem. I can't confirm if the EEC triggers the system or not, but I can confirm that it will store the code. In my case it didn't cause a Check Engine Light but the code was found trying to trace a problem.


Now that we have that cleared up, is it your assumption that your statements are correct, or do you have a source that conflicts with what myself and others here have stated and backed with sources?

 

Thank you Fatdad!! This is all I really wanted to know. I have no mods as of yet. The engine has a blown head gasket and I am planning the rebuild. The holley comment was more a joke than anything, However I am having trouble getting straight forward info as to when/what/how I need to upgrade the computer. I'll start a new thread and yet yall fight it out!