What Heads OHV 4.0?

[gaz]

@DPDISXR4Ti
1) the 95TM combustion chamber is SMALLER than the 93 TM combustion chamber and is often referred to as Fast Burn Combustion chamber
2) yes, the 1995 Explorer did get the 95TM HEAD in 1995; only the Aerostar OHV 4.0l's continued to use the 94TM heads for 95 and 96 (until 1997)

There are some great pictures of all 3 styles of OHV 4.0l heads in the forum Tech Library and...6 posts above your question in this thread ..)

 

[DPDISXR4Ti]

Okay, got it. So basically, if you see a plastic manifold, it's most likely got the 95TM (or 98TM) heads. Do we have any idea roughly how many fewer degrees of ignition lead are provided in the "Fast Burn" calibrations vs. the earlier applications?

I'm coming at this from a different angle... I'm currently running a '92 Ranger PCM (no EGR) and wondering how swap-able the '95 Explorer PCM (w/ EGR) might be. In this case, there's actually two different factors at play that might cancel each other somewhat. The faster burn head will require LESS ignition lead while the EGR will require MORE ignition lead when running (or, in this case, THINKS it's running). Unless perhaps there's some error-checking going on and if the '95 logic detects that EGR is not working, it doesn't employ the different ignition table.

 

[Shran]

Okay, got it. So basically, if you see a plastic manifold, it's most likely got the 95TM (or 98TM) heads. Do we have any idea roughly how many fewer degrees of ignition lead are provided in the "Fast Burn" calibrations vs. the earlier applications?

I'm coming at this from a different angle... I'm currently running a '92 Ranger PCM (no EGR) and wondering how swap-able the '95 Explorer PCM (w/ EGR) might be. In this case, there's actually two different factors at play that might cancel each other somewhat. The faster burn head will require LESS ignition lead while the EGR will require MORE ignition lead when running (or, in this case, THINKS it's running). Unless perhaps there's some error-checking going on and if the '95 logic detects that EGR is not working, it doesn't employ the different ignition table.

What's the purpose of what you're trying to do?

The '95 PCM would be looking for EGR and a cam sensor, and an automatic transmission (if that's the donor you use) and if those pieces aren't present, I feel like it is more trouble than it's worth. I kinda of feel like that's the case anyway. Why add more stuff if you don't absolutely need to...

 

[DPDISXR4Ti]

What's the purpose of what you're trying to do?

The '95 PCM would be looking for EGR and a cam sensor, and an automatic transmission (if that's the donor you use) and if those pieces aren't present, I feel like it is more trouble than it's worth. I kinda of feel like that's the case anyway. Why add more stuff if you don't absolutely need to...

I've found the '95+ PCM's to be more reliable and less prone to capacitor leakage.

I'm dealing with a Manual transmission, so no concerns there.

I was wondering about the cam position sensor - what's it even used for on the EEC-IV application? It's still EFI on the '95, right? SEFI didn't arrive until '96 with EEC-V, right?

My experience on earlier (late 80's / early 90's) EEC-IV applications is that there's no significant consequences of not having EGR even when the calibration expects it. (Note, as long as the timing isn't so close to the edge that it starts pinging). In fact, you won't even get an error message as long as the EGR solenoid is hooked up. Perhaps the late EEC-IV logic is more advanced with respect to EGR? Dunno.

 

[Shran]

I guess that I was under the impression that some 93's and most or all '94 Explorers with California emissions were SEFI and had cam sensors & EGR. I'm not sure how that translated into the Ranger side, my '94 has neither and a 5 digit odometer. I just junked a '94 B4000 that had everything. Seems like they were just using up what they had on hand.

Agreed about EGR, on my V8 swapped truck the EGR valve itself is the only piece still there and it's plugged in but causes no issues. Used to be able to buy an EGR fooler plug that was basically just a resistor IIRC. Then you could remove it all without setting off the CEL.

Not sure about the capacitors leaking, it is certainly an issue but I've actually never seen it happen in person. I don't open up every computer that I run across but I have yet to see a 94 and older truck roll through my shop with that issue... and dozens of them have been here. Maybe I'm just lucky that way or they weren't failed to the point of big problems.

 

[DPDISXR4Ti]

Not sure about the capacitors leaking, it is certainly an issue but I've actually never seen it happen in person. I don't open up every computer that I run across but I have yet to see a 94 and older truck roll through my shop with that issue... and dozens of them have been here. Maybe I'm just lucky that way or they weren't failed to the point of big problems.

I bet if you checked more you'd find more leakers. They can leak for awhile without creating issues. I've found that the ones that the cover fastens with six 5.5mm-headed screws are much less inclined to have problems than the ones that fasten with two T-15-headed screws on the sides. All of those that I've found lately are already failing.

 

[gaz]

@DPDISXR4Ti
@Shran is correct; with the exception of the Aerostar, Ford used both Federal (non-EGR) and SEFI (EGR) OHV 4.0l's in 93 and 94. Additionally, both the 93+94 came with big chamber heads and small dish pistons but many have been successfully rebuilt with fast burn cylinder heads (95-00). In fact, one of the 94's that I've used had been rebuilt using fast burn heads the other was rebuilt with 94TM.

The cam position sensor is what the PCM controls/adjust the timing on all SEFI engines. While I do not fully understand exactly how it is accomplished, the PCM can better control temperatures, reading the EGR values, then by recycling exhaust gassed it can yielding higher efficiency...as much as +10%!!

 

[DPDISXR4Ti]

@Shran is correct; with the exception of the Aerostar, Ford used both Federal (non-EGR) and SEFI (EGR) OHV 4.0l's in 93 and 94.

So are you saying that if the vehicle has EGR, it also has a cam position sensor and thus SEFI?

Is there any actual relationship between those two, other than they both are utilized to reduce emissions?

 

[gaz]

@DPDISXR4Ti

No, I'm saying for 1993-1994 SFI-MAP-EDIS California OHV 4.0l's all have EGR and camshaft position sensor (CPS). The 93/94MFI-MAP-EDIS, Federal version does not have a CPS.

1) The camshaft position sensor is use on:
• the 93/94 California SFI-MAF-EDIS (EGR) 4.0l's. It is how the PCM controls the fuel injection and timing advance.
2) on the 93/94 Federal MFI-MAF-EDIS 4.0l's, the PCM crankshaft position sensor accomplishes this.
• on the Aerostars through 96, Ford did not update from the 91-94 big combustion chamber/small dish; unless someone rebuilt it different, all Aerostar 4.0l's through 1996 will have the 91-94TM heads.

*REFERENCE*: "FORD FUEL INJECTION & ELECTRONIC ENGINE CONTROL"
by Charles O. Probst SAE

 

[DPDISXR4Ti]

No, I'm saying for 1993-1994 SFI-MAP-EDIS California OHV 4.0l's all have EGR and camshaft position sensor (CPS). The 93/94MFI-MAP-EDIS, Federal version does not have a CPS.

Thinking about this some more, let me ask the question differently... Did any OHV 4.0 application get EGR but not SEFI?

 

[gaz]

@DPDISXR4Ti
No, based on the information published in the "FORD FUEL INJECTION & ELECTRONIC ENGINE CONTROL" by Charels O. Probst SAE.

The SFI (sequential fuel injection) PCM'S [California 93-94] require the EGR system. The MFI (multi port injection) PCM's [Federal] do not use an EGR system; I have no working knowledge or technical support beyond 94, except that the 95-96 Aerostars used the 94TM heads/pistons with EECIV.

 

[DPDISXR4Ti]

The SFI (sequential fuel injection) PCM'S [California 93-94] require the EGR system. The MFI (multi port injection) PCM's [Federal] do not use an EGR system;

Interesting that SEFI Requires EGR. Do we have any idea what that even means? I suspect it's not entirely true. As I understand it, EGR control is primarily an output from the PCM. The only input back to the PCM would be if an error was encountered.

the 95-96 Aerostars used the 94TM heads/pistons with EECIV.

Mostly out of curiosity, I wonder how Ford was able to deliver 1996 vehicle without OBD2. Maybe there was a fine levied, or maybe some sort of exemption was offered? I recall reading once that the Aerostar production was extended beyond plans. I bet they never planned to have an OBD2 version and had to scramble, especially given that it did continue on into 1997 where they finally did have EEC-V / OBD2.

 

[gaz]

@DPDISXR4Ti
This is above my pay grade, understanding and compression but a forum member who is an authority on the subject matter, made a quick pass at explaining it to me.

MY READER'S DIGEST VERSION
Aside from the " pollution control measures, the SFI PCM program uses exhaust gas temp readings to control exhaust gas use to lower engine temperatures, making more power with the same amount of fuel (increases the overall efficiency). I will read the guidance again and try to explain it more proper in my own words but this is a stretch for me as it is not my field of expertise.

 

[gaz]

Also, is it written in the previously noted document that due to the lack of popularity in the Aerostar, Ford chose to use that setup unchanged until 1997. In regards to the legal implications...it took me 20 years to figure this out. There was another written reason other than simply saving costs in manufacturing but it eludes me.

I have no idea how long it took the aligned system regulatory enforcement agents. I don't even care except when I'm in the wrecking yard, sourcing components.

 

[DPDISXR4Ti]

@DPDISXR4Ti
This is above my pay grade, understanding and compression but a forum member who is an authority on the subject matter, made a quick pass at explaining it to me.

MY READER'S DIGEST VERSION
Aside from the " pollution control measures, the SFI PCM program uses exhaust gas temp readings to control exhaust gas use to lower engine temperatures, making more power with the same amount of fuel (increases the overall efficiency). I will read the guidance again and try to explain it more proper in my own words but this is a stretch for me as it is not my field of expertise.

It's above my pay grade as well. But I'm trying to be smarter and get a promotion.

I get how EGR works in general, but it sounds like perhaps the controlling logic got more sophisticated and granular from the late 80's to the mid 90's. Feel free to cut & paste whatever you have and I'll try to make sense of it.

I'm inclined to believe there's not any direct correlation between SEFI and EGR, it's just that both arrived on the scene at the same time for this application, as dictated by the ever-increasing emissions targets that had to be met.