My uncle is looking at getting a 96ish F-250. I know the 96-97 have MAF and the OBD-II system. I don't know a whole lot about the system, just that it has more 02 sensors and a more complicated emissions system, but is there any real drawbacks or problems with it? Whats the difference between the OBD-II on the 96s or 97 F-250 and the OBD-I thats on my 95 F-150?


Primary rig is Green Thunder:
95' F-150 XLT 4x4, 302, 5 spd, MSD 6A, Flowmaster Exhaust, Sunroof, Clear corners w/ Diamond headlights, CD player with 2 10" subs and some 32" BFG Muds .

Check out my Gallery for a look-see.


Justin - One Happy FTE Member

 

I thought about that before too. Seems like just more stuff you have to worry about (o2 sensors) failing on you... Aren't all vehicles 1996+ OBD-II now? Hmm.... I'm sure someone around here knows...

 

I found an article on the subject a few weeks ago. You must be questioning the same thing we do. This article says that OBDII is for emissions purposes, which would state why Ford derated the performance numbers of the engines in 1996, and not leaving them like they were.

Get ready for OBD III, it's on the horizon.

http://members.aol.com/carpix256/library/us796obd.txt

 

Probably the main difference between OBD1 and OBD2 is that OBD2 monitors all the sensors and systems to make sure there are working properly and not causing emission compliance problems. As an example, on an older truck you could remove the catalytic convertor and the PCM would never know that you did that. On an OBD2 system there are what looks like O2s behind the cat. They are actually used to check to make sure that the cat is working properly. If it isn't, because it failed or because you removed it, the PCM will see that and turn on the light. OBD2 also monitors for misfire which OB-one-kanoby didnt do. That's why when you have a #4 misfire due to a wet coil for example the PCM will turn on the MIL. On an older engine the miss would be there and the light might turn on due to some other sensor picking up a strange reading because of it but it wouldn't directly set a code due to the misfire.
Some vehicles used OBD2 in 1995, more in 96 (not all the heavier trucks used it) and I think they all did in 1997.

 

Isn't there a plug under the dash or something that will tell me if it's OBD-I or II?


Primary rig is Green Thunder:
95' F-150 XLT 4x4, 302, 5 spd, MSD 6A, Flowmaster Exhaust, Sunroof, Clear corners w/ Diamond headlights, CD player with 2 10" subs and some 32" BFG Muds .

Check out my Gallery for a look-see.


Justin - One Happy FTE Member

 

Yup if it's OBD2 the diagnostic connector is under the dash. It is a sort of flat D shaped connector. If you look under the hood there shouldn't be an old style diag connector.

 

I agree with these comments and thought someone might be interested in this, regarding OBD2 and the two O2 sensors at the cat. I used to have an Impala SS and someone had made a device to "fool" the computer into thinking there was still a cat after it had been removed. Everything worked fine then with no lights coming on. Might be something to look into for those who feel they must remove the cats on an OBD2 vehicle.??

 

I love my 96......I have 115k on it and have only seen the "Check Engine Light" on once and that was at 100k when a O2 sensor went out.

My buddy has the same engine in his F150 but a 95 with OBD-1 and speed density and my truck blows his away off the line and at top end so another plus of the OBD-II is the Mass-Air with it.

My OBD-II connector is under the dash in the center below the ash tray.

Another plus is the OBD-II gets much more performance gains when a chip is added because of the added sensors.
But I'm not sure other then the MAF and O2 sensors what other sensors there would be.

On my 96 4.9L I have 3 o2 sensors...1 on each manifold and 1 right after the pre-cat.

 

Mass Air trucks are quicker than speed density trucks. I noticed that difference right away after driving newer ones.

They don't get quite as good mileage though.

 

 

>Whats the difference between the OBD-II on the 96s or 97 F-250 and >the OBD-I thats on my 95 F-150?

40 pins at the EEC LOL

Take a close look, I have personally seen a '97 F350 that was not MAF ('cause it was a 460) or OBD-II. I can only assume the higher GVWR of the F350 exempted it.

 

>Take a close look, I have personally seen a '97 F350 that
>was not MAF ('cause it was a 460) or OBD-II. I can only
>assume the higher GVWR of the F350 exempted it.

Most 96-97 HD's were still OBD-I, as OBD-II was only required on vehicles under a certain GVWR. The exceptions I know of were the Powerstroke beginning in 94.5; and California 460's (and 351's?). These had OBD-II and gas engines had MAF.

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1995 F-150 Supercab XLT 155" 4x4 M5OD 302
1986 F-150 4x4 NP435 300

 

Some of the '95s have the OBDII connector under the dash and the OBDI (EECIV)connector under the hood. In those cases, the OBDII connector is non-functional. I think Ford did this since '95 was the transition year for going from OBDI to OBDII.

Mike