OBD-II to OBD-I conversion

[SIF]

Can I just literally take all the sensors and the PCM from a '93 to convert a '97 to 1st Gen? I've heard I probably need the chip modified to handle the fastburn heads but are there any other considerations I/m missing? Thanks

- Simon

 

[ma96782]

I don't get it....WHY WOULD YOU????

OBD-II is an improvement in engine management.

Aloha, Mark

 

[ExplorerDMB]

So what's the reason behind using the 97 motor? OBD-II is much easier to work with (since it was mandated in '96) and offers great benefits. Now, are you looking at just horsepower and don't really care about fuel consumption or what? My advice still stands in your other post - a custom computer would benefit you a lot!

 

[410Fortune]

To answer your question, it is very likely yes that your 97 block will workj with 93 sensors/intakes/ and computer.

But this is working backwards, OBD-II is better in every way

 

[SIF]

Hmm I'm so torn on this one and it sounds crazy I know, I'm starting from scratch here - no exisiting pcm/sensors etc nothing, so looking for simplest (read cheapest) solution. Without scrap yards to scour I can't get any of the parts to go OBD-II without importing the lot, whereas I do have some of the bits for an older OBD-I setup and I believe there are less sensors to buy anyway!? The main priorty and reason the engine is going in is POWER, this little car weighs under a metric ton so fuel consumption is never going to be a huge problem. Looking at OBD-II I agree a more modern system is always going to be 'better' in terms of engine management but it also seems so much more complicated/sophisticated and therefore harder to fool. Just the simple fact of no CATs on an OBD-II is a really big deal which involves either going to a custom computer ($$$s) or trying to fool the PCM into thinking they are still fitted.

I have had a quick look at custom computers but we really are talking big bucks, and would they not just mimick an OBD-I setup anway if they take over sensor inputs and substitue preset digital values, or are they far more sophisticated that that?

 

[410Fortune]

If the truck is a 97 and you have a 97 engine I suggest finding the parts you need from a single donor truck, on these forums or online.

Lets start over.
What are you doing?
Why do you need to find a new comnputer and sensors for your 97 engine?

 

[ExplorerDMB]

Lets start over.
What are you doing?
Why do you need to find a new comnputer and sensors for your 97 engine?

yup that's kindda what I asked above. That'll help us all out cause we will know what your goals are

 

[SIF]

OK, I've got a TVR S. The cars engine is a Ford 2.9l cologne V6 which for various reasons now needs either rebuilding or replacing. I was told the 4.0l ohv is basically the same engine with a bigger capacity... bigger capacity alway means more power so I brought a brand new (from Ford via EBAY) '97 engine. Said engine is just that - an engine; it has injectors installed on rail but no PCM, sensors, trans, throttle body, plenum, manifolds etc etc. The engine fits in the chassis and the RWD trans fits the engine, now I need to get the whole thing running. Being the UK I don't have access to hardly any ford trucks as they never sold well here so the only engine management bits I have come across were from a smashed '93 1st gen so I took various parts off including the UK model PCM and a member on here has very kindly shipped me a flywheel. Oh and the old 2.9 has got this PCM modding chip fitted which I hoped might overcome the '93 PCM running a '97 engine problem, and a TVR custom straight through stainless exhaust system with no CATs

That's the story so far... so when I said starting from scratch I really meant it! Hopefully that explains my dilemma and lack of any the parts required to go OBD-II and not many of the parts to go OBD-I!! Which is why I really really need all the help I can get from you guys

 

[410Fortune]

The easiest 4.0L OHV computer and system to use with the 2.9L to 4.0L conversion is 91-92 Explorer.
The BEST system to use is the 93 4.0L Ranger/Explorer intakes, sensors, and PCM.
Converting the 2.9L TVR to OBD-II would be pointless at this point UNLESS your 97 engine had the intakes, sensors, etc installed for the later model OBD-II computer.

I am going to assume your 2.9L equipped car currently has the car version of the 2.9L engine? Does it have a dual plane butterfly at the throttle body? What I am getting at is it does not have the truck style 2.9L upper and lower intakes, it has the Merkur scorpio stlye (Ford Cosworth? I want to know more about your 2.9L, it is EF injected correct??. These cars seem similar to the Sunbeam we had here in the US, though the only ones of those I have seen are 289 V8 cars)
If so this engine is speed density and uses a distributor ignition.
All you basically have to do to modify your 2.9L wiring is to add the Mass air flow sensor and DIS ignition on top of the 2.9L's harness, then use the 4.0L computer, BUT with the 2.9L intakes IF POSSIBLE.
OR
You can yank all the 2.9L stuff, everything and use the 93 harness from a Ranger/Explorer /Aerostar) anything 1993 with a 4.0L OHV in it.
the reason I like the 93 over the 91-92 and the 94 EEC-IV computer is there is no EGR, it has dual 02 sensors, and the power distribution portion of the wiring is far superior to the 91-92 (simplified and cleaner). It should not be difficult to find everything you need online, its just a matter of getting it all complete from ONE donor if possible to avoid complications. I would shoot for upper and lower intakes, all engine sensors, accessories, wiring harness (including trans and power distribution)


I did a 2.9L to 4.0L OHV conversion years ago into my bronco. I have done the wiring for many. Each one is different really because the recipient and the donor are always slightly different years, etc.

Do you have pictures of your 2.9 engine in the car?
What trans does it use?
Do you pictures of your new 4.0L?

This little car is going to have ALOT of torque when you are done with this....I suggested using the 2.9L intakes to kind of help make the power band a little more car like thehn the 97 4.0L truck version will put out. All your power comes under 2500 rpm, great for a truck, awkward in a car depending on the trans. the 2.9L was a rev happy engine, the OHV 4.0L can be made into one.

 

[SIF]

This music to my ears.. The 2.9 is the car type with twin MAF and twin input to the throttle body

It isn't the 24v cosworth but the bog standard EFI bosch L-jetronic injected (knocks out about 170bhp) with distributor ignition. Uses very few sensors from what I can see.. maf,coolant/fuel/air temp, throttle position. Trans is rwd Ford MT75. There are no CATs so no o2 sensors although I can retrofit these if they are really needed...

The new engine is definately '97 (engine no. 95MT6090AD, Heads: 97TM6015AA with U above exhaust manifold) here is a pic of it with the intake manifold and injectors off and one of the TVR manifolds offered up to it for fit - they sweep forward then under the car for extra 'acoustics'

When you say use the intakes from the 2.9 are we talking the inlet manifold and plenum? The Unichip I've got was 'mapped' on a rolling road to my engine and the tuner seemed to have the ability to move the power and torque curves around a bit so I guess that will help to give me a little more buzz and push the peak power up the range a bit.

As for the parts I found; the donor was a '93 I am led to believe, the PCM is a F37F-12A650-AGA. I did managed to take the upper air intake/plenum with throttle body and the dis box. I also have a Pro-M maf with a little optimizer computer to apparently calibrate it for any application. I really like the idea of simply grafting on the dis, maf and o2 sensors to my existing loom and then plug the PCM in, but is this the best way to go or would you honestly recommend the 'whole shebang' route?

The big worry I have is that little statement on the 4.0l rebuild article at the Rangerstation which reads something like; 'the early computer calibration will burn down a motor with fastburn heads in a few thousand miles' can you shed any light on this? You have made me a very happy man, Thanks - Simon

 

[410Fortune]

if it is a MAS 2.9L your conversion should be even easier, although I dont think you can use teh 2.9L computer UNLESS you drop the distributor into your 4.0L block.

I have no idea if the 93 computer will do any damage to the 97 fast burn heads, although I do know of quite a few people who have used 97+ 4.0L blocks in their pre 95 Explorer's, never heard of any problems.

the intakes pictured on your 2.9L are the same that we had here in the states in teh Merkur scorpio car. I was not aware they had a mass air flow sensor and I dont see one mounted to the airbox in your pictures? Are you sure its MAS? 2.9L's in the Ranger had MAS here in the US after 1990, especially if the truck was a California sold vehicle.
When converting from a MAS 2.9L (90-93 I believe) to a early OHV 4.0L (pre 95 in the US) the conversion was really simple, basically bolt in the 4.0L and then plug in the 4.0L wiring plug at teh firewall. I believe some of the wiring pin locations may have had to be changed.

I would make a map of your 2.9L 110 pin connector to the PCM (computer) then make the same map for the 110 connector at the 93 4.0L PCM, compare them. I bet you find there are only a coupld of additional wires, and the pinout should be the same or really similar, especially if your 2.9L was indeed MAS.

Are you aware your 2.9L likely makes the same power as th e97 OHV 4.0L? Just lakcing a bit of torque.
I do not think your lower plenum will bolt up to the 97 4.0L block and heads, but I could be wrong.

Also of guys used to talk about making a 4.0L run with the 2.9L computer by ditching the DIS ignition and runnig the 2.9L distributor in the 4.0L block (it has a hole for it).
The though process back then was to try and use a carbed intake on the 4.0L, or possibly dual carbs, similar to the Cosworth Cologne engines, but I can see this working with your dual plane, car style, 2.9L upper and lower intake plenum, if they will bolt up.

 

[SIF]

Its got twin MAFs sited next to the radiator, the air filter is pipercross and is just a foam box screwed to the front of the mafs.

I did see the hole for the dizzy and indeed wondered if it would fit so that gives me another option possibly - this is all starting to make sense now, the fog is clearing as it were! I know the power output is not a great leap but I was told to expect around 200bhp (without all the emissions stuff) with as you say an enormous amount of torque, which would be the top limit for the 2.9 without some extremely serious work (and would have cost a lot more than this whole engine replacement to get there),the thing I love about the 4.0 is that there is more to come if I want... I guess I can go bbk throttle body for a small increase through K&N induction to crane(?) cams all the way to a supercharger so around 200 is the starting point and not the max... there is also the fact that this engine is brand new never been run so that's a huge bonus as my 2.9 needed new heads and a rebuild anyway.

I'll have a very serious look at the connectors.. is there a site that details the 4.0l pin functions at all or do I just need a haynes manual?

Oh and do I need to fit a couple 02 sensors in the exhaust somewhere? - you're a diamond, thanks for all this help, Simon

 

[410Fortune]

yes you will need a single 02 sensor just after the manifolds on each side of the Y pipe (2 ea), that is if you use the 93 computer. The 91-92 computer have a single 02 sensor. the 95+ has 4 ea 02 sensors, 2 of which are the catalyst monitors.


Does this car have true dual exhaust, or does it use a Y pipe into a single exhaust?

Will the 4.0L intake manifold clear your hood???
wiring is not covered very well in the Haynes book, let me see what I can do, I have all sorts of wiring books, so I can post their names and publishers, etc.
It would be ewasy for me to give you a printout of the 110 pin connector for a 88 Ranger 2.9L EFI and a 110 pinout connector for a 93-94 4.0L Ranger.
But You will have to compare them to your european system and find any changes = yikes.

it can be figured out however, mapping the wiring is critical, then you can make the changes required to either piggyback, or modify the new 4.0L harness to fit the car.

 

[410Fortune]

I would love to see you adapt those Merkur style intake plenums and a distributor into the 4.0L block. With the speed density ignition it is easier to adjust the timing. You can run an aftermarket coil and even controller (MSD 6a) and really get some timing advance and spark in that 4.0L. Run larger injectors and tune the 2.9L MAF to control them. The 4.0L will be fully tunable for you this way.
With the car style intakes you will get more revs from the 4.0L better for a car.
Can we see a picture of the underside of your upper intake manifold?
I am curious if the lower intake is similar to the Ranger style 2.9L.

Just thinking out loud here.

 

[SIF]

True dual all the way to the pipes with one small backbox - they can be up to 110Db on full song. There is a handy J-peice between the manifolds and pipes proper which is just begging to have some bosses welded to it...

I hope to god the upper intake will clear, I've been told it will and I know someone has manged to get a sohc to fit with about 1/8" to spare! I have yet to refit the bonnet :gulp:

All info gratefully received

 

[410Fortune]

I have 1/8" between my 5.0L IAC valve and my BII hood

 

[Glacier991]

410? YOU RULE guy. Awesome help.

 

[SIF]

The Merkur ('Sierra' over here) intake manifold would fit except the cooling system has changed slightly. The newer engine uses an extra bit of casting with slots for coolant whereas the old manifold uses a pipe arrangement. Interesting to see the differences though, the port looks more 'open' in the car manifold and the injector is sited inside the port whereas the truck one is sited next to the port, the port in the truck is also a lot more 'direct' with less of a bend in it and seems slightly shallower;

The distributor looks like it will fit no problem... were you suggesting this is better than using the explorer DIS?

 

[410Fortune]

Not better, the DIS ignition is EXCELLENT.
The distributor ignition uses the TFI module, or thick film integrated ignition module mounted on the distributor. Ford had nothing but problems with those things. I personally never had issues, in my truck with the TFI but I had a spare in my glove box at all times

The advantage of the distributor setup is you can run an aftermarket ignition and coil, also adjust the timing easy. It is more "tunable" without the need to "chip" the computer.

You would retain your 2.9L computer, MAS, fuel injection, etc if you put a distributior in the 4.0L block. This is how we would keep your intakes and sensors. Esentially just swapping out the 2.9L long block in favor of the 4.0L long block.

In theory this would work, I am not sure it has been done.

 

[410Fortune]

Also this is from memory so I could be wrong, but I seem to remember something about the 2.9L distributior drive gear running the opposite direction from the 4.0L oil pump drive, so I think you need to use a revese cut gear on teh distributor when you put it in the 4.0L. I am not sure why but this has been sticking out in my head last night. We talked about all this stuff YEARS ago on teh 2.9L forums on Fordranger.com......

Some research is in order.