3800 Engine swap troubles. Need GM Guru

I'm having trouble completing my 3800 engine swap, and need some experienced advice.
My 1994 LeSabre blew its tranny and the engine was getting iffy recently. I had already purchased a relative's 1993 LeSabre as a parts car, since I was worried the engine might go on my car. The cars seem virtually Identical, so I put the lower mile engine/tranny from the 93 into my 94.

When I brought the engine home, I realized the main harness was different where it plugs into the firewall. I figured it was best to try the 94 harness and accessories on the 93 engine. Basically the only stuff that I used from the 93 was the main engine/tranny assembly. All wires, ignition, alt, ps, AC, cooling, and other bolt on accessories remained the 94 parts. All the 94 wiring connected up to the 93 engine nicely, except for the 2 exhaust sensors (front and back), so I put the 94 exhaust sensors on the donor engine.

Great, put the engine in and it started up right away, but didn't run well at all, very sputtery. Also none of the fans would come on (no rad fans or interior fan), and it will over heat if left running too long. The voltage never went above 8 volts, and dropped from there. Wasn't Getting a charge.

Now a shop has altered the charging circuit wires, so now the battery is showing proper voltage and staying charged. Thought that would solve the running badly issue and allow the fans to work, but nope.

What am I missing here? There's gotta be a common cause to it all. How different can the two engine years be, and what are they?

The 93 PCM/ECM is OBDI and the 94 is OBDI.5 and they are altogether different. If you have a 93 engine, it needs the 93 ECM, prom & wiring harness to communicate properly with the sensors. If you add sensors, like a downstream 02, the 93 ECM will not recognize it. BTW, the alternator charging circuit is not the same on 93 & 94 either.

The 93 PCM/ECM is OBDI and the 94 is OBDI.5 and they are altogether different. If you have a 93 engine, it needs the 93 ECM, prom & wiring harness to communicate properly with the sensors. If you add sensors, like a downstream 02, the 93 ECM will not recognize it. BTW, the alternator charging circuit is not the same on 93 & 94 either.

Those tricky buggers. So they changed the plugs on the exhaust stuff but not the rest of the incompatible engine parts. I've talked to a bunch of people an they thought the same as me (Why wouldn't the 94 harness work on the basic engine which looks the same).
I'll go to the farm and yank the ECM and it's harness from the 93. Does the ECM connect only to the motor, or does it go to other things on the 93 that I will want to take too? Lastly I'm using the ingition and it's wiring harness from the 94, will that work or do I need the 93's. I hope 94 is fine cause the other one is in bad shape and has exposed wires from being too close to the belt.
Thanks for the info.

Does the ECM connect only to the motor, or does it go to other things on the 93 that I will want to take too?
IIRC the 93 & 94 has a different plug & connector on the trans.

I have said this a few times in the past here... Research is the Key...

On many GM cars there were changes between years or every couple of years..


What you needed to do with the 93 Motor was swap the harness and all related sensors from the 94 Engine... After that you would have been ok engine wise...

The 93 Trans uses the same connector as the 94 Trans, but for the 94+ 4T60-E its pinned out differently as 94 was the first year for the PCM to monitor Tranny temps...

Basically the 1994 internal Trans harness needs to be parked on the 93 Trans( Behind the side pan )... You need the 94 Sensors on the 93 engine... The 93 Uses an AFH50M-02E MAF and the 94 uses an AFH50M-03 MAF... Slightly different calibration... iirc for 94 you use one temp sensor for both the dash and the PCM... In 93 it used 2 Temp sensors, one for the PCM and the other for the dash, and thats iirc...

So there are good differences between the 93 - 94 model years..

Hope that has helped a little

Don, the 94 has two temp sensors, one for the PCM and one for the IC gage. In addition, if you use the 93 harness & trans pigtail with the 93 ECM, there is no need to change the internals behind the side cover. BTW, the 93 & 94 both used the temp sensor and pressure switch models. They are wired different on both models and both years! See schematic below:

http://img352.imageshack.us/img352/4656/4t60ewiring2eo5.gif

So then the easiest solution is go with the 93 computer and main engine harness? I can swap sensors too but that looks like more work, and I'd be guessing as to which ones I needed to change.
I believe the main harness has the tranny wires. I remember two connectors on the passenger side firewall bottom corner.

So then the easiest solution is go with the 93 computer and main engine harness?Yes!
I believe the main harness has the tranny wires. I remember two connectors on the passenger side firewall bottom corner.The one on the passenger side is the VSS. IIRC, that is the only one.

Yes Bo you are correct.. I was wrong on that one and do apologize to the Poster..

I am at a loss as for swapping to the 93 PCM, as you will be required to rewire or repin as the 94-95 Harness to PCM is different than the 93 Harness to PCM.. I am speaking of the connectors at the PCM BTW...

As for the Temp sensor models for 93, Looking close at that Pic it actually shows this as a temp switch and is only used for Traction Control on the C and H bodies for the 93 Model year..

Forgive me if I am a bit lost here..:smile:

I am at a loss as for swapping to the 93 PCM, as you will be required to rewire or repin as the 94-95 Harness to PCM is different than the 93 Harness to PCM.. I am speaking of the connectors at the PCM BTW... No problem Don, the 93-94 were very confusing and that is exactly why I suggested changing the complete wiring harness and the PCM to a 1993 model. They are “apples and oranges” when it comes to wiring and programming. The PCM is a different part number, the wiring is not the same and the prom is programmed altogether different. It is difficult to make swaps between these two years because of the many changes that took place in only one year. 1994 was the beginning of the transformation to OBDII and the programming (prom) was a different animal!

My only wish was that they made the engine obviously a little different looking, so one doesn't assume they are all the same.
I plan to go to the farm tomorrow to the the rest of what I need from the 93.
Curious if I will notice a difference in performance with the 93 engine, or is it just a change in technology that would not even be noticable?

Actually I think the 94-95 PCM is a bit better in terms of functionality( But the failure rate is high ).... when it works it works... When the PCM decides to kill off an organ its a nightmare to say the least.. LOL

The 93 PCM in my eyes is a better animal..

I would comment on the 95 Series II with the 95 PCM and EPROM, But thats another freaky story...

Actually I think the 94-95 PCM is a bit better in terms of functionality( But the failure rate is high ).... when it works it works... When the PCM decides to kill off an organ its a nightmare to say the least.. LOL

The 93 PCM in my eyes is a better animal..

I would comment on the 95 Series II with the 95 PCM and EPROM, But thats another freaky story...

They changed it agian for 95? Brutal.
I went out to the farm yesterday, got the 93 PCM, but getting the wiring is a nightmare, it seems to combine into one big wire harness that goes to everthing in the dash. I ran out of light and patients, so I'll have to try again next weekend. Hopefully once I get the the wiring out the wires that go between the engine and PCM will be easy to pick out.
Does anybody have a link to a write up on these differences. All I have for the moment is a Haynes manual which covers every large GM car for 20 years. I'm starting to think, maybe switching sensors will be easier, but maybe that is opening a can of worms too.

Gave up on using the 93 wiring and PCM. That stuff goes everywhere, real pain to get out. I tried removing it on the 93, and there is no end to the wire yet, so I gave up. Not worth doing this to the 94.
Bought a new car, so this one and the parts car are going up for sale. I still would like to solve it thou and be able to sell it ready to drive.
I'm hunting down the sensors that need changing and swapping them over. Found one on the intake with the AFH50M-02E MAF / AFH50M-03 MAF numbering difference. I plan to swap the thottle linkage sensors too. Is the sensor hidden under the intake the coolant sensor? If so sounds like it needs swapping. Any others?

Hey Hotz28 think you could help me with a transmission filter replacement question that has me stuck on ramps?

Railroadman:confused:

Hey Hotz28 think you could help me with a transmission filter replacement question that has me stuck on ramps?

Railroadman:confused: You need to start a new thread on this subject and be sure to include the year of your LeSabre! Click Here (http://www.automotiveforums.com/vbulletin/newthread.php?do=newthread&f=102) to start a new thread.

I gave up on the wiring, so I took a few more sensors off the 94 engine to put on to the car. Swapped 2 coolant temp sensors, a throttle sensor, the air intake sensor, and put in a new thermostat. Also added an engine to frame ground strap. All that made very little if any difference. Revs ok (not perfect) when in park but in drive it has a hard time accelerating and sounds like it wants to stall. Interior and engine fans still won't work. Starts nicely thou.
Could it be the trans sensor? Any other ideas?

Update. Just went out to mess with it some more.
Took the rad cap off ran it for 5-10 minutes. Fairly uneventful, fluid started to move a little. Put the cap back in and revved it a little for about 2 minutes. Then stepped out and found the exhaust glowing red. Temp gauge was only at about 1/3, no where near the red zone. Rad hose didn't seem very hot considering either. I know the fans aren't turning on, but what could cause it to glow when the gauge still reads good?