I have a 95 dakota with a 3.9 and i will be putting in a 5.2 from a 1998 jeep grand cherokee.

Now, my current 3.9 has an EGR. If the 5.2 does not have one, will i have any problems? I plan on using my current wiring harness and just splicing in the new injectors, so if the 5.2 doesnt have an EGR, that connector will just be haning there.
Anyone have any experience on this? Thanks.

 

Also, will an ECU from a 1995 Dodge 1500 truck 5.2L work for me?

 

In regard to leaving the EGR unplugged electrically (on an engine with an EGR valve), the FSM says:

"If the electrical connector to the EGR valve control is disconnected, or the electrical signal is lost, the EGR valve will operate at all times. This may result in; poor engine performance, rough idle speed and reduced driveability during certain operating conditions."


If however, your engine had no EGR valve (or it was blocked off), the engine should be unaffected by the harness connector not being plugged in, since there would be no mechanical effect on the engine (no valve operation). I suppose the computer might throw a code, but on an OBD1 system that should be about it. But there are other issues to consider if you use a '98 engine, which is OBD2, in a '95 OBD1 truck with a OBD1 engine harness.



Because the '98 5.2 is OBD2 it will have sensors/devices on it that will not plug into the '95 engine's OBD1 harness. You may want to swap some OBD1 era parts onto the top end of that '98 engine, including possibly the throttle body assembly. I'm not sure right off hand if you'd need the earlier manifolds, but I would think so, if only to get the EGR ports.


Oh, the '95 OBD1 ECU will work as long as the 5.2 has the matching sensors, etc. The 5.2 Magnum motors are mechanically pretty much the same, other than some minor differences in the intake and exhaust manifolds to accomodate EGR ports, etc.

 

Hey thanks for the reply

I picked up the 5.2 today and it indeed does not have an EGR on it. So, im thinking about just saying forget it and not running one. But you say the exhaust manifolds from the 5.2 will not bolt up to my existing exhaust crossover? The only difference should be that it doesnt have an EGR port, correct?

Yes, i plan on using any sensors from my 3.9, if they are different on this new motor.

Also I think I am just going to pick up a 95 Dakota ECU from a 5.2 just to make sure i dont have any problems.

 

If you're going w/out the EGR than I think you can use the intake manifold from the Jeep OK, but the Jeep exhaust manifolds are a different story. I've heard that they don't fit correctly in a Dodge because the Jeep's starter is on the passenger side of the engine - and - supposedly the Jeep exits are in a different place and won't meet up with your Y pipe.

The good news is exhaust manifolds are usually cheap and easy to find in the junk yard. Note that the 92-93 exhaust manifolds have larger outlets, about 1/4" larger if I recall correctly. They're good if you want better flow, but you'd need to get a larger diam. Y pipe to bolt up to them.

I think the '95 Dodge Ram ECU is a good idea. Stay with an OBD1 computer and you won't have to worry with additional sensors, including another O2 sensor in your exhaust (or is it 2 more?).

 

Well darn, i wish I could know for sure if theyll work or not. I wonder how i could find out for sure... Otherwise my local junkyard has some exhaust manifolds i can pick up for 30$ a piece.

And yes, I only have 1 precat O2 sensor

 

Here's a 5.2L Grand Cherokee LH manifold:




And here's my Dakota LH manifold, note that the exhaust exit is farther to the rear:




The RH manifolds (Jeep and Dodge) look a bit more similar, but I couldn't say if they're interchangeable.

 

Wow that is great info. I got the motor all torn down today. I am just going to buy two new exhaust manifolds from my junkyard. I also discovered the Jeep has a much larger oil pan, so i will be picking up one of those as well.

Thanks for your help Ragged. I havent been to Dodgeforum in a couple of years, but it really feels like far, far less people are on here than their used to be.

 

Yeah, I've noticed that too, but there's a dedicated group at least. And I haven't found another place that's any more crowded when it comes to our type vehicles.