If I put an 03 engine in my 99 Blazer do I need to change the intake manifold or can I use the 03 intake manifold without the EGR valve? Why would I need the EGR valve? If necessary I do have the 03 ECM - I have the whole 03 vehicle here. Is there anything else different other than the crank sensor?

 

Change the intake.
Because the 99 ECM is the one for your particular vehicle and it runs/interacts with lots of different stuff. A 2003 PCM in not going to be happy in a 1999 without reprogramming to your particular vehicle.
Crank sensor is the same part between the two years. Knock sensor is completely different with different mounting and wiring. I'm sure you can buy an adapter.
Exhaust manifolds may be different for the A.I.R. injection valves.
Just use the 1999 intake/exhaust/wiring/oil pan if different/all external accessories on the 2003 engine, adapt the knock sensor from the 1999, have a crank sensor relearn done when it is running - then you're golden.

 

Thanks for your reply. I meant knock sensor, not crank sensor, and we already have a tap to change it. My concern is that this 03 engine we have now is still in the vehicle and it really runs great as is, so I hate to change anything on it where I might lose any of that great performance.On the 99 we took the cat off and I really don't want to have the EGR valve and air injection pump or anything that might compromise the performance of it as it is now. My 04 was always more peppy than both my 98 and 99. I did come across another post where someone had swapped an 04 engine into a 98 and they said they only changed the knock sensor, but who knows if they then had other issues they had to deal with?

 

There are many reasons besides engine, to not try to use a 2003 PCM in a 1999. Like all the other modules doing serial communication with it like BCM, ABS, SIR, Transmission, TCCM, Instrument cluster, etc - also know that many are programmed for your particular vehicle.

And then even if you use the same 1999 PCM, it expects to see the correct things attached and working. For example, which way are you going to wire that knock sensor? One wire like 1999 or two wire like 2003? Do you thing the 1999 PCM doesn't expect to see an EGR valve? What about A.I.R injection? Heck, it won't even start unless you reprogram the security system.

If you still want to follow in someone's internet footsteps, then just ignore what I said. Lots of Internet experts out there. It's your vehicle.

 

Yes, I'll use the 1999 ECM that is in it, with the original knock sensor. So the question is if it will run with the 2003 manifold without the EGR valve, or will it need to be reprogrammed. Maybe we don't know

 

Has anyone done this before and knows exactly what will happen. One person on another forum says it will run with the original ECM but idles high when starting then drops down to an extremely low idle. There are also forums that tell you how to remove the EGR system and plates available that you can buy to cover the EGR insert area in the manifold and does not say that you have to reprogram the ECM after you do this.

 

Im doing the same currently. I’m using 98 engine build in a 2000. I’m using the 98 intake with egr block off plate between egr valve and intake so the computer is happy with 2000 JBA headers effectively deleting the egr function. I also have the 2000 manifolds but F that. If all goes well my dad’s ZR2 will be getting close to 20 mpg or better when all upgrades are completed.

 

Let us know the outcome and what side effects you get - good and bad. And any other alterations that may need to be done..Thanks!