Will a 4.8L run with an ECM configured for 5.3L?

Am wondering if a 4.8L will run using an ECM configured for 5.3L and if so, how well will it run. Basically, I bought an ECM configured for a 5.3L with VATS disabled thinking I had a 5.3L. But it turns out I think I have a 4.8L. I was going to start the engine on a stand just to test it and make sure all is good before stuffing it into my 53 Chevy. I'm currently working to get my bench harness working to program ECM myself, can read but having issues writing to ECM. So until I get that issue resolved, am hoping I can at least use the ECM that already has VATS disabled but is configured for 5.3L. Anyone have success doing this type of test?

I think it will be OK for a short test, no driving of any kind. I've helped some local salvage yards with "Starter PCM's" for testing engines while the engine is still in the vehicle.

dave w

That's all it would be for, just an engine stand test. I was just curious if it would even run though being I'd think since the computer is configured for a 5.3L, therefore the timing of spark/injection may be incorrect due to computer using the different stroke in it's table/calculations? If I can get my bench harness LS Droid setup to work, then I'd definitely just use the ECM that is already configured for 4.8 after I delete VATS. I already bought an ECM setup for 5.3L with VATS removed, which in short term thought I'd try assuming it's even worth trying.

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Originally Posted by 53dawLsSwap

Am wondering if a 4.8L will run using an ECM configured for 5.3L and if so, how well will it run. Basically, I bought an ECM configured for a 5.3L with VATS disabled thinking I had a 5.3L. But it turns out I think I have a 4.8L. I was going to start the engine on a stand just to test it and make sure all is good before stuffing it into my 53 Chevy. I'm currently working to get my bench harness working to program ECM myself, can read but having issues writing to ECM. So until I get that issue resolved, am hoping I can at least use the ECM that already has VATS disabled but is configured for 5.3L. Anyone have success doing this type of test?

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It will run just fine even drive down the road and be perfectly ok. As long as the 02 sensors and knock sensors are hooked up it will be perfectly safe.

I have personally done a 4.8 to 6.0L and drove it on the stock 4.8 tune for nearly 6 months.

Fast355, interesting. I would have thought it would basically be similar to having the old school timing off as you adjust the distributor and may run rough due to it being retarded too far. Unfortunately I won't be trying this little experiment, the guy I bought this engine from is going to swap me with a 5.3L like I paid for. But maybe down the road I'll give something like this a try, am having fun learning/working on these newer engines. After I get my bench harness working properly, would like to learn how to tune these. Is there an algorithm table laying around that is/can be used to figure out what tuning parameters to enter to get the desired performance?

If you are going to run any O2 sensor feedback based engine on an engine stand I would bet with open exhaust you need to leave the O2 sensors unplugged so it does not go into closed loop.

why not segment swap the engine with Universal patcher. http://www.gearhead-efi.com/Fuel-Inj...versal-Patcher

did you get rid of the 4.8?