jc1270

What is required to make this conversion work? Are there any ecm differences?
I know all of the sensor locations are different. My main concern is whether the signal out from cam sensor is same.If not, what is required to make this work

MuhThugga

Do you plan on running the Gen IV engine on a Gen III PCM? Does the Gen IV engine have a 24x or 58x crank reluctor?

FourG63 97GST

iTrader: (1)

curious on this also. using GenIII pcm for 24x reluctor

MuhThugga

To run the Gen IV engine on a Gen III PCM, it would be best to install a 24x reluctor on the crank if the engine has a 58x reluctor, and a 1X cam gear to replace the 4X if the engine is so equipped. However, if you don't feel like going that deep into the motor, then you can buy a signal converter box from Lingenfelter that will convert the 58x crank signal to 24x and the 4x cam signal to 1x. It is plug and play, but adds a point of failure. If the engine is a 24x/1x Gen IV engine, then you just need to get an extension harness for the cam sensor since it is was relocated to the timing cover on Gen IVs.

You will need to get some EV1 to EV6 adapter plugs for the fuel injectors. Racetronix and other retailers sell them. This only applies if you plan on using a Gen IV intake and injectors.

The knock sensors are probably the biggest obstacle. You either can utilize unused M10x1.5 holes on the sides of the block for the Gen III sensors, or you can drill and tap the M8 holes on the sides of the block where the Gen IV sensors go. You will need to get a harness extension either way.

The large white plugs for the coil pack harnesses didn't change between generations, so you can plug the entire rack of Gen IV coils into the existing harness without issue.

You may need an extension harness for the MAP sensor depending on what intake you decide to use.

I think that covers it.

jclayc

iTrader: (8)

For clarity on the cam sensor/front cover... so when going Gen III to Gen IV do I understand you to mean that you also have to buy/source a Gen IV front cover with the cam sensor in it? Will it "confuse" the Gen IV cam sensor to have the 3 bolt cam in it?

About the valley cover - do I need to get a stock LS3 one with the PCV tube in the front or will a totally featureless/flat one be better? (and what's the raised cylinder thing at the back of the stock LS3 valley cover?)

I'm scared to death to drill/tap the block...

Thanks!

SydwayZ

If you're going with a IV generation front cover then you will need the 58X timing gear so that the sensor can get its readout. 3/1 bolt really doesn't matter because the sensor gets its information from the timing gear.
As far as the Valley cover, you can use the one with the provisions for the knock sensors as long as you have the right harness. GTO's came with these early on as well as most of the 2004 – 2005 LQ4/LQ9 engines.

Shaunk22

I’m having a backfire while trying to start the engine. It will happen once while first cranking I’ll stop cranking try again and it’ll fire up. I had a machine shop install a 24x reluctor wheel and am also running a 1x cam gear. I also have a gen 3 to gen 4 cam gear extension harness and knock sensor harness. I have checked the timing multiple times even had a few buddies look to make sure I’m not crossed eyed or something. I’ve tried switching the two outer wires on the extension harness. The pcm was tuned previously for the exact same cam, heads, etc except it had the original 5.7 ls1. I’ve tried a new cam sensor even. Could this be in the tune? Any ideas would be greatly appreciated thank you.

hiltsy855

iTrader: (35)

I have the exact same issue, except I don't get backfires and it doesn't happen every start. About 50% of the time it fires right up, the other 50% it just cranks. If it fails to start, it will fire right up on the 2nd try. I've tried 2 new cam sensors and swapped the outer 2 wires on the cam sensor harness. This is on an LS2 in my '02 Camaro.

rpturbo

iTrader: (47)

A friend of mine had that back fire issue also, and on his, when I would connect with HPT, you could tell the crank signal wasn't reading, or reading consistently. From my understanding the engine will fire the coils not knowing where the crank is, and if it doesn't start on the first try, it swaps firing order. He had a swapped truck with a home built harness. Ended up he had a bad wire/solder joint. In others case, I would watch the crank signal on startup.

64post

iTrader: (5)

Gray vs. black sensor and reluctor MUST be installed with some precision.