Does anyone know what the difference is between the 500E LH module and the 400E LH module ?

I suspected the problems I was having may have been related to the LH or EGas modules. It has been 11 months since the problem started. I replaced a bad cap and rotor, but still a slight miss, then it got worse, started surging. Especially bad when the weather was cold and/or damp. Replaced a couple sensors, timing chain (was overdue) and crank sensor....still nothing solved the problem, just made a minor (livable) improvement.

I had a SuperChip in my LH module, pulled that and went back to the OEM chip, darn thing would not start. Replaced the LH module with a 400E LH module running my OEM chip and the thing started and ran perfectly !!! No missing/no surging....

There is a part number difference of one digit in the xxx-xxx-XY-xxx position and they look different when you try to open them up. The 500E is nicely hinged, the 400E seems to be designed
to allow limited access to the eprom. The tipoff was there seemed to be something that caused the TBA to react when the LH module was wiggled around with the case open....possibly a bad solder joint on the board.

I need to investigate my options....but so far it looks like $2500 to get a new 500E LH module or run a free 400E module....at
opposite ends of the spectrum. I am going to investigate finding a wreck or possibly buying new from the fastlane....

I am curious what the differences may be, but I don't know if any of you out there have gone thru this....

Any sources for new / used modules would also be appreciated.

Thanks,

__________________
Bryan Harter
1992 500E Smoke Silver
2002 CLK55 AMG Cab Silver/Black
2001 Harley Fatboy - Pearl White
2004 F150 FX4 Silver/Grey
1969 GTO Liberty Blue
1956 F100 Black