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They do run allright on the 3.9 computer, I fired mine up like that, but the extra heat generated by the engine running lean will eventually burn the valves.It did run lean mainly under heavy throttle through the rev range. It only cost me $300 to get the chip and it is one to give reasonable power but be reasonably fuel effecient. The difference is worth it though. As long as you didn't leave it too long it should be OK
Tim
I do not buy this running lean stuff.
My 3.9 has been running lambda now for 100KK with no problems and no overheating, even towing in 45C.
Yes it will run lean at the top end as the 14CUX has no extra fuelling after about 5K revs and there is an artificial duty cycle cut off on the injectors (AFAIR 72%) which does this. The aftermarket chips remove this restriction.
If you fit o2 sensors it will keep it at lambda for most running conditions and the o2 sensor correction range should be ample to accommodate this.
You can also increase the voltage on the MAF to richen it across the board until you hit the duty cycle cut off.
I think it will run fine as long as your cam is compatable. If it does not give a good vacuum signal like a 3.9 EFI cam then the idle will not be stable.
Regard sPhilip A
Why waste the time with the Hotwire setup. Megasquirt is reasonably easy to get going on the 3.9 injection setup. A basic 3.9 fuel map that has a tad more fuel will get it running.
I agree that for someone who is dedicated to fiddling, knows wiring, is confident with electrics and electronics , has someone who knows a laptop and can ride shotgun, Megasquirt looks the gear.
However if you are not into trial and error there are much better alternatives for maybe $500 or so more.
For example Syntek do a plug and play modern ECU to replace 14CUX.
This was bought home ot me once at Stockton on a clean up day. It was 35C and we came off the beach. After 5 minute stop went to start. My 14CUX started first turn, my mate with 4.6 and professionally installed Motec took 5 minutes .
Aftermarket ECUs rarely have the sophistication of factory ECUs particularly starting straegies etc. in addition very few dyno shops know anything about Megasquirt.
But they will all cost more than a second hand 14CUX
Regards Philip A
Only reason I will start the motor up with the standard ECU is because of the rebuild - want it to run correctly on the first turn of the key for 20 to 30 mins to bed in the cam etc....been told this is very important, much as I feel confident setting up the megasquirt (DIY electronics and proffessional computer person) but not that confident; I expect some issues at first start with the aftermarket ECU.Quote:
Originally Posted by Waxenwane
Nothing seems to compare to the megasquirt for "adjustability" (if thats the correct word) - totally lost with carbies but I feel fairly good messing with the injection.Quote:
Originally Posted by PhilipA
If it all fails I will certainly look further into the Syntek but for now I plan to play with a megasquirt - just cos I like to play!! lol
Fair point. It doesn't matter how careful you are there is bound to be something missed with first time megasquirt conversions.
Starting from cold and acceleration enrichment are the most difficult to tune with Megasquirt.
Has anyone fitted the new Syntek swap in ECU? I'd be interested to know how they compare with the standard 14cux and the Tornado chips.