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Unread 09-18-2014, 11:32 PM   #1
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1999 WJ 
Join Date: Sep 2014
Location: Salem, Oregon
Posts: 1
Wj 1999 wj 4.7 H.O. Swap

I'm looking for some help as to if I can connect the knock sensors if I run 93 octane fuel? What about the PCM what do I need to retune it to the h.o engine?
I know that I need to run high octane fuel but do I need anything else like a tuned fuel pump to pump more fuel? Or how dose it work?

Dgjeep is offline   Reply With Quote Quick reply to this message
Unread 09-19-2014, 03:46 AM   #2
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Join Date: Dec 2012
Location: UK, UK
Posts: 90
The HO engine is higher compression and therefore has a "risk" of pinging on lower grade fuels. Therefore the HO ECU uses knock sensors to listen for pinging and will then adjust the timing to prevent it.

HOWEVER, I have never noted any pinging on a HO with any fuels in the UK - and I don't have my knock sensor fitted to my engine. So, the risks are low if you use proper fuels (in my opinion). But listen for it and you'll know.

However, the non-HO ECU and non-HO wiring harness has NO provision for knock sensors, so this is not an option.

Your only option is to test fuels and listen for pinging and base your fueling decisions on that.

No other changes are needed (i.e. fuel pumps etc).
SuperDragpack is offline   Reply With Quote Quick reply to this message

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