i recently replacemed my champion rc7yc4 plugs with denso k2or-u 3122 plugs is there a possibility that the new plugs are causing my idle revs to alternate and run at 1200 .?

Always a possibility, although I wouldn't have thought it would be at the top of the list. Did you set the plug gap according to Toyota's specs or just fire them in there?

They were already gapped. .i just put em inn

Personally I'd be running performance plugs - pretty sure the MR2 is supposed to run on Platinum plugs - but your copper shoudl run no problem

FYI - I'm running NGK BKR6EIX Iridium plugs for the last 25k miles without issue

your idling issue is most likely your shot ecu

Denso are owned by Toyota and there plugs come pregapped so once you bought the correct ones they will be fine. The plugs will only fire when they get a signal from the engine to, so its unlikely to have any impact on the 1200rpm idle.

Did you get to try another ECU yet or investigate why that part of the ECU was burnt out.

No not yet ..still watching on fleebay for the right one too come up.. MR2 ben wants a 120 sterling for one he has so ill wait another while see if cheaper one turns up as for why it burnt out.? i just put it down too age and dampness never thought it was anything else. ?

Could be down to age, but perhaps there was a voltage spike from a component on the car that caused it to burn out?

Not sure if the ECU wiring diagrams are available for that ECU, if they are I would investigate it before installing a new one. You might burn out a new one if it was a faulty component that caused the issue in the first place.

Also the ECU's and the connections (26p 16p 22p) may bear no relationship with the wiring pin outs, so installing an ECU IMO would need to be an exact part number match. Just because it plugs in doesn't mean it's wiring or the wiring loom on the car are arranged in the same manner.

Before you replace anything you may try first to let the ECU reprogram itself. It worked for me few times when battery was disconnected:
Disconnect battery and wait for 60s. Connect battery. Strat the car without touching accelerator. Let it iddle for 10 min and look if idle RPM stable below <1000.
I did that 3 times but between 2nd and 3rd no big difference.

Also you can adjust idling on throttle body to some point so you most likely know that already.Or maybe I don't know what else could cause higher idling RPMs - I know only what I experience so far on my MR2. Some advices I get from authorised Toyota Mechanics in Poland and Ireland.

i tried it luksander but no joy thanks anyway. . i disconnected the trottle body sensor ...and there was no differences in the revs... by the way erin that lad in trim wanted 160 to replace 4 flanges.. so i passed..

greg 1973 wrote:
i tried it luksander but no joy thanks anyway. . i disconnected the trottle body sensor ...and there was no differences in the revs... by the way erin that lad in trim wanted 160 to replace 4 flanges.. so i passed..

If the exhaust and cat are in decent nick €160 is a bargain - it'll cost you at least €500 in parts for an exhaust and cat and probably not as good as the OEM

@Slips Ray the caps in that era ecu are known to fail

www.mr2oc.com/showthread.php?t=435986

www.mr2oc.co.uk/forums/198/158280.html

Good info Erin, Kc'd

no cat for that price erin. . he was just by passing the cat with straight pipe thats a great link for the ecu thanks

greg 1973 wrote:
no cat for that price erin. . he was just by passing the cat with straight pipe thats a great link for the ecu thanks

I'd imagine he'd weld up the cat for you - he did for me

I'd sort out the ECU first and if that sorts the issues which I'm confident it will tackle the exhaust - no point on throwing good money after bad

you could fix your ECU for pennies if you are decent with a soldering iron throw in a few new caps - I'd imagine there'd be no more than an hours work and someone should be able to sort it for relatively cheap - bear in mind the electronics are 23years old in your jammer at this stage - a testament to Toyota they lasted even that long