mk2 mr2 rough running

[MadRob6]

Picked up an mr2 with. 3s-fe engine yesterday and everything was running beautifully.

Today I washed it, put it in the garage to give it a wax and now it's playing up.

It idles fine but when the throttle is pushed over a certain point it starts spluttering like crazy. Judging by the smell of fuel out of the exhaust it doesn't seem to be fuel starvation but failing to ignite the fuel. Distributor looks dry as a bone but don't have the tools handy to pull it off and check.

Any ideas?

[Wadeski]

dizzy cap, plugs, wires?

[MadRob6]

That reminds me. I pulled each lead out one by one when it was idling and all 4 cylinders are firing. Strangely I can build the revs up fine using part throttle but when pushed past a single point it starts spluttering.

[Ug_lee]

Test your throttle position sensor to see if it's working within spec?

[SamGad]

Sounds like water messing with the firing, my MK1 MR2 used to do this in heavy rain.
Changed the HT leads for a new set and presto, problem solved.

[MadRob6]

Found the problem. A big crack in the bottom of the distributor cap and a nice load of corrosion on the contacts.

Have cleaned it up and will get a new cap and arm pronto. Cheers guys.