rough idle and no power at cold start up

ginashamz

If I leave my RX-8 231 standing for at least a week and start it up, there is a rough idle for around 1 minute until the engine warms up and then disappears. While sounding rough, there is also a lack of low down power.
Once the engine has warmed up, everything sounds fine and the car pulls as it should. However, I did test drive another RX-8 231 with a newly built engine and on second gear it did rev a lot faster to the limit compared to mine.

I have recently changed all four coils, spark plugs and leads as well as getting it compression tested last year with healthy results. I opened up the air filter box and the front of the filter is a little oiled up from me over filling the engine oil but I can't image the air filter causing this sort of problem. It was only replaced last year and isn't that clogged up. I'll try cleaning the MAF sensor next with an electronic contact spray but not sure what else I could do? Any ideas?

thomasca

Sounds like the MAF sensor to me. Make sure to use a spray that is safe otherwise you can ruin it.

System

Who did the compression test, a general garage using regular compression testers or a rotary engine specialist? You cannot use normal compression test gear on a rotary engine, it has to be a specialist bit of kit.

The air filter shouldn't be oiled up from over-filling, it shouldn't be oiled up at all.

Scrapit

This will get good at some point.

Goudy

Check the PCV is working correctly.

reeac

ginashamz wrote: »

If I leave my RX-8 231 standing for at least a week and start it up, there is a rough idle for around 1 minute until the engine warms up and then disappears. While sounding rough, there is also a lack of low down power.
Once the engine has warmed up, everything sounds fine and the car pulls as it should. However, I did test drive another RX-8 231 with a newly built engine and on second gear it did rev a lot faster to the limit compared to mine.

I have recently changed all four coils, spark plugs and leads as well as getting it compression tested last year with healthy results. I opened up the air filter box and the front of the filter is a little oiled up from me over filling the engine oil but I can't image the air filter causing this sort of problem. It was only replaced last year and isn't that clogged up. I'll try cleaning the MAF sensor next with an electronic contact spray but not sure what else I could do? Any ideas?

A defective coolant sensor would cause those effects. The fuel injection thinks that the engine is up to temperature when it's actually cold.

AdrianC

What about a cold start after it's been standing overnight, or for less than a week or so?

That'll tell you if it's related to the standing around, or if it's simply a cold start question.

ginashamz

The compression test was undertaken by a rotary specialist and normalised to 250RPM. Both rotars showed readings in the high 6s.

ginashamz

Tarambor wrote: »

Who did the compression test, a general garage using regular compression testers or a rotary engine specialist? You cannot use normal compression test gear on a rotary engine, it has to be a specialist bit of kit.

The air filter shouldn't be oiled up from over-filling, it shouldn't be oiled up at all.

AdrianC wrote: »

What about a cold start after it's been standing overnight, or for less than a week or so?

That'll tell you if it's related to the standing around, or if it's simply a cold start question.

Apparently an oiled up air filter on the RX8 is common if the engine is over filled.
I will start up the car again today and check but usually if its I leave it for at least a week. Will get hold of a proper electronic spray to clean the MAF. I don't think its related to a sticking SSV as the symptoms would be different.

onomatopoeia99

Do you remember to pull out the choke when starting it from cold? Failure to do so will cause the indicated symptoms.:j

System

ginashamz wrote: »

The compression test was undertaken by a rotary specialist and normalised to 250RPM. Both rotars showed readings in the high 6s.

Good news then, at least its not an expensive fault. Unfortunately there's enough garages out there clueless about rotaries that a compression test being done with regular gear was a possibility hence the question.