Lumpy start up- misfire only on startup - no OBD codes
 

RX8 2005 with about 5,000 miles since reman replacement engine. Has Black Halo Racing ignition system. Was still stalling out after new engine put in so put in second hand throttle body, much better. Only odd symtom from this has been a little "hesitation" in 4th gear for the first three minutes of diving when engine cold (this is Maui so by cold I mean 80 deg F - cold for a rotary engine) but then fine but still with a dip in revs at traffic lights 40% of time 70% if AC on but virtually no stalling.

Drove her yesterday - absolutely fine. No issues.

In fact all has been pretty fine for the last couple of months. Tonight I go and start her up and ...

blum blum blum blum

... bit like a 4 cylinder with one of the cylinders not firing. Revved her up to about 5k and that sounded smooth. Held it there for a few seconds. Brought it back down and still lumpy. I did not drive her as was worried could do damage.

I will have a look at the ignition leads in the morning.

Apart from a dodgy connection to the coil or plugs anyone any other things I should be looking at.

BTW selling soon so anyone in Hawaii wants an otherwise excellent car... I am going back to the UK for a while.

Any ideas gratefully received I soooooooooooo do not want to go back working on this but am broke so needs must :-(

All the best and TIA for anything helpful.

Steve

Check fuel injectors if clipped on right since reman replacment.

Hmm but has been running fine for several months - would that happen now???


Had quick look at coils etc nothing obvious. :-(

Oh also if it is injectors wd it be OK to drive it 10 miles to dealer?

Thanks for thought and TIA for any other contributions from anyone.

Only about 65k - personally I blame Black Halo ... OK only kidding you were great!

Off to run an OBD which I should have thought of first lol

OK this is plain weird ...

Start up, still lumpy, no MIL. Short rev up, revs come down stay at the 2k warm up level and after 5 second of slight lumpiness starts ticking over fine.

So, for the moment - zero problem.

OK so obviously worried.

I tried to record data with OBDWiz but not sure what I got or how to read it (it is 111 kb - I may have overwritten data as it did not seem to be recording).

Grateful for any pointers.

Will not drive for a while. The good news is the missus just started driving a taxi so we have a spare car.

Any thoughts on what I should be checking on OBD? I am a Luddite with OBD stuff.

Thanks in advance to anyone who can give pointers.

Steve

My RX-8 made occasionally lumpy startups this summer too, after it became cold over the night. But my RX-8 had an exceptional condition: I was driving it very rarely (once a week) because it had winter tires on it (no travels on hot roads) and because one its headlights was missing (no night travels)

I noticed irregular startups in cold mornings. I almost thought that one or two plugs were not firing properly (all plugs and IG coils are new) But that irregular running happened only for the first 15 seconds, then back to normal. During those startup I smelled unburned gas coming from the exhaust and the exhaust was blue in color. I estimate that the engine had residues of gas accumulated through the night.

I suggest you try brand new IG Coils, even those coils which are fake, to see if it will make any difference.

Why no error codes????
 

Thanks for the thought. Coils are only about a year old and with the BHR ignition I would not expect them to be gone so soon.

I am now having a consistent problem:

Start, misfire for a minute or so.

Switch off.

Wait five minutes and then all is fine.

So what gets better on a quick warm up - it is something that does not appear to throw any error codes. I find this weird. I mean if it is misfiring why no error codes?

Any thoughts gratefully accepted.

ATB Steve