Andreas Nicolai

Hi.

I have been reading a lot of threads, but no luck so far. I am in need of help ! I also posted this on the UK Rx8 forum.

Symptoms

After long drives, 40-50 min+ I notice a significant power loss. Especially on hill climbs (my work place is on top of a mountain). I can rev it all the way, but it takes time. The power loss is barely noticable below 4k rpm, and become very noticable above 4-5k rpm. Also the exhaust tone is different when the power loss occours. The tone is deeper, and less "aggressive" than usual. Also when trying to go beyond 4-5k rpm I get a weird "strugling" noise from the engine area.

I first noticed the symptoms around 2-3 months ago, in cold weather.

What I have done so far

- I cleaned my very very filthy KN air filter 3 weeks ago, made wonders for the low rpm band - thought it fixed it, but after a long drive the symptoms was back again.

- Changed the fuel pump 1 week ago - the car ran better than ever, but today I noticed the symptoms again. Changing the fuel pump removed a CEL I had (never checked it, thought it was because I had a midpipe).

- Coil+plugs changed 4-5 months ago

- Oil and filter change every 5000 km

- Midpipe (no cat)

- No CEL's at the moment

- Did a compression test 6 months ago, it passed

My thoughts

I do suspect that the plugs may have gone bad because I drove the car with a very filthy air filter, I was probably chocking the poor b***** - yes I do feel bad. But is it even possible that the plugs can be the culprit here given the symptoms?

Do you guys have any thoughts on what could be the cause of the symptoms?

Dirtyswiff

What kind of coils and plugs do u have? and what type of exhaust system? Are u resetting everything after every repair or install? Or have you unplugged ur battery atleast a couple hours or over night to try to reset everything. See if that changes things up. Clean ur maf sensor too. If u said ur filter was dirty I'm sure that is too..how is ur idle?

Andreas Nicolai

Coils: RX-8 Ignition Coil

Plugs: NGK Spark Plugs (Set of 4)

The battery was disconected for several days when I changed the fuel pump (the damn retainer ring cracked).

Maf was cleaned a couple of months ago.

My Idle is stable/good.


I did some more diagnosing. The power loss is experienced across the entire RPM range. It happens at the same place when driving to work: When climbing steep hills, and after driving for 10 miles - significant power loss and a change in exhaust tone.

I did some test runs after I got home from work yesterday, and there was absolutely no sign of power loss - it drove as new (no steep hills where I live).

Andreas Nicolai

Coils look fine, a tiny white spot. I checked two of them, pictures below.

https://www.dropbox.com/s/e9gp95yve6...205_101135.jpg

https://www.dropbox.com/s/5nq00q1yir...205_100403.jpg

However, I did find something strange. 3 of the connectors (don't know the name) on top of the coils was not seated properly - especially the two on the right. I'm not talking about the plug leads, but the grey connectors. I pushed them all the way down - offcourse, but have not had an opportunity to test drive yet.

Alltough I don't think that is the problem - wouldn't those connectors be connected / not connected?

kevinande

I don't see where you changed the leads. You may want to change them as well to eliminate them from the equation.

Andreas Nicolai

Thanks for the tip - the leads where changed to performance leads by the previous owner. Roughly 1,5 year ago.

But why not, it couldn't hurt ! However, what are your thoughts on the grey connectors that wasn't seated properly - could those be the cause of my symptoms?

kevinande

I think it is a possibility that the connectors were your problem, but the only way to know for sure is to go and test drive the car. There are things like the ESS sensor that could cause you problems. There is also a solenoid called an SSV that actuates at higher RPM's that could be causing you problems. Don't ask me to explain that, just do a search for SSV there is plenty of information on it. Based on everything in your initial post sounds like your on the right track. If your ignition is in full working order, you may need to look at the other possibilities I mentioned. You have no CAT so we know that is not an issue. Maybe one of the experts will chime in and offer you some better insight.