RX8 issues - no CEL
 

Hello guys!

Had a good search on this forum and couldn't find the exact issue I unfortunately have.

The Car

Velocity Red - 192bhp - '06 model.
45,000 miles
I have owned it for 6 months today!

The Problem

On Saturday I was driving for around 60 miles, during this time the orange petrol warning light came on, after about 25 miles I managed to get to a garage and put half a tank in. At this time I noticed a shudder through the whole car when initially pressing the accelerator - between 1 and 1.5k revs. I then drove the 3 miles home with if feeling slightly sluggish.

On Sunday I went out to the car, started it up no problem, let it get to 50% temperature and tapped the throttle, the shudder remained. I decided to use the train for the Christmas shopping instead and left the 8 at home. Came home and decided to go and have a look at it, I removed the MAF sensor and gave it a good clean (the IAT was coated in crap). I only used MAF cleaner, never touched any of the elements. Put it back in, started it up and unfortunately the problem still exists. I have noticed also that if I let the revs build up to about 3-4k then let the revs drop the exhaust pops more than normal.

Went out this morning and it's still the same, took it for a run and it's definitely down on power.

The thing I find odd is during all of this, no CEL light has came on. I would have thought if the ignition was failing (common thought) I would have got a CEL at some point. The CEL bulb definitely works because it flashes up when I turn the key.

Here are my thoughts based on the info of your post:
- Failing ignition
- Clogged CAT
- Clogged Fuel Filter (don't run on low gas...deposits remain at the bottom of the tank)

Thank you very much for the response! I really appreciate it! I need the car for work so the quicker I can get it diagnosed the better!

Would it be normal for these issues to occur with no CEL? Any ideas on clearing the clogged filter? It's the first time in the 6 months the orange light had been on!

you people really have issues, you seriously think the computer can tell u every god damn problem ?

and since when its weird to have no cel but the car runs like complete shit? is this ur first car ?

start from regular maintenance first for god's sake.

and read the stickies, god

1st point) No, the computer won't tell me every problem but the helpful people on this board may well have experienced something similar and know what the solution is. No different than me phoning someone and asking their advice.

2nd point) Yes, this is my first car

3rd point) Regular maintenance has been carried out - what makes you think it hasn't?

4th point) I have read the stickies, and nothing really seems to represent my symptoms. Hence the reason I posted here.

Please read this thread: https://www.rx8club.com/rx-8-discuss...t-here-202454/

Lots of important things you need to know about the 8. Further, spend as much time as you can on this forum and learn about the car. The 8 is a bit different than other cars and the more you know about it and how to treat it, the better it will serve you.

Most of the problems or questions you might have, have already been discussed here. So it is a matter of learning how to search information in this forum and reading. Searching could be a daunting task sometimes. An easier way would be to do a Google search of your question/issue and add at the end rx8 or rx8club

^ It's more accurate to add site:rx8club.com to the beginning, then it will force the search to only look here, rather than just helping it to add results here to the list.



The OBD2 system is first and foremost an emissions control system. It is also not very intelligent. Nearly every single CEL code in the system is emissions related. Most of our failures will impact emissions at some level, but not really enough to trigger any CELs. There can be quite significant failures of non-emissions stuff without ever triggering a CEL.

This is true of pretty much every car out there currently. There are changes in the wind however, and this may improve in the next 5 years (only for new cars at that point though)

yeah you'd think if you notice the car runs weird, and its missing a bunch of power, that the ECU would also, but in my experience it doesn't.

in fact you can have 2 dead coils, and one rotor with low compression and it won't notice a thing

Just curious, is the fuel pick-up floating or static?

Thanks for all the replies guys, much appreciated! I have just went back out to it, let it run for 15 mins, took it for a spin around the block once up to full temp. It's not 100%, it's just missing between 1 and 1.5k now but after giving it a good blast the popping on overun seems to be cleared. The exhaust sounds more muffled now, I dunno if this is a bad thing, it just doesn't seem as throaty. New coil pack being ordered in the morning as I reckon it could well be that and dirty crap being dragged up into the fuel filter.

I've looked at the fuel tank diagram, and it looks like the fuel pick-up is static and at the bottom of the tank, now it might be .5" off the bottom, but it's at the bottom. Running your fuel low should have no baring on deposits getting sucked into your fuel filter. Now I would say keeping the fuel above 1/4 would help in the longevity of the fuel pump by keeping it cooled by the gas, but since the pick-up is by the bottom and stays there, if there are deposits, they can get sucked in regardless of the.fuel level.

decarb



junk in the tank getting sucked up by running lower than normal is an urban myth. yes it can happen but about as often as injectors actually get clogged, which is quite uncommon. i've run many cars until they are out of gas after the engines are rebuilt, do i worry about crap getting sucked up the pump? no. there is a fuel strainer before the pump and then another filter after it as well as micro screens on the injectors and it takes a lot to plug up even the first sock in the system and it will plug up even if you have a full tank if you happened to be the very unlucky person to get a rotten tank of gas. the 8's have a plastic tank, so you already have a head up in avoiding additional crap that gets stripped from metallic tanks(rust from condensation in particular climates).

stuttering could be as simple as a failing coil, fouled spark plug or it could be more in depth, like a sticking internal seal due to carbon buildup. decarbs should be done regulary on the renesis anyways because the sophisticated intake system gets carboned up rather quickly, i have seen it to the point that the 5/6th port sleeves work hard enough to break bits off the sleeve retainers and where do those little fragments of metal go? inside the engine. additionally simple carbon sticking to the rotors can stick any seal on the rotor.

beyond that check the plugs for spark with a timing light on each plug induvidually.

if it persists get a compression test done and hopefully you still have warranty left.

clogged exhaust systems do not affect transitional throttle or low end RPMs, they affect high RPM high load scenarios. so it isn't your cat or exhaust.

also, since i feel like i've said this a thousand times here already.. pop off the inspection cover on the driver side top of the tank under the passenger seat and check for leaks with the engine running. the pump modules have been failing quite regularly i've been seeing lately. result is low fuel pressure, crappy fuel economy, erratic fuel trims, pinging from the engine, and even in some cases engine failures.

Thanks for the in-depth reply there. The issue now appears to have gone, at least 95% of it has. I guess my monotonous daily commute along the motorway may have taken it's toll on the car. After I took the car out and red lined it a number of times, combined with cleaning the MAF, a new tank of petrol (Always BP Ultimate or Shell VPower), as well as a brake stomp reset it seems to be almost perfect.

I received the coils (I got all 4 OEM coils for £60) and will probably fit them anyway this weekend as at times there is just a tiny hesitation when blipping the throttle but this could just be me being picky and paranoid.

I am also going to do as you say and check for leaks in the pump module, am I just looking for bubbles? While I'm doing that I'll clean the sock. What do you recommend to decarb? Seafoam seems a popular choice, I think I'll just need to warn the neighbours before doing it! lol:wiggle:

Seafoam seems to be preferred here than Zoom Zoom cleaner.

It still could be a overheating fuel pump. The fresh gasoline cools down the pump and the problem goes away.