Hi guys, advice needed please.

04 RX8 80000 miles, no hot/cold start issues owned for a little over a year and other than brakes, tires etc I haven't had a single problem.

Then 6 weeks ago I changed my plugs, coils, cat convertor and rear o2 sensor as my Rex failed it MOT on emissions. Turned out to be a leaky back box but I needed to do the above as it was well overdue.

Everything was OK till last weekend when I needed to take a motorway journey. The engine was at operating temp as I reached the sliproad of the motorway and I began to build up speed as to join.

As I joined the CEL started blinking which I know is a misfire and this continued for around 5-10 seconds then disappeared and car returned to normal. I obviously came off at the next exit to check everything was at least visually OK and everything looked fine. I rejoined motorway and continued my journey.(had no choice needed to be where I was going) Then as I reached my destination I had to overtake a lorry so I give it a little gas.......6000rpm hit (roughly) and the car lost all power for a second and a lot of white smoke came out the back. Then on the return journey the car seemed fine.

Since then it has developed a only slight jerking whilst driving. Its not that noticeable but as the driver I can feel it. Did some reading on this forum and it seemed I am the victim of carbon build up (I admit I don't push the car too hard, something I know now that I should)

Sooo I take the car out to the nearest high speed road and aim to get it up to 6500 rpm to clear some carbon but before I can I get to roughly 50mph and the car starts shaking like its going to fall apart and it seems to be coming from the passenger side.

Shes now sat outside my house and I dont want to drive her for fear of damaging her more but I need to go to work and I have no other way.

Please help.

Thanks.

 

So, misfire, then rough, then white smoke, then ran fine.

Later, at high RPM, car shakes, misfires (my guess), then limped home and parked it.

if it will start, and if it will run, I would get the cooling system pressure checked. White smoke is often steam. If it fails, pull the plugs and see if coolant is in the chambers.

If that checks out OK, maybe a compression check is next. But, let's wait and see if anyone offers other advice.

 

^^ Check coolant in chambers, get a Compression check and check the motor mounts which also be going at your mileage. See list below for maintenance recommended at specific mileage. This is a more accurate sked of things to check and change than what the Mazda maintenance sked calls for.

30,000 miles:
- Replace Ignition coils
- Replace Plug wires
- Replace Spark plugs
- Clean MAF (mass air flow sensor)
- Clean ESS (e-shaft sensor)
- Reset ESS profile
- Clean power steering connections
- Clean battery terminals and clamps
- Replace transmission fluid
- Replace coolant (Mazda FL-22 is highly recommended)
- Replace air filter
- Replace brake fluid (fluid in the brake lines AND the clutch line)
~$300 USD in parts if you shop smartly.


every 60,000:
...all 30,000, plus...
- Clean all chassis electrical grounding points
- Replace accessory belts
- Clean OMP lines
- Replace rear differential fluid
- Replace thermostat
- Clean / Straighten AC condenser fins
- Clean / Straighten oil cooler fins
- Inspect catalytic converter
- Clean / Inspect intake valving
- Consider / inspect all points in 90,000+ as well, many items fail early
~$130 USD in parts if you shop smartly.

90,000:
...all 30,000, plus any 60,000 not yet done, plus...
- Replace coolant bottle
- Replace radiator hoses
- Replace radiator
- Replace front O2 sensor
- Replace motor mounts
- Inspect clutch pedal assembly for flex / weld breaks
~$900 USD in parts if you shop smartly.
At 100k, anything original in the cooling system is really suspect and failure prone. It represents the biggest threat to your engine.

 

Flashing CEL is misfire. Change coils wires and plugs. You've had it for a year and unless you have paper work to show the last time coils have been changed assume they haven't been. Coils last about 25k miles some can even fail right out of the box. Loss of power at 6k RPM could be a sign of SSV problems or fuel pump problems as your right at the point most 04 fuel pumps fail. Smoke could have been part of the SSV problem. If you don't run the car the SSV can get build up and due to not opening and closing on a regular basis causing the build up to stick it closed. At that point the secondary injectors kick in dumping more fuel than can be burnt because the AFR is so far off giving you a big billow of smoke.
Other things to look at is your air filter and intake tube is there a lot of oil in there? Over filling is common at service stations on oil changes. I've seen lots of the same reports on here of the same thing your reporting and they found oil all in the intake. If this is the case clean the MAF, intake, and change your filter this could cause your SSV to stick as well. To check your fuel pump you need to some how install a pressure gauge and go for a drive after 10 or 15 minutes hit it hard (be sure you are under a 1/2 tank as pump over heating is common place at under 1/2 tank) and see if pressure drops off. Hope some of this helps most of what I mentioned can be done by you and only cost will be some of your time.

 

Ok thanks for the advie guys. Appreciate it.

 

Since you already replaced the coils, what about a bad fuel pump or leaking injectors? Have you tried cleaning the MAF?

 

Yeah cleaned it with some electric contact cleaner. I am more concerned about the shaking at high speeds than anything else. Feels like a wheels going to come off.

TBH I'm starting to think the rough running and shaking are unrelated and its just coincidence they went at the same time. The engine still turns over fine and has the power Im used to..............its a head scratcher alright.

 

Does the shaking go away if you push in the clutch?

It is much more likely to be a wheel/tire issue than the engine from your description.

I have had a tire break a belt...and it got an bump on it...felt like I was driving a tractor.