mattaff

Hi guys, Whilst I am newly registered I have abused your knowledge for quite some time having owned an Rx-8 for the past 5 years. I am on my second car after selling my previous one before some travelling.

As you know I cannot post this new thread anywhere else. Too miserable to get involved with off topic chat and not really confident to offer any advice of my own its only my thank you posts that will get my post count up...

Recently My car went in for a service. I should add that I have a 2008 with 25k on the clock. I had felt that it needs a service months prior. I always get it serviced main dealer primarily to maintain its full service history. Actually its the only reason.
Prior to it going in I had asked them to investigate a grumbly idle symptoms. My own research had flagged up the potential for compression issues being one of many possibilities. So I also had a compression test done. It passed with honors so that was a relief. During the service I had the usual Air filter, oil filter and spark plugs renewed.

This had improved the idling grumble significantly but I was advised to change the leads.

Literally days later a cell came on. The catalytic converter was failing. ( Note to anyone who does not know. Sell your used Cat to a Metal Dealer(£110+))

since then I have replaced the CAT , Lead and coils
Cleaned the MAF and throttle body.
20 break stomp

The car is running like a dream. Great power, smooth idle.

So here's my issue.
From a cold start I find the engine starts immediately, idles up at about 2000 rpm before dropping itself down to the 900 mark. It does this without missing a beat. However if I touch the throttle in the first minute or so It revs terribly and feels unbalanced.

Where should I look in your opinion?

I'm no mechanic everything listed above is my current experience in tinkering

Matt

Legot

iTrader: (1)

Question, did you pay for a new cat, or get it under warranty?

Are the wires from your coils securely seated to the spark plugs?

Mysterion

^^ Like he said, plus check to make sure none of the ignition wires are contacting any metal directly. They should be secured in plastic retainers where they are anchored to prevent contact which could allow the spark to jump through the rubber/neoprene shielding and arc to the metal/

mattaff

I purchased a new CAT ( an aftermarket one.) It is a cheaper version than the OEM however I have used these previously ( on my xj8 and mx-5 ) and had no issues with them

I Will double check my leads. I did harness them up in their original position once changed. Got to admit I have not double checked if their seated on the plugs properly. will do that before my next start up.

My concern is that this only happens from cold for the first minute or so after that I can rev it up with no noticeable sounds or vibrations

Thanks for the support

Legot

iTrader: (1)

Not gonna lie, you screwed yourself on that one. The EPA has laws in place that require manufacturers to replace catalytic converters for free within 8 years/80,000 miles. The aftermarket cats do not last on RX8s because the exhaust temperatures that we produce are several times higher than that of a standard piston engine, it has no chance.

Edit: Ahh... Sorry, I didn't realize you were in the UK. I'd assume they have similar laws in place though.

Other than the wire connection, you could have a vacuum leak which could be effecting upper RPM trims.

patriotjj

+1^ check for vacuum leaks real quick with smoke test or carb cleaner

Mysterion

Just did a quick check online and the EPA ruling does not apply in the UK and the best one could hope for would be the manufacturer agreeing to subsidize the replacement for customer good-will.

mattaff

I will do the carb cleaner test also.

Were about a decade behind on customer service. I explained how disappointed I was to have a Cat fail at such low mileage on a Mazda serviced vehicle, only to be given a splurge of excuses and a £50 discount( the diagnostic Fee) on the potential £1600 bill ($2.4k). It has enthused me to crack on with my own basic repairs.

I'll report back my findings.

Thanks


Matt

04Green

iTrader: (1)

have you done the ECU reset (20 stomp)?

I would also look at cleaning the MAF and ESS. Your car likely learned to run with a hosed cat. There is some unlearning to do. Cleaning those two, and resetting the ECU, might make a world of difference. Afterwards, start it, and let it idle for several minutes, until the revs come all the way down..

Legot

iTrader: (1)

Green, he said that he did the 20 brake stomp.

I don't know how I missed it until now, but did you do both resets? There are two, the NVRAM and the KAM. The KAM reset is the 20 step stomp, and resets some codes, ESS, MAF, and other sensor profiles. The NVRAM is the memory that stores actual fuel trims and stuff like that.

Most people either reset one or the other and never both.

mattaff

Thanks for the ideas so far. I have Now
double checked the leads
Reset both KAM and NVRAM
Gone over the intake system with carb cleaner
Had the entire exhaust system checked for leaks( I thought maybe it was blowing and sealed once warm)

Still not found the issue. I'ts worth noting that this seems to be happening once the car is stone cold only. Meaning I can only test to see if my last tweaks have made an impression a day later/ over night.

Is there anything that is or should be closed/open during the first 30 seconds of a car being started up that could cause this issue?