2007 RX8 Coughing Up Start w/ Video
 

Year: 2007
Mileage: 58,611

This is one of its better starts lately. I just had my spark plugs replaced because that's all the dealer could find wrong with it, but it still sounds bad on start. The problem has been happening for the past week and been getting progressively worse. Any ideas what could be causing this?

what about the ignition coils? Search around for a DIY to test the coils, to see if they're working.

Sounds fine to me :dunno: Although I couldn't really hear shit over your radar detector.

Would the compression test that the dealer performed have caught a problem with that? They said that it could be a result of carbon buildup. Thoughts on that?

Updated the thread with a cold start. When I cold start it I hear a squealing sound too. The video kind of caught it.

I cant really hear anything that bad but I do hear and understand what noise you are talking about. When you start your car maybe try putting the key in the on/acc position for a maybe 3 - 4 seconds before cranking it though. Do you always just turn it on without waiting?

You said the dealer did a compression test, what were the numbers for it(psi/kpa and at what rpm)? If they did not tell you anything then I would assume your engine is ok.

I always have turned it on without waiting. Never had any problems with it before. I'll try waiting and report back when I get back from work.

The dealer only told me that they performed the test and found nothing wrong with it. Do you know if the test would have found anything wrong with the ignition coils?

Yeah that definitely doesn't sound normal. It sounds like when an engine has low compression. The starter spins faster and more freely since there is less resistance from the rotor faces. I would have the dealer give you the compression numbers so we can see. Also, if you haven't done an ignition tune up yet I would definitely do so as well.

I only mention waiting because when you turn it to on/acc you should hear some whirring and the fuel pump priming/pressurizing the line(and whatever else the rx8 does when in on/acc). If the car sat for a day or a few hours(honestly not sure how long it takes) then its always a good idea to let the pump prime for a second I think. Not saying it will somehow fix the problem.

Well if a car fails a compression test they will generally make you replace plugs coils and maybe even wires. The compression test has nothing at all to do with your coils, it is just checking compression inside the engine itself.

Call the dealer back and ask about the results of your compression test, if you paid $100+ for the test then you should be given the results no matter what. As it is they could have just said "oh yea we did the test, its fine" and charged you for it. I know the chances of that are slim but when you pay them $$ always make sure they give you something for it.

I'll call the dealer in the morning to find out about the results. Hopefully they're open. I don't think they charged my for the test because they were already charging for the new plugs cables and labor for that.

Just got off the phone with Mazda. They said they did the compression test but the only thing that they wrote down was that it passed and not any of the results which leads me to believe that they didn't actually perform the test. If I wanted to get it done "again" then it would be $120. I'm not really willing to pay that for some numbers. What are my other options?

Home compression test. Won't be as accurate, but it will tell you what you want to know.

Post in your regional forums and see if anyone has a compression tester you can use. If Mazda is sure it passed then I guess do not pay for another one from them but why wouldn't they log the numbers/rpm somewhere? Even just puttin a note on the account would help. I am actually very surprised they gave you a free test.

It seems you have to ask for it, otherwise they just put pass. When Mazda tested mine I told the mechanic before I gave him the keys I wanted the numbers, he looked at me kind of funny but did it.

The paper work had the compression numbers in the notes. And at the top where it said "Compression Test ------ $XXX.xx" it just said 'Passed" by it.

My startup sounds exactly the same, i think it might be ignition coils.

Have you tried cleaning your MAF?

hmm old thread...but did anyone ever find out the source of the 'coughing' noise in the videos?

tweek, did you ever change your coils and/or wires and did that remove the 'coughing' noise from your startup?