Alright, I'm new to this forum. I have a 2004 RX-8 6 speed manual with 105k...that's just FYI. My friend is having an issue with his 2005 automatic rx-8 with about 103k.

Yesterday he called me complaining about his car not starting saying there was a weird noise. I assumed it was a dead battery. Upon research and hearing the noise it's coming from the air pump located in the engine bay on the passenger side. It's making a weird whining noise when starting and humming when the key is in the ignition. Common sense on my side says this shouldn't cause the vehicle to not start since it is just for emissions.

This car does have starting issues already, mainly after it has been driven. Or as he says after he really romps on the car while he is driving. I'm hoping I can just replace the pump for him and it'll start back up again. Any help would be greatly appreciated guys, thanks.

 

You are correct, the air pump has zero impact on the ability to start the car.

The lines: "mainly after it has been driven" and "he says after he really romps on the car while he is driving" makes this sound heat related, and the common "hot start" issue. This is almost certainly low compression. (engine heats up, housing expands away from the rotors slightly, decreasing compression. The seals on a good engine can span this increasing gap without issue, but worn housing and/or worn seals get to the point that they can't seal the gap any more. Compression increases as the rotor speed increases, compression at the low speed cranking is already the lowest. Combine the issues and you get hard hot starts.)

He may be able to mitigate the issue for a while with brand new ignition (enabling a lower speed/compression ignition) or a brand new starter to keep the cranking speed up as high as possible, but it's going to come back.

 

If you do a search for "hot starting issues" you will find a wealth of information at your disposal. I do not do much troubleshooting on here, but I am 99% sure that replacing the air pump will do nothing for your friends problems.

I will offer up these possibilities. Your friends car may be flooded. If so search for "DE-flooding procedure". As your friend owns an automatic, a rolling start is not an option. Once it is started proceed to a Mazda dealer and get a compression test done. This will likely be the source of his problems.

It would be great if you report back and let us know how it turns out. Perhaps others will be kind enough to offer their insight as well?

 

^ You are correct in that "flooding" is a possibility for this current occurrence (if it isn't starting right now). It is a symptom however, not the problem. Whatever caused the flood will continue to cause the flood (even to the point of actively flooding it as you are trying to deflood it if the issue is severe enough) until the root cause is addressed.


Flooding is never the issue for "does have starting issues already, mainly after it has been driven" when they don't indicate that they have to deflood it regularly.

 

[quote=kevinande;4182778]If you do a search for "hot starting issues" you will find a wealth of information at your disposal. I do not do much troubleshooting on here, but I am 99% sure that replacing the air pump will do nothing for your friends problems.

I will offer up these possibilities. Your friends car may be flooded. If so search for "DE-flooding procedure". As your friend owns an automatic, a rolling start is not an option. Once it is started proceed to a Mazda dealer and get a compression test done. This will likely be the source of his problems.

It would be great if you report back and let us know how it turns out. Perhaps others will be kind enough to offer their insight as well?[/quote]

Thanks for the responses and help, I'm gonna start with replacing that air pump (due to noise) first and if by some fluke miracle it starts again, well good. But then I will start digging into the compression issues and all of that. I'll keep updating this as we figure it all out, might take a while but better than nothing .

 

FYI, you don't have a location listed, but the air pump's only use at all is to accelerate the time that it takes to get the cat up to temperature after starting. Deleting it completely is an option if you can either mask the CEL (with an AccessPORT) or ignore the CEL, and you don't need it for emissions tests where you live. If the car doesn't have a cat, just unplug it and/or remove it. At 103k miles, you are past any warranty the car could possible have regarding it, so emissions tests are literally the only reason to keep it.

 

We are stationed in AZ and I don't wanna remove it and then PCS to another state because my friend is too stupid to reinstall it when he gets an emissions test haha

 

Fair enough.

 

Quick update: He got the car towed into the Mazda dealership here (Jim Click) and they managed to get it started and begin some compression tests. Ya the stupid little fan part was busted no relation, but is supposedly 654 dollars because it's only a special order part. Screw that we can go to a junk yard later. But Madzda called him and said compression is so low the engine has to be replaced. He has an extended warranty that he purchased with the car and they are going to cover it supposedly they just have to have a guy come down and confirm the results. Mazda I guess replaces engines less than 100k on RX-8's if they have issues but he just missed the mark. So if you are having motor issues I would bring it in for a check up! lol