2004mazdarx8tx

I have an 04 rx8 that has been in the family for over 10 years, recently wouldnt start, I found that one coil was bad at 60k, original coils I believe. Changed all 4 with spectra premium from rock auto, ngk wires and plugs. Now it starts fine cold, fixed that problem but it has developed a hot start issue? Since it didnt have the hot start issue before the new coils, plugs, and wires id have to assume its one of the three causing the issue? Compression was done recently and is slightly low but still within spec. Id have to assume its the coils since they are aftermarket but not sure if anyone else ran into a hot start issue from ignition coils that start fine and run fine just wont hot start? thanks for any advice or info.

9krpmrx8

iTrader: (46)

What is slightly low?

2004mazdarx8tx

mid 7's, was done at the local mazda dealership.

9krpmrx8

iTrader: (46)

Well that's pretty low (assuming it was done right) and you would have to test the coils to know for sure but my guess is that the engine is done. It can go from low to bad overnight.

2004mazdarx8tx

im curious, if the engine was bad wouldnt it just die when it warms up? It drives fine and I have driven it recently over 100 miles and back. It just wont start when hot, so I let it cool for about 20 mins and it starts just fine, thank you for your reply.

9krpmrx8

iTrader: (46)

Not always, I have seen plenty of engines that were blown still run.

This engine still started and idled.

Loki

iTrader: (1)

At what rpm? It's obviously not perfect, but if that's at 250rpm, properly measured with the correct tool and properly compensated for altitude, it's not tragic. It should be able to start.

How fast is your starter turning / do you have the upgraded 2.0kW starter? It won't fix compression, but it will help start up.

2004mazdarx8tx

ya it runs great can redline it all day, not sure about the rpm and i believe the starter is original, so I was thinking about a starter upgrade but i guess its risky spending the 200 on a hunch, I guess I need to do a compression test my self to check their numbers,

gwilliams6

No it is worth it to upgrade to the better starter, if you have the original one. If you plan to keep driving it, the upgraded starter will help until you can get an engine rebuild. And you will want the upgraded starter for your rebuilt engine anyway.

Charles R. Hill

iTrader: (7)

Often times, with aftermarket coils, this issue will arise not only as a result of slightly lowering compression but, more importantly, because the aftermarket coil manufacturer fails to fully understand how the OEM Mazda coil is designed and how it integrates with the RX-8.

I strongly suspect that if you were to switch to actual Mazda coils your hot start problem would disappear as compression in the 7s is rather common and should not pose a hot start problem. Of course, I assume the fuel pump assembly is not at issue and, if you have more than 70K miles on your car, you should replace the fuel pump unit anyway.

BigCajun

iTrader: (1)

My engine is currently at high 5's, low 6's, (according to Mazda stealership)and takes an extra second or 2 to start when hot.
Drove it on two +2000 mile road trips within a month and no issues.

BigCajun

iTrader: (1)

Fwiw, I'm on my 3rd fuel pump and both times problems became apparent while driving and not on start up.

9krpmrx8

iTrader: (46)

No issues except you're likely making less WHP than a base model Chevy Spark.

BigCajun

iTrader: (1)

Maybe, but still driving it like I stole it, no problems redlining, and I've had a few ricer Hondas and some late model sports cars that try to keep up with me in traffic and fail.

gwilliams6

You have a number of options for coils:
- The Cheapest option: BWD/Intermotor coils from auto parts stores like Advance Auto. 4 coils, 4 plugs, and 4 wires can be had for around $190-220 total based on whatever promotion is running at the time, shipped to your door for free. They are considered to be the first coil revision and you should expect to need to replace them around 20,000 miles, 30,000 miles max. They often come with a "lifetime warranty" by the auto parts store, which could potentially be leveraged for perpetually new coils.

- The Best Upgrade: The BHR ignition coil upgrade can be had for around $500, which eliminates the need to continue replacing coils periodically, as well as deliverying a significantly stronger spark for minor mileage and power gains. It is a proven kit with top notch customer service supporting it. It includes the wires, you still need to add plugs ($80)

- The For-Sure OEM: Mazmart sells all 4 coils of the latest OEM coil revision (C) for around $250, (just the coils, you still need to add plugs and wires) Supported by top notch customer service. They will likely last longer than 30,000 miles, but we don't have much solid data on how long the latest coil revision will last.

- The Most Expensive option: Buying from a dealer will run you around $300+ for the coils, $500+ for coils, wires and plugs, and if you have them do the install, expect to get a bill for anywhere from $700 to $1,800. You may not get the latest coil revision. Yes, you are getting shafted if you take this option, so bring lube.

- The Highest Risk option: Ebay coils continue to pop up as counterfeit, mislabeled, dead on arrival, and have zero post-purchase support largely. They are the "cheapest" listed price, but when you add that $92 or whatever to the price of anything in the list above from having to do it over again, you can see that they are no longer the cheapest option. Do it right the first time. "Motor King" coils are popping up at an attractive price on Ebay, but are being proven as ineffective, to the point of being unable to get the engine fired. "Mazda" branded coils on ebay are almost always counterfeit. Check the seller's name though, since some of our vendors sell legitimate coils there. The price will be $200+ though. Anything sold as "Mazda OEM" under ~$26 per coil should really be considered as suspect and probably counterfeit.

Be wary of "LSx D585 coil upgrades", as not all D585 coils are created the same, and the standard generic D585 coil is not properly designed internally for the RX-8's ignition needs. They generally "work", but there are anomalies and performance issues that have to be solved, if they can be solved. Definitely NOT a plug and play option, even if it is advertised as "plug and play"

- SakeBomb Garage IGN-1A Ignition Coil Kit



Be careful, some labeled RX8 coils sold aren't really up to snuff with the ignition firing demands of a rotary engine. Stick to ones listed above.

And as Charles said, check that you don't have a failing fuel pump. Series 1 fuel pumps tend to be failing at the age of your car.
________________________________________

Charles R. Hill

iTrader: (7)

I have had customers whose "hot start" issues ended up being a weak fuel pump motor due to clogged filters. So, the issue can arise with either symptom. According to the FSM, replacement is suggested at 70K miles and Mazda was pretty accurate on that as I see them start to fail around 80K. Aftermarket units like the Spectra and AirTex can fail even sooner than that.

2004mazdarx8tx

well its stock fuel pump never even considered it as a culprit seeing how most fuel pump issues happen on start up cold or hot.

2004mazdarx8tx

just doing a little research on fuel pump signs it seems people have problems with idling and revving at high rpms, my car idles perfectly with ac and its currently 98 degrees here and it revs just fine with no lag, so i think i can rule out a fuel pump?

2004mazdarx8tx

i took two vids of cold and no start hot start, fixing to upload if i can figure out how to

2004mazdarx8tx

https://streamable.com/tq5wd cold start


https://streamable.com/70zi0 hot start

see if this works

I have to let it sit for around 20-30 mins before it will start again.

gwilliams6

Don't be foolish and dismiss the possibility that you might have a failing fuel pump. Folks here on this forum collectively have millions of miles experience with these cars and their parts.

Any 2004 with an original stock fuel pump, is a fuel pump on borrowed time or already out of time.

You came to this site for expert advice, so don't just ignore advice repeated by more than one experienced member and a top vendor and aftermarket parts designer/builder.

40w8

After running for a while leave car running and check all 4 spark wires with induction timing light.

Also, be premixing with smokeless FD 2 stroke at 1 ounce/gal.

And if that doesn't fix, put a new fuel pump LIKe Charles said.

I have his BHR ign and fuel pump for $10k miles and 5 years. Works great!

On my 07 at 20k miles neither worked very well stock (would throw cells at high power)

2004mazdarx8tx

I didnt ignore anything posted

Williard

iTrader: (18)

Gentlemen,

If the OP is ignoring the sound advice, walk away.

You can lead a horse to water and all that.

Travis

2004mazdarx8tx

I thought there was a age limit for mods?