Last post on Oct 18, 2006 at 9:17 AM
You are in the Mazda RX-8
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Mazda RX-8, Coupe
#1171 of 1414 Pre-ignition or tranny rattle on RX-8 AT
Jan 30, 2006 (1:25 pm)
So my Group 2 2005 RX-8 AT has had a little noise since day one, which sort sounds like preignition only much software. It noise seems to exist at lowish RPMs.
After months of searching online and after discussions with my dealer, there does appear to be some official confirmation of the sound by other owners of the RX-8 AT, but there does not appears to be any official response from Mazda.
Some dealers say it's very bad and replacing the engine is the only fix. Some dealers says it's a bad fuel pump, but there are no fuel pumps available currently to replace it. Some dealers says it's just bad gas. Some dealers says it's normal, but they don't say why.
My engine get 24.9 MPG on the highway and 14 MPG to 18 MPG otherwise. I think that millage is fantastic! I've never had a start problem nor a fading power problem at high RPM. And my RX-8 never produces the sound while revving the rotors in neutral.
So does an automatic transmission have a normal little rattle sound at low RPMs? Is it some kind of normal slippage until it's spun up over 4K?
#1172 of 1414 Re: Pre-ignition or tranny rattle on RX-8 AT [trispec]
Jan 30, 2006 (3:20 pm)
There's 8K on my RX-8 AT. Like to get this settled before 15K.
What's so bad about a little bit of preignition?
I can remember every car made had preignition knock from 1970's through much of the 1980's. The engine designs and unleaded gas additives got worked out. In 1979 I worked for a nutty guy who paid $700 to some guy to rip out the Cat converter just so he could run leaded (no knock) gas.
#1173 of 1414 Re: Pre-ignition or tranny rattle on RX-8 AT [trispec]
Feb 01, 2006 (9:50 am)
Sounds like motor mounts to me. They are fluid filled and seem to be easy to damage during manufacture, as there were quite a few replaced. Have a dealer check them.
#1174 of 1414 Re: Pre-ignition or tranny rattle on RX-8 AT [pathstar1]
Feb 01, 2006 (11:25 am)
It's a soft sound, not at all like a metal on metal. Wouldn't a lot of vibration occur if a mount was bad too?
I'll have them look on next oil change. Thanks.
#1175 of 1414 Re: Pre-ignition on RX-8 AT [trispec]
Feb 02, 2006 (5:24 am)
Well, after three days of carefully listening to my little knocking noise I'm more and more leaning back towards minor preignition. Here's are the symptoms:
On cold starts: 1) Tiny bit of knocking can be detected even with 2-3K revving while still in neutral/park. 2) On shifting to reverse, immediately a little knocking noise is there continuously. 3) Driving out of my drive way at home or the parking garage in 1st gear only, the knocking noise is there going up the hills or garage ramps, but the noise goes away going down hill or down ramps as I take my foot off the gas to coast down the incline. 4) On flat surfaces the noise comes and goes, but mostly seems loudest at low RPM acceleration.
After warmed up: 1) The noise seems to lessen considerably, and is clearly gone for high revving or constant cruise speed driving. 2) Comes back very slightly once I return to low speed, low RPM driving in traffic and in my neighborhood. 3) Is not present when stopped and in forward or reverse gears. 4) Is not present when revving in neutral.
#1176 of 1414 Re: Pre-ignition on RX-8 AT [trispec]
Feb 02, 2006 (9:02 am)
Are you using high octane gas? It is not required for the RX-8...but it is recommended.
#1177 of 1414 Re: Pre-ignition on RX-8 AT [saxon987]
Feb 02, 2006 (9:32 am)
Nothing but Shell Super Premium 93 for my baby. Of course, I buy it from the same place mostly. Maybe I should switch vendors. I buy from a place that probably does more volume than any place around Boston. Lowest prices. There are twelve pumps and there are always lines.
Pathstar said if there was significant preignition the sensors would cut back on power in a serious way and the check engine light would flash. I've never experienced any loss of power nor have I ever seen the check engine light. Maybe the amount of preignition is not triggering the sensor? Is a little preignition really bad? Will even the slightest preignition slowly damage my engine in some way?
Back in the 70's and 80's every car on the road had preignition knock because of the unleaded gas and engine design issues.
#1178 of 1414 2005 RX-8 engine crapped out 3,000 miles
Feb 02, 2006 (4:42 pm)
They said I had a defective engine after 3,000 miles. It has been in shop now for 10 days. They have to replace the engine. They will not give me a new vehicle, they said first they will give me a remanufactured engine and I raised hell. They then said they will get me a new engine even though on my service report it will say remanufactured because the serial numbers will not match up. They said the engine is in but other parts will have to come from Japan. I have a had an RX-7, GLC, 626 and 929 but being treated like this, I will probably never own another Mazda. Any legal help would be greatly appreciated.
#1179 of 1414 Re: 2005 RX-8 engine crapped out 3,000 miles [lonecow]
Feb 03, 2006 (10:37 am)
What were the symptoms? Sorry. Your State's Lemon law may help, but usually, the all the lemon laws do is give the dealers plenty of tries to fix the same problem before the declaration of "lemon" can legally be applied.
#1180 of 1414 Re: Pre-ignition on RX-8 AT [trispec]
Feb 03, 2006 (3:17 pm)
Leaving the windows down on these weird warm winter days here in Boston to listen to the little noise. Here's a new wrinkle: with windows down, to catch the sound bouncing of walls and Jersey barriers out side, the sound is more of a gurgling sound than a crackling sound.
Windows up you can't hear the true texture because it's muffled.