RX-8 Bogs Down When I Put My Foot Down
11-05-2008, 05:23 PM
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RX-8 Bogs Down When I Put My Foot Down
Hi, this is my first post here and I did search the forums to see about solutions to my problem, but it seems to be fairly rare (or I'm not searching well enough) so I hope I didn't miss anything. If I did, I apologize.
Background
I bought a used RX-8 (2004 automatic) just under a month ago. It had 36000 miles on it, so pretty low-mileage. On the test drive, I noticed a rather startling lack of power below 4000 rpms. I was assured that this was normal and (having did a little research on the RX-8 before biting) decided that this was the car for me.
Long story short, I've been to the dealer a few times now, and they said that (besides the car already having the latest flash (the MSP16 I believe)), the spark plugs, wires and ignition coils are all very bad and need to be replaced (of course, them being a dealership (and they wanted $1000+ for the job) I decided to get another opinion). As this was a problem when I bought the car, I went to the dealers I bought it from and demanded that they inspect it then fix it (I reasoned that the car shouldn't come with damaged parts, used or not because they're one of the big used car dealers (Car Connection)). After enough complaining (where their "rotary guy" told me over and over that the spark plugs should be okay for up to 50000 miles until I insisted that he pull them out and actually look at them) they replaced the spark plugs with Mazda OEM ones (the new ones apparently). They also decarbonized the engine (not using the seafoam though, they used something else that they mixed with the fuel).
After this, I was still having the same problems and was getting irritated at the dealer, so I took a trip over to a mechanic that I knew. He took a drive in the car and said that when he pushed the accelerator all the way down (from a dead stop while the car is warm) it'll bog and feel (in his words) "like it's flooded". However, if he didn't push it from a dead stop and slowly accelerated, it would actually go faster and would do just like I expected after 4000 rpms.
Description of Problem
I've deemed the car somewhat unsafe to drive because it has absolutely no power below 4k rpms. It takes the car a little over 4 seconds just to hit 20 mph, about 7-8 seconds to hit 45 mph, and about 12 seconds to hit 60 mph. I did the runs several times (the 0-60 runs I only did on the on-ramps for the interstate) throughout the past few weeks to confirm my observations. The times changed only slightly after replacing the spark plugs (maybe a second faster overall, but 0-20 (the important bit) is still over 4 seconds). I know that the rotary engine doesn't have much power down low, but over 4 seconds to hit 20 mph seems very excessive, and in the traffic I have to drive in, downright dangerous sometimes. The runs were also done without dropping from neutral or brake-torquing. Just pushed on the gas pedal and counted the seconds.
Also, the power delivery feels very much like a switch, where the change from 0-4k and 4k-7.5k is immediate and extremely noticeable. I know the engine is somewhat peaky, but this much of a change doesn't make sense.
Other Observations
Just to put this into perspective, I've sat at several traffic lights, watched the light turn green, pushed the throttle all the way down, and gone almost nowhere while minivans, trucks, semis and people on bikes go zipping past me (until I hit 4k rpms, then the car flies).
I have heard that ignition coils might be the problem, but could they cause this much of a difference? What I've been told by the dealers and my mechanic friend was that a problem with the ignition coils should be felt throughout the entire rev range. Granted, I have never driven another RX-8 (I've asked the dealers for a drive in another automatic 04 (or 05, but the newer ones have the 6-speed auto so they're out of the question and I'd rather drive one that's more comparable to mine right now) but they've refused) so maybe the entire rev range has been affected, and is certainly possible, but would that explain the strange behavior when I push the accelerator to the floor?
Also I asked the dealer to do a compression test (in case the engine was failing) but they absolutely refused to do it unless I got all my plugs, wires and ignition coils replaced. Is that normal?
Sorry for the long post, but I really love the car and want to have it restored to good condition.
Background
I bought a used RX-8 (2004 automatic) just under a month ago. It had 36000 miles on it, so pretty low-mileage. On the test drive, I noticed a rather startling lack of power below 4000 rpms. I was assured that this was normal and (having did a little research on the RX-8 before biting) decided that this was the car for me.
Long story short, I've been to the dealer a few times now, and they said that (besides the car already having the latest flash (the MSP16 I believe)), the spark plugs, wires and ignition coils are all very bad and need to be replaced (of course, them being a dealership (and they wanted $1000+ for the job) I decided to get another opinion). As this was a problem when I bought the car, I went to the dealers I bought it from and demanded that they inspect it then fix it (I reasoned that the car shouldn't come with damaged parts, used or not because they're one of the big used car dealers (Car Connection)). After enough complaining (where their "rotary guy" told me over and over that the spark plugs should be okay for up to 50000 miles until I insisted that he pull them out and actually look at them) they replaced the spark plugs with Mazda OEM ones (the new ones apparently). They also decarbonized the engine (not using the seafoam though, they used something else that they mixed with the fuel).
After this, I was still having the same problems and was getting irritated at the dealer, so I took a trip over to a mechanic that I knew. He took a drive in the car and said that when he pushed the accelerator all the way down (from a dead stop while the car is warm) it'll bog and feel (in his words) "like it's flooded". However, if he didn't push it from a dead stop and slowly accelerated, it would actually go faster and would do just like I expected after 4000 rpms.
Description of Problem
I've deemed the car somewhat unsafe to drive because it has absolutely no power below 4k rpms. It takes the car a little over 4 seconds just to hit 20 mph, about 7-8 seconds to hit 45 mph, and about 12 seconds to hit 60 mph. I did the runs several times (the 0-60 runs I only did on the on-ramps for the interstate) throughout the past few weeks to confirm my observations. The times changed only slightly after replacing the spark plugs (maybe a second faster overall, but 0-20 (the important bit) is still over 4 seconds). I know that the rotary engine doesn't have much power down low, but over 4 seconds to hit 20 mph seems very excessive, and in the traffic I have to drive in, downright dangerous sometimes. The runs were also done without dropping from neutral or brake-torquing. Just pushed on the gas pedal and counted the seconds.
Also, the power delivery feels very much like a switch, where the change from 0-4k and 4k-7.5k is immediate and extremely noticeable. I know the engine is somewhat peaky, but this much of a change doesn't make sense.
Other Observations
Just to put this into perspective, I've sat at several traffic lights, watched the light turn green, pushed the throttle all the way down, and gone almost nowhere while minivans, trucks, semis and people on bikes go zipping past me (until I hit 4k rpms, then the car flies).
I have heard that ignition coils might be the problem, but could they cause this much of a difference? What I've been told by the dealers and my mechanic friend was that a problem with the ignition coils should be felt throughout the entire rev range. Granted, I have never driven another RX-8 (I've asked the dealers for a drive in another automatic 04 (or 05, but the newer ones have the 6-speed auto so they're out of the question and I'd rather drive one that's more comparable to mine right now) but they've refused) so maybe the entire rev range has been affected, and is certainly possible, but would that explain the strange behavior when I push the accelerator to the floor?
Also I asked the dealer to do a compression test (in case the engine was failing) but they absolutely refused to do it unless I got all my plugs, wires and ignition coils replaced. Is that normal?
Sorry for the long post, but I really love the car and want to have it restored to good condition.
11-05-2008, 05:43 PM
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Sounds like coils. Remove one of the coils and check for white marks under it. If it does have the marks then just throw some coils in there.also another thing it could be is a plugged cat. Start with the coils first though its cheaper
11-05-2008, 06:16 PM
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white marks are not a true indication of a burn coil. You can take a multi meter to it to be sure.
http://www.finishlineperformance.com...16-07-1793.pdf
http://www.finishlineperformance.com...16-07-1793.pdf
11-05-2008, 07:28 PM
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Alright, thanks for confirming my suspicions guys. I called Car Connections and they said they'll bring the car to Mazda themselves (because I clearly strong-armed the mechanic into offering me a $1000 tune-up... or something. I'm not sure what they're thinking) and they'll have Mazda check the ignition coils. Of course, before I actually bring the car to Car Connections tomorrow, I'm going to try checking the ignition coils myself, and recording the readings so I know what's going on. Now to find a multimeter...
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