profase

Hey,
So at the beginning of this summer, I drove from VA to CA. Going through the desert areas in UT and such, I noticed I had lost a good amount of power. None of the gears were pulling like they normally were for the first 2k miles of the trip, and in going up modest inclines, 6th gear couldn't keep me going. I just went with it and attributed it to the heat. When I would start the next morning, power seemed fine, but then would get worse.

Throughout the summer, the power has been fine. Didn't notice anything abnormal even on a few 2-3 hour drives.

Now I'm on my drive back. I'm two days in, and I've gone through AZ and CO, and the power loss is definitely back. Even in the morning, acceleration was definitely off. Some points of the day it would be better, some worse.

A few notable things about my car:
-Engine replaced by Mazda about 45k miles ago. Car is at 101k.
-Front undertray is pretty banged up(which might be messing up air flow into the radiator?)

I don't know what system to look into first. Is it more likely to be a cooling thing because I've only experienced this in long drives through hot weather? Is it a compression problem? I'm hoping you guys can tell me the best first step to take.

Thanks,
John

djfa

iTrader: (3)

I have the EXACT same problem. And guess what? My engine is 600 miles old. Its impossible its the engine already. Today i installed new mazda OEM plugs coils and wires that I had as a spare set for my new engine. I cleaned my k&n filter, cleaned my MAF sensor, disconnected negative battery terminal, did the 20 brake pedal stomp afterwards. My car cant be in any better condition right now. I went for a drive since its pretty warm and I want to diagnose the problem. It feels like when it gets hot my engine seems to be under load. Throttle response is poor at best, acceleration on 6th gear is minimal.

When the engine is cold it seems to be a little better, but nothing like when I got my car back last week.

My theory behind the power loss since I eliminated all other possible variables:

1.Partially clogged CAT. It wouldnt glow red if its partially clogged, so you wouldnt know its slowly decaying. Have you had misfires sometimes? That can make a CAT slowly go bad.

2. Fuel pump is going bad. Even with my old engine I had the same loss of power after long drives. But it was much worse since the engine was dumpster worthy. Symptoms of bad fuel pump would be hesitation when you go full acceleration, you might get a misfire or it would take time to get to the red line. Fuel pumps get pretty warm and tend to go bad early on rx8's. I read threads where fuel pumps got changed 2-3 times on one car. Apparently if your fuel pump didnt go bad after 75k miles, its probably dying.

If you did all your maintenance and your are confident that your plugs, coils and wires are still good, your filter is clean as well as your MAF, then its either a partially clogged CAT or your fuel pump. And lastly, your engine might be going bad again. (lets hope thats not it)

Im going to install my AP midpipe this week and see what happens. If thats doesnt work then its likely gonna cost me 800$ to change the fuel pump at the dealer since I cant do it myself.

By the way, whoever reads this. What would be the symptoms of a dirty SSV or dirty fuel injectors? Is that a possibility?

Sorry for writing a book... lol

04Green

iTrader: (1)

Altitude when this occurs?

profase

Not sure what the altitude going through UT was, but right now I'm in the 4000-7000ft range.

Thanks for the suggestions djfa, I really appreciate it. I sincerely hope it's one of those things, and not my apex seals slowly going. With it out of the powertrain warranty, there is absolutely no way I'm affording a rebuild.

I'll keep ya guys updated.

04Green

iTrader: (1)

you will lose power at altitude and with heat. Cold, sea level air is the best.

Check MAF and stuff like that too. Sounds like you have an 04 or 05, engine grounds and the like make a difference too. It is not causing the problem, but the extra strain may be exposing other weaknesses...

RedDream

Make sure your ignition is good, wires plugs coils, and then change your fuel pump for a walbro from BHR. your fuel pump stops working when it is extremely heat soaked and becomes weak to the point of no return. so Change your pump and you will see a major difference, remember it will take it some drive cycles before it adjusts so dont worry. by the way there is a great DIY for the walbro fuel pump which has worked great for me and for many here. that way you dont go spending money at the stealership :-)

cheers from the country below

AreAxeAte

iTrader: (1)

I am experiencing the same power loss problems as you. After a 3 1/2 hour drive over a high mountain pass from Vancouver to Kelowna BC there is a major loss in power. The power loss usually last for a week or so after every time I drive. Most of my daily driving is short 15-30 minute trips and I don't experience this power loss then, in fact it runs great!

I know its not a clogged CAT as I have replaced my old clogged stock CAT with a BHR midpipe w/ CAT last year. I know it is not my Ignition system as I have replaced all my coils, plugs, and wires with a BHR ignition set in May.

Your idea of replacing the fuel pump seems like the best solution for me. I had been thinking that way recently and its nice to see someone thinking the same thing, . Have you replaced your fuel pump yet? What results have you found?

tza0001

iTrader: (2)

Before you drop money on a fuel pump I would make sure the car is flashed with MSP16.

Mazurfer

^.......................explain thought process here?

tza0001

iTrader: (2)

When I bought mine back in 2008 the previous owner had not done the MSP16. In long trips (over an hour) the car was performing very different...Acceleration was slower and it was feeling not as powerful. After doing the MSP16 car is consistent. No matter if I drive 30 minutes or 10 hours it accelerates the same and power is present. Definitely high altitude or fuel pump could be the cause but from my experience MSP16 could also be responsible for the issue the OP is experiencing. Plus it costs nothing. Maybe when the engine was changed they did not flash the car with the most current flash???

Mazurfer this is one of your older posts

MAZDA SPECIAL PROGRAM (MSP16) - ENGINE LACK OF POWER - PCM REFLASH
Bulletin No: 01-013/08
Last Issued: 03/14/2008
Service Bulletin Mazda North American Operations
Irvine, CA 92618-2922
2004-2008 RX-8 - MAZDA SPECIAL PROGRAM (MSP16) - ENGINE LACK OF POWER - PCM REFLASH
APPLICABLE MODEL(S)/VINS
2004-2008 RX-8 vehicles, produced from April 10, 2003 through November 9, 2007
• VIN Range: JM1 FE17** 40100053 - 80215462
DESCRIPTION
Some 2004-2008 RX-8 vehicles may experience a lack of engine power and/or low/rough engine idle speed in
high ambient temperatures. A revised PCM calibration is available which increases metering oil lubrication amount during engine start and changes ignition timing control during high ambient air temperature conditions.

It won't effect your mileage at all.
__________________

Mazurfer

^.................yeah, I guess I never considered that it only may show up the way the OP is describing his issue, but you're right...........if it's free do it.
Was mainly as stated, increased oil and igntion during high temps.

xxskyyxx

Ok so it sounds like I am having the same problem as you guys I made my own post but will now be deleting it and posting it below.
Ok so here is the skinny, Have an 07 standard rx8 and I have found that after driving up mountian roads or on the Interstate that my car feels sluggish. My coils are new but plugs and wires will be done soon. Oil is done regualarly, only check engine light I have seen recently is the SSV which I have not had the chance to fool with. Along with the sluggishness I get the MIAC sound from about 4k-6k rpms. Car has 65k miles on it I have tried to look to see if the CAT is glowing after one of these drives but I never see anything noticeable. Anyone have similar issues, I have read through quite a few posts and nothing seems to fit just right car doesn't cut out, doesn't stall once stopped though it tries sometimes just takes a tap on the gas. It also does not do this at all on my ride to work which is about 15 mins and can hit 60mph drives like a dream. So what do you guys think fuel pump going bad? SSV? Bad Cat?

Thank you for your collective wisedom

edit: Forgot to add that last time I drove up the mountian the car thermostat read about 32F and by the time I hit the top it read 50ish I am not sure if that helps but I found it odd being that it was snowing...... Ya stuck a magnetic ski rack on my 8 and went skiing. So many looks of bafflement I almost started taking pictures.

Carbon Fibr

go pick yourself up a AEM wideband air / fuel gauge.
Check your numbers while its good and check your numbers while its bad.

leaning out probably is my guess

tza0001

iTrader: (2)

Well if you have a CEL and is the SSV I bet this is your issue....Do some reading on SSV stuck open...

xxskyyxx

I am just wanting to know if that might be all it is. I only feel like disassembling my engine bay once. The CEL light hasn't come back on for over a month.

bse50

Fuel pump and catalytic converter issues might show up only after a long or "hard" drive.
The cat doesn't necessarily glow when clogged. The ignition may or may not have something to do with it, that's hard to say. If you changed the coils for the first time at the aforementioned mileage chances are the OE pig rich tune and crappy spark messed your catalytic converter up.

The SSV may marginally play a role but i'd get those 2 items checked as well. A compression test for the added peace of mind doesn't hurt too.

Se serve altro mandami un pm

tza0001

iTrader: (2)

^What he said. OP based on your post I thought that you still had a SSV CEL. If the CEL has not come up for a month now, do what bse50 suggested.

xxskyyxx

have new plugs, wires, air filter and a racing beat dual res prototype race pipe on the way. Will let you guys know if that helps once they get here and I get them installed. Will also doing the SSV clean and a Coolant flush. Should be a long day

Trackcars

Hi I was wondering if any one can help me on my rx8. It starts hot or cold and drives fine for the first 25-30 mins then after that it seems gutless between 5 And 8 rpm and some times the lower rpm with a bit of a splutter and popping blowing sound from the exhaust? It's just had new plugs filters and oil but the problem still persists. could someone give us an idea of what it could be thanks.

xxskyyxx

Check fuel pump for overheating and catalytic converter for clogging. I replaced both of mine and it worked wonders

alnielsen

iTrader: (4)

Check the MOP and make sure your injecting oil into the rotor chamber. Also, like everyone else says, fuel pump & cat.

Trackcars

Hi thanks or the replys. Would I be able to tell if I took the cat off ie clogged up or blocked and would I be able to take the comb out thanks

alnielsen

iTrader: (4)

You could look at it from the front to see how much deterioration there is to the honeycomb that makes up the catalyst. I don't know if this would work to check the flow, but you may be able to rig a air hose, from a compressor, through a tennis ball to check that.

whitelight42

I'm having similar issues as the OP and several others in this thread. But it's been years since the last post and no one has posted if or how their problem was resolved..(?)

Stubbs

iTrader: (1)

I had a similar issue of losing power on long drives. It would progress to bucking and popping/back firing on acceleration. I checked the cat and it showed to signs of deterioration of the catalyst bed. I replaced plugs, wires and coils with no effect. I also cleaned the maf and ess with no improvement. What did solve it was replacing the fuel pump assembly. When I cut open the filter from the old pump assembly it was packed full of fine black silt. My theory is that the dirty filter was causing high back pressure at the pump outlet causing the pump to draw high current and run hot which led to a slow degredation of output to the point where the engine would lean out causing loss of power and backfiring. It's too bad you can't get the filter separately from the assembly. It would be cheaper and better to just replace the filter and the pump with Deatschwerks DW200.