maffatato15

well, lets just get right to it. I'm a mechanic and have done all the work on my car to date (coils, plugs, wires, tranny and diff fluid, all oil changes.....you get the idea.) When going on an extended drive on the highway , maybe 20-30 mins (or more), when trying to pass a gar downshifting into 3rd gear, the car gets loud 9possibly marbles in a can) and has a lack of power. This only really happens when ambient air temp. is roughly 80 degree or higher. At night when its cooler the car runs like a bat out of hell so to speak, with no issues.
I called the mazda dealer to see if i had the latest flash (msp16) and he verified it has been done. I thought for sure with high ambient temps and description of the bulletin that this would be it. Turns out, im wrong.
I hooked up my scanner to read fuel trims and the short term fuel trim at times spiked to +21 which is from what i learned on piston engines atleast, is way out of spec and the engine is starving for fuel since the ecu is trying to add fuel. Plus or minus 10 seems to be the norm with 0 being perfect. So im wondering if i possibly have a fuel pump that is dying out when its hot out? Seems to be strange to have an engine seem "blown" when its 80 plus degrees out and run amazing and smooth when its cooler.

Plugs have about 13k, bhr coils and wires with about 9k and aem intake.

Any input is appreciated.

maffatato15

well i looked over my fuel trims and it was close to zero under acceleration when the noise occurred so fuel pump seems to be fine. It would randomnly spike to 21 but did it only once after i let off the gas.

I guess im going to go to the dealer friday and see if they can hook my car up and double check to make sure i have everything needed for my car.

Javii

iTrader: (1)

What? Can you be more specific? Where is this 'loud' coming from? Exhaust/Engine?

I would say it's the cat, did you check it?

wcs

iTrader: (2)

What is the LTFT ...
STFT isn't really a good way to measure how things are doing, especially during WOT and Fuel cut.
You'll also see a spike in STFT immediately after pressing the Go Peddle .. this is Tip-in enrichment

Once you're in OL you'll get 0% STFT that is why it looks good under acceleration.
STFT when you take your foot of the gas isn't really valid either. The fuel is cut to the engine when your engine is in deceleration.

There are several areas across the Maf scale that accumulate LTFT

Check you Maf screens in the AEM Intake ... make sure they are there and straight.

Do a compression test if you can.

HiFlite999

iTrader: (2)

Are you running 91 octane? Ppl try to save money with 89 or even 87, which may work at lower temps, but then run into trouble when it's hot outside. CW is that the knock sensors are crap so you can get engine destoying detonation without a peep from them.

maffatato15

Loudness is coming from the engine/aem intake.

Long term fuel trim is good too. It was roughly around 4.

My car does have 71k and I'm hoping it would be an easy fix like fuel pump rather than engine.

I have only used 93 octane since the day I bought the car almost 2 years ago.

Thank you guys for the posts so far.

maffatato15

The cat has never glowed at night time as far as I know. I have yet to take a temp reading before and after to see if there is a major difference though

wcs

iTrader: (2)

What about the fuel level? Was the tank full or almost empty. This could also impact a failing fuel pump.
Reasonable to suspect this but there is no "real solid" supporting evidence here.

Diagnosing a fuel pump by trim values and a butt dyno saying it runs better when the weather is cooler vs. hot.


Might as well pull out your divining rod and magic coco-puff powder.

maffatato15

butt dyno on hot vs cold weather is a no brainer. Car barely wants to move when its high ambient temp. outside and the intake/engine is VERY loud. It does not do this at nighttime when its 60ish or cooler out.

As far as telling the fuel pump being bad its hard to say. It does this no matter what the fuel level is. Did it on the highway the other day with 3/4 of a tank. Maybe if i get around to it later after work i can do a voulme test when the car is fully warm. See if its putting out a reasonable amount of fuel at said psi.

maffatato15

Hotline Archive With diagrams, specifications, and parts and labor
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Number: 469420
Vehicle Application: 2006 RX-8 1.3

Customer Concern: After the engine runs for awhile and the high pressure fuel pump relay turns off, the fuel pressure then drops down to around 20 PSI and then the engine runs rough.
Average Reported Mileage: 56954

Tests/Procedures: 1. This sounds like a weak fuel pump issue. In this case, the fuel pressure was only around 40 PSI even when the fuel pump had full voltage from the high speed fuel pump relay. There is a document attached to this archive that has the fuel pump R&R procedure.



Was able to find this under our Napafix here at work. May be something to try.

wcs

iTrader: (2)

LOL
I'm saying other than the mileage on the fuel pump, I don't see any evidence that isolates a bad fuel pump as being the problem here.

wcs

iTrader: (2)

Well clearly then you find no evidence of needing a fuel pump in this thread as well, otherwise you wouldn't be falling back on your day to day experiences and "trending."

I'll grant you that Ray, and its a considerably more experience than myself

However its still a gut feeling ...

Unlike yourself I had to go on the information provided by the OP which at some levels were very incorrect assumptions ... especially about the fuel trims, or at least the way it was explained how he arrived at those values.
There's no fuel pressure reading ... so I would recommend getting a fuel line pressure inspection at least.

Case closed then ... buy a new fuel pump OP

wcs

iTrader: (2)

Likewise ...

And I did in the early post, agree that the fuel pump was a reasonable point of failure to suspect.

"I figured he would get the hint to move forward with his pressure-testing procedures on his own."

Me too

Brettus

iTrader: (2)

If you can read fuel trims then i would also assume you can read AFRs as well ? Best way to see if it is a fuel related problem is to log AFR .
Should be around 12 or below on a stock tune at WOT . Would expect your issue if it went higher than 14 .

maffatato15

i am a mechanic and perform my own work. There is no need to treat me like a spoiled 16 yr old that got his first car. GRANTED there are almost no rotaries on the road compared to cars with cylinders being a almost 2 yr owner, i have researched. I understand there may be threads that are similar, but please link them to me. I'm just asking for a few opinions guys, not the EXACT answer since it is almost impossible from over the internet.

I used to own an '89 mx6 gt (stock turbo) for a few years so , i know my way around cars.

I was just trying to see if there were anyone on this forum that had similar symptoms that could report back. I know you guys are knowledgeable from reading posts (like mx6.com) over the years, so besides, charles r. hill, (which im leaning towards) please let me know your non-wise-*** opinions, Anything appreciated, thanks.

I DID NOT get around to testing fuel pressure today. I got swamped at work.

maffatato15

ill, look into it and see if my scanner has that option. If not, ill see if i can get the shop on hooked (which is a brand new 3ek launch) and log it.

wcs

iTrader: (2)

You've quoted me, quoting Charles.R.Hill so I'm not sure how to take this ...
Albeit it was quoted not using the forum quote method. I just used "..."

Doesn't matter ...

You can try and get in touch with forum member nycgps. I know "New York" is a huge place but it something.
NYCGPS also has the official Mazda Compression tester if your interested in getting that performed at any point.

I can't think of any 1 thread I would link you too.
If you're not aware there is a way to use google to help narrow your search.
You'll notice these links are for LMGTFY but I've entered the forum recommended method for searching threads on the rx8club.com

Lack of power search:
Let me google that for you

Fuel Pump Failure:
Let me google that for you

What wise-*** opinions?
Minus the bullshit between Ray and I and you've had great responses/opinions.

Search the forum a bit more and you'll see just how well your thread here is behaved. (No really I'm serious)

Doooooo it
Keep us updated please.

maffatato15

ok disregard my last post, i was a little drunk last night. I still have not been able to test fuel pressure because we were swamped at work yet again.

I did notice today though the noise happens right at 4500 rpm and up everytime when its hot like it was today. Secondary intake/injectors? I cleaned my ssv in february. I took it out and physically cleaned all the carbon off it. So i highly doubt that is sticking. I used to have a code for it over a year ago, but it never came back since.

Rx Eight 7s

I'm not going to be much help, but you might be "happy" to know that I am having the exact same issue right now (minus the marbles noise). I have about 47,000 miles on my 8. I replaced the coils, wires, plugs to no avail. I have not taken down the cat to inspect yet, but that is my next step. If you figure this out please post your solution. There is at least one other person having the same issue.

I took the car to Mazda 3 times so far and they can't find anything wrong, but then I drive it home from the dealer on a hot day and can hardly make it over a hill with my foot to the floor in 3rd gear. On a cool day it runs perfect.???

maffatato15

yeah when is not 85 and humid out it runs not very well. Extended highway runs and heat seems to make me lose power and get rough idle. Never have this problem in the winter time from what i can remember. Since my shop is closed sat n sun i did not have access to our fuel pressure gauge. I hope i get some free time here within the next couple days.

makina323

I am having similar problems...

Until last night the rx was running perfect. Today was specially hot and the car was giving me all kinds of hell. Power loss wont rev past 5k. I do notice the car loses performance the longer i run it. Tho i have to fing idea what that could mean lol.

I Changed plugs and coils not so long ago.

Gonna take out the cat this wed and see what that tells me. Ecu code says my air pump is dead. So maybe the cat is clogged molten... w/e?

Though slowly i am losing any fate on that being the problem. Might be the pump or dying engine.... ugh expensive repairs is not what i need right now ....

wcs

iTrader: (2)

The Secondary Air Pump is not your problem.
It's only purpose is to operate when the car is cold, it injects air into the exhaust stream to help heat the catalytic convertor up quick thus improving emissions.
That's it.

maffatato15

well just tested my fuel pressure, may be flawed though. The gauge i used was our older shop one since the master tech had his at home. The gauge read 7 psi unhooked, but here is what i got.

At idle, the fuel pressure was roughly 64 psi.....as the car warmed seemed to dip into the 62 range mostly, not a huge difference. I didn't see a drop in fuel pressure during regular driving either. I did not get a chance to take it to redline at WOT because i did not have the correct adapter and didn't feel safe punching the gas.

So if the gauge read 62 psi at idle being 7 psi off, im wondering if i only had 55 psi which is just barely in the spec of 54-65. But it seems to hard to base my facts off an incorrect reading.....

And one more thing, is it normal for the exhaust to pop at idle when warm? It will do this very frequently. Its not loud and you can only hear it standing behind the car.

nuke007

I got the same issue as maffatato15. Lack of power after driving 10-30 min on highway. Wire/coil/plug changed less than 2 mounth (coil and wire last week), changed cat 2 mounth ago (jobber one for rx-8 :walker). Over 4k Rpm, I can hear a weird metal sound and I get a lack of power over all RPM but more over 4K. I can notice it happen faster and more often on warm day.

I don't know what to do at this point... i already spend a lot of cash this years.. maybe the fuel pump?

Car 165 000 km (engine change at 128 000 Km)
2004

I've ordered the OBDII blutooth thing to read sensor with my cell phone recently to get stats of my car.

Thx for repply

maffatato15

well im getting out of work now and im going to borrow our new Launch x-431 scanner which is made to deal with mostly imports for those of you that are famililar with them. I am also borrowing the laser pointer thermometer to get a before and after reading of the converter at idle after driving. Anything specific i should look for while using our Launch scanner and driving?

The scanner will also tell me when the ports open. If i can find someone to drive my car for me tonight while i monitor the intake ports i will try that too, though im not sure why they would not open when the car gets hotter on the highway...