Hiccup at 5k RPM, loss of power at 6k plus, dealership CAT is fine
#26
I know this will sound odd to you but it's your fuel pump. Get in contact with charles at BHR order the walbro pump that way you know you are getting a legit pump. Melt your siphon together as per DYI and install... What your problem is is that the pump is not supplying enough fuel at that rpm range because of load and starvation... Your pump is weak on other words... It seems to be common and I was getting the same things as you with my 8 when flooring it. Get back to us after doing this mod and let us know if it worked for you too ;-)
#27
Im getting good power once the car hits 6.5 to 7k rpms. So when the car is u fer max load, it's good. But now my low to mid range feels real heavy. I would have. I problem upgrading my fuel pump tho but would this help my situation? I'm ready to do whatever to fix my 8
#29
Im going to go ahead and order the walbro 255 HP pump as well as the BHR ignition kit. Kill two birds at once and put my mind at peace! Plus they both sound like a legit upgrade.
I appreciate the help. Keep an eye out because I will be posting here again after the parts come.
I appreciate the help. Keep an eye out because I will be posting here again after the parts come.
#30
Just noticed upon removing the SSV the other week, my heater wasn't working. The car is blowing cold A/C as it used to but my heater control doesn't work. Not a big deal since I'm in southflorida but it'd be nice to be able to defrost the windows in the morning before work haha! Coils coming in today. Will install today and test run to check of the problem persists. If it does on to the fuel pump..
#31
Check your coolant level to make sure its full (if low coolant, then no hot coolant is getting into the heater core, which means no heat to blow), and then test your heater head unit to make sure the temp dial is working properly (there's a thread that explains how to do that on the forum).
BC.
BC.
#32
I have checked the coolant twice since I cleaned the SSV. I will check again as well as look up your other proposed diagnostic.
A quick summary of what I've done to fix my bogging issue:
Replaced spark plugs, on leading plug on the front rotor was actually cracked on the ceramic part. Coming up with my own maintence schedule to make sure I don't keep plugs in to long anymore. Plug replacement fixed the issue for about a run or two, but quickly came back.
Proceeded to the SSV, removed the piece and noticed more than enough gunk covering it. I had to use a pry bar to dislodge the SSV from the intake housing! Rediculous....during reinstall action and after cleaning both SSV and housing, it slid right in like a Friday night hokey pokey.
After a quick run I noticed a huge power spike in the upper rpm band, 6500 +. Also it fixed my sputter which was happening at 8,000. Now the car hits redline at this point but still kinda choppy.
I was still having issues with my low and mid rpm band. Felt like I was low on power. Decided to replace coils to accompany the new plugs I installed earlier that week. This really topped off the repairs. Car sounds smoother and picks up better. Before coils, I would shift at 8~8.5 k and my rpms would drop to 5~5.5k, now my rpms stay higher than 6k when I shift!!
One of my plug wires seemed a little loose when I replaced the coils, so I grabbed needle nose and split the end that enters the coil so it would have a tighter fit.
Car is running great again, thanks to all for the input and ideas!
A quick summary of what I've done to fix my bogging issue:
Replaced spark plugs, on leading plug on the front rotor was actually cracked on the ceramic part. Coming up with my own maintence schedule to make sure I don't keep plugs in to long anymore. Plug replacement fixed the issue for about a run or two, but quickly came back.
Proceeded to the SSV, removed the piece and noticed more than enough gunk covering it. I had to use a pry bar to dislodge the SSV from the intake housing! Rediculous....during reinstall action and after cleaning both SSV and housing, it slid right in like a Friday night hokey pokey.
After a quick run I noticed a huge power spike in the upper rpm band, 6500 +. Also it fixed my sputter which was happening at 8,000. Now the car hits redline at this point but still kinda choppy.
I was still having issues with my low and mid rpm band. Felt like I was low on power. Decided to replace coils to accompany the new plugs I installed earlier that week. This really topped off the repairs. Car sounds smoother and picks up better. Before coils, I would shift at 8~8.5 k and my rpms would drop to 5~5.5k, now my rpms stay higher than 6k when I shift!!
One of my plug wires seemed a little loose when I replaced the coils, so I grabbed needle nose and split the end that enters the coil so it would have a tighter fit.
Car is running great again, thanks to all for the input and ideas!
#33
It may not be the fuel pump but it could be the fuel sender unit! I know it sounds strange but i cured all my problems by changing the sender unit (with the fuel pump in). I had hesitation at 4500rpm as well as starting problems....Bought starter (bit better) battery (little better starting) Walbro pump (slightly better) then finally i bought the bullet and bought a fuel sender unit. Fitted it yesterday, Now starts right away, has no hesitation WHATSOEVER and when driving like a hoon she doesn't cut out and backfire! Wish i'd done this first as i would have saved around £500. The new sender unit has the standard fuel pump in. I might as well sell the Walbro
#35
Thread Starter
Dammit Jim, I'm a doctor.
Joined: Aug 2005
Posts: 31
Likes: 1
From: Gulf Coast of Florida
KZ
#36
Recently I had similar issues as you guys had. I, however, did not have a CEL. I had normal power until about 5400rpm then I noticed (only because I've had the car for so long) that it wasn't picking up with the normal haste, then when I hit 6500rpm I would receive a surge of power that lasted all the way to redline. Upon shifting into the next gear and landing about 5500rpm the car would hesitate (the best way to describe it is if I were to press the gas, but have my foot slip off and then press it again) and then do the same thing - lower power until 6500rpm then surge.
I have coils, plugs, and wires all under 5k miles and I noticed that in this region the car ran rich, down to and AFR of 11.2 --- not enough air. I had just replaced/ cleaned my SSV so I new it wasn't that or the actuator. Next step was SSV solenoid. It wasn't pulling any vacuum but I couldn't figure out why. Eventually I saw the the VDI vacuum hose on the UIM side of the check valve had come disconnected from the UIM nipple. HUGE vacuum leak. Interestingly enough the only symptoms of this unhooked VDI solenoid feeding hose was a lack of power and slight idle hunt after reconnecting the battery.
P0661 Mazda Secondary Shutter Valve (SSV) Low Input OBDII Engine Light Trouble Code | Engine-Codes.com
I have coils, plugs, and wires all under 5k miles and I noticed that in this region the car ran rich, down to and AFR of 11.2 --- not enough air. I had just replaced/ cleaned my SSV so I new it wasn't that or the actuator. Next step was SSV solenoid. It wasn't pulling any vacuum but I couldn't figure out why. Eventually I saw the the VDI vacuum hose on the UIM side of the check valve had come disconnected from the UIM nipple. HUGE vacuum leak. Interestingly enough the only symptoms of this unhooked VDI solenoid feeding hose was a lack of power and slight idle hunt after reconnecting the battery.
P0661 Mazda Secondary Shutter Valve (SSV) Low Input OBDII Engine Light Trouble Code | Engine-Codes.com
Last edited by Lord ET; 09-04-2015 at 10:58 PM.
#37
Loss if wer at high rpms
I just bought my rx8 with the same top of rpm power loss with no other issues. Replaced engine 35k ago. I have checked and marked off everything but the fuel pump. But from everything im reading on here id say its this- the lady i hit it off of had a new jeep and let the rx8 sit for 4 mnths... Im thinkin driving off that old gas was no good for the car and a seafoam treatment and injector cleaner might actually be my fix from running old gas that sat. Anyone agree/disagree? Ive seen no good answer to this problem but did read from another guy that has this issue that he let his sit for a few mnths and then when he went to drive he found he had a loss of power over 6500 rpm. Me 2. It just so happens we both have driven rx8 that sat for more than a couple mnths... He said his is getting better with time after a seafoam treatment. I have good compression/ignition set/exhaust/intake. Dirty fuel my only guess
#38
Engine Power Loss
• chokes as revs increase
o O2 sensor failure (too rich)
o MAF failure
o MAF disconnected
o e-shaft sensor fouled
o accessory belt fraying
• high end power loss (hard fuel cut)
o Rev limit reached
• high end power loss (jerky and stumbling)
o Ignition failure
o fuel pressure loss
o e-shaft sensor fouled
• high end power loss (smooth)
o Catalytic converter clog
o air filter clog
• low end power loss (smooth)
o Engine compression loss
• low end power loss (stumbles)
o Ignition failure
o front O2 sensor failure
• revs slowly but smoothly
o O2 sensor failure (too lean)
o catalytic converter clog
o air filter clog
• sudden power drop at a specific rpm
o Intake valving actuation problem
• trouble getting to redline
o Ignition failure
o front O2 sensor failure
o catalytic converter clog
o air filter clog
o e-shaft sensor fouled
o fuel pressure loss
o MAF failure
• chokes as revs increase
o O2 sensor failure (too rich)
o MAF failure
o MAF disconnected
o e-shaft sensor fouled
o accessory belt fraying
• high end power loss (hard fuel cut)
o Rev limit reached
• high end power loss (jerky and stumbling)
o Ignition failure
o fuel pressure loss
o e-shaft sensor fouled
• high end power loss (smooth)
o Catalytic converter clog
o air filter clog
• low end power loss (smooth)
o Engine compression loss
• low end power loss (stumbles)
o Ignition failure
o front O2 sensor failure
• revs slowly but smoothly
o O2 sensor failure (too lean)
o catalytic converter clog
o air filter clog
• sudden power drop at a specific rpm
o Intake valving actuation problem
• trouble getting to redline
o Ignition failure
o front O2 sensor failure
o catalytic converter clog
o air filter clog
o e-shaft sensor fouled
o fuel pressure loss
o MAF failure
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