Flat spot on Kuro 2

[goodeggbob]

Good day all,hope you are all fine. Kuro 2 has developed a flat spot at between 4.5 to 6.5k revs when accelersting hard. It is fine up to 4.5,and really kicks back in after 6.5, so this tells my novice mind that something is not doing it's job properly.
I would be very grateful for any hints or tips that may solve this.
For some background ,i have rrp mk2 coils recently fitted ,together with leads and plugs,it runs a cofs system and is premixed too if that helps, and i have spares of most of the likely culprits,so any pointers would be most welcome.
Please don;t hit me with abbreviations,as i probably won't know what it means,thanks,rob

[mrspiller]

Try putting the standard coils on for a start


Sent from my iPhone using Tapatalk

[Nickp47]

Sounds like the symptoms of a stuck SSV, though I can’t remember if the rev levels tally up with when it should open

[casey]

I recall the SSV opens at between 3200 and 4000, depending on load, so not sure it's the culprit.

As you have you fitted the RRP coils recently, I'd agree with Wayne, go back to what you had previously as a diagnostic.

Did you have D585 coils on before and was the ECU tweaked to alter the dwell time?

[goodeggbob]

This problem has only just started,so can eliminate coils,thanks.

[SmuttyHutty]

Saw this on the American RX8 Owner website:

Renesis has 6 Intake ports

First two are always open

@3750rpm

Third and Fourth opens

@6250rpm

Fifth and Sixth opens


https://www.rx8club.com/showthread.p...e+port+opening

[PaulAV]

Ssv issue, first check by hand if it will move freely, if it does then check the small vacuum pipes that join to it and the upper intake manifold (look for splits and any that are loose, including the 2 service nipple's that may have either a pipe and T piece or just a cap as any lose of vacuum will cause poor activation) then move onto the solenoid at the rear and underneath the upper intake manifold if it is stuck then the ssv will not activate

[PaulAV]

It's possibly that whilst changing the coils you've managed to dislodge a vacuum pipe (the one under the throttle body is the most likely candidate)

[v-rex]

Not that you need it but another vote for something SSV related. When my SSV was full of gunk a few years back, on acceleration the revs slowed down at just over 4k and then i think at just under 6k suddenly went back to normal speed up to the redline. Just a period of slowness in rev build up which was sorted once the SSV was cleaned.

[goodeggbob]

This sounds exactly like mine v rex

[v-rex]

This sounds exactly like mine v rex

Before I was wise enough to use specialists I had Mazda do it. I remember nothing was replaced it was mostly labour, and they simply cleaned the gunk out of the SSV.

Once kids are in bed in a bit I'll hunt out the page where they described the work to see if it gives any clues. Yours may not be the exact same reason but I am pretty sure SSV related.

I remember it was weird at the time as the revs it did it at were not where I thought the ports opened but I am sure something else happens at 5.5k-6k before the 2nd port as that's when the needle suddenly sped up again.

Report back in a bit. Kids are a pain to get to bed these days and involves a tag team effort between me and my wife. I'm behind the ropes currently but could get tagged anytime.....

[v-rex]

Ok tell a lie, it looks like they also replaced 3 solenoids as part of this but I seem to remember them only mentioning the SSV sticking. It seems I also had an engine light..... cannot remember the code but if it comes to me I'll let you know. Hope some of this is useful in diagnosing your issue.

[goodeggbob]

Ssv issue, first check by hand if it will move freely, if it does then check the small vacuum pipes that join to it and the upper intake manifold (look for splits and any that are loose, including the 2 service nipple's that may have either a pipe and T piece or just a cap as any lose of vacuum will cause poor activation) then move onto the solenoid at the rear and underneath the upper intake manifold if it is stuck then the ssv will not activate

Thanks Paul, how do i check it manually?

[PaulAV]

Just try to move the actuator arm by hand (it's s little difficult to reach, but you should be able to reach it, even if you have to use a screwdriver it something to push against it)

[goodeggbob]

So,having spoken to PaulAV, i have found that the ssv is frozen solid despite using quite a bit of force. as i have a spare engine on the bench ,i do know that it should move manually with no more than finger pressure.
It seems that to reach it to remove it,i am going to have to take off quite a few bits to gain access,and am fairly confident i can do this.
While i am going to all this trouble ,i am considering taking out the air pump and i realise that to do this i would need to remove the stainless steel tube which goes from the air pump to the bottom of the engine and then fit a blanking plate, my preferred method.
The issue i can see i will have is loosening the 2 10 mm nuts where it joins the engine and don't want to run the risk of snapping them off.
Can anyone see a reason why i couldn't cut said pipe close to the engine and blanking the open end, and possibly if i need to reconnect it for some reason,i could couple it back up with a piece of pipe. I am also aware but unsure of what to do with the barometric connection should i opt for a full delete,which would also allow more room to fit a larger 2t oil tank,any tips would be much appreciated,thanks,rob.

[qwakers]

i went further than that and cut all the circled pipe off of the manifold and welded up the 3 tiny holes left behind... mostly because i could. means you wont need a blanking plate and you'll save a few grams too.

s-l1600 (1).jpg

s-l1600.jpg

i cut them off with a slitting disk and welded them up with tig because its neater... but there's no reason mig couldn't do it too...

[goodeggbob]

Thanks James, i really don't want the hassle of taking the manifold of,so does my idea sound reasonable?

[goodeggbob]

sure, if you can get good access..

you know all the rusty bolt tricks im sure being a capri guy anyway, so im sure you know what is likely to go wrong if you try to undo those two m6 nuts off the studs to fit a blank. nothing stopping you cutting and blanking as you say.

as for the baro sensor, you still need it, you can attach it to a now free stud on the strut tower upside down as i did, will work fine.

[30405]

Rob, to cover off the fuel resistor and barometric sensor I used the below video.

[goodeggbob]

Both the Baro sensor and the fuel pump resistor are mounted the Secondary Air System and can be relocated to make room.

The Baro sensor needs to be away from moving air, while the resistor gets hot, so shouldn't be tucked away too tight.

Sent from my SM-G800F using Tapatalk

[PaulAV]

I had issues removing my hard pipe as you mention Rob, I was dealing the manifold so I cut the hard pipe, removed the manifold, then I had free access to the little 10mm buggers. If your cutting the pipe removing the manifold isn't a massive job, certainly with a lift, I would imagine trying to seal the pipe effectively could be a problem is though.

[PaulAV]

The other option of course is to leave the hard pipe in place and cap the top off, at least you'll have a decent flange to bolt a block off plate to

[goodeggbob]

Well,Kuro 2 breaths properly again. i have full power all the way up and the problem was indeed the ssv.
It was absolutely jammed solid. The hardest part by far was removing the 2 10mm nuts from the hard pipe by the manifold,as they were rusted to hell. thank goodness for my dremel with a flexi shaft which enabled me to take one side off the nuts and then knocking the remainder away,leaving 2 clean undamaged studs. Under the bonnet was pretty easy although it is very tight in there and there are quite a few things to remove in order to gain access to the ssv. Pulling the ssv out was a bit of a challenge,but it came out eventually with a combination of pull a bit and turn a bit until it was out.
Putting it all back together again was fairly painless,and was completed in about 1.5 hrs,although stripping down and cleaning took most of the day.
I shall go for a spin tomorrow and get everything warmed up properly and check it all over after,thanks,rob.

[SmuttyHutty]

That's a result! Did you get any pictures of the SSV itself? Was it properly gunked up or was it seized somewhere else?

[goodeggbob]

Yes Alistair,i have piccies of the one i removed but will have to wait for my lad to upload them,being the dinosaur that i am.
As a matter of interest,what air the gains from having air pump delete,apart from weight and space? . As i managed to not break anything,i now have the choice of either or,instead of being forced into it, and is it true that you would only do a delete if running a decat,thanks,rob.