So I have a 08 RX8 rebuilt recently. Compression tested when hot and compression is great. But it bogs down when trying to accelerate from a complete stop. I feel intermiten power loss through the rev range sometimes. I’m nearing my limit with it. But I would never sell it. It’s my pain/pleasure working on it. I’d like to get her all healthy and able to cruise without problems. Fuel trims are good at idle but jump high when I accelerate. From 3-5+ to 14+

What I have changed:
Fuel Pump
spark plugs
Coils
wires
MAF
SSV Valve ( still ticks even though it’s new)

 

So if I’m at a complete stop and I press the gas it bogs and has no power or it might almost shut off. It’s not until I reach 3.5k that it picks it self up and gets going. I changed the fuel pump cause it was going out and changed wires and plugs as well as coils. But nothing helps the situation. It isles okay and it’s been recently learning to stay on with A/C (thinking the compressor is going out)
my fuel trims at idle are okay but when I accelerate its increases to 14 or above positive.

no cats!

 

Fuel trims are meant to be read at steady state in a given load interval. If you watch them while giving inputs they will jump around for sure.

Do you have any codes? What is the airflow and long term fuel trim on a steady warm idle?

Also are you saying it had difficulty staying on with A/C on?

 

codes I got are for my air pump solenoid and my ssv solenoid at high rpms. But those just went out.

stock air box, steady warm idle is around +4

yes A/C is something I struggle with but seems to stop doing it as much if I drive the heck out of it.

 

Try pulling your catalytic convertor and see if it is clogged. Sounds like what mine was doing and come to find that was my issue. Worth a shot!

Brian

 

it’s straight pipes. No cat.

 

Vacuum leak would be my guess. Or maybe fuel injectors.
You changed you ssv. Is it tight? Is it moving freely?

 

the SSV only has a code for being stuck open so perhaps you did something wrong there with it ticking too, that generally indicates a bad motor but since you messed with it there might be more to the problem

the engine runs on primary fuel injectors until the SSV and secondary injectors come on line around 3800 - 4000 rpm, might be bad at higher cycle/flow rates, used high mileage injectors on a new rebuild is not the best idea

Not that I don’t trust you, but what is the actual compression test information?

 

No prob i don’t mind sharing my compression numbers. I get 86 on each side. My ssv code is that annoying p0661. got new solenoids just in case

i notice I have literally no power at low rpms until around 4000. After that I’m good to go on speed and response.

 

Thank for bringing up the injectors I was just reading a forum on that very subject. Got me curious that it might be that too.

 

the only thing I’m left to change is injectors. Smoke test results in no vacuum leaks

 

A bad check valve between the UIM and the solenoid tank won’t show up that way imo. Neither will a bad solenoid or solenoid seals.

Did you check the line from the UIM with a vacuum tester?

.

 

i haven’t checked it yet but I do have a brand new check valve just in case. I’ll put it on later today when it’s no pouring out.
ill keep you updated.

 

Ok you have the same opposite problem of mine no power after 4k rpm it fluctuates up and down after 4k dies at idle

 

All I read is is problems after 4K but mines is under.
I’m leaning on injectors cause everything else is changed and compression is good.

so my theory is either my AT is trashed or my Injectors are clogged.

both are good theories cause my AT didn’t want to up shift to 5,6 yesterday but is feeling better.

 

Mines a manual rebuilt engine new fuel pump ess sensor it was dying after half a tank of gas first then when it idled after when they changed the fuel pump all the codes disappeared and then came back after 4 days the p00 one you have didn't die at idle for 4 days then began dying at idle again but entire time after 4k fluctuating power and codes are back

 

I have no idea what your problem is on your car. But If you do have a problem that you need advice on please open a new thread. I’m trying not to go off the trail with two people asking for help. Thank you.