RX8inSTL

iTrader: (7)

Ive been trying to put off making a thread about this but ive finally decided to do so.

I first had this problem more than a month ago during a long cruise I started to get power loss from 3250-6500rpms. I shut the car off and let it sit and the power was back so I thought nothing of it. Since then it has progressed to being a constant issue.

The car seems to accelrate okay but there is defiently power loss. Once I hit 6500rpm the car starts to pull much harder.

Ive had a code for the SSV solenoid low circut. I pulled all three solenoids and tested them. All three checked out working.

Also I cleaned the contacts on both the wire and solenoid with alchohol and put di-electric grease on the contacts.

I have also swapped out the AIR and SSV solenoids to see if that helped which it didnt.

I also have replaced the SSV with a new unit. It works under vacuum pressure and also has no resistance. I cleaned out that part of the LIM also before installing it.

The hose connecting these two pieces is also good. No leaks in it.

I am not getting any vacuum pressure whatsoever, I tested this by hooking up a vacuum gauge and shutting the car off. The valve doesnt actuate and doesnt show any pressure on the gauge.


So the only three thing I can think it would be is something with the Vacuum accumulator, the wiring harness itself, or the ECU. Can anyone tell me which might be the most likely problem or if theres something im missing?

DarkBrew

The vacuum accumulator is, as you probably know, the box the air solenoids plug in to. The vacuum feed comes from the UIM via a one way check valve.
If you have a vacuum tester you can check the one way valve, the vacuum accumulator and the hoses.
Vacuum accumulates in the chamber at idle and anything less than WOT: The one way valve holds the vacuum during heavy throttle use.
Any leakage from this chamber or any of the attached systems must be repaired.
If you have no vacuum at all then you may have an issue with the one-way-check valve. It could be defective or installed incorrectly.

The usual picture

RX8inSTL

iTrader: (7)

Thanks for that Darkbrew. The one way valve is installed the correct way. And I can blow air through it in the direction of the accumulator but it is fairly difficult. Id imagine to test these things I should hook up the vacuum pump and then apply vacuum and see if it holds steady at that pressure?

Is it possible that I could hook up the Vacuum pump to the accumulator then apply vacuum pressure and then apply 12v to the SSV solenoid and once I did that the SSV should opperate?

Im not sure if that would actually work but just something I thought of.

EDIT: Thank you darkbrew for bringing up the one way check valve. I believe what happened was my electrical contacts on the solenoids were dirty but when i cleaned them and put it all back together i reversed the way of the check valve. I figured the arrow meant towards the accumulator. Turns out it meant towards the intake.

DarkBrew

So it works again?

Is your original problem solved?

BTW, the system should not lose vacuum so even a static vacuum using a vacuum tester should operate the system. I believe that a slight amount of vacuum is lost as the solenoid operates but in a steady state the vacuum should hold.

RX8inSTL

iTrader: (7)

Yes it is. I thought the one way check valve was installed the right way but it wasnt. Dumb little mistake but everything seems to be back to normal.

Bladecutter

Here's the real question:

How did your one way check valve get reversed in the middle of a drive a couple months ago?

BC.

Brettus

iTrader: (2)

Not the first person to do that .....

RX8inSTL

iTrader: (7)

Blade it actually didnt. What I think happened is that my contacts on the solenoids were bad so I took apart the whole UIM and cleaned them. Cleaning them actualy fixed the problem but when I put it all back together I put the check valve on the wrong way. I had nearly the exact same problem so I fugured the cleaning didnt help. Turns out it was because I swapped the hose around.

And thanks Brettus. Makes me feel better. Haha.

DarkBrew

The arrow on the one way check valve indicates the direction of air flow.
The air in the vacuum chamber must flow toward the low pressure behind the throttle body in order to generate the vacuum.

I've updated the vacuum drawing above to include arrows by each valve representing the arrows on the valve bodies.

RX8inSTL

iTrader: (7)

Makes much more sense now that I stopped to think about it. And the picture change is helpful too.

DarkBrew

Experience is what you get right after you need it.
I can't imagine why the valve detail was omitted from the picture.