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Hi everyone,
So I noticed recently my car idles a little strange. I bought a 2008 RX8 GT Auto about 2 months ago with 107k miles (I know its alot. All prior maintenance has been recorded and is original engine) and have slowly been fixing and going through things that needed to be fixed.
Ill start with a brief run down of fixes Ive done and modifications. Also its probably good to mention, the car had a over heating issue I managed to fix with a aluminum mishimoto fan kit.
Ive replaced the battery to a optima red, (This fixed my warm start up issues) thermostat with stock oem unit, Control valve solenoid B or 2, Fixed tire pressure, Coolant flush and change, Cat delete with eBay mid-pipe and exhaust, I know cheap but I like the sound and wanted to start pre-mixing. My oil change is due soon in about 800 miles. Oil levels are good. Previous owners put Full Synthetic off the shelf oil in, but will be replacing with idemitsu oil. My pre-mix is idemitsu two stroke pre-mix.For my first premix I put 1oz per gallon. Noticed white would come out the back end. On next 2 fill ups ive used 1/2 oz per every gallon. Fixed the white smoke issue. Also I have the typical engine light with code P0420 because of de-cat. I also have code P0076 Intake valve control circuit low.
So heres where my story starts now that you see everything Ive done to the car. After installing the mishimoto fan shroud I noticed a chatter or rattle coming from the engine bay at a stop with my foot on the brake in drive when fans kicks on. I figured its due to using spare bolts i had sitting around on the bottom of the shroud. The noise also happens more dramatically when going from park. to reverse and drive. Except Ive noticed its more violent of a rattle and the engines rpms drop down to about 702 rpms. I figured maybe its a fuel air mix issue. My lt trims are at 5-6 on cold start. Then drop to 2.3 once warmed up under no load.
This morning before work I let the car warm up and sit a little longer than usual while i watched a youtube video. During this time i was in park and had the A/C on 1. Once it was time to leave I put it in reverse and realized it did something different today. Its rpms dropped to what I can only guess was around 400-200 rpms. I waited to see if it would stall out. But as usual it just jumped right back up to 850-780 rpms like usual. Ive also seen my tac needle jump less than a half a inch occasionally. Because I pay so close attention to it I see it happening. Could this be because ive reset the fuel trims by removing the battery terminals and pressing the break for 30 mins. Ive also done the 20 brake pedal trick to re learn idle. I figured the needle jump was because of that. Or is this a spark plug or coil issue??
I need help, Ive tried to provide as much info as possible. let me know if I missed something. Thanks! Ill post a youtube video of it tomorrow morning if it persist after i change my spark plugs tonight.
Sounds like it could be ignition related since you haven't yet changed out your plugs. That or there could be an intake issue. Is you air filter clean and intake tube in good condition?
My filter is brand new. But I also forgot to mention my air box accordion tube thing is in rough shape. I looks like someone had put rubber seal on it instead of replacing the part. Im going to post a photo of it.
What temperature is it outside? Coolant at 214 while sitting idle doesn't sound great.
+6 ltft is not great not terrible. The computer is compensating enough that it's probably not causing your stumble.
Replacing coils if of unknown condition is the obvious first thing to do on a newly acquired RX8.
That cat died for a reason.
Based on the pictures that repair done on the intake is pretty ghetto. I would recommend getting a new intake tube, if you can find one on ebay or a junkyard it would be better than what you are running currently. It may be the source of your problems especially if its leaking.
Yeah thanks I think that's the next step. I swapped my plugs today. No fix for the idle drop from park to reverse to drive. But does seem to idle better. But something strange happened after filling the car up with gas. I put the key in and turned to on position and waited 10 seconds before I turned it on as I always do. The door was open at the time. And my key is a second hand key. I've never seen anything like this, but I turned the car on and all lights were on including key light. When given gas abs light came on and tachometer was jumping from zero to 2k repeatedly tripped a bunch of odd codes. Giving the car gas didn't change tachometer. And then it returned to normal lights went out except the red key light. I was able to capture the codes. This cars seriously suicidal
Last edited by Imgunnaownu; 10-13-2019 at 09:52 PM.
Did a quick search on the codes I probably accidentally kicked the obd reader during start up which cause the start up issue.
The only code that is of concern is your p0076 code. It's definitely an issue in your intake. I would guess it's the VDI solenoid under the UIM. It's not too difficult but does require removal of the UIM to get to it. Before you do that though, make sure the actuator is still working on the SSV. Can check it with no tools, just reach in and ensure it can lift.
Did a quick search on the codes I probably accidentally kicked the obd reader during start up which cause the start up issue.
The only code that is of concern is your p0076 code. It's definitely an issue in your intake. I would guess it's the VDI solenoid under the UIM. It's not too difficult but does require removal of the UIM to get to it. Before you do that though, make sure the actuator is still working on the SSV. Can check it with no tools, just reach in and ensure it can lift.
I reread this again.
Dropping to lower rpm when in drive or reverse is complete normal on any automatic car. The engine has to work against the torque converter in D and R, but not in P. It's not even connected to the transmission in P.
The only code that is of concern is your p0076 code. It's definitely an issue in your intake. I would guess it's the VDI solenoid under the UIM. It's not too difficult but does require removal of the UIM to get to it. Before you do that though, make sure the actuator is still working on the SSV. Can check it with no tools, just reach in and ensure it can lift.
So I checked out the SSV actuator. I was able to move the arm connected to the plastic washer. It doesn't feel locked or anything.
I reread this again.
Dropping to lower rpm when in drive or reverse is complete normal on any automatic car. The engine has to work against the torque converter in D and R, but not in P. It's not even connected to the transmission in P.
I figured its normal but the amount of rpm drop is what freaked me out
So I checked out the SSV actuator. I was able to move the arm connected to the plastic washer. It doesn't feel locked or anything.
Good news, I would replace those 3 solenoids. Would imagine it's just the VDI solenoid that went bad but better to change all 3 since you are there. If that one went bad, likely the other two not far behind.
If it were my car, I would also change the coils, then 20 brake stomp (or leave battery disconnected while changing coils), and when you start it, do not touch anything until it completely warms up. This is a relearn phase. Coils go first, foul plugs, then when you change plugs, does not help for long.
10-13-2019, 10:58 AM
Could it be my sparks?
