Hey guys, I have a buddy with an rx8. I have not yet seen his car, he took it to his cousins general mechanic shop after some issues. They diagnosed it as a bad engine and got a remanufactured engine.

I was wondering if there are any rx8 specific problems that other people might have dealt with. I will be helping him look at it soon, he has only told me it starts but does not stay idle

The car starts, so I am guessing there is spark and fuel. Possibley a fuel pump that is dieing out, or low fuel??

idle air control valve issues???

very low battery with alternator problems???

something in vacuum not hooked up properly???

clogged cat is not a possibility, there is none.

I'm sure the shop he takes it to has a generic obd2 scanner. My plan is to scan it and hope there is a code, maybe an eccentric shaft position sensor or camshaft sensor problem?? lol jk jk, no cam, but you never know what a generic code scanner might tell you

I might consider a rotary compression test, but most of the time compression is never an issue with a rebuilt engine.

Any help would be great. Any rx8 guru help would be greatly appreciated.

 

normally with bad compression there is a long starting period where its crank crank crank crank start specially when hot . as for the car not idling it could be a million things . i'm not to familiar with the 8 so I cant tell you with any kind of certainty . But maybe adjusting the idle air control screw until the car idles . and a compression test the general shop must have a reason for wanting a reman , they should of given him the reason . weather its low compression or what ever the case might be that they diagnosed .

i dont think there is an OBD2 code that says blown motor replace apex seals! LOL

water seal going bad and getting into the engine may cause the spark to drown out and the car to die under idle loads . same with oil , is he getting smoke of any kind ??

 

If I'm not mistaken there isn't a Idle Control screw, idle is control by ECU and Tunning software is required to change the idle values on the RX8.

 

Unmetered air can cause the car to not idle. Check all your hoses...carefully inspect the plastic intake manifolds for any cracks.

 

You should post on RX8club.com

 

Thanks guys, I haven't gotten a chance to look at my buddies car yet, but now I am wondering if they cracked the intake manifold when swapping engines. Thanks again

 

you should actually put a timing light on all 4 wires, it can easily have a dead coil or two and run ok

nope, it doesn't have one

possible, also check the battery connections.

yeah look for loose/bad hoses, there are only about 6-8 of them, but a vacuum leak will make it unhappy

i would clean the CAS sensor, and reset the profile in the ECU, its easy, with the key on engine off, you hit the brake pedal 20 times, or until the oil pressure gauge moves, and you're done.

if none of this other stuff fixes it, then compression test it.

 

after doing the KAM reset that j9fd3s suggested let the car idle for 15 minutes without touching it, this will do an idle learn in the ECU. driving the car will just prolong the process.

resetting the KAM is something almost no one does when replacing an engine and is an important step on the RX8.

if that does not help i would check the coils to see if they are firing with the timing light. faulty coils and plugs are quite common on the 8's.

depending on who rebuilt the engine, it is quite possible it was rebuilt with inadequate parts and still has excessively low compression. if the compression does not come up within 1500 miles contact the builder and ask him about his warranty. keep in mind most no one will warranty engine R+R labor unless the builder was the one who installed it.

 

I finally got to see his car yesterday. no vacuum leaks, battery and charging is fine. when revved the engine is still smooth but it barely idles especially if you snap the throttle, it usually dies. I didn't drive it, but my buddy also mentioned the rpm won't go past 8k or something. the engine sounded healthy, just rough idle

I did not get a chance to reset the computer like you guys mentioned.

I read on the internet of some people having issues with the throttle body which is also the idle air control.

 

I'm going to reset the ecu and see if that helps.
the shop changed all the coils already.

if it still acts up after the reset, we may throw a throttle body at it and keep our fingers crossed

 

how old are the spark plugs? always change the plugs before or with the coils otherwise you may fry the new ones.

 

These cars dont have a throttle cable...check the tps??? Not sure what that sensor is actually called on those cars. But throttle is controlled by a motor. It can be all confused and out of wack.

 

yeah, I'm thinking that's the problem if resetting the ecu does nothing.

I'll ask about the plugs.