Hey yall i have an 03 coupe 6MT and recently ive had an issue where i lose power, it seems fine up to like 3500 rpms or before 3rd gear but then after that the engine sometimes sputters and bogs like its choking, then sometimes it will feel like its about to go but it wont, i have no codes and cant think of anything ive done recently that would cause this, was thinking maybe crank or cam sensors or injectors but not too sure, i heard this is similar to a knock sensor but i replaced that and the harness about a year ago, thanks in advance!

 

Check your intake. Maybe a vacuum leak. Check fluids. Check spark plugs for oil. Are there really no codes? It kinda sounds like you're in limp mode.

 

Yeah, id say its in limp mode no codes checked vacuum lines but didnt see any problems, do you know the best way to check them, no codes and fluids look fine the only thing that i can think of was high pressure ac line busted from my intake, just replaced it but havent got it recharged yet, dont think thats on the same vacuum as the intake tho, thanks for the input!

 

 

Pay the diagnostic fee at the dealer to have them use the Consult lll to check out your vehicle

 

but will they give me an actual answer, ive heard they dont usually help, how much is it?

 

Go to your local Nissan dealership, the Infiniti stealership isn't worth the visit will their high cost and marginal mechanics...Gary

 

brought it to the dealership, told me a/f ratio was at 100%, fuel pressure was good and no vacuum leaks, told me the clutch and flywheel needed to be replaced- $3400, i did it myself and now the problem remains, dont know what to do or if i should bring it back to the dealership

 

brought it there and they told me everything was good but clutch and flywheel needed to be replaced, i did it but the problem is still here, any ideas

 

Dang that sucks. If you take it back to a dealership go to another one imo. Really only thing I can think of is vacuum leak. Friend had your problem and found a crack in the intake accordion.

 

Take it back!

You've got a seventeen year old vehicle. If you took it to Nissan they may be a little cheaper but Infiniti most likely has techs that have worked for many years on your vehicle model and have seen your problem previously

Going cheap very often results in paying twice.

 

Have you logged oxygen sensor data before and after your power loss RPMS to see what your engine computer thinks is happening? If you see a change in the waveform when your problem is happening a knowledgeable mechanic will be able to diagnose based on that alone.

Most Bluetooth readers also count misfires, it might not be missing enough to throw a code but you'd definitely feel it as a sputter or power loss


What about fuel pressure? If your fuel pump was going out, you'd lose pressure and miss/lean out only at high throttle and high RPMS when the engine needs the most fuel. Did the dealership monitor pressure while doing WOT pulls or just revving the engine...?

The dealership missed the problem while doing the tests. If your AFRs were actually good your engine wouldn't be sputtering.

 

Who knows what they did, theyre not that smart seeing that today my slip light and vdc off light came on, i went into my scanner and saw code c1143 and that was the only code, my car is badly aligned but i was waiting to figure out the problem before dumping a whole bunch of money into it ( i did a bunch some suspension stuff recently), now the code is for steering angle sensor , when these lights came on i had a terrible idle and felt like the car was shaking and ready to stall, these light have cane on 3 times since the problem started but they go away after i turn off the car, i was wondering if this could cause a problem where the computer would tell the car to lock up because it is slipping or not going into a straight line, thanks for the input

 

Steering angle sensor sounds like an unrelated issue but if your car only starts running like crap when that code comes up, good luck man sounds like a partout to me lol

 

Steering angle malfunction will definitely cause the car to misbehave. Fix that code and see if the problem persists.

Question about those cam/crank sensors you replaced. Did you use Hitachi or Genuine Nissan OEM ones? If not then you should probably replace them because these engines don't play nice with aftermarket sensors.

Another question about the clutch you replaced, did you make sure to get the alignment pin dowel correctly lined up on the crank? It probably wouldn't run at all if you did NOT but it's worth asking.