Been having a really bizarre issue with my 06 5AT coupe. Car has what feels to be a dead spot or a flat spot in the RPM range when I'm cruising down the highway around 2100-2200RPM and other speeds at this rpm range. It feels as if my position on the gas pedal is not there like its worn out "the dead spot" what is even more bizarre is my cruise control which works fine will not engage in this dead spot. Its annoying because this is right around my highway cruising speed of about 65mph. Car has all new plugs, new 02 sensors x4 and runs fine other then this weird hiccup. If you give it more gas the the car starts to accelerate fine, it just seems like the light throttle input for cruising and normal acceleration doesn't react. I'm thinking a new Throttle body and or accelerator pedal position sensor? I have not been able to find anything on this issue except one guy who had a 07 with a similar issue. Any help here would be huge.

 

Get an OBD2 scanner and watch realtime data for the APP and TPS, APP is displayed as a % value and I'm not totally sure about TPS but I think it's displayed as a voltage value.

You probably just have a vacuum leak though.

 

That's the consensus I've seen. I found a few other threads with this issue at different RPM's and a vac leak was mentioned. Judging by the hard rubber intake couplers I just replaced I'm sure there are other rubber hoses that are deteriorating. Any usual suspects for the vac leak? I have no CEL so if it was a fault in the APP or TPS i guess it would trigger a code. I'll try and run some live data with my buddy for the values on the APP and TPS. Really need to diag more before I start tossing parts at her.

 

Usual suspects are the PCV vacuum lines, there's 3 total, one from the intake duct right before the throttle body and it goes down to the left side valve cover, you probably just need to add clamps because I don't think there's ones factory installed on either end. Then there is a second vacuum line at the front of the engine that connects the two valve covers together, and one from the right side valve cover at the PCV valve that goes up to the intake plenum.

I would also clean the MAF thoroughly with MAF cleaner and do the resets listed here.

https://www.nicoclub.com/archives/g3...procedure.html

The intake pipe should also be thoroughly inspected for any cracking, usually a vacuum leak will first feel like a "hesitation when you give it throttle" and it's usually the worst at low rpm. Once the leak is bad enough you will get a diagnostic trouble code but it's got to be a really bad leak before the ECM starts trimming fuel enough to throw the code. It's uncommon for the brake booster hose to leak but might as well check it while you're in there, be aware there's a check valve pushed up inside the brake booster line so don't accidentally install that hose backwards

 

Well still have the problem after more then 2+ years. I replaced all my PCV hoses yesterday from Z1, car has a brand new MAF, new plugs and coil packs, still does the exact same thing. You can floor the gas at idle it goes up to about 2500 RPM sits there for a second and then it will go the rest of the way. Same thing when driving I can floor it from a dead stop and wait 3-4 seconds then it will take off. Car runs great in upper RPM all the way to redline at full throttle but is a mess down low. My cruise control does not work either, you can turn it on and the cruise light turns on but when you go to set it won't set and the set light goes on for a second and then goes away. This did used to work before my car had this weird hesitation issue. I'm leaning towards replacing the ECU/ECM.

 

I dont think a bad TPS would turn on the check engine light. Did u ever test it?

 

Check the PCV valve itself, if it's stuck open then it's basically just a giant vacuum leak sucking crankcase air.

If that's not it I would pay Nissan a diagnostic fee to look it over, probably cost you $150 to have them look at it for an hour.

 

That's what my friend has been saying, I also replaced my gas pedal that did nothing, I guess the Throttle Body is next.

 

I can throw another one at it I replaced it a few years back, for how cheap they are its worth it. I really don't want to pay a dealer to diag the car, I'm sure it will come back as a dead end with the cause being my ISR Y pipe and test pipes.

 

You can just take it off and shake it, if it rattles it's good.

Are you sure there aren't any exhaust leaks?

Is it a 5AT or 6MT, I know that the cruise will disable itself if it determines that the relationship between engine rpm and wheel speed aren't what it thinks it should be.

Like if a 6MT has a slipping clutch and you're in cruise and it slips a little it will turn off the cruise because it sees rpms start to run away but there is no increase in wheelspeed. Same will happen with the 5AT.

Does the cruise not work at ANY rpm or is it just highway speed it won't work? Just trying to rule out that the cruise function isn't actually a symptom of the powertrain problem. I've never heard of anyone having a problem where the cruise will turn on but be unable to set except when there was a clutch issue or the spiral cable/button/other stuff that's obvious.

 

I don't have any major exhaust leaks, my muffler disconnected itself from the y pipe via rust years back and never had any issues.

My car is a 06 coup 5AT, the cruise will not work at any speed. The CRUISE light turns on and if you hit set it illuminates for a second and then goes right off and doesn't lock in the speed. I was messing with it the other day you can hold the set button and the light will stay on but still not arm, I tried pulling up on the brake too and that did nothing. This issue started when my car got this hesitation. I can't even maintain a lower highway speed of 60-65 because the dead spot on the pedal is right in that RPM range. It feels like the potentiomer in the throttle body burnt out.

 

*Also I have since fixed the y Pipe and muffler issue was just using that as a reference point.

 

Do you have an android phone, you can use the app Torque Pro with a bluetooth OBD2 adapter like the one from BAFX to watch realtime data on your sensors. It would be interesting to see both APP (accelerator pedal position) as well as TPS (throttle position sensor).

I'm leaning towards this being an APP or throttle body issue, the gas pedal is just a two rheostats, they operate inversely of one another, one scales from 1-5vdc the other scales from 5-1vdc.

You can buy a 3x AA battery holder and use it to make 4.5vdc which is close enough to 5. Then use it to bench test your APP switch to see if there is actually a dead spot in it, I've never heard of BOTH sides of the switch failing at the same time though, and if one side fails but the other side works the ECM will give you a diagnostic code for the APP.

You should also remove your intake tube and see if the butterfly plate on the throttle body is loose, I think the screws are actually on the inboard side of it but you should still be able to gently wiggle it with your finger and see if there's any abnormal play on it. Just don't press it too hard to force it open, it's hard on the electric motor gears when you do that.

Also since you don't have a rev-up, with the intake tube removed you can turn the key to ON, then work the gas pedal to open/close the throttle plate while the engine is not running. Either set up your phone to record it or have someone else work the gas pedal. Go through a series of slow and fast throttle movements, fully closed to fully open, and see if the throttle body is working like it should or if there's some kind of hesitation/stutter/dead spot that doesn't 100% correspond to actual throttle position.

 

One other thing, unplug the MAF sensor and go for a drive, it will be in a semi-limp mode with a CEL diagnostic code. See if it still misbehaves.

 

Thanks, I already replaced my gas pedal a few months ago with a brand new one from rock auto, but that did nothing so I'm leaning toward the Throttle body. The most bizarre thing is I never got a check engine light from this issue and it's been going on for well over 2 years. If this doesn't fix the problem I'm guessing my ECU is bad?