Hello, I purchased a 2004 5mt coupe in Sept. Of 2018. Car had 232k miles when I bought it but has been very well maintained by previous owner. So far I've replaced a/c compressor and spark plugs.

Problem: when accelerating hard (anything above 60-70% throttle) from 0 the car seems to stutter a bit before shifting into 2nd gear. It jolts backs back and forth just before shifting at around 4500-5500 rpm. It only does this from 1st-2nd and 2nd-3rd. 3rd and so on feel strong and actually pull harder then the lowere gears.

If I'm going highway speeds and mash the accelerator it pulls hard and shifts fine. Issue only seem to happen when I accelerate hard from low speeds.

Any ideas? Btw other than this car runs as well as you'd expect from a car with so many miles.

 

check the intake tubing for any rips in the "accordion-like" portion of the tubing. had the same issue, even made a vid of the problem.

 

Thank you for your response! Question; do you still have the video?

 

https://g35driver.com/forums/drivetr...-slipping.html

at first, I though my trans was slipping and then i started to see under the hood and found that there was cracks in the bellows between the intake tubing, just to make sure it was that was causing the issues i wrapped it in duct tape and viola problem solved. of course i took the opportunity to upgrade to z tube lol

 

Omg that is it! Haha didn't think I'd find someone so fast with the EXACT same issue. Good video, o was thinking of doing one but that is exactly what is happening.

I just stepped outside and took a look and see that it is wrapped in duct tape at certain parts. I also see some minor cracks but dont know if cracks are significant to cause leaks or if duct is coming undone. I took pics and video.

Also, in the video there is a sound coming from the are around the intake manifold. Sound is loud at initial start, then lowers to the noise heard in video and eventually isn't heard at all when car is warm. Noise doesn't happen when car is warm. ONLY on cold starts. I live in Oklahoma so it could be 20° one day and then 70° 2 days later; especially during this time of year. Start up sound and ambient engine noise sounds normal on warmer days after a couple minutes of driving.

Last thing I noticed that could also pertain to intake leak: on initial start up there us a gas smell on drivers side of cabin. My passengers cannot smell it. Today, I started car with the hood up and immediately went to look at intake manifold and noticed the smell coming that area. Dont know if these issues are all related.

Again, thank you for your help!! Someone already did the tape so I guess I'll have to replace it lol

 

Ahh so THIS is the other thread, don't worry about the other one if I come across it again I'll close it out. As for the gas smell I would start by inspecting the fuel dampers on each fuel rail. The smell is probably being pulled through the cabin air filter behind the battery so I would start with the passenger side damper. There are also.some EVAP lines in the area, get an inspection mirror and a flashlight and start looking around. Should be pretty easy to find.

 

Glad you found it! I can tell you are very knowledgeable when it comes these cars. I must my knowledge about cars in general is not as great and I am slowly learning...

To be sure I am investigating exactly what you are referencing do you have any helpful tips or what to look out for? I've been trying to find a diagram or something showing the specifics of the engine or something I can use to get to know my car better.

(yes I have the original owners manual but of course its main purpose seems to be to send me to the dealer instead of teaching me about the inner workings of my car lol.)

Again thanks! I will have to look into that. PS: the video file from my phone is not supported so I will have to look into getting that posted as well

 

At the end of the fuel rails near the back of the engine is a round piece bolted on with a fuel line on it. There is one on each fuel rail, those dampers can fail.

Passenger back side of the motor is a couple hard vacuum lines, one has a green cap that says FUEL, and they go to a piece with an electrical harness. That's the EVAP stuff in the engine bay.

Inspect all that stuff, turn the key to ON (engine not running) and look around for anything that looks wet, probably not dripping unless it's a BIG leak but it will look like it's wet or damp. Stick your gloved finger on the wet spot and smell if it's gasoline.

Usually these leaks are not hard to find with a good flashlight and a cheapo inspection mirror.

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https://youtu.be/GTIuic17jsk here's a video I found on YouTube of g35 startup pertaining to bad fuel damper I guess? The noise is almost identical to mine. The rattle seems to be muffled by all the other engine noise in the vid so I'll have to listen from the outside from the view in the vid.

 

More pics after taking a look. Didn't see any obvious moisture on the lines, but I could just looking in wrong spot.

 

That video is for a different type of damper, a motion damper that bolts to the intake and then to the chassis to keep the engine from moving around in the bay.

The pictures you took are of the piece I'm talking about though, there's also one on the driver side fuel rail, an inspection mirror is needed to thoroughly look around them though because you cannot see the back or bottom of them. I don't see anything obvious in those pictures.

You might also remove the cabin air filter and check to make sure it doesn't have anything on it, if it's more than a year old just replace it with a new one.

Also check your gas cap to make sure it's fully tightened but I doubt that's the problem.

The rest of the fuel lines can be inspected from under the vehicle, I'm not sure how many fittings are in the line set between the tank and engine but there's usually one up on the firewall, not totally sure where it's at on the G35 though because I've never taken it off.

 

This thread has good pictures of the other end of the damper.

https://g35driver.com/forums/engine-...ml#post6950225