First post on this page, am I in the right section? I’ll delete if not.

Anyways hello! I have been lurking on this page for quite a while and am not sure if it’s still active or not. I read every single post about limp mode and still haven’t figured out my problem, any suggestions will be great.

I bought my first 03’ 350z (yewwww) in early December last year and it always had a rough idle and a check engine light (which was cleared by a scanner after it showed an airbag code)

To pass rego I had to fix an exhaust leak in the flex joint (took it to a professional) replace a brake light bulb and fix the door mechanism. Additionally, I changed the oil filter, engine oil and spark plugs and two weeks later it went into limp mode. I pulled up the codes and replaced the knock sensor and knock sensor harness (p0327) and replaced rocker cover gaskets but didn’t fix limp mode. It did however make the idle sound better. I then cleaned the throttle body and MAF sensor and still no luck. A mechanic said I got the wrong spark plugs (ngk plfr5a-11) so he replaced them. When we took out the NGKs though the tips were all black so it doesn’t look like fuel was burning. I then replaced the speakers for better audio. Afterwards I went to the wreckers and got a second hand MAF sensor and it didn’t fix that. I then replaced the coolant, brake fluid, power steering fluid and the problem is still there. I did an ECU reset, checked the accelerator pedal position and nothing has fixed limp mode so far. It was then noticed that the temperature gauge went halfway in the first minute of idling so then we changed the coolant temperature sensor and still no luck.

A couple days before limp mode I do remember smelling coolant inside the car.............. no leaks or anything though and don’t know if it’s related

No loose wiring, no aftermarket taillights, no mods that haven’t been put on within the last year to change anything and no idea on what to do.



I might get a new ECM, but any other suggestions would be greatly appreciated. I will upload a video of the idle soon, I just attached a photo of my car because I think it looks perfect!!!




Also, I posted this in the 2003-2009 general discussion and moved it here but I’m trying to figure out how to delete the thread from there. Any help there would be great too. This old HTML platform is too different for my basic zoomer generation ***

 

Deleted your post in the general section, as this forum is where such a post about repairs should go. It also helps to post mileage, and what kind of maintenance has been done to this Z. Also, while you mentioned a rough idle when you first purchased it, how did it run off idle? And what the hell is "rego"?

 

Thanks dkmura.

it has 137,000 miles. When I first bought it two months ago it would idle rough (sounded like an old muscle car with the pulsing sound) and when under acceleration it sounded like it was misfiring. After driving for 20 minutes the acceleration problem went away and it drove good. As I have only bought it I do not know whether it’s missing power or anything. As for maintenance the car was sitting in a driveway for 8 months prior to me buying it. Rego is registration in Australia. I’m from down under!

I also forgot to mention I got two new back tires when I first bought it (245/45/r18) while the fronts are (235/40/r18)

 

Here is the idle, it wasn't as jumpy last week.

 

Did you perform the relearn for the throttle body position after replacing the valve cover gaskets? Unplug the throttle body, plug back in, then perform the relearn.

 

Sweet, I'll try that in a couple hours, it's currently 1:30am here. Cheers!!

 

Did the idle relearn, acceleration pedal position and throttle body closed position resets and it idles below 1000rpms which is great! Still not going past 3000rpms though.

I checked for codes using the flashing CEL morse code in between the ECU reset and it came up with 0000 which says it thinks there is nothing wrong.

 

Try using a high quality code reader plugged into your OBD2 port. It's a tool that really helps as a 350Z owner.

 

Yeah the mechanic came and plugged in his multi tool scanner but it was showing no codes. Even looking at the real time feed from the ECU showed that everything was working fine except the airflow going into the car being delayed if I remember right.

I’m going to get it towed to a dyno place and see if they can use their better diagnostic tools or even tune it out of limp mode on Tuesday (Australian) which is your Monday

 

Strange- most USDM Z33s that go into limp mode ALWAYS have a code(s) held in memory. Good luck and enjoy that summertime Oz!

 

To those who are still reading (and for those in the future who have the same problems)

The mechanic diagnosed the problems as:
Camshaft timing being off
Cylinder 1 not firing, cylinder 2 firing bad
Bank 1 and Bank 2 getting different readings

He called me and told me the problem, he hung up and called me 10 minutes later and said he pulled out an IR gun and found out my passenger catalytic converter was at 117 degrees C after 20 minutes of it being off while the driver side catalytic converter was 47 degrees C or something close to those numbers. I'm getting the cat on the driver side replaced and see how that goes. Will keep you updated.

 

Strange that the cam timing is off. Has this Z ever had a timing chain replaced? Seems like your car has had a lot of component failures since you bought it. Did it come with a full service history?

 

I doubt it; the car didn't come with a full service history or anything. It wasn't looked after the best I believe. I got it for $2,400 US so I'm not complaining, I'm happy to get it all fixed up.

It's so hard to find a catalytic converter; there's one from another state for $310 US for a single catalytic unit that will come in a week or two, so I reckon I'll just smash the cat and see how it goes from there because I did that with my ute that had the same problem and it runs great.

 

Update: We took out the cat 2 days ago and it was clogged with solid gunk. Smashed it out, put it back in and it runs great!!! It ran great for two days up until now because white smoke is coming out the exhaust. I checked the coolant and there's non in the reservoir..... Rip.

Maybe I can use a chemical sealant and it would work fine because I actually did drive it home from 30 minutes away and it didn't overheat. I'd try that before replacing the head gasket itself because I don't have time to do it and mechanics here cost a tonne. Reading all these reviews people either are strongly for ones like blue devil or against them entirely. I'll see how it goes. Or better yet, I could just sell the car and not have to worry about it anymore!!!

 

Running a Z with a faulty head gasket compromises the VQ in several ways. Besides overheating and warping the precision cast heads, there's the problem with oil dilution. As the dilution increases, you face increasing ring and bearing failure. Ring and valve deterioration may already be causing severe damage; particularly if you blowing large clouds of white smoke through the combustion cylinders. For a car with 137K miles, it sounds like this Z was abused and in need of some TLC. Now that you've solved the limp mode issue, it seems like you have a decision to make. Either rebuild the engine properly or cut and run. Any chemical sealant is a temporary fix,