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03' 350z Popping Noise and Acceleration Hesitation
I have a 2003 350z Touring 6MT. I have had this car for almost a year (Will be 1 year in May). I have never had any issue with this car! The previous 2 owners before me kept ALL of the service records so I knew it was taken care of.
Anyways, since the day I bought it, its always made this little popping sound under the car. (My fiances 07 bmw 335i 6MT does that same thing.) Sounds like its coming from the exhaust mostly. About 5 months ago, I did a resonator delete and muffler delete so it is loud and annoying (Yes I am one of those people). After I did that, the popping was louder, but it would only happen like once every 30 seconds or so until I would start to drive it, and then it would go away.
Yesterday, while driving home from work, I was getting onto a freeway and I was accelerating just like I do any other day, and the car hesitated at about 4k+ rpms. It would jerk back and forth lightly, almost as if the rear tires were slipping and couldn't grip anything. I continued on driving and it did it through all of the gears. If I would lightly accelerate, it was fine. But under hard acceleration it would do it. When I got off the freeway and sitting at a stop light, the popping was insane! It sounded just like it always did before, but louder and every second. After I took off, it was almost like the clutch wouldn't grab? I let off the clutch to give it gas and the car hesitated so I pushed the clutch in and tried again and it was fine. The next few stop lights and stop signs, it did this, popping and hesitation. I have been researching NON STOP since last night and neither myself nor my fiance know whats wrong. There are a lot of people on here claiming on thing or another, but not both things at once. Anyone have a similar thing happen or maybe know what is going on? The drive to work today was fine, just some pops while sitting at lights. I wouldn't be so worried about it if it had been doing this the whole time of owning. But since yesterday was the first day it was acting up, I am afraid something is going on.
Sorry for the long and detailed post, I wanted to make sure I put everything that happened so someone might know whats going on.
We appreciate long detailed posts here. What's the mileage? Is it throwing any codes?(I'd be surprised if it's not throwing a P0300 for a random misfire) Did you check the condition of your spark plugs? Have you tried cleaning the MAF sensor? If not, I would try that first. Have you tried something as simple as resetting your ECU/ECM?
My mileage just hit 158k. Spark plugs are all fine as well. No codes at all and first thing we did was reset the ECU last night. After that we drove it around and it seemed fine. No unusual pops or hesitation then, but the pops were definitely back this morning. We can try cleaning the MAF next and hope that is it. Thank you for your quick reply! I really appreciate it!
Are we talking about an intermittent backfire here? With that kind of mileage, I'd check the injectors first. You could be experiencing a fuel delivery problem that got worse with the muffler and resonator delete
With the reduced back pressure caused by the muffler and resonator delete it makes sense that the issue became more pronounced.
Can you do an open loop to closed loop scan on a drive cycle to see if you're running rich?
No problem.. What viscosity motor oil are you running, and how is your oil pressure?(Because timing chain tensioner is oil pressure dependent). Anyway, pick up a can of this at Advance Auto or Auto Zone and try cleaning the MAF sensor first. And if that doesn't work. On with the next.
With the reduced back pressure caused by the muffler and resonator delete it makes sense that the issue became more pronounced.
Yeah that sounds like unburnt fuel to me. I just cleaned my MAF too. It's a pretty easy job. Also as a shot in the dark you could run some injector cleaner through the system.
After the ECU was reset, I haven't had anymore of the hesitation with hard acceleration. Very little pops happening too when I am stopped at a light. Drove it home from work yesterday and all was fine. Drove it pretty hard at one point on the way home just to see if it would act up and it didn't. This morning it drove just as smooth as it has since the day I bought it.
I'm going to check my spark plugs this weekend as well as trying to clean the MAF. I do get a lot of popping coming from the exhaust every time I shift and that's been going on for a couple of months. I appreciate all the replies I have gotten. It's narrowed things down a lot and I know where to start working tomorrow.
Alright, thought I would do a second update in hopes of some more help.
So we got under the hood and started checking coil packs and spark plugs. 2, 4 and 6 were all good so we stopped there. Went back the following morning to check 1, 3 and 5 since they were really hard to get to and the spark plug well 5 has at least 2 inches of oil in it. Coil was soaked and same with the spark plug. Anyways, found out it was from a messed up valve cover. Replaced the valve cover and valve gaskets on both side and since then, no more oil. Drove the car the next day, HOPING that the original problem would go away. Thinking maybe there was just no spark because of the oil. The problem is still there and apparently the mechanic that replaced the valve covers said it was two different issues but didn't know why it was still hesitating and popping. I had my father ride in the car with me last night in hopes that it would mess up so he understood more. Drove for a total of about 8 minutes. I didn't drive the car all day because I didn't want to risk it. Well we came to a stop light and the car started doing its popping. I had it in neutral and revved it and the whole car shook the first two times I did it and then the rpm's dropped to about 200-300 and then went back up to about 700. 3rd time was fine. Smooth as can be. I took off when the light turned green and the car hesitated like a ****. Jerking back and forth and then after a few seconds, was fine again! Shifting through gears there was a lot of backfire like it was burning off excess fuel which has been happening for months rather so I thought it was normal because of the whole muffler delete.. This has been going on for 2 solid weeks and not ONCE has the CEL ever come on. We are stumped!!! I ran some fuel injector cleaner through it, changed the spark plugs, tested the coils, cleaned the MAF, cleaned the throttle body and even changed out the valve covers. What else could it be since no codes are popping up.
Last edited by MissFairlady_Z; 05-11-2018 at 08:32 AM.
04-19-2018, 09:01 AM
03' 350z Popping Noise and Acceleration Hesitation
What's the mileage? Is it throwing any codes?(I'd be surprised if it's not throwing a P0300 for a random misfire) Did you check the condition of your spark plugs? Have you tried cleaning the MAF sensor? If not, I would try that first. Have you tried something as simple as resetting your ECU/ECM?
