Not sure what's going on, I went for a drive in the canyons on saturday and thought I was imagining it at first. Felt the car shaking or vibrating in the front.
Today I felt it again and this time I tried to figure out what causes it. When I accelerate, after about 2000rpm (and rising with the foot on the gas) the car would jerk/stutter/vibrate in the front. never experienced this symptom before. The car wouldn't accelerate well when it does this. And it doesn't always do this, it went away after a few mins. I need to clarify, it only does this when I am accelerating, from a red light or something. And it is not continuous throughout the power band, only for a little bit maybe between 2k-3.5k RPM.

Another issue may or may not be related but when I start the car up cold and put it in gear, when I release the clutch it will make a loud, deep squeaking noise that goes away when I fully release the clutch pedal or depress it. It's the kind of noise that sounds like rubbing without lubrication. Think about when you're doing the dishes and it makes a squeaky friction-like noise. It's like that but louder, you can hear it groan as I back the car up out of the drive way.
This noise goes away once the car gets warm and doesn't come back ever. until the car is started up cold.
Because it is controlled by the clutch and only makes this noise when the clutch is trying to grab, my thought is that it's the clutch, pressure plate or something in the clutch assembly.

I'm not sure if the jerky, vibration upon acceleration is also the same issue.
It's not the engine, there's no check engine light either. The engine runs very strong. I am not sure if it's the transmission but I've never had any grinds or problems there. It's definitely not the differential.


Also out of my many previous cars, I've had the traditional worn clutch symptoms so I tried to put it in 6th gear at about 40mph and floored it and the RPMs don't run up. The needle moves slightly like it bounces but it doesn't slip at all. but I have had a car need a new clutch when it wasn't slipping before.


Any input? I'm guessing if it's the master or slave cylinder, the pedal pressure would be affected, which it isn't.
****, don't want to spend $1k on a new clutch at this point.

 

is this the clutch noise you are hearing?

https://my350z.com/forum/maintenance...ing-noise.html

When it gets cold in vegas I get that noise as well. Just let your car warm up like you should before driving. Never had problems accelerating so this might not be causing your acceleration problem.

 

Hmm that's not the noise I hear. In that case it would be the throw out bearing I had a few cars with that issue. Mine only happens on a cold start and when releasing the clutch and the clutch is trying to engage. I guess I'll just keep driving it until some other clue shows up.

 

Sounds like the clutch. My guess is condensation on the flywheel since this happens during cold start and goes away, but it could also be the throw out bearing.

The jerky vibration during acceleration could be a number of different things.
Fuel delivery(weak fuel pump or clogged filter), dirty injectors, bad coil pack(s), timing, busted motor mounts, busted transmission mounts, MAF sensor issue, all kinds of things. If your ECU isn't throwing any codes, that helps narrow things down a bit. If the issue gets worse, you could have a mechanic hookup a high-level scan tool that records all the ECU data while driving, that's probably the most sure fire way of finding the root cause, but this won't be free.

I know you mentioned it's not the engine. But if it only happens during acceleration that leaves only a few other possible culprits. The transmission sounds like the most likely suspect based on your description, but to be sure...

I would start with some basics, check your wiring harness, particularly around the injectors, coil packs, and MAF. Look for corrosion, exposed wiring(busted shielding), signs of moisture. I would also get a good look at the motor mounts and transmission mounts. Even without an ECU code, sometimes you can still have loose/corroded electrical connections and if your motor mounts/tranny mounts are cracked, you could expect some nasty vibrations.

Anyway, I'm probably over-thinking this since all the major signs point to the clutch system. But better safe than sorry. Never hurts to check.

 

Thanks. I have an update. I started up the car today and drove around and after about 10 mins the bogging started to happen again. I tried to keep it there so I can see what the hell's going on. It seemed it would bog/stutter/loss power when around 2.5k RPM or so. Then the check engine light started to flash (was not on before) so I pulled over immediately. The code came out to be P0300, random misfire. I didn't clear the code but when I started the car back on, the code was gone. I drove it home shifting at low RPMs and did not drive it hard and the check engine light never came back but I can tell if I were to step on it it would freak out again.

So it IS engine related it seems. I'm going to clean the MAF in a second. But my gut feeling tells me it's a coil pack. I read you should unplug one and start the car. If it misfires at idle, then put it back and unplug the next one. Eventually if you have a dead coil pack it won't do anything when you unplug it. So I'll try that next. If that doesn't work I dont know what else to check for. I was told by the previous owner that the coil packs were all replaced and the spark plugs were also but he didn't have the records. Otherwise the car is running fine.
It's obviously getting worse gradually since I drove about 6 hours straight last saturday in the canyons and it happened toward the end of the day.

Any other things to check I'm all ears. Well at least my clutch is good!

EDIT: Im just going to add just in case: I installed a plenum spacer and cleaned the throttle body about a month ago. So far had no problems with it and it ran well and could be pushed hard without problems. But when I first cleaned the throttle body it gave me a CEL for a high RPM idle, which I took care of by doing the relearn procedure. I highly doubt this is related but in case this helps..

 

One other thing, I just remembered something randomly. I was at a gas station last week (maybe 2 weeks ago) and there was a guy who's battery died. So I offered to go home and get my jumper cable and start it up. I came back and I hook up the cables. And I assumed he knew how to hook up the red to positive but I guess you should never assume. I mean I asked him if he knew where it goes and he said yeah. Plus it was his car. So I did my side, hand him the other end and tell him put it on the positive side and the black one on the ground. Well he ended up putting the red cable on the negative end of the battery. There was a big spark from my battery. But nothing blew out, and I've been driving the car fine for the past 1-2 weeks. But that reminded me that maybe that incident could have fried out a coil pack.
Not sure this is giving me a headache.

 

Didn't read the whole thread but the part that caught my eye was the flashing check engine light. My car did that when the coil pack was goin out then for about a week or two I got the p0300. Eventually one coil pack went out but it still has the p0300 so I had to find which was out and fixed it.

 

Yeah I just remembered I cleaned the MAF not too long ago. Same time I did the throttle body.
I'm going to check the coil packs tomorrow and see if that helps.

 

Yea, sounds like a Coil Pack issue, does the code tell you which cylinder is misfiring? You can always try clearing the codes, swapping coil packs, and then see if the misfire follows the coil pack.

If it does, then you've fingered the problem. If it doesn't, then I bet your fuel injector is going out, and when 1 starts going, the others are prone to follow. Before replacing any fuel injectors though, use some injector cleaner additive. It's a cheap and simple fix that usually works. If you use really cheap gasoline, the injector pintles will get build up on them and that nice conical fuel spray you want, will soon become a mess leading to misfires.

Regarding the battery incident, it may or may not have contributed to the problem. If an electrical short like that occurred, then usually the more sensitive components would fail first. But your fuses should have protected your electrical components from a nasty short (I think).

 

Unfortunately it only said "random misfire" which could mean any cylinder. And the code is also gone now for some reason. Only started flashing when it was stuttering. I'm going to unplug the coil packs one at a time and start up the car and see if that works. Then I'l run some Chevron techron fuel cleaner through it. I have been filling up arco this entire time its just down the street from me right before the onramp.

 

Bummer, you would need a deep level scan tool to find out which cylinder is the culprit based on live ECU data in that case. These scanners can get expensive though. Try a search on the forums about this code, there's been a lot of in depth discussions on diagnosing and resolving it.

 

Did you follow your clue?

 

I pulled the coil plugs one by one today and started it up in between. Every one of them caused the engine to misfire when pulled which means they're not bad. At least at idle. With them all connected the engine idles fine.
I also checked the intake and hoses and there's nothing wrong on the air side in my opinion.
I'm thinking it is fuel related now. The problem only occurs when I'm accelerating hard and sometimes the engine shaking will go away if I accelerate harder or let off the gas. It ALSO occurred after my all day hard driving through the Malibu canyons this past weekend so I'm guessing either one of my injectors are clogged, not closing properly, dirty fuel filter or bad gas. I'm going to go put a concentrated dose of Chevron Techron and fill up with Chevron 91 and run the car pretty hard all day to run the gunk off the injectors and lines. If it still gives me problems, I might drop it off at the dealership.

 

This definitely sounds like an intermittent misfire, especially if you received the code, but it no longer shows up.

I had a coil pack failing that after throwing a code a few times just stopped throwing codes all together and just ran like ****.

 

You should be able to check your coil packs with a multimeter... But definitely don't rule out a bad injector.

 

How did you end up figuring out it was the coil pack and which one it was without a code?


It might be too early to tell but today I pulled all the plugs and check the coil packs. I cleaned the MAF good with the CRC cleaner. I ran a bottle of Chevron techron and filled up with chevron 91 at a nicer gas station and drove around for a bit and had no misfire situation. I tried to run the fuel cleaner out in quick full bursts by redlining at WOT and then dropping it to neutral, slowing down, then WOT again, then neutral. I figure if it goes from idle to 7000rpm to idle to 7000rpm, etc. whatever gunk is stuck in the hoses and in the injectors will wash out better.

I'll update if it either comes back or stays gone.

 

I was getting a specific cyl code not a random misfire code...so I knew where to start. Eventually the coil degraded and it was rumbling at idle also so the coil dance worked to isolate. The random misfire code is def harder to isolate.

You did a lot, not sure if it can be attributed solely to the fuel additive with any certainty, but glad it seems it all worked...Good luck!

 

Hey Studd,

Any update on your issue? Are the symptoms gone?

 

Yeah I think so. It hasn't come back since I did the stuff I did. I'm wondering maybe it was a bad batch of gasoline. I'll be sure to update if it comes back, just thought it was weird.

 

Not sure what it was cause it has never come back after I did some stuff including filling up with Chevron and using a bottle of fuel cleaner. I'm chalking it up to bad gas.