Jeremy1607

Hi guys,

Just have a quick question. My car jerks while acceleration or driving and the rpm bounces up and down. This only happens in the first 2-3 minutes of driving and when driven with the engine warm (about 5-10 minutes after starting from dead cold).

Do you know what it could be ? I'm sure it's not bad ignition coils or spark plugs as I've just installed new OEM spark plugs and Splitfire SDIS ignition coils not long ago. I have cleaned both my MAF sensors last weekend, and it's better (jerks less) but it's still there and I still can feel the jerking when I'm driving it. I'm going to clean my throttle bodies this weekend and see how it goes.

Thanks !

Jeremy1607

I took a video of it today, as you can see the rpm bouncing up and down. Any ideas ?

vqsmile

Did this ever happen before you replaced the coils? If not, then why did you replace the coils?

Jeremy1607

I'm not 100% sure as I changed the ignition coils quite awhile ago.

I doubt it's the ignition coils. They're supposed to be better than OEM, no ?

It says :

"Increases horse power and response due to giving a stronger spark at all levels through the RPM range and reduces misfire due to a poor spark"

vqsmile

I'd trust the OEM coils for durability and reliability over the aftermarket ones. It's a fairly simple swap to put the OEM ones back on just as a basic troubleshooting exercise to return the car to the 'last known working condition'.

Jeremy1607

Also is there a fix for the rattling/vibrating passenger seat (seat back and headrest) while driving ?

crookncastle

why would you change out the factory oem ignition coils? i highly doubt splitfire makes a better ignition coil then whats supplied by nissan/infiniti. as for your posted video its hard to distinguish what is going on with your car other then engine rpm fluctuation while under slow acceleration.
does your engine idle ok in park or neutral? does the engine want to stall out during acceleration? any check engine light malfunction displayed in cluster after putting the vehicle in a couple of drive cycles?

Jeremy1607

Yes it idles okay and no, the engine never stalled/or wants to stall while accelerating or sitting at the traffic lights.
Everything is all good and smooth after about 5 minutes of driving. The jerk only happens in the first 2-3 minutes of driving after starting from dead cold.
Nope, no lights has ever came up on my dash .

Rochester

iTrader: (8)

I agree with you about using Nissan coil packs. This is one of those things best left OEM. And the OP's car is a 2007 G35... so 7 going on 8 years old. It's not a bad idea to replace the coilpacks at that age, IMO. But I would do it with factory coil packs.

crookncastle

nissan/infiniti ignition coil packs were made by hitachi before but i have no idea who makes them for nissan now. hitachi ignition coils are freaking solid. the smart thing to do is when you replace the spark plugs for the engine to also replace the coil boots. the coil boots can be ordered and replaced by themselves without replacing the entire coil pack. the ignition coil boots tend to burn out or short due to age and exposure to heat in the cylinder head. if i was the original poster of this post i would first swap the oem ignition coils back into the car and drive to see if engine mapping changes to how the car originally operated.

Magowin

I thought this was the seat and headrest in my car but I don't think it is I think it's the seatbelt. My seatbelt bracket was in the bottom position on that side of car and when my brother got in car and lifted it to the upright position when he got out he kept it that way and ever since then the noise was gone.

Jeremy1607

It's not the seatbelt, it's the actual seat that shakes/vibrates .

crazjayz

I have the same issue, especially at freeway speeds. It's like the resonant frequency of freeway vibrations PERFECTLY matches that of the seat. The seat will start vibrating/shaking pretty strongly. I have no idea what the fix is, but I'm getting my car serviced tomorrow, so I shall ask.

vqsmile

If that's the case, it seems like it should alter the frequency characteristics depending on the seat position (i.e. whether the seat is all the way forward or back, tilted fully or upright, and raised or lowered). Just as a test, have you guys tried adjusting the seat into some bizarre configuration like all the way forward, all the way up, and all the way reclined at the same time?

Jeremy1607

I finally got the chance to clean my throttle bodies, however my car still jerks like I explained on my very first post ? I cleaned my throttle bodies, MAF sensors (with CRC) and air filters, change the ignition coils back to OEM and did an ECU reset but still the same. Any other ideas ?

Thanks