Clutch and Flywheel Installation Woes: Check engine light and sputters...
 

I had a Stage IV Competition Clutch and Flywheel installed today. The shop I had it done at is known for their work on hondas, but informed me that they had done these jobs on G35s and 350zs. 4 hours later I came to pick up my car.

The car started up very differently. It started up very weak, as if it had a weak battery. When driving and giving it a little gas at 3k rpm, it did not have the torque it usually has but felt very sluggish, as if it was running too rich. When revving the motor, the exhaust pops (backfires?) after letting off the gas with the rpms dropping. After driving it for a block, the service engine light came on. I returned to the shop immediately and they ran the code. It came up as a code for the camshaft sensor and the timing was off somehow. They checked to see if any of the connection to the camshaft sensors were loose, but everything was good. I am returning this Monday to let them figure out what is wrong.

They reset the check engine light twice, and on both times the light came back on. When I left, they resetted the light once again and it has not come back on during the 3 mile drive back to my house. However, the car still starts very weakly and the exhaust still pops. Any idea to what could be wrong? Was the flywheel installed wrong? Please help. Any input would be greatly appreciated. Thank you

I haven't had a chance to tear into my car yet... What other sensors would have to be messed with in order to do the work you had done? What I find most disturbing though is that you actually took the car from them in worse shape then when you dropped it off. It's also horrible that they even said the car was ready when it is obviously not. I wouldn't have even driven 3 miles back home with it backfiring and such. I cooked the cats on an old car of mine because of a cam positioning sensor, and it took less then 3 miles to do it.

I have a feeling that the flywheel is misaligned, but they want to run a test on the cam position sensor to make sure that it isn't the problem before they drop the transmission again. The first thing I noticed was the weak start up, but I assumed that was due to the new clutch and lightened flywheel. It wasn't until the check engine light came on that I knew for sure something wasn't right. The car doesn't backfire much, but does make popping sounds when the revs drop, something it had not done before. I am hoping that more people can varify that these symptoms are due to misaligned flywheel.

You are probably right. I bet this will have something to do with your crankshaft positioning sensor.

Since driving it 3 miles home from the shop after having it reset, the SES light did not turn on. So I decided to drive the car a little bit tonight to see if the SES light would come back on. When I started the car it started normal like before the clutch install. Once the engine warmed up, however, I restarted and the start up was once again weak. The SES light did not come on though.

I drove the car very conservatively, keeping the rpms below 3k and barely giving it more than 1/4 throttle. I went onto a highway and drove for 25 miles. Still the SES light did not turn on. On my way back as I was stopped at a light, I gave the car a few quick revs at half throttle to 4k. Immediately, the SES light came back on. I noticed that my exhaust sputters and pops a lot.

Does this further support the fact that the flywheel is misaligned? I assume that the SES light came on after revving the motor since during these revs, the flywheel is under the most stress since it is freely spinning. So any misaligned issues would immediate become apparent, resulting in the SES light that occured. If there was a problem with my cam position sensor as the code indicates, wouldn't the SES turn on during those 25 miles of easy driving?:dunno:

very possible that your flywheel is not aligned right....but does it have a timing ring on it?

im not sure on the Z since i havent worked on the trans yet but on my maxima...we have a cps (crank position sensor) between the engine and trans..the cps reads the timing ring on the flywheel....not sure if this would help you since its a Z...my jwt flywheel for the Z is at the shop so when i get a chance..i ll take a look at it.

I just installed a SPEC super twin clutch/flywheel combo and I had the same problems. Except my car would even start. I had to unplug the ckp sensor to get it to start. It ran in limp mode though and there was definitely a loss of power. I replaced the ckp sensor and no help. Turns out we didn't install the flywheel correctly. It was misaligned like you guys are saying. The bad thing was, there was no mention of this in the instructions provided by SPEC. I even called them about it and they had no idea. They said it shouldn't matter how it goes on. Well, we had to rip it all back apart again. Aftermarket flywheels are supposed to have some kind of a timing mark on them that has to be aligned with the crank, but mine didn't. Luckily, I still had the OEM flyweel. The OEM flywheel has one bolt whole that is smaller than all the others (at least on mine it did) so there is only one way to put it on. We put it back on and compared the notches on the exciter ring to the SPEC flywheel and aligned it that way. Put it all back together and problem was solved. Hopefully you can take it back to the shop that installed it for you and have them fix it for free because that's a lot of labor. Good Luck!!

This is great info... thanks! I am really starting to get a picture of things. I never checked if my aftermarket flywheel had the timing marks. I'll have to check with the vendor I bought it from. If not, I hope the shop still has my old flywheel :o

ahhh...350z fly wheels have timing marks...my maxima has a timing ring on the flywheel! well hope you get this problem fixed soon!

Question
 

OP what ended up happening to your car? I bought my G35 a year ago and since I bought it I've had the exact same issues. Lack of power, sluggish response, p0021 engine code, and crazy backfires. I've spent thousands of dollars already trying to fix it and having people tear apart the engine trying to find the cause. If it's just the old owner installing the flywheel incorrectly that would be amazing