Help!! Car Wont Start After Clutch Swap (25$ reward for solution!!)
 

*** SOLVED****

Out of all the cars Ive ever worked on Ive never been so stumped…. Just swapped a clutch in and now it won't start, yet it turns over just fine???
I officially have no ideas where to even begin… so Im offering 50$ to anyone who can lead me to the solution because I REALLY dont want to have it towed to a stealership.
2015 manual brz with prox key

Symptoms:
-wont start
-cranks perfectly fine
-key worked fine the night before
-no CEL
-all plugs plugged back in
-Doesnt even sputter or try to ignite…



What I did:
Swapped the clutch just exactly as the DIY says (including unplugging the battery), and changed the fluids with it.

Things Ive ruled out
-Battery is fine
-Starter turns it over fine
-Checked all fuses
-can hear fuel pump working
-rechecked all grounds
-has half tank of gas and started perfectly the night before
-(turns over, eliminating clutch switch, any jams, key, etc)


*** SOLUTION: Make sure the timing disk behind the flywheel does NOT rotate at all. Not 100% sure it was what caused it but after reinstalling everything and repositioning the disk it now starts.

Did you forget to plug something back in? Check any harnesses.

Also see if there are any codes set

No codes and there were only 2 plugs unplugged plus the battery, all are fine

Sounds like the anti theft system to me.

You sure you didn't pinch any wires between the block and bellhousing?

Absolutely positive.
Would the anti theft system allow it to still turn over?

I tried starting mine with the two plugs on top of the transmission unplugged and it fired right up (just fyi).

Does the exhaust smell like raw fuel?

Watch this.

[ame="https://www.youtube.com/watch?v=4uwZpFu8Z10"]https://www.youtube.com/watch?v=4uwZpFu8Z10[/ame]

I know his wasnt turning over. But it might be worth a watch.

Nope doesn't smell like fuel at all, I HIGHLY doubt its flooded

Yeah my key light goes green and it turns over fine so idk…?:iono:

Do you have the ability to scan for codes?
Have you tried disconnecting the battery again?
Perhaps check the owners manual under antitheft.


Is there a crank position sensor that reads off the flywheel? Because if the ECU doesn't see the crank position signal it won't fire the injectors or the coils.

No but there also aren't any codes being thrown…
Yeah twice
Going to do that, but wouldn't that cause that to not turn over at all?

Yeah thats my main idea, however theres a sensing disk behind the flywheel that senses the position and its on the right way (as I can see from the opening at the bottom of the trans.

Awesome, dealership is closed. Upping it to 50$

You sure you don't have that disk 180 out of phase or something like that? If you can pull the #1 coil put a plug in it and reconnect to the harness and watch if it fires, that can narrow down problems. If you get one spark, and one spark only the problem likely lies with the crank sensor or the tone wheel. My money is on the tone wheel not being installed correctly or damaged.

clutch switch not plugged in. Nvm, seems like the clutch is connected. lol

Ozzman, dont you have to pull lift the engine up like 4 inches to pull the plugs?

samisons- that would explain it if it would not turn over at all

You're supposed to but you can probably snake the coil out without raising the engine, use some random spark plug you have laying around to check for spark.

No, and no. There might be codes in the ecu that aren't giving a check engine light. Also if it's not picking up the disk, it will still turn over.

are the starter teeth actually lining up with the flywheel? Have you confirmed that the starter is actually turning the engine over and not just spinning freely?

Yep, Im quite familiar with cars, I know what the sound of an engaged starter and one that the solenoid doesn't kick it out and it turning over.

Its easier to pop the trans off than the plugs at the rate I'm going so Im going to pop the trans back out and check to see what the deal is. Ill post up after

Are you tuned on anything? If you have an Ecutek cable or OFT check for injection time and see if it's actually injecting and adding fuel. I actually did my clutch just 2 weeks ago myself, trying to remember anything.

You said the exhaust doesn't smell, but if it was injecting fuel as it should and not firing up you SHOULD smell it.

Crack the throttle while cranking. The ecu forgot how to idle or the spark plugs are wet.

No tune, bone stock (for now)
It doesn't even cough or attempt to start, so something isn't right, not the idle.

Gona drop the trans

Sometimes after pulling the battery it has to crank for a solid 6 seconds or more before it fires. It seems silly to me but have you tried just letting it crank for a long time?

- AdrianG

crank it for 20-30 seconds with the accel pedal about halfway down. There's an SB because the ecu forgets to reset the default throttle position for idle.

Does rpm show when engine cranking on instrument cluster?

And how about checking spark sparking?

Maybe some male pin bend on some kind connector?

Sory for bead grammar

Have no first hand knowedge of this issue but did an web search and several post from several car brands with a similar problem. Solutions were--> car was flooded, flywheel not lined up or backwards, sensors not re-connected or damaged during the install, something about a plunger not re-installed correctly and not going far enough, and grounds not reconnected or poor. Hope you figure it out...I am sure it is frustrating as hell!

No. Don't crank it for 30 seconds. I don't care if the "ecu forgets", it will still cough or stumble. Regardless of what the "default throttle" position is it will still try to start.

This isn't a carbed car, you absolutely don't have to crank it that long. - I'm willing to bet the crank sensor is not picking up the reluctor for some reason.

Or he forgot to put the ground on top of the bellhousing back on and the di computer isn't on.

Yeah those were all the first things I figured (like I said I do have a decent car background).
No I'm not cranking it for 30 seconds that would drain the battery or even possibly burn up the starter. Yeah I cranked it multiple times for up to 10 seconds.
No I wasn't quite that careless haha all grounds and all plugs are back in their places double triple n quadruple checked.

Almost off, just got the clutch to go, can't remember but I'm pretty sure the rpms didn't show but not positive (can't check now that the starters off but ill check again after its back)

Think I may have found it, The timing disk behind the flywheel appears to have rotated a bit, so that may be slightly in the realm of what was causing it. going to put it back now.

Well????
The suspense is killing me!

Ok well I'm not sure what it was but something along the lines when I redid it worked. I have a feeling it was the timing disk. Thorpedo ill shoot ya a pm.

Unfortunately now I have the problem of a grinding noise when decelerating between 2800 and 2200. Not sure if its the fact that I used redline MTL or what. And the struggle continues >.<

Did you get a lightweight flywheel? It could just be gear chatter, I have a similar sound on deceleration. It's common with lightweight flywheels.

Yuuuuuup Just found that out. Glad to know its normal. Wish there was a way to fix it

Going to start a separate thread to see if anyone knows of any way to fix that.

To fix what? Gear chatter from a lightweight flywheel? The stock flywheel is engineered to be as light ad absolutely possible without causing gear chatter. Some manufacturers use a dual mass flywheel in an attempt to go even lighter without causing chatter. A lighter than stock flywheel WILL chatter no matter what you do. It's physics.

Ugh.... No

OP just do some searching, there is lots of evidence out there that Reaper is incorrect. I know of two cars locally that run lightweight flywheels without gear chatter.

"It's physics"..... come on man.

? Good luck. Gear chatter is caused by a flywheel not holding enough inertia and on deceleration. This is well known and the purpose of dual mass flywheels.
I'm not arguing this. Let the world know if you find a fix. Because BMW couldnt.

You beat me to it!!! That was the issue I had when I replaced my first clutch. That damn disk behind the flywheel LOL! I'm glad you figured it out :)


As for the other questions on chatter. I'm getting some pretty good chatter between 2-3K RPMs on acceleration and deceleration. I'm not 100% sure it is the clutch but it is quite possible. I'd love to troubleshoot it but I haven't found much on alternate possibilities than the clutch creating that noise. I'm currently using an Exedy Stage 4 clutch.

- Exedy Forged Chromoly Flywheel
- Exedy 6 Pad Cerametallic Friction Disc
- Exedy Hyper-single Forged Aluminum Cover

I'll have to check out the new thread when created. :)