2007 Fit Crank Sensor Keeps Going Bad

[mckenziepiping]

Hey all, I just got back from my regular garage for the 3rd time regarding the same problem and this time he said he simply can't figure out what's going on and doesn't want me to waste money by continuously replacing the same part without addressing the root cause. He advised me to try gaining some insight from forums and/or bring it to the dealership for a diagnostic. It seems as though something is causing my crank sensor to go bad repeatedly. Each time I replace it, the car works well for some time and then the sensor goes bad again.

About 4 months ago, the car start exhibiting 3 symptoms that will always start intermittently while driving and after about 10 min of driving, they happen consistently:

1) Inability to exceed 3000RPM. Once I hit 3000RPM, any attempt to give it more gas will just make the car stutter and I won't get any extra acceleration. If I want to speed up after hitting that RPM, I need to upshift. This also means the car can't go faster than 90km/h (55-56mph) because that's when I hit 3000RPM in 5th gear.

2) When I depress the clutch or otherwise shift into neutral, the engine stalls. Sometimes it'll even stall when I'm rolling at high speed if I depress the clutch and don't shift quickly enough. After stalling, I can start the car again easily by turning the key.

3) At all RPM's below 3000, there will be random stutters that are short-lived. Not like the ones at 3000 which will last for as long as I keep the throttle open to maintain those RPM's.

These symptoms never occur within the first 5 min of the first drive of the day (unless it's really hot outside). They only start once the engine has warmed up. I'll try to take a video and post it here soon.

When this started happening, I brought it to my mechanic and the code said crank sensor fault so he replaced that. Then the car worked fine for 2-3 days until the same problems started happening again. Same code so he replaced the crank sensor again (didn't charge me for it, since we figured the new crank sensor must be a lemon). Then the car worked perfectly well for 5000km (~3000mi) until a few days ago when the problem returned. We haven't even bothered checking the code this time because of the highly specific nature of the symptoms being exactly the same as the previous times.

Most of the explanations I can find online regarding other issues that can cause a crank sensor to fail seem inconsistent with the fact that the most recent replacement bought the car so much time & distance.

Anyone have any ideas?

[Stealthee]

It's possible you have some thrust bearing issues internal to the engine. If they are having issues/failing when you press the clutch the crank is being shoved forward and that can cause issues with the crank sensor.

This is just a theory, but it was my initial theory before even reading the entire post, then when you said it will stall it when you press the clutch it became even more plausible.

[mckenziepiping]

Thank you! My own research brought me to a similar conclusion. Well that or the wiring harness. But if it were electrical, I don't think the car would start so reliably when turning the key right after stalling.

I'm just researching the problem you've mentioned now. Do you know if thrust bearing, clutch release bearing and throwout bearing are all different terms for the same part?

[mckenziepiping]

Also the bearing isn’t making any of the telltale noises when the clutch is moved through various positions while the car is idling. Could this rule out the bearing issue? This video shows the noise I’m looking for: https://youtu.be/_FcDOqHav7o

[mckenziepiping]

The nature of the issue has changed from the details mentioned in my earlier post. It's now very random. Sudden and short-lived hiccups/shakes when driving, followed by a stall once revs are low. Seems to be independent from the clutch and totally dependent on revs. The issue is temporarily remedied by turning off the engine and starting it again several times in a row. I've been finding myself turning off the engine while driving and then just bump-starting (dumping the clutch with the key set to position II) while in 2nd or 3rd gear, testing an aggressive acceleration and if problem recurs, then I just restart the engine and eventually it'll run just fine for hours. I just did a scan with my Bluetooth OBD and saw crank sensor again. *But as explained in the original post, something keeps causing that sensor to need replacing repeatedly.*

[fredjacksonsan]

Loose wiring? Or even physical contact between engine parts and the sensor.

What codes is it throwing?

[mckenziepiping]

Could loose wiring destroy a crank sensor? Each time the crank sensor is replaced, the car works normally again for some time.

[fredjacksonsan]

Originally Posted by mckenziepiping

Could loose wiring destroy a crank sensor? Each time the crank sensor is replaced, the car works normally again for some time.

Yeah I thought of that after I posted (when I read the rest of your posts)