Haven't checked the fuel pressure. I also haven't checked the purge valve yet. All the coolant/intake temps are normal. MAP readings are below 10mmHg. The CEL has been going on and off the this same issue now for the last several weeks (about every 50 miles or so). It also ran fine at our last track day. I think the first track day fault was the bad fuel injectors. This P0172 error is less serious since it's quite intermittent. So, while it's there, it hasn't been as large of a priority for me.

 

I guess you mean 10 inHg? Fuel injectors would be the other thing to suspect, of course. Glad you're having fun with the Fit in the meantime!

 

Not sure of the correct etiquette here whether I should start a new thread but my problem with my manual 2008 Fit Sport has been throwing some of the same codes, then they recently switched so I’ll share my story.

Had the problem about a year and a half. Since I bought the car it’s had a cold start stalling issue and slightly rough idle but initially ran perfectly while driving.

Was throwing the P0420 code. I replaced all plugs and coil packs myself (cylinder 3 has a helicoil insert) Plugs did not look that bad but cylinder 3 looks like it’s running a little bit hotter perhaps from helicoil itself making it hotter?

I also got a good deal on a brand new OEM catalytic converter with install because mine looked pretty bad and old possibly plugged, the original and I had 160K on it in the car Loses a quart of oil every 4 to 5000 miles, So basically down a little less than a quart every oil change. Also smell unburnt gas when it stalls at cold start And when warming up.

The code went away but still cold start stalling only on cold days, NOT when ambient temperature was warm during the night. Still Slightly rough idle.

Fast forward a year later 200k, Now cold start stalling all the time even when Ambient temperature is warm overnight. Rougher idle and dipping down very low almost stalling at times, Also engine started to stutter at speed occasionally, then got worse And lack of power ABOVE 4000 RPM.

Throwing codes P0172, P0108, and misfires on cylinders 3 and 4 plus random misfires P0304 P0303 P0300(random).

Ran a compression test and all cylinders measured 149 psi except I could not run proper test on cylinder 3 because I couldn’t find an insert to fit the compression tester at the time for the helicoil, but I was able to slightly screw in larger adapter but cylinder 3 blew it out of the well when I crank the engine, My opinion the compression is probably OK on 3 but not sure.

(Sidenote: cylinder 2 and 4 also measured 120 psi ONE TIME each since I tested each cylinder 4 times, but that is still within spec).

Unplugged each coil while it was running: 1,2, and 3 dropped RPMs consistently but cylinder 4 had no change. I replaced all the spark plugs and the coil pack for cylinder 4 as upon inspecting I noticed coil 4 had an imperfection at the end of coil.

This completely solved ALL stuttering issues for sure, car has slightly more power BUT still struggles getting past 4000 RPM in gears 4 and 5, still the consistent cold start stalling every single day and now it’s stalls even if I let the car sit for just 2 hours.

But now it’s throwing completely different codes.

The P0172 and P0108 have GONE AWAY completely and in their place I now have a
P0139 and P0304.

Car runs good when driving (still rough idle and cold start stalling) except for gears four and five struggle getting past 4000 RPM lack of power thereafter.

Now, I have a feeling that the valves do need to be adjusted, however I’m pretty sure that’s not the only problem.

I’m wondering if this could be related to the throttlebody?

I’ve cleaned mine a bit it doesn’t look bad at all, But I’ve heard there is a another air to fuel sensor or an IAC valve or something inside the throttle body they can get gunked up, but that you should replace the whole throttle body because it’s tuned from the factory. My throttlebody also makes a ringing noise and a click when I shut it off is that normal? (I Think it’s my throttlebody Making the noise, not positive).

I can’t get my MAP sensor out and neither have three mechanics been able to, we only succeeded in completely stripping the screw so we mad it flat head area and we still can’t get it out (even with lots of PB blaster sitting overnight). But when I unplug the MAP while the car is running, the engine shuts off, And also when I unplugged the map sensor and drove half a block I was capped at 3000 RPM with a hard stutter. I don’t think the MAP sensor is bad but perhaps I should buy a volt meter and learn how to do the diagnostic procedure.



To the original poster have you tried replacing the throttle body I’ve seen them for $50 online they say they’re guaranteed to come from a well working engine but since they cost a lot more new, I don’t know whether to trust those. Do you think it’s worth a shot?


Does the doctor have any suggestions for what possible ails my fit?

Thank you for reading.



edit: I also replaced my EGR valve gasket because it had a hole in it on the left side and cleaned the EGR valve thoroughly which seemed fine, Plunger moves fine and it wasn’t that dirty.

 

One other thing: my car has developed a new tick or rattle that goes away when I press down the clutch pedal… However I’m not sure it’s transmission related because the sound also comes and goes occasionally when I turn the air conditioning on and off.

In other words sometimes when at idle it’s not making the rattle at all and if I turn the AC on which creates a slightly rougher idle, the tick or rattle appears instantly but if I shut the AC off the rattle goes away instantly as well.

But, the rattle also always always goes away if I press down the clutch pedal… But does pressing down the clutch pedal create slightly less load on the engine? In other words could it be NOT transmission related for that sound even though it goes away when pressing down the clutch pedal, which would normally signal the transmission intake bearing??

My clutch is great I had it replaced 30,000 miles ago and it’s very strong, no clutch issues.

I’m wondering if this rattle is actually telling me the valves need to be adjusted, even though it goes away instantly when I depress the clutch pedal.

Much thanks for any suggestions.

To the original poster please let me know when you have a chance if you’ve fiddled with or tried replacing the throttlebody, thanks!

 

Ik im.very late to this thread but I thought it might help someone else who maybe having the same issue here my car also had this code I took it to the honda dealer to get it diagnosed they said it was the fuel injectors so they repaired them I took my car back home 2 days later the check engine light comes back on so I decided I'd change the maf sensor and clean the map sensor on my own but still that didn't fix the problem so I took it back to honda come to find out my throttle body was badly clogged they cleaned it out and that was the problem hope this helps anyone else going through a similar situation 😊