Just bought an 07 with P0172 - Page 4 - Unofficial Honda FIT Forums


1st Generation (GD 01-08) The one that started it all! Generation specific talk and questions here!

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  #61  
Old 05-17-2017, 09:15 PM
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Would you be able unplug each injector one at the time and note fuel trim change (this way we will rule out leaking injector (just in case).
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  #62  
Old 05-17-2017, 09:19 PM
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Good call. On it...

This time around I warmed the engine up and they all performed about he same. about -10 stft with any injector wire pulled.

As it was nearing warmed up (160F) I noticed that the o2 voltage reading was holding a solid .65ish, then dropping to .1, holding that for a second, and then climbing back to .65 for another 10 seconds and then repeating. By the time I finished the test it was just flatlining at around .7v.

Last edited by gijoe985; 05-17-2017 at 09:32 PM.
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  #63  
Old 05-17-2017, 09:25 PM
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Try unplugging remaining injectors (on idle after warming up ) one at the time and check the trim changes.
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  #64  
Old 05-18-2017, 07:36 AM
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Quote:
Originally Posted by doctor J View Post
Try unplugging remaining injectors (on idle after warming up ) one at the time and check the trim changes.
I did. They all had the same effect. Went from -30ish to -10ish dor each injector.
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  #65  
Old 05-18-2017, 10:59 AM
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on your last scanner shot the idle was at 850 with TP around 2.4% it should be 750 with lights and blower off did you disconnect something at this time? Also do you still using K&N air filter?
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  #66  
Old 05-18-2017, 03:38 PM
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Quote:
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on your last scanner shot the idle was at 850 with TP around 2.4% it should be 750 with lights and blower off did you disconnect something at this time? Also do you still using K&N air filter?
AC may have been on.

Yes I am, but I did remove it, clean it, and recoat it with the proper amount of oil. The previous owner installed it and I no longer have the airbox. It'd be a pain to locate one. I could run no air filter for a short bit? Everything inside seemed clean. MAP sensor and IAT sensor...
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  #67  
Old 05-18-2017, 07:49 PM
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See above on the air filter, but I did confirm that my idle is at 850, consistently, AC off, lights off, etc.

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  #68  
Old 05-18-2017, 09:53 PM
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I have stupid idea (wish I had it earlier). When you checked your valve clearances and put #1 cylinder in TDC (lined UP mark of the cam sprocket with cylinder head) have you confirmed that TDC mark on crank pulley lined up with pointer on the timing chain cover as well?
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  #69  
Old 05-19-2017, 10:56 AM
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So, if the engine idle speed without load is 850 rpm in neutral with throttle fully closed, the ECU may try to lower the idle by cutting amount of fuel at idle ?? It is unusual behavior to me (however, if RPM is not over 1000 IIRC (in tolerances), the idle will not surge).
Can you post a picture of your intake set up (or link to the model if known)?
When I removed air cleaner assembly on 98 Camry 4 cylinder that uses MAP (speed density control) the rpms went to 1500 and stayed there after I started engine up.
(I did master cylinder port blocking test to troubleshoot soft pedal issue)
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  #70  
Old 05-19-2017, 11:28 AM
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  #71  
Old 05-19-2017, 02:14 PM
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Originally Posted by doctor J View Post
i wish!


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  #72  
Old 05-19-2017, 03:55 PM
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primitive conversion
EGR valve looks different (connector at 3 o'clock position not at 12 o'clock) but may not be relevant. Any modification to under hood fuse box (ELD control?)
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  #73  
Old 05-20-2017, 03:08 PM
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I don't think there are any modifications in the fose box, but I'll check.

You are right on the EGR! That's odd. I can't find any pictures online of one pointed like mine...

So, maybe the egr is not circulating exhaust gas in (stuck closed) and the computer is expecting the extra flow, hence running rich? Maybe? Hmm.....
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  #74  
Old 05-20-2017, 03:09 PM
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Maybe they blocked it off as a "modification"? I'll have to check...
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  #75  
Old 05-20-2017, 06:12 PM
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Well, another small observation, after pulling a tree stump out with my fit (a small tree... just needed about 105hp of nudging), my car was obviously warmed up and I had the AC running to keep my son cool and the stft was lower -25. Then I turned it off and it went to -29. And back and forth. With the extra load on the motor it is slightly less rich.

Also, I visually inspected the EGR and if someone had it apart, there are 3 screws inside. I think you could reassemble it wrong and have it face ar 3 o'clock like mine. I guess I could take it apart. I'm short on ideas...
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  #76  
Old 05-20-2017, 09:53 PM
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Hmm, this Delphi rep on youtube said that a stuck open EGR could cause the p0172. "It will dilute the fresh air and so less dense exhaust air will get in and it will be rich. " The only problem with that theory is that I assume the idle would be garbage.

I do have that 850 idle. What might cause that? Should I try adjusting my idle, just to see...


EDIT- I just kept watching, possible a rupture in the vacuum operated fuel pressure regulator. It can leak fuel from the regulator into the vacuum line. (I'm I just getting desperate?)


Last edited by gijoe985; 05-20-2017 at 09:55 PM.
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  #77  
Old 05-20-2017, 10:06 PM
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On Club Jazz, someone described their stuck closed EGR as "Symtoms as described by others: at 1500rpm cruise it behaved like a rat was dancing on the throttle cable" and I can say that my one performance complaint is that at very low throttle, cruising, it does kinda bounce. I just thought it was me... I'm going to take it off and look...
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  #78  
Old 05-20-2017, 11:06 PM
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The fuel line is returnless with relief valve type pressure regulator in the gas tank; in the fuel rail the gas only goes one way.
the idle that high can be due to "hacking" idle up diode, programming of the ECU or low restriction intake (as observed on 1997 Camry after removing entire air cleaner box)
The leaking EGR will cause vacuum loss at idle (which will reflect MAP reading, but it looks normal);if EGR valve head (that seals the gas flow) is ground off on one side (so it seats but not seals) it may allow extensive flow without setting a code
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  #79  
Old 05-21-2017, 06:41 AM
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There is the cavity on the intake that could coke closed with soot and act like a malfunction in the EGR, as well as a hose that is under there that could leak vacuum if it was old/cracked/loose.

Your motor has a lot of dusty sandy stuff,, I have seen that kind of stuff infiltrate places it shouldn't and cause the most bizarre problems,, Especially sensor heads, connectors and relays,,, so some compressed air in the fuse box area, the connectors Pull the relays and check for grunge under them.
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  #80  
Old 05-21-2017, 09:28 PM
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On my car I found dust and sand under rubber boot of C103 connector (that provides power to the ign.coils and both speed sensors!
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