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Discussion Starter · #1 ·
Hello! Car- S60 2001 2.4 (170hp) AT. Found out about this code 2 months ago when bought this car. Just registred and was viewing alot of these P0172 codes and even solved ones most of them had vacuum leak! Tryed to check for them but could not find them tho I dont know where all hoses are located so gona have to take it to service i guess. When engine is warm idle is shaking a bit not a lot but like once in 15sec goes from 800 to 700, also at cold start rpm goes to 1500 then drops to like 1000 and goes back up to 1500. Fuel consumption is increased a bit.
FUELSYS1_________CL____CL______CL_____CL_____CL (Fuel system status 1)
FUELSYS2_________N/A___N/A_____N/A____N/A____N/A (Fuel system status 2)
LOAD_PCT(%)_____27.8___35.3____23.1___22.7____19.6 (Calculated load Value)
ETC(C)___________88_____88_____87_____86______85 (Engine coolant temp)
SHRTFT1(%)______0.0_____7.0____9.4_____18.0____20.3 (Short term fuel Trim-Bank1)
LONGFT1(%)______-23.4___-23.4__-21.3___-23.4____-22.3 (Long term fuel trim-Bank1)
MAP(kPa)_________31_____35______30____33______36 (Intake mainfold Absolute pressure)
RMP(/min)________748_____968____1776___2570___2763 (RMP)
Vss(km/h)________0______0_______0______0_______0 (Speed)
SPARKADV(temp)__7______17______36_____38______42 (ignition timing advance for 1)
IAT(C, temp)______52_____53______53_____53______54 (Intake air temp)
MAF(g/s)_________4.14____6.18____7.95____9.39____14.01 (MAss air flow sesnsor)
TP(%)___________7.1_____15.7____16.5____18.4____22.7 (Absolute Throttle position)
O2B1S1(V)_______0.500___0.560___0.475___0.500___0.605 (02 sensor output Voltage(B1S1)
SHRTFTB1S1(%)___0.0_____14.1____12.5___12.5_____18.0 (Short term fuel trim(B1S1)
O2B1S2(V)_______0.750___0.025___0.125___0.130___0.020 (O2 sensor output voltage(B1S2)
SHRTFTB1S2(%)___0.0_____-0.8___-0.8_____0.0_____-0.8 (Short term, fuel trim(B1S2)

So the code is P0172 System too rich Bank1.
- I have clened the throttle valve
- Cleaned MAF( but in tests shown i found out that it runs normal g/s as it should for my engine)
- Sprayed carb cleaner around Intake and throttle body, no change in idle
- Replaced Air filter and Fuel filter

Besause i cant locate all Vacuum hoses myself(didnt find any diagram of showing them) i will take it so some service shop for them to check.
Havnet yet checked fuel pressure(dont have tools for that)
Havent check fuel injectors

About OBD data, Fuel trim show greatly added fuel, but i am still learning about them, O2 2 sensor voltage drops big and if its bad shouldn there be a seperate code for that?
Anyting to say about OBD data or what to do, check i didnt mention? I am learning about this stuff so dont be harsh to me. :)
 

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Discussion Starter · #2 ·
was still checking for unattached hoses or with crack and found this..In second image is close up and one green connection have hose other dont. i think its eletrical connection but why there is no hose to it and i cant find any hanging there without connection...any ideas of what this is?
 

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are you sure those MAF readings are in spec? For some reason, the spec of 14 g/s at idle is in my head.

Your LTFT are compensating for a rich condition (too much fuel or too little air). If the ECM expects 14 g/s at idle and your MAF is saying 4.14 g/s, that would be "too little air" and the ECM would respond by dialing back the fuel trim to match the lower air flow the MAF is reporting.

If 4 g/s from the MAF at idle is in fact the correct spec, then nevermind. But I am pretty confident that there is a problem in those LTFT readings. Find out what is causing that.
 

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Discussion Starter · #6 · (Edited)
Was at specific volvo mechanic and he was diagnosing for about 30min and cheking engine compartment, sad there are no leaks. He said i should replace rear 02 sensor which had strange values and at time it just showed 0.00V and if problem dont go away replacing MAF is last option. Already ordered O2 sensor and will let you know if it did the job.

As for qaz996 i started to wonder myslef but 4-5g/s should around for many cars at ilde. 2005 2,5T have the same value but will search around just be sure.
Also this code is triggered by O2 sensor not MAF, so first to check should be O2 sensor, but yeah if maf reads not enough air it should fck up everything. tho when i cleaned it and it was dirty i didnt notice any change and check enagine light re-apeared.

BTW VIDA DICE should have this info about default values, if anyone have such info feel free to post it. :)
 

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I'm at work now so I have VIDA access. The spec I have is "Normal value with the engine at operating temperature and idling, neutral and air conditioning (A/C) switched off: approximately 14 kilograms per hour."

So whatever that converts to grams/second.

I agree w/ you mechanic. o2's affect fuel trim as well. Sounds like you're in good hands. :thumbup:
 

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Discussion Starter · #8 ·
I'm at work now so I have VIDA access. The spec I have is "Normal value with the engine at operating temperature and idling, neutral and air conditioning (A/C) switched off: approximately 14 kilograms per hour."

So whatever that converts to grams/second.

I agree w/ you mechanic. o2's affect fuel trim as well. Sounds like you're in good hands. :thumbup:
its around 3.9 g/s so not far away from my avg. This was specific for my engine right?
Tho its close the gap becomes bigger at higher values.
 

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Discussion Starter · #10 · (Edited)
OK so i fixed it, changed rear O2 sensor and it was no good, check engine came up again, then i clened mass air flow sensor myself (it was previously clened in service shop). and checnk engine light havent come up for 2weeks now or about 20 full engine warm ups(usualy takes 6-7 to get back on), also there is no more rmp strange jumping when i start cold. Also i had this hesitation in engine when i step on gas like 0,2-0,5 sec, and its gone too, fuel consopmtion is lower a bit now.
So yeah P0172 and have some symthoms as i did, clean MAF really good ( not just two visible wires but theres also two wires deeper inside MAF), i used electrical contact cleaner. Also if check engine goes back on after month or two this might mean you have to replace it or just clean it again, until you get tired of it. OBD data show very small fuel trim adjustments now, so everynthing is good :)
Hope this helps to anyone. And thanks Qaz996 for help :)
 

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Discussion Starter · #11 ·
I guess mods can change name of topic only so it would be nice to add ''solved'' at end so people can learn from this :)
 
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