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1998 S70 P0171 vacuum leak, bad hoses 9155862 Topic is solved

Help, Advice and DIY Tutorials on Volvo's extremely popular car line -- Volvo's 1990s "bread and butter" cars -- powered by the ubiquitous and durable Volvo inline 5-cylinder engine.

1992 - 1997 850, 850 R, 850 T5-R, 850 T5, 850 GLT
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1997 - 2000 V70, V70 AWD
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rugbygrrl_15
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1998 S70 P0171 vacuum leak, bad hoses 9155862  Topic is solved

Post by rugbygrrl_15 » Sun Jun 02, 2013 7:48 am

Hey everyone,

I have a couple questions. If these answers lead to a successful DIY repair, I will gladly take many pictures and create a repair guide:)

1. My check engine light is on and I cannot smog check or register my car until my P0172 code is repaired. What system within the car does this error code fall under?
i.e. fuel system, Engine, or even Brakes. (I've got access to VADIS and diagrams to guide my repair efforts but I have to weed through a lot to get to the stuff I need.)

2. After replacing my MAF with the correct Bosch part, my check engine returned with the P0172 code, however, when I started driving to work at 4am (outside temp. about 60F) the check engine light was off but turned back on within 10mins. Does anyone recognize these symptoms?

3. In my opinon, my Haynes manual is a better door stop than a guide to fixing my 1998 S70. Can anyone recommend a better repair guide? Should I begin a search for an equivalent to my 240's "green book"?

Thanks



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Re: 1998 S70 P0172 just replaced MAF

Post by deepsouth » Sun Jun 02, 2013 10:40 am

Had the same problem on my S70. All Data says:

p0172
EFI-231 LONG-TERM FUEL TRIM, PART LOAD
EFI-232 LONG-TERM FUEL TRIM, IDLING

The Engine Control Module (ECM ) receives information from the Heated Oxygen Sensor (HO2S ) about the fuel/air mixture in the idling and partial load ranges. If the fuel/air mixture deviates from optimum the short term fuel trim will compensate for this by adjusting injection time so that optimum mixture is achieved. When the short-term fuel trim makes an adjustment, the integrator median must be adjusted by the long-term trim. When adaptation is almost at its maximum level diagnostic trouble code (DTC) EFI-232 (idling range - 0.48 ms to + 0.40 ms ) or diagnostic trouble code (DTC) EFI-231 (part load range 0.773ms to 1.227ms ) and the status message Upper limit (lean fuel/air mixture) or Lower limit (rich fuel/air mixture) will be stored.

Substitute Value


•None.

Possible Source(s)

Upper limit:


•Defective mass air flow (MAF) sensor
•Low Fuel pressure
•Air leakage
•Faulty pulsation damper
•Faulty sensor signals.

Lower limit:


•Defective Mass Air Flow (MAF ) Sensor
•High fuel pressure
•Leaking injectors
•Leaking Evaporative Emission (EVAP ) System
•Contaminated engine oil
•Oil level too high
•Faulty sensor signals.

Short explanation? For me it was a vacuum leak--The elbow behind the power steering pump that is under/behind the intake manifold. Here's a photo. If this elbow leaks it will throw a p0172.
Eric
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2000 S70 GLT SE, 175,000
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Ozark Lee
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Ozark Lee

Re: 1998 S70 P0172 just replaced MAF

Post by Ozark Lee » Sun Jun 02, 2013 4:40 pm

The elbow on the end of the intake manifold is the "usual suspect" but any vacuum leak or leak in the intake snorkel will cause that code.

You said you just changed the MAF. Is there any chance that the short vacuum line from the intake pipe to the turbo control valve got overlooked on re-assembly?

I always look at the last place I was working when I get a new code after I change something.

...Lee


'94 850 N/A 5 speed
'96 Platinum Edition Turbo
Previous:
1999 V70XC - Nautic Blue - Totaled while parked.
1999 V70XC - RIP - Wrecked Parts Car.
1998 S70 T5
1996 850 N/A
1989 740 GLT
1986 740 GLT
1972 142 Grand Luxe

demian5
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Re: 1998 S70 P0172 just replaced MAF

Post by demian5 » Tue Jun 11, 2013 1:30 am

I had to run a new vacuum hose across the engine to the PTC nipple from here for the rich code. I bought the elbows but the plastic tubing was too brittle and I didn't feel like pulling the intake for this.

All good and the code cleared the next day before I could get the scanner out and do it myself.



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abscate
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Re: 1998 S70 P0172 just replaced MAF

Post by abscate » Tue Jun 11, 2013 3:46 am

Your off-on observation is pointing to a vacuum leak as the likely culprit for your CHeck engine light (CEL). Take a picture of your vacuum hose diagram, print it out, and start at each piece doing a VAT inspection. That's not a European tax, that's Visual, Audible, and Tactile! :D


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Ozark Lee
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Re: 1998 S70 P0172 just replaced MAF

Post by Ozark Lee » Tue Jun 11, 2013 8:35 am

To the 3rd part of your question about repair guide resources. The Haynes for the 850 actually falls into the "decent" category. I'm not sure how good it is for the 70 series since I don't have one.

It is a tool in the tool box that I use. Other tools are the 850 manual that we host here on the site. Most of the resources in the 850 manual apply equally as well to the '98 70 series cars.

Another resource is VADIS or VIDA. Both can be had from P2P sites or you can buy a bootleg copy that someone else snagged off of one of the P2P sites on eBay. The eBay sellers refer to them as "Volvo Factory Service Manuals" and then list a bunch of cars that they cover. VADIS is typically under $20.00 on eBay.

VIDA needs a dual layer DVD player to read the disks or you can create virtual DVD drives on the hard drive with freeware programs like Gizmo. VIDA also wants more computing horsepower with 4 gb of RAM and Windows 7 Professional version. I've heard it will run under Windows XP Professional so long as it has enough RAM but I can't confirm that.

As far as repair instructions go VADIS and VIDA are fairly equivalent. VIDA interfaces with a DICE diagnostic tool and there are Chinese copies of that interface floating around in the $125 to $200 dollar range which puts it in the same ballpark as a good OBD-II code scanner. The VIDA/DICE combination is a very powerful tool. The DICE sellers typically include VIDA ad part of the package.

You are already using what is perhaps the best tool of all, this board. If something breaks on the car you are likely not the first person that it has happened to and the collective wisdom here will ultimately lead you to a solution to most problems.

...Lee


'94 850 N/A 5 speed
'96 Platinum Edition Turbo
Previous:
1999 V70XC - Nautic Blue - Totaled while parked.
1999 V70XC - RIP - Wrecked Parts Car.
1998 S70 T5
1996 850 N/A
1989 740 GLT
1986 740 GLT
1972 142 Grand Luxe

calvinshire
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Re: 1998 S70 P0172 just replaced MAF

Post by calvinshire » Sun Oct 13, 2013 6:31 pm

The photograph of the vacuum hose behind the power steering pump was very helpful. I found mine and it is cracked. Would someone be able to tell me the part number for a replacement? I don't want to pull the defective one without something in hand to put back on.



calvinshire
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calvinshire

Re: 1998 S70 P0172 just replaced MAF

Post by calvinshire » Wed Oct 16, 2013 6:19 pm

I went to a volvo dealer and purchased the correct vacuum "Coupling" - the one that is behind the power steering pump on my 1998 s70 non-turbo. For anyone reading this post who would like to replicate the purchase, the volvo part number is 9155862.



goVolvo
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Re: 1998 S70 P0172 just replaced MAF

Post by goVolvo » Tue Feb 10, 2015 5:36 pm

I got this too. P0172 "Bank 1 too rich". MAF is just replaced also. 1998 S70 non-turbo engine. I reset CEL and after 30 miles or so it comes back with P0172.

So vacuum leak will cause ECU to think air intake is low, so it would either open throttle more or inject less fuel. Why this causes exhaust oxygen too little, hence "bank 1 fuel too rich"?

Read multiple threads here about the elbow below the power steering pump. I looked at it roughly. Seems pretty clean and in good shape. I cannot reach it with finger so don't know if it really cracked. What else to look at? If do smoke test, which hose I should blow smoke into?



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Re: 1998 S70 P0172 just replaced MAF

Post by mecheng » Tue Feb 10, 2015 5:52 pm

Check the elbow "calvinshire refers to, common cause


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