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Can Cylinder 5 Misfire / Clogged Injector Unclog?

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
1997 - 2000 S70, S70 AWD
1997 - 2000 V70, V70 AWD
1997 - 2000 V70-XC
1997 - 2004 C70

AnyMajorDude
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Can Cylinder 5 Misfire / Clogged Injector Unclog?

Post by AnyMajorDude » Tue Mar 26, 2019 10:22 am

2000 V70 with 150K miles has been diagnosed with a clogged injector and misfire in cyl 5.

Fuel injector cleaner has been added to the fuel since diagnosis. I do not have any codes or other metrics.

Can this resolve on its own by running the vehicle at idle or local driving? What are dangers of trying this?

Thanks in advance.

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abscate
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Re: Can Cylinder 5 Misfire / Clogged Injector Unclog?

Post by abscate » Tue Mar 26, 2019 11:44 am

It’s so rare that I don’t think we have enough data to help here.

How sure are you on the diagnosis

0= crystal ball told you
1= Mechanic said “ it’s a clogged injector”
....
10. You have removed all th einjectors and tested the flow rates into graduated cylinders
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Re: Can Cylinder 5 Misfire / Clogged Injector Unclog?

Post by oragex » Tue Mar 26, 2019 12:09 pm

as above, don't trust right away what mechanics say

may as well be a leaking valve seal, very common on these engines

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Re: Can Cylinder 5 Misfire / Clogged Injector Unclog?

Post by greenellie » Tue Mar 26, 2019 12:11 pm

How are your vacuum lines? Also might be a wonky valve seal. Misfires around that mileage are more often caused by vacuum leaks. I had to replace a few until I finally found the leak that was causing my misfiring. I hope your car is doing better, get back to me! 8)

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Re: Can Cylinder 5 Misfire / Clogged Injector Unclog?

Post by AnyMajorDude » Tue Mar 26, 2019 1:41 pm

I don't trust the local mechanic, that is why I am seeking forum advice. I will inquire if the vacuum lines and valve seals were considered. Idling and local driving... yes or no?

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Re: Can Cylinder 5 Misfire / Clogged Injector Unclog?

Post by erikv11 » Tue Mar 26, 2019 1:48 pm

AnyMajorDude wrote:
Tue Mar 26, 2019 10:22 am
2000 V70 with 150K miles has been diagnosed with a clogged injector and misfire in cyl 5.

Fuel injector cleaner has been added to the fuel since diagnosis. I do not have any codes or other metrics.

Can this resolve on its own by running the vehicle at idle or local driving? What are dangers of trying this?

Thanks in advance.
I wouldn't run more than a couple weeks on a clogged injector (if indeed, that is actually the problem). A clogged injector will make the cylinder run lean = excessive heat = burnt valves = thousand bucks. A week should be ok, depending on the demands on the car.

A good way to know if it is the injector is to swap them between two cylinders, see if the misfire follows the injector.

#5 misfire is often a leak in the intake manifold gasket.
'95 854 T5-R, Motronic 4.4, 185k
'96 855 NA, 145k
'98 S70 NA, 220k (living out west)
'98 V70, T5 tune-injectors-turbo, LPT engine, 286k
'06 S60 R, 167k
'99 Camry V6 :shock: 125k
gone: '96 NA 850 210k, '98 NA V70 182k

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