What's up volvoforums people? Been a while since I've posted on here, hoping you guys can help me out.
I've got a 2000 S40 that's been a pretty reliable car for the past year but today I started having idle and accelerating issues (rough idle, hesitant under acceleration). It threw a misfire code, so I replaced the plugs but that only helped a little bit (acceleration got slightly better). It's still throwing a misfire code for cylinder 3 and unplugging the injector for that cylinder has little effect on how the car runs, so next weekend I'm going to attempt to replace the injector. My questions are:

- is it ok to only replace one injector at a time?
- how hard is it to pull the fuel rail/injector assembly out without damaging anything? I've seen videos where people just grabbed the rail with two hands and pulled the rail towards them, is it really that easy to do?
- is there anything else that could cause a misfire code in that cylinder?
- if I replace the injector and it doesn't fix the problem, how do I burn the car to the ground in a way that looks like an accident? Hahaha jk. Mostly.

Any advice is greatly appreciated.

 

It's ok to replace a single injector, could be clogged and need a cleaning only. Also could be a coil or bad wire. You could try inspecting the coil for cracks and swap it with the other to see if the problems move to another cylinder.

 

It's normally the coils or wires that cause misfires. They get hairline cracks on the plastic part that goes down into the spark plug hole. These cracks allow the spark to jump to the head causing your misfire.

 

SF, not sure where you are located or if you need the car daily, but there are services which clean injectors (ie via ultrasonic "jewelry" cleaners). I agree with Hudini to start with the plugs/wires/coils however. If you pull the injector(s) best to have new o-rings handy to ensure a tight seal. You can also shop eBay for a used replacement set (then send those for cleaning before install) and resell your old ones... (I did that on my 850T)

 

I'm in Columbia, SC.
The car is my daily, but I've got other cars to drive, it's just sitting in the garage right now.
I've already changed the plugs, so should my next step be to have the injectors cleaned and change the wires/coils? Should new injectors be my last choice?

 

Yes, I'd say a stage 0 tune up is the next step. Since you have an 00 S40 (like mine), its really the age not the miles. Next step would be wires (there's only two in this model - one plug fires directly from the coil a second fires from a wire - and there are two coils) not very expensive - check out FCP Euro or EEuroparts for good prices. Yes removal of the fuel rail is that easy. The aluminum cover plate just pops up (its held in by a clip) if you want to look see. There's also a schraeder valve (like a tire) to test/relieve fuel pressure - if you remove the injector from the rail, have a rag handy as they will have some fuel behind them. When you say new injectors - do you mean replacements or brand new? Injectors can be cleaned with good results - you can try a home solution (see vids on YouTube) or a service. It may be just as easy to pick up a set from a yard near by or get a spare from ebay for about $25.

 

A well-known European car based shop around here told me yesterday that the injectors on a Volvo almost never have issues, but the coils are commonly replaced items. I'm going to swap the coils on injectors 3 and 4 and then run the obd2 scanner again. If it's the coil, the misfire code should move from cylinder 3 to cylinder 4, correct?
Is there anything wrong with remanufactured or cleaned junkyard injectors should the need arise? New injectors are $100+ per piece and are special order at every parts store I've called.

 

With the ignition system on the 1.9L engine the ECM cannot reliably tell you whether it's the cylinder with the coil or it's paired cylinder with the wire only. You would swap both the coils and the wires to make sure.

Te reason is because when the coil fires it also fires the wire to the other cylinder. Since one cylinder is on the compression stroke and one cylinder is on the exhaust stroke, only the cylinder on the compression stroke fires.

 

SF, I don't see anything wrong with getting recycled injectors - they are essentially an electrically operated valve. I was reading somewhere that 98% of injector problems are due to crud clogging the flow and spray pattern vs a broken valve (ie bad solenoid switch). I agree its rare for injectors to even crud up where the coils are a common replacement item every 100K miles. If after replacing wires, coils you still suspect the injector you can make a home made tester using a couple of AA batteries and a spray can of carb cleaner (to push some fluid through) - see Youtube for ideas.

 

If cylinder 2 fires off of the coil on cylinder 3, wouldn't a bad coil mean I'd have two misfiring cylinders? I'm going to try to find a place that'll clean injectors tomorrow, seems like the average cost of that service is around $120, seems worth it (I hope).
I haven't had time to mess with the car this week, probably won't be able to get under the hood until Saturday.

 

I can almost guarantee it's not your injectors but if you want to go that route I highly recommend Hurst Injector Service in Fitchburg, Mass.

The DIY type of injector cleaning as seen on YouTube is completely worthless, don't bother with that. To remove the internal varnish the injectors need to be cycled while being ultrasonically cleaned with heated cleaning fluid.

 

No because the coil itself is not the problem. It's the plastic part of the coil that sticks down inside the spark plug hole. This part will have hairline cracks that allow the spark from the good coil to jump to the head. Since the spark plug wire is connected directly from the coil to the paired cylinder spark plug connector (what is its name?) you could have one misfire and one perfectly normal cylinder.

 

Mass. is kind of a far drive from SC for an injector cleaning haha. Having had injector issues with my T/A in the past, my gut instinct tells me that it's the injector that's bad, but all you volvo-knowledgeable people tell me it's something on the spark side so I'm going to trust y'all (that's why I came here in the first place).
Does the injector cleaner that gets poured in the gas tank do any good?

 

If you drive your car to a place that offers "injector cleaning," they are going to hook up a 3M injector cleaning kit (I have one) to your fuel rail and run a $10 can of this stuff through your injectors.



This service is a great little profit center for the shop (15 minute job - $120) but not so great at actually cleaning your injectors.

The only way to properly clean your injectors is to remove them from your car and ship them to a place that has the equipment (heated ultrasonic cleaner, flow bench) to clean and test them.

 

Agreed. I had this exact same problem a short time ago, it was even giving me the same misfire on cyl 3. Changed the coils and problem solved.


In my case I could see the crack in the plastic tube that goes down from the coil to the spark plug. I would pull the coils and look them over. The crack was pretty fine but in sunlight at the right angle it was pretty noticeable.


I wouldn't mess with your injectors until you have ruled out the wires and coils.

 

I agree with Migs on the injector cleaning. My comment was more about testing whether the injector is totally clogged or broken. There are services which will clean using ultrasonic for about $10-20 per injector which will truly recondition them. Having several high mileage cars, and never having a failed injector, I'd focus on the coil/spark first.

 

Exactly.

 

I would also agree with those who say it isn't likely an injector. I think I've replaced one, maybe two, injectors in over 10 years working on nothing but Volvo's.

If the coils, wires and plugs don't fix it, I'd do a compression and cylinder leakage test next.

 

Alright I'm gonna get a new coil tomorrow, should they be replaced in pairs? Any reason to do the wires too?

 

the Gen 1 S40s only have two spark plug wires - Bougicord's can be found for $30. I've seen plenty of wires fail due to age. If you have a dark garage (ie at night), try removing the cover and start the car - you may see it arc from the coil or plug wire...