1999 s70 (GLT) 2.5L turbo

Check engine light Po303 is on which indicates a misfire #3.
I have replaced all the spark plugs with Volvo dealership plugs.
I switched coils with firing order plug 3 and 5 to see if the code would move and it DID NOT.
I then switched injectors with firing order plug 3 and 5 to see if the code would move and it DID NOT.
The vehicle is still idling rough and takes a moment to start on cold starts. Once vehicle is warm is appears to run fine, but still idles rough when stopped.
After all the changes the code remains the same.

I've seen discussions about compression and possible wiring. Can anyone please give helpful information?

 

#1 Issues with these cars is with burnt valves. Do a compression test.

 

Thank you rspi.
After watching the video it sounds like there is a good chance the valve is burnt. I plan on taking it in to get a compression test. One thing that was confusing in the video was that he kept referring to the actual spark plug number as they lay and not the firing order. Does a misfire indicate the firing order of the plugs or the order as they sit in the car?
Really don't like the idea of a burnt valve, sounds expensive.

 

Well, the cylinders do not move. Firing order has nothing to do with it. If #1 is misfiring, it will misfire regardless of the order.

If you can figure out how to pull a spark plug, you can do a compression test yourself. Just go purchase a gauge for $40 and do the test yourself. Pull a plug, screw in the gauge, disconnect the fuel and spark, crank the car.

As for the issue, it is what it is. Nothing you can do about that but fix it. If you have a bad spark plug, the cost will be $4. If you have a bad wire, replace them all $50. If it's a burnt valve, you need to know that so you can decide if you are going to fix the car or move on. Burnt valves cost as much as a head gasket job.

 

Thanks again.
I have rented a compression tester from my local parts store and will be doing the test myself. I have become pretty handy under the hood since getting the car. I enjoy the satisfaction of making a repair myself not to mention the money saved.
Like I stated in my original post I switched out coils and injectors on misfire #3. But I was going by firing order because I thought the code read firing order and not order of plugs how they sit in car. Appreciate the clarification.
Your videos are fantastic by the way.

 

The error actually tells you which cylinder is missing. The car has the cylinders in order from front (timing belt side) to rear (rotor end) 1 - 5. So if it says #3 is missing, that is the cylinder in the middle. If it says #1 it's the one closest to the timing belt.

How did your test results come out?

 

rspi,
These are the readings I obtained when I did the compression test.
#1 cyl dry 150 wet 210
#2 cyl dry 155 wet 220
#3 cyl dry 0 wet 0
#4 cyl dry 155 wet 195
#5 cyl dry 155 wet 200
Now the release valve on the gauge didnt seem to want to hold my readings but overall these should be pretty close. Based on your video is this a piston issue? And if so what is the approximate repair cost? Trying to get idea if going to be worth fixing.
Again thank you.

 

I also wanted to add that it appears that my PCV system is clogged. I performed your dipstick test and there was smoke. I also performed the glove test and it blew the glove up.

 

Ouch! I would say that you have a burnt valve. Common for cars of this age and these Volvo's have their share of them.

To fix the valve, you will need to pull the head, change the valve, then install a new gasket and put everything back together. Chances are, you have an injector that is not working properly that caused the valve to burn so you should get that injector (the one that was there) tested. How did that spark plug look?

You can actually drive the car with the bad cylinder if you really need to (if it will run). Unplug that injector (and coil if you'd like) and drive it till you can't stand it anymore.

I did a head job on my daughter's car, it cost me about $850. A good quality valve cost $75. If your car has a VVT exhaust cam, it adds another degree of difficulty to the job and may require a special tool to DIY. I actually have written instructions and a YouTube video on doing a head on the '98 car, again, if you have a VVT exhaust cam, that would be the main difference.

You can get a rebuilt head for about $530 from Florida. You can likely get your head rebuilt for about $450. I can get you a head for about $410. You should be able to get your injector(s) tested and repaired for maybe $100. Labor to have the head replaced by a shop will likely cost between $800 and $1,200. If you have basic tools and have to purchase what is needed to do the job, I believe I paid about $120 on tools. If you have the VVT, not sure what that tool will cost but you may be able to poke around to figure it out. May even be able to find someone that has one that would loan or sell you theirs.

If you do the work yourself, expect to be out of pocket about $1,100, not counting any VVT tools.

If you have to pay to have the work done, my guess would be between $1,600 to $2,400. Add in the cost of the PCV system and you will add another $250 to the job (parts $150).

If you have any questions please let me know. I hope this info is clear.

Head Removal and Installation, Volvo 850 / S70 Turbo B5234T, B5254T, Head gasket replacement, valve replacement.

 

If you are strapped for $ and want to attempt fixing the valve, let me know, I'll write you a process for replacing/re-lapping valves. It's trivial once the head is out but it also means the head surface won't get planed, etc.

 

Thank you rspi for all the information. I have become pretty handy under the hood and if I was being honest I really want to try fixing it myself, but just don't feel that confident doing a job this detailed by myself.

Anyway I have a long time mechanic that I trust and I am going to let him take a more in depth look at the problem and give me an idea of what I am looking at and cost.

I will certainly keep posting to share my experiences and how I was able to get it fixed.

Also kwatt, I will let you know about your offer. Again thank you both.

 

I look forward to hearing how it was fixed. Everytime someone feeds back the details it makes it better for everyone. Some people have little experience and want to learn to tinker and others have lots of experience and can share thinks they've learned.

I am on the lexus and Benz sites and I can tell you for fact this is the best of the 3 in terms of sharing information and getting useful information.

 

I've never done laping on valves but I did watch a YouTube video about it.

 

I've done it a number of times. Getting the head off is always the hardest part. I think people get intimidated by it. I used to have a special tool for it. It had a suction cup on the end and your turned the crank like an old school egg beater. The mechanism would cause the suction cup to oscillate and viola - lapped valve. If you understand the wear issues with guides and the thickness issue of the valve edge, it's a piece of cake. I started doing it becaues I was pretty poor back in the day and did what i had to do to keep a car running.