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Probably valve seal problems. Generally the piston rings are forced out when engine breaking occurs. That creates a pressure that effects the valves seals.

With 95K + on the clock, you probably just need a normal valve job.

You should perform a wet and dry compression test. Followed by a leak down if the wet looks normal.

Valve jobs in these cars are up around 1200.00 considering that you must buy band new exhaust valves with the job.
 

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Discussion Starter · #22 ·
The engine is now at 112k, I just have not updated my sig in a while. It seems like this problem and the consumption started fairly suddenly; I sure hope it isn't valve seals. I'll have to swing by harbor freight and get a compression tester.
 

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The engine is now at 112k, I just have not updated my sig in a while. It seems like this problem and the consumption started fairly suddenly; I sure hope it isn't valve seals. I'll have to swing by harbor freight and get a compression tester.
Plenty of videos on youtube if you're stuck on how to do that test. You could also have a shop perform both tests for roughly a 100.00.

You're getting into the normal valve job area with 112k. It really depends on how hard the car was driven. Mine saw track days almost every week and needed the first one at 95k. Some people go to 140k.

User Chilled man on this forum has some helpful tips and connections if you end up needing them.
 

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Discussion Starter · #24 ·
Did a compression test. Dry was 109 psi +- 2 psi across all cylinders. Wet was 150 +- 10 PSI across all. This was with a $17 harbor freight tester.

Spark plugs had a bit of white ash. Inside of the OTE pipe was not wet with oil.
 

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Discussion Starter · #25 ·
I realize those dry readings are low, I suspect the calibration of the (cheap) gauge. The engine otherwise runs fine and makes great power, and the dry readings are incredibly consistent. Also, I did not have the throttle wide open while cranking, some instructions tell you to do that, not sure how much of a diff it makes.
 

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143 is on the low end, but ok. Typically 5 cranks with the foot off the gas, on a warm engine.

Where do those white ash plugs fall under: http://www.4secondsflat.com/plug_chart.html

Check your injectors and see if they need cleaning.

If the compression checks out ok, and you think the plugs look lean on the chart, then you could have a dirty injector or a bad MAP sensor. Typically engines that run lean, will burn oil off the cylinder walls a little quicker and consumption is noticeable. That being said, your down hill example wouldn't apply, because the car runs extra rich down hill, lean uphill... which would point to a Valve, but the compression test looks fine. It might be over rich down hill that you are seeing, not oil... that problem would shoot smoke and your oil consumption might be lean mixtures under load.

What kind of MPG's are you seeing on the Highway? It's another clue to any of the above problems, if they exist.
 

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Also, I did not have the throttle wide open while cranking, some instructions tell you to do that, not sure how much of a diff it makes.
VIDA instructions for checking compression indicate that the throttle must be wide open for the test. Also remember that the ETM will close after two minutes regardless of pedal position if the pedal is held to the floor, so you have to complete the test within that timeframe or start over.
 

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Discussion Starter · #29 ·
Plugs were somewhere near #s 19, 14, and 11.

MPG is approximately 22-23 @ 70 mph.

So to clarify, a weak PCV could not cause this? Is there any way to clean out the PCV short of replacing the whole thing?
 

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Plugs were somewhere near #s 19, 14, and 11.

MPG is approximately 22-23 @ 70 mph.

So to clarify, a weak PCV could not cause this? Is there any way to clean out the PCV short of replacing the whole thing?
Causes similar problems, but clogged PCV means pressure would build and one of the few places for it to escape is the dip stick. There is no weak. It's either positive pressure or negative pressure. You've verified that the negative pressure is there, so you are fine on the PCV.

Your problem is that you're running lean at times.

Your MPG should be higher with the iPD tune. Bunch of threads here on MPG, so that you could verify. I've had 30-35mpg when I had the same amount of mods and tune. I believe you'll find at least 27mpg in the appropriate threads.
 

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Discussion Starter · #31 · (Edited)
Here is a plug; though the flash made the ash on the plug look more white than it is; the ash is more tan IRL:



Ok, so I should just toss in some lucas fuel injection cleaner or sea foam?
 

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That plug looks like it's been running lean. As I said before

Your problem is that you're running lean at times.
Why don't you see about pulling all the plugs, keep them in order or number them, and see if you see a difference between plugs. You're looking for if the plugs look like that in 2 cylinders only (injectors) or if all of them look like that (fuel system)

You could service the injectors and I was looking at ARD's site a while back on the subject. You could just be at the point that you just need to clean stuff out. Fuel can do that too if it's too low in octane or has water in it. We were discussing octane levels back in 04/05 when they started first showing up on the forum... and if I remember right, these are tuned to 95 octane. A certain percentage of ethanol in fuel will do that too, because it has a problem of absorbing water. A bad O2 senor will do that. A bad IAT sensor will do that.

Why not just start with look at all the plugs so you know which direction to take.

Here is a thread you might want to skim through:

Plug Thread
 

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Discussion Starter · #33 ·
Ok, so full (fuel?) disclosure, I am using an OBX DP without a cat, and a rear O2 spacer to prevent the CEL. Could that have any effect on this?
 

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Ok, so full (fuel?) disclosure, I am using an OBX DP without a cat, and a rear O2 spacer to prevent the CEL. Could that have any effect on this?
Why don't you have a decat in your sig? That's totally your problem. An iPD tune is an out of the box tune and it's not made for Decat systems. Those setups require a Dyno tune and they always run lean until you do. The problem is that back pressure plays a huge role in how your fuel is mixed. Clogged CATs make the system think it's running lean and add fuel... DeCAT systems make the car think it's running rich and pull back fuel. I thought at first that this was caused by how you change the readings on the front O2 sensor, in regards to how pressure flows over the sensor, but something about it leans towards the MAP. Why not throw a Sport CAT in there? you would only lose a few hp... or maybe even gain a few horsepower. If it's running lean right now, you're probably losing a few hp because the car is pulling back timing.

You could probably throw a stock DP back in and the problem would probably clear up. Have you ever swapped the DP back to clear this issue?
 

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Discussion Starter · #35 ·
My tune was originally for a Phuz DP, but the one I got from him had a pinhole in a weld for the upper O2 and it kept throwing a code and making the car run rich. I swapped it for this OBX. Phuz repaired the DP and sent it back, but I never installed it. I will toss in the Phuz DP next week and let you know how it goes. Will the rear O2 spacer have any effect on this problem, or can I install it in the Phuz DP to prevent the CEL?

Interestingly, the oil smell problem first manifested after I put in the OBX DP; like that day. I always assumed it was because the oil fumes weren't getting burned off by the cat, not that the car was running lean and the fumes were BECAUSE of the DP. I will keep you (and everyone else) appraised of what happens when I put the Phuz back in.

Also, thank you so much for your continued assistance. If it really is the DP and I get more mileage, power, and less oil consumption from this swap, I will be thrilled. I really appreciate how much time you have spent trying to help me.
 

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I know of this problem from my experience on N/A cars. I know you could probably search a decat and lean mixture on the internet and find all kinds of stuff... it's really well known. Someone who has looked into the subject more would have to pick up from here. Maybe you can throw in a older plug. Maybe you could run a slightly higher injector. Someone else here has the cut out CAT on their system... what are they doing? Phuz uses a Sports / High Flow CAT system on their DP from when we bounce emails back forth 2 years ago about options on my car.

I can ask my friend who has a decat system on his Subi, but I think it's tuned for that from COBB.
 

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Reducing back pressure (by removing the catalytic converter) can cause a lean condition in speed-density based fueling systems. However, MAF based systems (like the one in the R) should not be impacted, because the actual mass airflow is being measured, rather than being calculated.
 

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Discussion Starter · #39 ·
Ok...so if it isn't the DP, I have a bad sensor that isn't throwing any codes? All the plugs did indeed look the same, so it has to be some kind of engine-wide issue.
 

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It's the decat pipe and it will cause the car to run lean. It's been discussed here many times before. The most experience guy for that will be Matt... aka Phuz.
 
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