Failed Acceleration, 2001 XC70

Lead Chalcogenide · Post by **Lead Chalcogenide** » 03 Aug 2011, 08:49

Hi All, long time lurker, first time poster.

I have been a successful garage mechanic for years, and am thinking my 2001 XC70 may be the car that forces me to retire the garage tools. Please help me diagnose this problem so I can fix my ego, and redeem my reputation in the eyes of my wife who currently thinks I am an idiot for one: buying this car, and two: spending a grand and about a month of evenings and weekends messing with the internals.

Here is the problem: The car will fail to accelerate after reaching a cruising speed. i.e. You can accelerate to any velocity just fine, say 40mph, and then, if you'd like to go from 40 to 60, no dice. The gas pedal becomes useless and you just sort of coast, slowly loosing speed. You have to bring the car to a full stop, and sometimes wait a few seconds for the idle to smooth out, before you again accelerate. This is sometimes associated with an "Engine System Service Urgent" warning message. Not a service light, a warning message where the MPG is usually displayed. There are no other warning lights.

What I have done to solve it that has thus far not worked:
- new MAP sensor
- new silicone boost tubing (the old ones had a rip)
- new xeMODex throttle body. (This was actually replaced a week prior to this problem, as we had had the dreaded ETM light)
- cleaned the MAF sensor
- cleaned the banjo bolt as it had a PCV problem. (that is a HORRIBLE system)

I am now thinking the wastegate may not be functioning, or perhaps I just need a new MAF. I am not going to buy a new MAF on the hopes that it will just magically work (already did that with the MAP). I would think, if it were the MAF, there would be a check engine light. If anyone is in Denver and has a new MAF I can try as a diagnostic, that would be great.

Also, while taking apart the intake manifold for the throttle body install, I noticed a small crack/missing piece on one fuel injector. Could this be the source of the problem?

I really cant afford to keep buying parts on the hopes that they will work. I am hoping someone has had this exact problem before and can direct me toward a known solution.

Thanks much,
-adam

FCPEURO · Post by **FCPEURO** » 04 Aug 2011, 09:10

Hi Adam, welcome to the forum.

Have you ever checked the computer to see what codes are coming up? If not, I would definitely do that first and then post the codes up here.

Lead Chalcogenide · Post by **Lead Chalcogenide** » 04 Aug 2011, 23:16

yes, the codes. I'll see if I can get the codes read tomorrow at the local auto shop with just a generic reader.

This is such a mystery.

I should mention. The car still has a plugged PCV system. Air and fumes are coming out the oil dipstick tube like mad. I did clean the banjo bolt but that did not seem to work.

I also forgot to mention, due to the PCV problem, one of the coil packs was fouled with oil spilling out of the oil filler cap. This lead to a misfire. I have replaced the coil and all 5 plugs.

I think thats it. I'll get the codes read asap.

volvofl · Post by **volvofl** » 05 Aug 2011, 07:24

As horrible as the PCV system is, you need to fix it. If you don't, it WILL blow a seal out and you will have a whole new set of problems, along with still needing to fix the PCV system. My friends S60 blew a cam seal out and he lost all the oil in his engine while going down the road. When all the waring lights came on he was luckly enough to shut down engine right away and save the engine. Not a good thing to run with a bad PCV system.

Lead Chalcogenide · Post by **Lead Chalcogenide** » 06 Aug 2011, 12:33

got the codes. There are none. This was with a generic code reader, so who knows if there are other volvo specific codes.

I am wondering if this is related to the PCV. Could it be so clogged that it causes severe loss of power?

I dont know. I am probably stuck going to the local dealer. I seem to be out of options. I could do the entire PCV system, but I cant afford to buy the parts on something unless I am absolutley sure it will fix it. I cant imagine a clogged PCV system actually causing this problem. I need to fix this first...

Lead Chalcogenide · Post by **Lead Chalcogenide** » 08 Aug 2011, 13:11

idea...

Could the CBV be stuck open, due to oil and crud from the clogged PCV. The PCV is sending oil back into the intake via the PTC, and that crud is hindering operation of the CBV.

Would a clogged CBV result in little to no acceleration?

Its pretty easy to check the CBV, so I'll probably do that tonight. Unless someone tells me this is going to be a waste of time.

Post by **DGM** » 09 Aug 2011, 06:14

Lead Chalcogenide wrote:got the codes. There are none. This was with a generic code reader, so who knows if there are other volvo specific codes.

I am wondering if this is related to the PCV. Could it be so clogged that it causes severe loss of power?

I dont know. I am probably stuck going to the local dealer. I seem to be out of options. I could do the entire PCV system, but I cant afford to buy the parts on something unless I am absolutley sure it will fix it. I cant imagine a clogged PCV system actually causing this problem. I need to fix this first...

Have you verified that your air intake is free of restriction. Like an accumulation of liquid at the base of the intercooler or a hose that collapse during acceleration? Just a thought because you mentionned your PCV isn't in great shape. I have seen it on the S70 serie.

Lead Chalcogenide · Post by **Lead Chalcogenide** » 09 Aug 2011, 15:50

Could be that, thanks for the thought. Do you know of an easy way to diagnose that? Not sure how long it would take to take off the intercooler. I think the intake hoses are all fine.. I have taken them off and on quite a bit during the XeMODex install.

Post by **DGM** » 09 Aug 2011, 17:27

Lead Chalcogenide wrote:Could be that, thanks for the thought. Do you know of an easy way to diagnose that? Not sure how long it would take to take off the intercooler. I think the intake hoses are all fine.. I have taken them off and on quite a bit during the XeMODex install.

May be you can have a look inside by the bottom hose. I do not recall if there is a plug or something like this at the bottom. Or with a "Shopvac" on the blowing side to see if air can go through easily.

Lead Chalcogenide · Post by **Lead Chalcogenide** » 10 Aug 2011, 08:09

Well... I have done what I can do. I finally ran out of credit with the wife, and we agreed to call a tow truck to take it to the dealer last night. During the "conversion", she used the term "White Whale". I see her point, this is turning me into a young Captain Ahab. I suppose I will try and divorce myself from it before I loose a leg. I am curious to hear what the dealer says, but if I had my druthers I would take off two weeks from work to remove and inspect all the parts myself. The whole engine probably needs a good cleaning due to the PCV system.

Anyway, thanks for the help, and I'll post an update when/if this thing gets fixed.