1998 V70R PO172 Fine under idle, dies under load

[eyeballumbrella]

So my car has been acting really funny. I pulled a po172 code recently and have been having issues with the driveability of the car. Whenever I try to give it almost any throttle under load the car wants to die on me. I have replaced the front o2 sensor and checked the cat. I also have cleaned the MAF sensor, but none of this has solved my problem. Anyone have any ideas? Thanks

[Ozark Lee]

Code P0172 is usually caused by a vacuum leak and the usual suspect is the elbow on the end of the intake manifold that ties back to the intake snorkel. It is part of the PCV system.

P0172, however, usually doesn't cause any driveability issues though so you may have more than one thing going on. Check all of the vacuum lines from the TCV as well since they can cause both problems if one of the lines is bad.

...Lee

[ThommyKent]

Sounds like plug wires. My `97 T5 would idle fine and under almost any load would want to die. Plug wires were the problem. When they get old they start to leak voltage between each other and when load is applied it get`s worse. Sometimes you can start the car at night and see flashes between wires when the engine is revved while looking under the hood, Volvo date stamps their wires so if the date is most likely the same year as the car it`s time to replace them. Don`t use anything other than Volvo OEM Bougicord wires. Ozark is right that PO172 is not your problem

[villagepc]

I can verify that your car will still run with the vacuum leak Lee is talking about, and that a leak there will throw the PO172 code.

Not only check your vacuum leak, check all your intercooler pipes / clamps / etc. Its likely you have a good sized leak - either vacuum or under boost - Check all your rubber interconnects, especially the one at the throttle body - the underside of it.

[eyeballumbrella]

I don't believe that plug wires are the issue because I replaced them with bougicord wires about a year ago. I looked at the intercooler hoses and couldn't find any issues with them. I will take another look though. Also I just pulled the plugs and the outside two were fouled with carbon from running rich and the inner three were fouled, but not as bad as the outside two. Does that mean anything?

[kahl]

You did'nt say the mileage and age of plugs, rotor and cap. Had a similar performance issue on a 99 V 70. Finally found the short 90 degree turbo hose going into the intercooler was collapsing under heavy or high boost.

[Reys]

Check small rubber line after pulling fuel pump. They slide down after years of vibration. Easy to do, common on these cars. Inspect/clean/replace pump sock while your in there. I suggest anyone with acceleration issues to check this first before replacing parts unless codes tell you otherwise.

[Reys]

Check small rubber line after pulling fuel pump. They slide down after years of vibration. Easy to do, common on these cars. Inspect/clean/replace pump sock while your in there. I suggest anyone with acceleration issues to check this first before replacing parts unless codes tell you otherwise.