XC90 cruise control causes poor performance

parker19 · Post by **parker19** » 15 Oct 2019, 11:19

Hi. My wife’s 2006 2.5T XC90 was running fine until one day when I used the cruise control. From that point on it now hesitates/shudders when I give it gas. Worse if the air conditioning is on. This happened before and the garage fixed it by replacing the turbo boost solenoid. So I replaced the solenoid myself and it still runs bad. What is the correlation between the cruise and it causing the car to run bad. (Haven’t touched the cruise since). Thanks

Post by **ggleavitt** » 16 Oct 2019, 22:07

If you could write something on how long you've owned the vehicle, current mileage and previous service (PCV, fuel filter, any other engine work), it'll help put context behind your question I think.

That someone "fixed" the earlier problem with a boost solenoid (aka TCV) suggests it probably was coding a pressure something error. No check engine light, huh? Just runs like crap?

This vehicle has an electronic throttle so it's possible in my mind that cruise, doing what it's supposed to do (small change increments with expected and measured result/response), is giving you an amplified symptom of another problem. Unless there's an old battery wackiness to add to the mix (which is always possible), cruise is maybe just not capable of doing what it's designed to do. I really don't think it correlated other than to give you a new reference point for moving forward with getting back to how it's normally supposed to work. Why it worked fine then did not that's odd, it's possible to try a battery disconnect (do it how Volvo likes it done), see if the performance gets any better. I'll guess no but it's an option.

A clogged PCV plus old plugs plus a dirty throttle body plus an old fuel filter, some hoses that could use a tightening or a re-attach, and an older battery could all do what you're suggesting. Out of curiosity, is the PCV hose going between the intake manifold made of rubber or plastic?

I'm pretty sure you'll get more responses with some more background, and there's a good level of 5 cylinder experience on this forum.

parker19 · Post by **parker19** » 31 Oct 2019, 07:34

Thanks ggleavitt! Good information. The battery and fuel filter are newer. I swapped an older turbo boost solenoid I had kept around and it ran worse. I ordered a new Bosch MAF sensor and am about to dig into the plugs. Could you give me clarification on the PCF hose being rubber or plastic? Thanks

parker19 · Post by **parker19** » 04 Nov 2019, 03:57

Changed MAF sensor No change. Still getting hesitation after running for a bit. Weird thing, if I shut the car off and restart it, it will run fine for a while. Possible electrical?

Post by **ggleavitt** » 04 Nov 2019, 15:29

Early XC90 had the oil vapor hose that goes from the top of the camshaft to the oil trap (between intake manifold runners) made of nylon, got heat cycled and disintegrated after a few years, starting at the accordion bends. Check that hose, if made of rubber someone has swapped it out already. When the hose breaks, you basically have a non-functioning PCV. No idea chassis range for the nylon part, 2005 for sure had this hose (mine fell apart right around 60k, discovered at 85k).

parker19 · Post by **parker19** » 10 Nov 2019, 16:06

Praise the Lord! After replacing the turbo boost solenoid and the MAF sensor with no success, I replaced the spark plugs and it fixed the issue. Who knew? Recap: Car ran fine until I used the Cruise Control. Started hesitating on medium to full acceleration. Had this problem a couple of years ago and the shop changed out the turbo boost solenoid and it fixed the hesitation. This time it did not. The shop said they were going to replace the MAF sensor and spark plugs for 985.00. I paid them for the diagnosis and scooted(300.00 to replace 5 plugs. No thanks). Solenoid and MAF Sensor may have helped behind the scenes but the final winner was the new plugs.
What had me confused was that if you pulled over and shut the car off, it would run better for a short while.
Out of curiosity, anybody have an answer for the last paragraph?