My daughter was recently driving her 2007 XC under 30 mph when a warning "slow down or shift up" appeared on the dash - although she tried to press the accelerator, the car would not move. We had it towed and a mechanic tested the compression and said that 1, 3 and 5 were reading low compression - and he was unable to get the motor to turn over.
I've been reviewing YouTube videos on low compression and people suggest putting Restore in the oil reservoir; removing the spark plugs that are reading low compression and putting a little oil down in the hole where the spark plug goes and then trying to start; and just read something about putting Seaforam (1/3 can) in the oil, (1/3) in gas tank and putting the rest (1/3) in the vacuum tree (which I have no idea what a vacuum tree is).
I am trying to get suggestions so that my son and I can attempt to repair ourselves. I have been making the payments on my daughter's car myself and, frankly, cannot afford a costly repair. Does anyone have suggestions? PLEASE!
Your advice/suggestions are greatly appreciated!
2007 XC90 "slow down or shift up"
I have not come across this dash board warning before so do not know what it actually means. If you think its a compression problem you have to look at why first to get a remedy. Putting oil down the bores will increase the compression as this causes a seal between the piston rings and bore so the air will not escape down to the sump past the rings but it is only temporary because as soon as your engine fires up the oil will burn off and you will back in the same position.
Looking at the causes of low compression it could be a couple of things. You have not mentioned the mileage on the car whether this is high or low and this is something which needs to be considered. High mileage points to wear. Low mileage points to something more sinister.
First cause could be piston ring wear caused by high mileage and no amount of oil down the plug hole is going to cure this. New rings at the least rebore at the worst. The rings on a lower mileage car could be caused by crud or carbon deposits forming on the rings due to driving the car at low revs, short journeys, bad servicing and over fueling. All these things cause a carbon deposit to build up around the rings stopping them from rotating or moving in the ring slots therefore not causing a good seal with the sides of the bore. Worst case they need to be stripped out and cleaned or instead of oil try a dose of REDEX down each bore. You might have a different product in the States but it is basically an engine cleaner which you add to fuel but can put directly in to the bore to try and decarbonise the system.
Second low compression can be caused by valve wear or carbon deposits stopping the valves from closing completely. The same factors apply here as for the rings. High mileage and you might be looking at an engine top end strip and a head rebuild, new valves or at least having them cleaned and re seated. Low mileage and you might get away with the Redex down the plug holes again followed by a good thrashing to clean out the crud and Carbon.
Lastly low compression can be caused by bad timing. If the timing of the valves opening and closing is not as factory then as the pistons rise to compress the air the valves could be opening early or late allowing the air to escape rather than be compressed. The only real cause for this would be a stretched cam belt or if the cam belt had hopped a tooth but as the engine is what is known as an interference engine where the valves and the pistons take up the same space in the engine but at different times, hence the timing, this is unlikely. If the timing was one tooth or a stretched belt out then the valves and the pistons could hit each other causing the valves to bend, not seat properly and effect the compression. Worst case Head rebuild, new valves, pistons and cam belt and no easy fix.
Hope this helps and sorry is it's all bad news.
Looking at the causes of low compression it could be a couple of things. You have not mentioned the mileage on the car whether this is high or low and this is something which needs to be considered. High mileage points to wear. Low mileage points to something more sinister.
First cause could be piston ring wear caused by high mileage and no amount of oil down the plug hole is going to cure this. New rings at the least rebore at the worst. The rings on a lower mileage car could be caused by crud or carbon deposits forming on the rings due to driving the car at low revs, short journeys, bad servicing and over fueling. All these things cause a carbon deposit to build up around the rings stopping them from rotating or moving in the ring slots therefore not causing a good seal with the sides of the bore. Worst case they need to be stripped out and cleaned or instead of oil try a dose of REDEX down each bore. You might have a different product in the States but it is basically an engine cleaner which you add to fuel but can put directly in to the bore to try and decarbonise the system.
Second low compression can be caused by valve wear or carbon deposits stopping the valves from closing completely. The same factors apply here as for the rings. High mileage and you might be looking at an engine top end strip and a head rebuild, new valves or at least having them cleaned and re seated. Low mileage and you might get away with the Redex down the plug holes again followed by a good thrashing to clean out the crud and Carbon.
Lastly low compression can be caused by bad timing. If the timing of the valves opening and closing is not as factory then as the pistons rise to compress the air the valves could be opening early or late allowing the air to escape rather than be compressed. The only real cause for this would be a stretched cam belt or if the cam belt had hopped a tooth but as the engine is what is known as an interference engine where the valves and the pistons take up the same space in the engine but at different times, hence the timing, this is unlikely. If the timing was one tooth or a stretched belt out then the valves and the pistons could hit each other causing the valves to bend, not seat properly and effect the compression. Worst case Head rebuild, new valves, pistons and cam belt and no easy fix.
Hope this helps and sorry is it's all bad news.
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Faust
- Posts: 394
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- Year and Model: xc70 2008
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I question a compression test on a engine that won't "turn over". Since motor is stuck and won't turn over, I suspect that at least one of those cylinders would have a partially open valve. Do you mean won't "turn over" with the starter?
2004 V70
1964 Plymouth Convert (small block)
1967 Dodge Coronet (big block)
1964 Plymouth Convert (small block)
1967 Dodge Coronet (big block)
This may be needing a new main valve cover gasket kit. If your car has over a hundred thousand miles, these gaskets dry out, crack and need to be replaced. It's not holding engine compression the way it's supposed to. Real obvious signs would be seeing oil and grime on your valve cover and around where the spark plugs go. Pull out the plugs. If you see oil around any of them, that's a real sign. The valve cover kit, has new seals for around the spark plug areas, as well as the main casing. Or...you could do what I did and systematically replace things until you are sure. 
I replaced the fuel filter, mass airflow sensor, put in new spark plugs...before figuring it out. Hope this helps.
I replaced the fuel filter, mass airflow sensor, put in new spark plugs...before figuring it out. Hope this helps.-
FLXC90
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- Year and Model: 98 V70 T5
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Zombie Thread Alert- possibly good info in last block, way too much info missing, like which engine?
Current Volvos:
1998 V70 T5, 112k sat 5 years, still in mechanical coma (finally at the top of the pile )
2004 XC90 T6 AWD: 186k, 60 on transaxle ( traded in )
1998 POS70 N/A: DD/training aid, 236k but really about 240k, I think...ABS module( passed on to son who sold it)
1998 V70 T5, 112k sat 5 years, still in mechanical coma (finally at the top of the pile )
2004 XC90 T6 AWD: 186k, 60 on transaxle ( traded in )
1998 POS70 N/A: DD/training aid, 236k but really about 240k, I think...ABS module( passed on to son who sold it)
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oragex
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Nice zombie find. Any way, that car must be now in the form of recycled metal bars, perhaps it was a failed timing belt or a seized engine due to lack of oil.
Several Volvo Repair Videos https://www.youtube.com/playlist?list=P ... s0FSVSOT_c
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ggleavitt
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V8 specific for this message- http://forums.swedespeed.com/showthread ... -Triangle), on a normally running vehicle.
Surprised more folks have not reported this message, I'm the only one who drives the V8 all the way up through it's software neutered limits?
*edit- fix link, drop highlights*
Surprised more folks have not reported this message, I'm the only one who drives the V8 all the way up through it's software neutered limits?
*edit- fix link, drop highlights*
2006 V8 Ocean Race #740/800 200k, 2008 V8 Sport 183k
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Jpainter187
- Posts: 1
- Joined: 10 February 2019
- Year and Model: 2007 XC90
- Location: Texas
Hey all,
I’d like to revive this thread once again to see if there are any other possible suggestions for a remedy to this problem. My wife has a 2007 XC90 3.2L AWD w/ 180,XXX miles, and it’s giving us the same message. She actually just called me to say she pulled off to the side of the road because this “slow down or shift up” message was back and the car was idling rough and wouldn’t accelerate. Usually when she kills the motor and starts it back up the message clears but this time it took multiple attempts.
I’ve replaced all ignition coils and spark plugs, one upstream O2 sensor, and am about to place the 2nd upstream sensor because I think it’s also failed. Should of replaced them both at the same time but oh well... I have checked for oil around the plugs when I replaced them and there was none, so I don’t think the plug gaskets are failing. There is some oil behind the PCV valve so I may go ahead and replace that unit since it’s fairly cheap. Although I don’t see a leaky PCV causing this issue.
If the problem persists after I replace the second upstream O2 sensor then I will be at a loss of what to try next... It should be arriving in the mail in a day or two.
I’d like to revive this thread once again to see if there are any other possible suggestions for a remedy to this problem. My wife has a 2007 XC90 3.2L AWD w/ 180,XXX miles, and it’s giving us the same message. She actually just called me to say she pulled off to the side of the road because this “slow down or shift up” message was back and the car was idling rough and wouldn’t accelerate. Usually when she kills the motor and starts it back up the message clears but this time it took multiple attempts.
I’ve replaced all ignition coils and spark plugs, one upstream O2 sensor, and am about to place the 2nd upstream sensor because I think it’s also failed. Should of replaced them both at the same time but oh well... I have checked for oil around the plugs when I replaced them and there was none, so I don’t think the plug gaskets are failing. There is some oil behind the PCV valve so I may go ahead and replace that unit since it’s fairly cheap. Although I don’t see a leaky PCV causing this issue.
If the problem persists after I replace the second upstream O2 sensor then I will be at a loss of what to try next... It should be arriving in the mail in a day or two.
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