I've got a 1998 S90 with about 150,000 miles. About a year ago my one of the spools that my timing belt goes on loosened and shot through the cover. Because of this i had to replace 22 of the 24 valves and i went a head and changed a lot of other parts that would probably need to be changed in the near future such as gaskets and spark plugs. The only reason why i mention this is because i'm not sure if this may be part of my current problem.

Lately i've been experiencing lag while driving especially in the morning. When i first start the car everything seems to be all right, i'll pull away from the curb and drive at a pretty slow pace through my neighborhood. When i finally hit the road that takes me out of my neighborhood and pick up speed the engine almost seems likes it's going to stall and then eventually engages. Then while i'm driving it seems like something is holding the engine back like it wants to really kick in but doesn't. I've pretty much lost that overdrive feeling when you want to pass someone, it seems like it takes forever to really pick up and go. This has all started in the past month or two. I've tried fuel additives and changing over to mobil 1 oil instead of the bulk oil that i get from Midas.

After cleaning the engine i have found an oil leak coming from one of the bolt on the top of the engine holding down the valve cover. I don't really think that could be the problem but then again i'm not really to sure.

Please help if you have any input

 

Sounds like you have a fuel delivery problem. Have you replaced the fuel filter lately? Could be the fuel pressure is low. Do you have a CEL? These types of problems are usually affiliated with fuel/air mixture. My guess would be low fuel pressure or a bad MAF. How smooth does it idle?

 

Agreed with above, check the CEL's first. It could also be a misfire issue at 150k.

 

I do have a CEL. It's been on for almost as long as i've had the car. I got it checked awhile ago. I forgot what it was on for exactly but i was assured by the mechanic that it wasn't anything that would affect my car. That being said if there was something wrong i wouldn't be able to tell because the CEL is always on.

I have not changed the fuel filter since i've had the car which has been a couple of years. It's rough when it idles but it will eventually smooth out. If i'm stopped for a long period of time then it will go in and out of running rough to running smooth.

There's also a problem when i start it. It will try and start but won't the first time, and it rumbles so hard that the car will shake. Usually the second time i try to start it, it starts right up.

 

my s90 does the same thing at start up. but i never have an idle or power issue with it. still has that inline 6 pull to it

 

Start up problem could be the air pump. It runs when you 1st start the car then cuts off after a minute or two.

PULL THE CODES!!! Then post back.

 

oh really? i can hear the airpump at startup but its possible for it to not work properly right?


i have 2 cel codes. one for small and one for large emissions leak. i forget the code.

 

If you hear the pump, it is probably working. I believe emission leaks are air leaks in either the fuel system or vacuum. Not sure what to tell you from here except look real closely at your tubing and replace/repair any that have cracks, splits, or are loose.

 

I am having the same problem. Mine always runs very smooth when at idle. Sometimes it will shutoff while setting at a redlight. Always starts up smooth and then lags after a couple of miles and usually when on the freeway. I'm not sure what a CEL is? I will have the gas filter changed and check the Mass Air Flow (MAF). Any other help would be appreciated.


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'98 S90 Silver 318K (Driven daily)

 

CEL = Check Engine light.