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I have had my s70 to the shop many times now for a check engine light. The code is 4-5-4, misfire on #4 cylinder. The shop just can't find anything that is causing it. The latest thing they tried was to replace the o' ring on the oil pump, thinking that was causing the compression to leak off. That didn't work.

Could it be the fuel pump causing this? Would a fuel pump problem trigger this error code or does the fuel pump have it own code.

The symptoms I am seeing are excessive cranking when we start it. It will crank for a good 15 to 20 seconds before finally starting. When it does start it usually expells a small cloud of smoke then we are fine. The engine seems to run normal. I haven't seen any loss of horse power and it never stalls. It is just really hard to start and the Check Engine Light is on.

Any thoughts?
 

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Is it hard to start all the time or just after it sits for a while?
 

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It is hard to start about 95% of the time. If it sits more than 10 minutes, it is hard to start. But, sometimes it will fire right up in the morning. I'll drive it to the store, park it for 10, and it will be hard to start. other mornings, it will crank away for a good 30 seconds. I'd say it will start right up only 1 in 20 times. the other 19, it is a good 15 to 30 seconds. sometimes i give it about a half a pump on the gas pedal at it will start a few seconds sooner, but smells of being flooded.

I bought the car used with 53k. It now has 113k. This problem started at about 85k. we have only used Chevron gasoline and, based on the dealers suggestions, have been running Redline fuel system cleaner through it about every 6-8 tank fulls. I am also running Redline Oil. They thought this would help with any possible carbon build up.
 

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Is there anyway you can gain access to a fuel pressure guage.Sounds like the pump might be going bad and isn't holding residule pressure.Try to install a fuel pressure guage and look at it after it sits overnight or it acts up.It should hold almost all pressure after you turn it off.
 

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Discussion Starter · #5 ·
Thanks. The dealer still has it and I just asked them to check it. Frankly, I am kinda surprised they haven't already. Based on all I have been reading today on the forums, it seems like the fuel pressure / fuel pump might be the issue. Thanks again for the quick response.

Do you think carbon build up could be an issue? I don't know what kind of gas was run through it in the first three years. Based on the car fax report on the car, it looks like it was originally sold in Conneticut.

Do you know where I can find a list of the Diagnostic codes for this car? I found some for the Fenix 5.2 system, but it said that was for a 850 w/o a turbo. Mine is a S70 with a turbo. Based on the codes the dealer told me, they match the list I found, but not sure if all match.
 

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Ok, here's the latest. Dealer says that in their history with this particular car, the fuel pump is either good or dead. so, they don't think it is that. They still think it is compression related since the number 4 cylinder is the last to come up. They changed the o ring on the oil pump already, now they want to change the check valve in the oil pump. I told them if they are going to do that, then just replace the entire pump. Since the car has 113k on it and if this fixes it, then what the heck. Are we just drilling another dry hole with this approach?
 

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I don't think that is the problem.I thought the same thing about the fuel pump as well till I was proven wrong.I messed with a car for a week and found out in the end it was the fuel pump.Some times when they get hot they will skip.
 

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Discussion Starter · #9 ·
are the fuel pumps easy to change on the S70. do you know approx. how much is should cost (parts and labor)? They are already working on the oil pump, so if it is still not working, I will change the fuel pump next. I guess I will have them do it since they will need to reset the check engine light anyway. thanks again for staying with me on this one. I really appreciate your help.
 

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The fuel pump is pretty expensive because it comes with the fuel guage sending unit.It is all 1 peice.I think it is between $200.00 and $300.00.
The labor shouldn't be all that bad because they can access it through the inside of the car.Maybe 1 to 1 1/2 hours labor.
 

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Discussion Starter · #11 ·
well, the oil pump is going in as we speak. I have a very low confidence level that this will fix it, but my dealer still thinks it is the problem. We have discussed the fuel pump, fuel pressure, wires, coils, computers, and just about everything else.

I'll let you know what happens after this is done. I
 

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Ok cool I don't really believe that it is the oil pump as well but we will see what happens.

I can't see how a bad oil pump will throw a missfire code.
 

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Discussion Starter · #13 ·
Their thoughts are that it is allowing a compression leak-down and since #4 is the last to fire it is causing a hard start condition and a misfire condition due to low compression in #4. Sounds really bizarre to me too. Sure sounds more like bad valve, fuel pressure/pump/injector or coil/spark to me. I am just waiting for the call stating I just blew another 600 bucks and it still didn't fix it.

If I replace the fuel pump myself and it was the problem, will the check engine light go off once the computer senses the problem is no longer there, assuming that fixes it of course? Or, will I have to take it to the shop to reset it?

Will disconnecting the neg. battery cable clear the code?
 

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I think that leaving the battery disconnected will clear the code.But they should also clear the code before they give it back to you.

That theory doesn't sound like a good one to me either.
 

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Discussion Starter · #15 ·
New Oil Pump. Same problem. You were right. It didn't fix it. They did check the fuel pressures though and they were perfect. They are doing a compression leak down test again with the new oil pump in place to see what that shows. Could this be in the valve train?
 

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Im not sure you never broke a timing belt did you?The valves are pretty hard to bent unless the belt breaks.The only other thing I could think of would be a bad fuel injector.
Does the car run funny?
 

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Discussion Starter · #17 ·
Never broke a timing belt. Got car back last night. The compression check showed compression was ok after the oil pump, but it is still hard to start. The light is off, for now anyway. I give it two to three days before the light comes back on. I'll keep you posted. Oh yeh, The car runs great. No hint of a miss or loss of HP. Just excessive cranking when starting it.

I am sure a new starter is in my near future. Are they easy to install on this car? I have done my own starters on my other cars, but never attempted this one.
 

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It shouldn't be that hard.I have done it before.Depending on if your car is turbo or not.
If you can find a fuel guage to install and keep on there and check your self that would be nice.That would also help you keep track.The excessive crank sounds like lost fuel pressure.
 

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Discussion Starter · #19 ·
Well, it has almost been 2 weeks and the check engine light is still off. However, I still have my starting problem. Another issue I am having is that I am getting exhaust smells through the ventilation system when we first start the car. I clears itself in a few minutes, but is quite strong at first. any thoughts?
 
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