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Hello All,
I have a 1996 850 GLT wagon with a 5 speed manual, non-turbo with 375,000 on the odometer. Recently the “Check Engine” light came on. Before it did, I had just started up my car and the engine was warm because it had just been driven. Once I started the car, I noticed the idle was rough and thought I sensed a “misfire” in one of the cylinders. The afar a few seconds, the “Check Engine” light came on. I noticed that the RPM level was slightly elevated. Normally with the engine warm, it sits at between 800 RPM to 1,000 RPM. Now it was at 1,200 to 1,300 RPM.
I brought my car with the CEL on to my private mechanic, and he attached a scanner that indicated all cylinders were misfiring. He believes the problem could be a fuel pump relay or the fuel pump itself could be failing. However, he does not want to replace them unless he is absolutely sure. He cleared the CEL and then drove the car and it ran perfectly. Both O2 sensors were fine. The spark plugs are replaced ever 30,000 miles with Volvo plugs and the spark plug wires are replaced every 60,000 miles. Currently the car has 15,000 miles on the spark plugs.
The CEL came on again, so I will be bringing my car back. I picked up the car at the garage when the engine was stone cold. When I started it, it ran fine. About 2 miles later when I came to a stop light, I could sense the car’s idle was slightly rough, and within seconds the CEL was triggered again. I noticed that again the RPM level is elevated (1,200 to 1,300 RPM). My mechanic told me the CEL only tells him the cylinders are misfiring, it doesn’t tell him the cause. Again because all the cylinders are affected he believes it could be a fuel pump relay or the fuel pump. The cylinders are not getting enough gas, so that is what is causing the misfires.
Does anybody have an other theories as to what is causing this problem and how to fix it? Thanks in advance to all who respond.
Hugh
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posted by
someone claiming to be dg
on
Mon May 16 07:27 CST 2016 [ RELATED]
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Fuel pumps are all or nothing usually- unless the screen is plugged or the fuel filter is very old. When was the last time you replaced the fuel filter?
Do the 96's have distributor caps? The spring connection to the rotor could be weak or the contacts could just be super worn.
The misfire thing is also an indication the coil is going.
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DG,
So far since the fuel injectors were cleaned the CEL has stayed off and the car has run fine. But to answer your questions. I replace the fuel filter every 100,000 miles per the owner’s manual. The car has 375,000 miles, so the last fuel filter was replaced 75,000 miles ago. Yes the car does have a distributor and I replace the distributor cap and plugs every 30K miles. I replace the spark plug wires every 60K.
I’m saving your reply in case the CEL comes on again, because I have never replaced the coil.
Hugh
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posted by
someone claiming to be dg
on
Tue May 17 14:05 CST 2016 [ RELATED]
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Keep your AAA plus card handy. A dirty injector might trip a misfire in one cylinder, but all at the same time? A new coil even if you get a volvo OEM is only 140.00 or less on FCP- iv'e seen as low as 120.00 on sales. They don't last forever. Take a good look at the protective plastic coating around the windings. Cheap insurance.
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DG,
You are right. It is cheap insurance. I have two ’96 850 wagons, with 300K on one and 375K on the other. They both have the original coils. Maybe I’ll be “on the side of the angels” and replace both just to avoid a potential headache.
Thank you for your suggestion. I confess, every time I tune up the cars and replace the coil wire, I think about the coil itself.
Hugh
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Bad coils and particularly bad power stages tend to act up when the engine is warm. You could try the arcing test. It is a basic test but a good indicator. Find a very dark place at night. With the engine warm and idling check for electrical arcing at the power stage and coil.
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JWalker,
Thanks. If the problem returns, I will try your suggestion.
Hugh
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Hello All,
I want to thank everyone who responded with their suggestions. I share them with my mechanic. He worked on the car several days this week. He ruled out that the fuel pump relay was bad, the fuel pump was bad, or that there were any vacuum leaks.
He cleaned out the throttle body, but more importantly he cleaned the fuel ejectors. He applied a cleaning agent that you hook up to the ejectors and run the engine with it, instead of gasoline from the tank. Since he cleaned the ejectors, the “CEL” has not come back on again. He told me to drive it for a week and get back to him. He made this decision to clean the fuel ejectors because of the age and high mileage (375,000 miles) on the car. He had another 850 in the past that also had about the same mileage as my car, threw a “CEL” that indicated mis-firing cylinders. After he cleaned the fuel ejectors on that car, the CEL went away.
I just got the car back last night and so far the CEL has not come on. If it does return, I will immediately provide an update. I think my mechanic diagnosed the problem though. He’s pretty thorough and doesn’t like to “replace parts until the problem is fixed”. He also said, if the problem returns, he would recommend replacing the fuel ejectors. The ejectors for this car retail in excess of $150.00 each, so I hope this ejector cleaning is successful.
Hugh
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I wonder if it may be your MAF sensor.
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Al,
I don’t think so. Because I have had a MAF sensor fail on my 850’s before. Usually the symptoms are: you can’t start the engine, and if you do, you have to pump the pedal up and down to keep the engine from stalling. Driving the car is a nightmare because every time you come to a stop and depress the clutch (my 850s are both sticks) the engine stalls. I have not had those symptoms. Still, I will share your suggestion with my independent mechanic. Thank you for your suggestion.
Hugh
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Fair enough. It's just that your symptoms were similar to mine when my MAF bit the dust.
Please post back when it's solved.
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Al,
When this problem is finally resolved, and will in deed post what was causing the problem.
Hugh
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I seriously doubt it is the FP relay. If the fuel pump is original, it could be tired when it warms up. Pulling the spark plugs and finding them 'clean' would point to the fuel pump. Easy to determine:
Once the engine warms up and the CEL comes on again, take a fuel pressure reading. If it is low, thank the gods that you aren't just stranded and in need of a tow.
With the engine idling higher than normal and running 'lean' (clean plugs), it could also point to a vacuum leak in the intake manifold gasket.
--
Keeping it running is better than buying new
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Klaus,
You may be on to something, This morning when I went to start the car, the “CEL” did not come on. I didn’t have a chance to drive the car to allow it to warm up to see if that would trigger the “CEL”. But I will tomorrow. If the “CEL” is triggered by a warmed up engine, maybe it is a fuel pump. To my knowledge (and the car has 375,000 miles) I don’t think I ever replaced the fuel pump on this car. I’ve got three Volvo wagons that I have owned for nearly 20 years, and after the while, although I keep written records, the repairs between the cars start to “blur”.
I will share you earlier comments with my mechanic. I am thankful I have not been stranded on the side of the road with this car.
Hugh
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Happy Sunday Hugh,
Having owned a 240 and now an 850, both of those Volvo models came with Bosch fuel pumps which are notoriously robust! For example, my 90 240DL had 300k miles on its original Bosch main fuel pump when I sold it. My 95 850 GLT wagon has its original pump at 250k and it is still going strong.
That said, if your 96 still has its original fuel pump at 375k that is pretty remarkable! I wonder if there is any way to test one?
Vacuum leaks are another possibility. Have you checked your throttle body air hose for cracks and leaks? How about the vacuum lines at the "vacuum tree". As Klaus mentioned, check your intake manifold gasket for leaks. That happened to my 240.
Jim
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Jim,
Thank you for your response and advice. I’m saving your comments and the other I have received and will provide them to my mechanic when I drop my car off.
Hugh
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