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Hi. I've got a 1990 240DL wagon with a '93 engine installed.
I just had the fuel pump relay replaced. I'm now noticing a slight hesitation while driving. It happens during acceleration. While idling, there's an occasional "catch" which is like a small knock/movement coming from the undercarriage.
I'm wondering if one or both of these things might have been caused when the fuel pump relay was being replaced and/or if it's something else.
Thanks for your time.
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It was raining the morning and the problem was MUCH worse. No longer a subtle continuous hesitation. It's now bucking a little while I accelerate at any speed. I reparked the car and took the subway to work.
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Hi again,
Having the engine cutout out on a rainy day is a good sign of real bad ignition wires. A nighttime test with a spray of water mist may show voltage leakage down the outsides of the wires or jumping over to metal.
Onkel is pretty sharp on suggestions. I believe it about the caps on the spark plug ends. I have learned to tighten them with pliers if by chance I have to use those type of wires that require them.
Bad wires or connections can cause delays in spark delivery so while thinking about knocking or timing the wires would not necessarily cause an early firing but power loss is definitely in the mix for sure.
A word of caution about the AMM. Do not plug or unplug it while the engine is runnning. As far as that goes never unplug anything electrical on a car while it's running.
Having the morning rain was a "blessing from nature," even though, it's the weather that breaks things down with age and corrosion that may be interpreted differently.
Phil
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Bad wires or connections can cause delays in spark delivery so while thinking about knocking or timing the wires would not necessarily cause an early firing but power loss is definitely in the mix for sure.
While I was searching for the cause of rough running the first min. after the cold start (which turned out to be the FPR), I also checked all ignition components.
With an Ohmmeter I measured the leads and oh boy, out of five (yes, 5) three measured infinite. This didn't really cause any misfiring but after the replacement, the enigine ran smoother at highway speeds. But, they didn't leak to other parts (the head), nor did the plugs themselves, a friend of mine once had three new plugs fail on a Mustang 289 V8 after a short while, so it happens.
I agree now the first check should be the running the engine in a pretty dark environment and look for the tell tale blue flashes.
Good luck!
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If you are getting sparking, a good spray down of the electrics with WD-40 will often improve things. Wipe down the wires with it and also the inside of the dizzy cap. Any improvement might show you are on the right track so you can do the spraying one area at a time if you like. WD stands for water dispersant and it works well for that when your electrics are suffering from damp and condensation.
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This is sound advice, as it's coming from the UK, home of Lucas, Prince of Darkness ;-).
More seriously, as the D in WD-40 stands for "displacement" it should even be better than a dispersant. But before you apply it, run the enigine in the dark and see if you can spot anything...
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You mention bucking. Would the term 'bogging' be useful? I'll let you look that up with regard to describing auto engine and acceleration performance.
Bogging may be attributed to a failing throttle position switch (and other items) and these can be well along in failing before the ECU sets a fault code for you to check using the OBD.
Have you inspected the electrical system? The well-lamented engine control system 25-AMP fuse and fuse holder on the inner fender behind the battery. Corrosion. Zen Master Uncle Arty B. treats the topic well.
http://cleanflametrap.com/emfuse.html
Also, in the fuse box, try the "spinning the fuses" trick to dislodge corrosion between the fuse end and the fuse holder clip. Also, give a close inspection to the fuses. Also excellently treated on the aforementioned cleanflametrap.com page.
Though, for a lark, before you futz with power and ground issues, have you checked the engine control system for fault codes using the OBD fault checker box?
https://www.brickboard.com/FAQ/700-900/EngineOBDCodes.htm
Specifically, for the Bosch LH-Jetronic 2.4 / 3.1 fuel injection and emissions (socket 2) and the Bosch EZK 116 ignition and emissions (socket 6). Repeat the procedure until no new fault codes display. Though not all items that may have a fault will be so faulty as to broach the threshold for the engine control units (ECUs) to set a fault.
Else, a timing belt so in need of tension-reset it may have slipped a tooth on one of the timing gears. Doubtful.
Then check the 25-AMP fuse holder. Give a wiggle to all connections along the watchtower, oop, I mean the engine control wire harness connectors in the engine bay. Such as the connector at the ignition power stage. Disconnect, inspect, replace. (DeoxIT would be great if you have any of the ointment or spray. Don't lose the connector seal!)
May want to test the AMM for fault by unplugging it and seeing if the engine runs better, if rich, yet 'better'. Any exhaust leaks upstream of the 02 sensor?
Hope that speculative helps.
International Clash Day - Rock the Casbah!
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if you haven't already done so, check condition of distributor rotor/cap.
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'91 244 200k auto
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I replaced the distributor rotor and cap last spring, but I'll check again. Thanks.
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With your comment about really bucking in the wet weather you likely need to change the wires. You did the other electrical components. Speaking of that , Push down the existing wires onto the Distributor Cap, they tend to walk up.
Look at the wire from Coil to Cap, it chafes on the power steering hoses.
--
'75 Jeep CJ5 345Hp ChevyPwrd, two motorcycles, '85 Pickup: The '89 Volvo is the newest vehicle I own. it wasn't Volvos safety , it was Longevity that sold me http://home.lyse.net/brox/TonyPage4.html http://cleanflametrap.com/tony/
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I'd say it's not related to the fuel pump relay. It either works or doesn't.
Hesitation while driving may be a bad electrical connection. I more than once experienced a sudden drop in revs and a shock through the car when it picked up the revs again, all within a fraction of a second. Cause: intermittent bad electrical contact in the air mass meter (AMM) connector. Cure: disconnect and connect a couple of times. If that helps, you may want to clean the contacts more thoroughly.
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I had an identical symptom when the nipple on a spark plug backed off. Unusual but a misfire will often not trigger the CEL unless it is continuous.
Cap, rotor, wires and plugs
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And that was the problem. The nipple had backed off of plug #1. Needed to replace it, as the lip was no longer able to hold the snap seal.
Thanks to everyone! Great site for Volvo lovers!
Bob
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Thanks for posting an update!
Onkel does good doesn't he!
Did the knock go away too?
Phil
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Hi,
This is just an off hand thought but it sounds like thermal expansion could be the knock. The exhaust system come to my mind. I know after a shut down you will hear the pipes cooling down. That's mostly heat shields.
If they get loose they can buzz at certain RPM. You may also check the bracket down near the transmission that hold the exhaust pipes. It can crack or lose it bolts.
Since this engine was replaced, that in its self, could warrant an inspection underneath.
Since you are having hesitation under acceleration there may be a blockage or restriction in the exhaust flow.
First thing that comes to mind would be a catalytic converter that has collapsed internally. Sometimes the chunks of honeycombs can travel into the mufflers. Mufflers can collapse from rust too.
I sincerely doubt an electrical relay can cause any knocking but they do click! (:-) Now a great big 100 ampere, three phase electrical contactor clunks.
Phil
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Thanks, Phil. I'll start out with a look underneath.
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I hope that helps as it always seems like a long shot from this distance.
If not, if I take the knocking part out of the story or try to put both together because I don't know when that happens, you might have a timing issue. A bad knock sensor would cause it all under acceleration.
The engine should be able to run on 89 octane or better with out a knock but if you are running a lesser octane fuel the knock sensor get to be even more important. This is a CPS engine, which means, it's a little more sophisticated or tightly tuned around the knock sensor and the ECU. No basic timing adjustment to get out of whack except for the timing belt tension.
Also I thought about the FPR for a brief second during the last post. It needs to provide extra fuel under acceleration or the mixture runs lean. When that happens the timing has to compensate to prevent pre-detonation.
Maybe if you could explain when the knock happens this will help other posters narrow down the hunt.
Just remember, we're are all "remotely influence" by your observation and descriptions. We play it back in our guessing.
(:-)
Phil
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Also I thought about the FPR for a brief second during the last post. It needs to provide extra fuel under acceleration or the mixture runs lean. When that happens the timing has to compensate to prevent pre-detonation.
The fuel mix going lean or rich beyond which the ECU can compensate throws a fuel mix error code and the check engine light comes on. I know from experience with a faulty FPR on my 1992 245 that this may go totally unnoticed, apart from the light switching on.
I would suggest to see if the ECU has other stored error codes, as not all errors make the check engine light go on.
Does the hesitation during acceleration feel even or does it feel "wobbly"?
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