This is a two part question. First part, a week ago changed a universal fuel pump(cylinder was thin)to a Bosch fuel pump(much wider). Now I am experiencing a rough idle. Does the fact that I went from a thinner fuel pump to a wider fuel pump have anything to do with this rough idle.
Second part. Saw an advertisement for Bosch Super copper spark plugs, has anyone tried these or have any feedback on these sparkplugs?

I would think that as long as the pump is delivering the correct pressure to the fuel system, how thick or thin it is wouldn't matter. These are good plugs. Stay away from platinum's

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Jeff Lawrence
1989 300e
2000 Dodge Grand Caravan SE

I think I just bought 6 Bosch platinums from Germany for my 300.. That is what the Auto store recommended. What is wrong with them?

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'89 420 SEL
'90 300 SEL
'68 Olds 88 Convertible
'84 300 SD (sold it)

Matt, do a search on Platinum.

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Jeff Lawrence
1989 300e
2000 Dodge Grand Caravan SE

The platinum plugs should be used only in the MB engines designed for them. There have been a number of discussions on this board regarding plats vs copper cores. As a result of one of the earlier threads, I pulled the plats from my 4.5L and replaced them with Bosch copper cores. Idle improved, seemed to run better and a slight increase in mileage.

Best bet, if the engine isn't designed for plats, stick with copper

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Mike Tangas
73 280 SEL 4.5

Is it possible, (stick with me here) that the universal pump could have some how fouled out the plugs? Or do I sound ridiculous? I don't know,the thought sounds good.
In regards to the 2nd part of the quest. I am presently using Bosch copper plugs, the benefit of the Super Bosch copper plugs would be what?

The pump is not in any way going to foul your plugs. The pressure is regulated downstream from the pump. The only thing the super plugs will do is give Bosch a bit more pocket change to jingle. The standard coppers last forever..

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Jeff Lawrence
1989 300e
2000 Dodge Grand Caravan SE

Thanks jeffsr,just weird the way the car started to have a rough idle all of a sudden. Purely coincidental then. Guess my next task is to figure out why all of a sudden the rough idle. Any suggestions where I should start. I have been using Citgo Super Premium 93 octane. Read somewhere on one of the posts that 89 octane is probably the better grade to use, any thoughts? How do you feel about these gas additives to clean the injectors? Or should I leave them alone? By the way, I really appreciate the replys now and in the past!
Just my type of luck, finally breakdown and buy the euro headlights and now the lights will shine jiggly from the rough idle :D. Just kidding..

[This message has been edited by rich30769 (edited 09-15-2000).]

Go with the lower octane. I have had great luck with it. Sure, dump a couple of bottles of injector cleaner in the gas. Won't hurt either. See if these steps help. If not well..let us know. BTW, you might also add some dry gas as well. You might have gotten a load of "wet" gas.

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Jeff Lawrence
1989 300e
2000 Dodge Grand Caravan SE

You did not mention why you change the pump in the first place, nor if you changed the fuel filter at the same time. If you did not change the fuel filter, maybe you released some junk in the fuel filter. Just a suggestion.
J.H.
86 300E

J.Hidalgo,
Changed the first pump because it stopped working, didn't change the fuel filter was going to do that tomorrow.
Jeff,
Will try some injector cleaner and dry gas after changing the filter. Brother suggested the filter, never got around to changing though.
Will let everyone know how it turns out. Thanks everyone for advise.

Rich - what make/model of MB did you change fuel pump in? Thanks.

Mike Murrell

It was a 1986 300E. The firsr fuel pump had to be a universal one(much thinner than the Bosch, the electrical post were positioned differently and there was an adapter added to the end). By the way, with this rough idling I'm still experiencing, my tach stays steady at around 7500rpms any advice?

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1986 300E W124
192,000 mi.
tint windows
clear corners
euro headlights
chrome lorinsers(now)
soon to be 94/95 taillights

750 RPM, I hope! Rough idle seems to be one of those wild-goose-chase things since the cylinder is where it all happens. I would check electrical next--often a few of the resistor-tips of the spark plug wires need replacement. Let us know your results, as many of us (including myself) are tracking the elusive rough idle. Also invaluable is going to an MB tech and having an oscilloscope test. The trace seems invaluable, as it is described on the CD-ROM anyway. Best of luck, Andrew Seidel.

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89 190E 2.6
83 300TD Turbo
75 240D

Soon as I find the problem I'll let you know the culprit. Likewise if anyone else finds a solution please let everyone know. Thanks

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1986 300E W124
192,000 mi.
tint windows
clear corners
euro headlights
chrome lorinsers(now)
soon to be 94/95 taillights