slight surging of engine power - Defender Source
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  #1  
Old January 26th, 2008, 11:04 PM
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Matthew Carey
95 D90 SW349
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slight surging of engine power

Need some diagnostic advice, 95 SW on the highway, 2,100 rpm and 5th gear. Turn on the blower fan to its highest setting and there is a slight surging of engine power, select lower fan speed and surging goes away?



Thanks Matthew
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  #2  
Old January 28th, 2008, 03:42 PM
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Chris Davis
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Sounds like you have a problem with your alternator--probably your Zenier diodes. Almost sure of it. As the diodes fail, you start bleeding A/C into your system and it is causing your fuel injectors to fire irregularly--somehow the added load on the alternator from your blower is causing it.

Granted, this is conjecture, but it is an educated guess.
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  #3  
Old January 28th, 2008, 07:05 PM
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Matthew Carey
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Chris, thanks for your reply, it's a brand new alt maybe 150 miles on it. Do you think it could be a defect or mis-installed?


Thanks Matthew
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  #4  
Old January 28th, 2008, 09:43 PM
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Chris Davis
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Surging with powering an electrical device leads me to believe the electrical system is playing on the fuel delivery system. I would totally check the alternator first thing--especially if this problem started after receiving it.

The only other thing I can think of is possibly causing a big pressure differential from the fuel pump, but that just doesn't feel right. Surging is usually fuel delivery issue and tying that to the heater motor leads me to think it is electrical. Now knowing you have a new alternator, it makes me think that more strongly.

Interesting issue--please let us all know what you find out.
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  #5  
Old January 29th, 2008, 10:05 PM
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Matthew Carey
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Chris

Thanks again for your help, if I come up with anything all post my findings.

Matthew
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  #6  
Old September 26th, 2008, 10:05 AM
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I am having the same issue. Was the alternator the problem or was it fuel related?
Thanks.
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  #7  
Old September 30th, 2008, 12:56 PM
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Thanks for the help Chris Davis.

I just replaced the alternator with a refurbish alternator and I have been unable to recreate the surging issue mentioned earlier! The real test will be on Thursday's ride down to MAR. Hopefully the trip will be uneventful...Well then again, why did I get a D-90. Itís not about the destination right???

On another note, I would like to keep my old alternator as a spare. Does anyone have a recommendation for refurbishing my old alternator? Do it myself? have an experienced shop do it? If done by an experienced shop, do you recommend anyone?


Thanks,


Chris
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  #8  
Old September 30th, 2008, 11:25 PM
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Chris... BonJourno... There is a place right by me that I use to rebuild that stuff.. let me know...
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  #9  
Old October 1st, 2008, 12:13 AM
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Nando Zorrilla
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I suspect the power surge comes from that vibrator you keep plugged into your cigarette lighter.

In any case, I suspect that the reason you have a brand new alternator is because the last owner was chasing the same issue and replaced the alternator without need.

We should put a volt meter on the electrical system and see what kind of voltage drop you get when you run the blower. We can compare it to my truck and determine if we need to keep looking at the electrical system or look elsewhere. It it drops severly, we can put an current meter on the blower leads and determine if the blower is drawing too much current.
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  #10  
Old October 1st, 2008, 12:26 AM
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Quote:
Originally Posted by TDI Guy
Chris... BonJourno... There is a place right by me that I use to rebuild that stuff.. let me know...
Randy -- Where abouts? I have a D2 alt. that needs a rebuilding.

-Ryan
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  #11  
Old October 1st, 2008, 09:39 AM
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It wasn't a new alternator. I replaced the original alternator with a refurbished alternator and I think the problem is solved. If I experience any problems during the MAR trip, I will follow your suggestion. Thanks.

By the way...I highly recommend keeping a charged vibrator in your D-90. It's a great conversation piece that quickly breaks the ice and it doubles as a useful tool to breakaway the Virginia mud that gets caked up in the radiator.
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