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Old 09-06-2007, 10:27 AM
dpetryk's Avatar
dpetryk dpetryk is offline
Electrons can do anything
Join Date: Sep 2001
Location: Houston, Texas
Posts: 1,071
Well let put it this way. Long story short - The symptoms you describe exactly match ones I had including inconsistency.. I tried everything saving the FD for last. Well guess what - the FD fixed the problem. Nobody can say for sure what the problem is without proper diagnostic work. But given everything you said and the age of the vehicle and the trend for the FD things to begin failing at this mileage and age etc. My best guess is a FD. I have seen it a number of times.

Nobody wants to accept that the FD might be at fault. 3 of my 5 have had failed FD's and all were within 2 years of each other. Is there any significance to this? Only you can judge.

For years I had my 87 420sel would start right up but for 30 seconds or so it would run rough. I always told myself it was the injectors. Well is slowly got worse, and then the hesitation set in, then rough idle, poor acceleration, bad mileage etc. and so on. After checking and changing all sorts of stuff and no real improvement I replaced the FD and the problem was solved. It was like a new car.

When I read a post like yours I can related to how I went down the road of rejecting the idea the FD is bad mostly because the cost of these things only to find the problem wads the FD after all.

I try to express my opinion which is based on experience to arrive at a conclusion that in my opinion is the most likely culprit. I don't like to type so I tend not to go into lengthy explanations as to why I arrived at my conclusion. Just the conclusion itself. But then the questions come. Also, in many posts where I have made recommendations, the person asking for advise almost never reports back as to that the cure was. It is important for everyone to know what worked and what did not. SO if you would please report what the fix is when you get it repaired and running properly. It helps everybody here. To ask a question, get a dozen suggestions, and not report the outcome is not very helpful. Knowing the cure is.

dugald - what fixed your problem? - Sounds like a fuel delivery problem to me.

So anyway, do as many suggest, swap out stuff for EOM, non-OEM, resistor, non-resistor plugs. Do the "low cost" items first "because it does not cost much" -- ??? -- WTF. I hear all sort of logic as to how to approach finding the problems. Many are expensive if you add up all the time and "low cost items" replaced that really did not need to be changed. It is a waste of time and money in my opinion. I tend to diagnose the problem and be sure of defective parts before replacing things. I don't believe in the "lowest cost first - shotgun approach" method. I don't believe in the "lowest cost first shotgun approach" method. Unless you have unlimited funds.

Let us know what you find. Everybody will be grateful.

Jfawcett - you need to come by my shop sometime - 290 & BW8 area. I would love to see your car.
I got too many cars!! Insurance eats me alive. Dave

78 Corvette Stingray - 3k
82 242 Turbo Volvo - Manual - 270k
86 300e 5 speed manual - 210k
87 420sel - 240k
89 560sl - 78k
91 420sel - 205k
91 560sel - 85k
94 GMC Suburban - 90k
97 Harley Davidson Heritage Softail - 25k
00 GMC Silverado 1 ton 30k

Last edited by dpetryk; 09-06-2007 at 10:35 AM.
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