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Old 11-19-2004, 01:07 AM
dgreen1069 dgreen1069 is offline
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Default Rough idle/ low rpm miss

I just purchased a mint 87 GN with 4722 miles. The car is completely stock except for a new fuel tank/sending unit (original sending unit rusted inside the tank). The car runs very strong, but it seems to have a slightly rough idle. It almost rumbles like a car with a big cam. The engine also has a stumble or miss in the 1400-1800 rpm range. It is most noticeable when the TC locks up....the car then has a slight jerk to it. When I first apply the throttle there seems to be a slight hesitation, then the boost rises and the car runs like a rocket.

Everything on the car is original and looks to be in like new condition. My gut tells me the problem is electrical, but I'm not sure where to look. Does anyone have any ideas on where to start? Does anyone know of any good mechanics in the Northern VA area. I know there are several in PA, but that can be a bit of a hike. Any help will be greatly appreciated.
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Old 11-20-2004, 02:56 PM
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Keller Keller is offline
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Lightbulb Re: Rough idle/ low rpm miss

Quote:
Originally Posted by dgreen1069
Everything on the car is original and looks to be in like new condition.
...which could mean that your injectors are full of junk - just like your fuel tank was. They might need to be pulled, cleaned, and flowed. Change your fuel filter as well. The problem could be your TCC solenoid in the transmission sticking and holding closed, too. See info on the web site.

Letting a car sit too much is not good for it.
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Old 11-24-2004, 02:13 AM
dgreen1069 dgreen1069 is offline
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Default Re: Rough idle/ low rpm miss

Thanks for the reply. As far as I can tell, the original owner (whom I bought the car from) did a good job of storing the car. He changed the oil once a year and ran the car periodically. Before the car went up for sale, he replaced all the hoses, serpentine belt, plugs, filters (including fuel), fluids (brake, oil, trans, antifreeze), and replaced the tank. I have a receipt for $1700 in preventive maintenance he performed prior to the sale.

I was also thinking the injectors might be a little gummed up. Any suggestions on what I could use to clean them? Would a decent additive do any good, or are they mostly snake oil. My idle problem may not be a problem at all. After reading a bunch of threads I have come to realize that the 3.8 is not the smoothest idling vehicle in the world. My car starts right up and idles without stalling or surging....maybe that's what is to be expected. I haven't seen enough turbo Buicks to know whether or not they idle like a hotrod or not. The slight surging doesn't seem right and is my bigger concern. Any insight would be appreciated. Anyone know of a good mechanic in the Northern VA. area? I'd love the have the car looked at by a true professional who is familiar with these cars.
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Old 11-24-2004, 04:02 AM
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Post Re: Rough idle/ low rpm miss

Part of the issue is that the MAF is so far away from the engine and throttle blade. Its basically a 1960s era engine with 1980s technology grafted on to it.

The only right way to clean injectors it to remove them. And doing it right might be a bit tricky. A few lines are easily bent/broken if not removed properly.

You may not have a real problem. There are some sources in our vendors list...which is also sorely in need of updating.
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Old 11-24-2004, 06:03 PM
turbogn86 turbogn86 is offline
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Default Re: Rough idle/ low rpm miss

well before u do any of the injectors, just take a minute to check all the vacume lines an plugs. just check the little things before u jump to the big stuff, but an injector cleaning isent a bad idea though.
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