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-   -   Please help Buick rpm's increase while parked/neutral (https://www.fuelly.com/forums/f11/please-help-buick-rpms-increase-while-parked-neutral-11050.html)

Monkey Prey 04-05-2009 01:41 PM

Please help Buick rpm's increase while parked/neutral
My Buick has started to accelerate uphill, the rpm's increase while idle, parked, neutral, coasting. It had a little difficulty starting a while back but starts fine now. I have no clue what's going on. Any help is appreciated. I don't drive the car much but I like to know that it will start when I need it.:(

theholycow 04-05-2009 02:29 PM

What year, model, engine, and transmission?

I had similar problems with my 1987 Cadillac Deville, 4.1l V8 "HT4100", 4 speed automatic, TBI. I never did find out what was wrong.

Monkey Prey 04-05-2009 03:15 PM

1990 Buick Century, automatic transmission, I stopped by autozone to get directions and they mentioned either an air leak, injector problem, or idler setting being off...

Ford Man 04-05-2009 04:55 PM

I don't know anything about the way the Buick is set up. My '88 Escort has had that problem in the past and it was the idle speed control motor. That's one possible problem or an idle air control valve or a vacuum leak. I also had to replace the ECU in my '88 once because it would suddenly raise the idle a couple thousand RPM's.

Monkey Prey 04-05-2009 06:14 PM

I'm not really sure if that would be the problem. The difficulty it had starting. seems like it might be some other problem than the idle motor.

Jay2TheRescue 04-05-2009 06:35 PM

I would look for a vacuum leak. Get a can of old fashioned carb cleaner. While the engine is idling spray down the vacuum lines. If the idle drops, or the car stalls when a particular part or hose is sprayed you have a vacuum leak there.

Monkey Prey 04-05-2009 07:14 PM

Thanks for the tip, I was told to check for a leak but I couldn't hear one. I'll see if I can find the leak and post the outcome.

bobc455 04-06-2009 08:54 AM

Extra air is getting in the motor somehow. Stuck throttle (cable, linkage, throttle blade), IAC motor, vacuum leak, etc.


JanGeo 04-06-2009 11:14 AM

The engine speed may increase not decrease when the flamable liquid is sprayed on the air leak as it would be adding fuel to the engine. A small spray of water could also be used as it is safer than a flamable liquid. Always good to check the gas pedal, its linkage and carpet around it too.

Jay2TheRescue 04-06-2009 11:59 AM

I've heard both carb cleaner and starting fluid being used to test for vacuum leaks. I think carb cleaner is far safer... Its always worked for me.


Monkey Prey 04-07-2009 10:37 AM

I went ahead and had a diagnosis done. (paid way too much for it) Two fuel injectors were found to be bad and the computer could be also. The place wanted $700 to fix it...I can get fuel injectors myself for $60 apiece. I'm planning on replacing them this weekend but the mechanic said he wasn't sure which two needed replacing after he'd put everything back together. My belief is that when you take them out they will have buildup on them or have some leak. Any tips?

bobc455 04-07-2009 03:20 PM

Personally, I'd recommend six new injectors. I've been involved with many different injector projects over the years, and I consider them to be a maintenance item. Every 100k miles they should be removed and cleaned and tested on a bench (not just a bottle of miracle juice). And it's amazing how many people are driving around with bad injectors, and when they are replaced (or properly cleaned) the cars drive SO much better.


Monkey Prey 04-07-2009 05:54 PM

I would like to but I just don't have $360 to spend. I can buy the 2 injectors but not all six. I'm a poor college student who doesn't have a job. Thanks for the advice though.

theholycow 04-08-2009 02:38 AM

I vaguely remember a post about a company that you could send your injectors to and they would refurbish, test, and rate them. You could buy a set of injectors from a junkyard and send them so you wouldn't have any downtime.

Does anyone else remember it, and can anyone find it?

bobc455 04-08-2009 03:54 AM

I've used these guys before, with very good results - https://www.codymotorsports.com/

-Bob C.

Monkey Prey 04-10-2009 12:00 PM

I just wanted to say thanks for the help. I appreciate the quick responses.

JanGeo 04-10-2009 04:44 PM

Faulty injectors will result in some change in the spark plug ash buildup so by checking your spark plugs you may find the bad cylinders and thus the bad injectors. Other than that you have to see how much fuel they spray when activated in CC per minute and actually measure each injectors spray volume.

VetteOwner 04-10-2009 05:00 PM


Originally Posted by JanGeo (Post 132292)
Faulty injectors will result in some change in the spark plug ash buildup so by checking your spark plugs you may find the bad cylinders and thus the bad injectors. Other than that you have to see how much fuel they spray when activated in CC per minute and actually measure each injectors spray volume.

granted the mechanic put them back in where they came from:D

since it sounds like ye olden car and you dont have money, i would try a can of "miracle" (what i liek to call Sea Foam) dumped in the gastank.

i also like to let the engien suck some up thru a vaccum line and let it clean the top end and cylinders.

Jay2TheRescue 04-10-2009 06:23 PM

Either that, or a bottle of BG 44k. Seems like the first thing to try before taking the whole thing apart again.

Monkey Prey 04-10-2009 10:02 PM

I found an old buick at the junkyard and got the fuel injectors from it. The owner had just replaced the injectors before crashing the car. Lucky find, I'll be able to replace all six. I was told the ECU could be damaged because of the faulty fuel injectors, is this true?

Jay2TheRescue 04-11-2009 06:08 AM

While this is possible the ECU could be damaged, I find it highly unlikely.

Monkey Prey 04-11-2009 01:31 PM

Thanks, again. I swapped out the injectors and its running great. I'm glad to hear about the ECU. I searched online and everyone said the ECU shouldn't be damaged. My car idles normally again and is driving fine. Thanks for quick responses.:thumbup: :)

Jay2TheRescue 04-11-2009 04:57 PM

Good to hear... She's ready for the next 100,000 miles... ;)

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