Start, stall

Bob393

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2004 Lesabre Limited
Thread starter #1
Just the latest of weird new things creeping into my 2004 limited.

First it always starts and seems to run fine but.
When it's warmed up sometimes I will start it and it will stall
try again same thing 2,3 perhaps 4 times then it starts and runs fine.
The wife just told me it also does it from cold sometimes.

Then occasionally when you put it in gear, drive or reverse, the engine
surges causing it to bang in gear if you don't wait a moment for it to
idle down to normal.

Any thoughts will be apreciated.
 

HotZ28

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1996 Roadmaster Limited Collectors Edition 58k - 1996 PAU
#2
MAF, throttle body, vacuum leaks & IAC would all be suspects with the symptoms you mentioned. Any codes??
 

Bob393

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2004 Lesabre Limited
Thread starter #4
Thank you, no codes. I was thinking fuel pressure but cleaning the MAF and IAC first sounds like a plan.

I don't think there are any air leaks only because anytime they cheeped in I got a code for lean fuel mixture.

I hate to be a part changer so I love the idea of cleaning and testing first.
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Bob393

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Goshen, NY
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2004 Lesabre Limited
Thread starter #5
Well the IAC was carboned up like crazy. Took a bit to clean but got it nice and shiny. The seat wasn't to bad but cleaned that up too.
It was a bear to start and the idle seems a bit to high but the wife just took it out and she thinks it's better. I'll know for sure in a week or two.
Thanks for the input, I think we got it. I also cleaned the MAF but that looked brand new.
 

Bob393

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Goshen, NY
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2004 Lesabre Limited
Thread starter #6
To keep this going I started to have the same problem as before so I replaced the IAC after cleaning the carbon out of the port even better. I still have the same problem. It almost seems like it can’t decide where the idle should be. Now to be specific. On my other Lesabre when I start it the idle runs up to say 1500 RPM for a bit than settles down to 6 or 800 and all is good. This car never runs up that high. When you shift it from park into gear, either drive or reverse often the idle stumbles or runs away and the transmission bangs. And of course it often takes three tries to start the car unless I blip the throttle to save it. I also need to mention that once it starts and is in gear and on the road it’s fine...
 

Alan 55

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2001 Buick Park Avenue, previously owned 1997 Park Avenue
#7
It could be time to break out the scan tool and take a look at the IAC counts. The total counts range from O-255 with 10 to 40 being typical. A larger number of counts means that more air is being commanded through the idle air passage. IAC position should respond fairly quickly to changes in engine load to maintain idle RPM. This info is from my FSM. Hopefully the new part is working correctly but it is not impossible to purchase something that is faulty. If you have another Buick with a 3800 you could use the scan tool to check and compare the counts of the IAC.
 

Bob393

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Goshen, NY
Buick Ownership
2004 Lesabre Limited
Thread starter #8
Excellent idea, I didn’t know that a scan tool could do that but when I get back home it will be the first thing on my to do list. I’m on vacation right now and have driven the car 750 miles this weekend and I can tell you if you hold the gas down a touch just after it starts it does not stall and idles fine, with the gas on so there is defiantly something up with the way it reads and controls the IAC.
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Bob393

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Goshen, NY
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2004 Lesabre Limited
Thread starter #9
I just ran my scan tool and I don't see a data stream for the IAC. I have an Actron CP9185
and I'm going to check the website right now.
However there are defiantly no codes present or stored.
 

Bob393

A Regular
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Location
Goshen, NY
Buick Ownership
2004 Lesabre Limited
Thread starter #12
Another common thing to go is the FPR when you have bad hot starts. Although the MAF and IAC are good culprits too.
Never thought of that but I sometimes have the problem with cold starts too.

concerning the transmission bang, have you checked for a broken mount?
Interesting, I have been questioning the front mount for a while. It does seem to move more than I remember
in my other Lesabres.
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