i need to pick your automotive minds

RUDY PU RACING

RUDY PU RACING

DIRT FAN FOREVER
my wife has a 91 chevy lumina 3.1L fuel injected car. it has a rough idle and dies when she comes to a stop at a light. i have noticed a small hesitation when you get on the gas and a slight miss in the motor when in park.. it only dies when it is in gear.. i replaced the battery last saturday and since then it has develpoed this problem. it had the rough idle before but never died, so i don't think the battery has much to do with it... im leaning toward dirty fuel injectors, just wanting to get a second opinion from some of you chevy mechanics... thanks for any replies....brandon hogenson
 
Im not a mechanic but i know the 3.1 motors computers have to be reset when you lose power or change a battery.Im sure mechanics have a procedure for this.but im sure your computer has to relearn your settings.
 
there are so many things that could cause this to happen.check the fuel pump,the coil packs,see what kinda pulse the injectors have,millions of different sensors,tuneup,dirty clogged injectors,weak injectors,you have to go through the process of eliminations.also the variable speed sensor on the tranny when bad will make the car die,they are a pain..good luck!
 
The 3.1's many times have to relearn idle after loss of power, generally putting 10-20 miles on it it should meet all the criteria to readapt, in short drive it, it should be ok soon.
 
Engine Computer

If you still have the maual that came with it, it probably says to start and let run for five to ten minutes and it should clear up.
 
ohm out the injectors. They all should be around 12.4 roughly. One that does not read or chks around 9 or lower. Will cause one hey of a problem. If that is the problem?? And that is a comon one. It will eventualy stop all together. One bad inj. will open or short the rest.
 
The idle air control is carboned up,there fore when ya killed power to the system
it can not relearn the idle because of the carbon not letting the idle air control seat fully, pull it out clean it and the bore with carburetor cleaner and an old toothbrush,put it back together,disconnect the negative battery cable for a minute or two,then retry it,it should relearn the idle in a couple minutes. Now this probaly won't help your miss but should at least get it to idle for ya.....
 
thanks for the ideas. hworrell i was thinking the same thing because it happend on my fiero and it drive me nuts trying to figure it out. this morning i was thinking about what i did to get the fiero running good and that was it .. looks like a set of plugs and cleaning the iac valve will be my first task then the valvoline 80 dollar injector cleaning.. i tried to get her to let me put a 350 in it but she said no!!!! lol thanks again
 
My painter had a similar problem and it ended up being a throttle positioning sensor. He had to drive with his foot on the brake and gas at the same time and it wouldnt idle. The sensor had a intermittent dead spot in it.
 
Yep..check the iac solenoid first(idle air control) and clean the throttle body out(cant even comprehend how a little piece of crap can cause those to freak out). If there is a black plate..on the throttle body..square...has 4 philips screws in it with 3 wires plugged into it...see if you can get it out(gentley) Its called a mass air flow sensor(not a meter...as was used in later years) If you pull it out..looks like a diode in the middle...ckeck it for carbon(the slightest piece will throw it off!!) Check the injectors(usually..no1 starts going bad...first..if it does..it will even kill the car!!). Also..those were noted for the torque converter lock up switch for occasionally fail(meaning..its like pulling to a stop sign..in 2nd gear..and not pressing the clutch in). There is a square...4 prong connector..directley in the front of the trans...it controls it(near the cooling fan). Disconnect it..and redrive..see if its curedSome used this to shift the trans also..if..it doesnt shift...replug the connector). Can just leave it diconnected..and be ok(will hurt gas mileag...a little) Last but not least..relearn the idle. I was told..by gm to do this...turn all acc's off...start the car..put it in drive with the brake on...turn on the a/c...and..work the wheel...back and forth...5-10 minutes(or..you can drive it..but..it may stall) This pretty much will relearn the idle..used it many times...good luck!!
 
Brandon you need to relearn the idle.Unhook the batt again then hook it back up.,start the car and let it idle in gear for ten minutes and the stall should be gone.3.1 loose their idle memory whenever power is lost.As for the rough idle some of the other sugestions could be it.

Kevin Diveley
 
thanks kevin, i found #1 plug was bad (fixed the miss) and cleaned out the iac valve, and found a vacuum leak. the 3 tubes on the throttle body were loose so i sealed them and reset the idle like you said.. runs like a new 189,xxx mi. car lol how is the new car comming??? and are you guys going to the godfrey banqet?? talk to you guys soon... thanks
 
idle air control motot

in my opinion hworrell is right the computer learns what the motor needs os it goes, over time the comp. slowly compensates the diffenerent snesors and youll never realize it. when you disconnect the battery it cant immediately learn how bad off the iac or tps is what about the egr, there are quite a few things that could affect the way these cars act.

good luck w/ some more info we might be able to help more
i/e fuel pressure
are all cylinders hitting gm coils are bad about goin out

mike
 
1 thing to keep an eye on..if a plug fouls...causes the ignition system to strain..therefore..it may knock a coil pack..or plug wire out in the future. Glad you got her fixed.
 
i spoke too soon, my wife just called and it died 3 times today...:mad: :mad:
looks like im back to sauare1. im going to try to reset the idle again... anyone know where i could take it to be analyzed???
 
Well..1 thing id do...is try to get any codes out of it...or..unplug the lock up converter first(look at my first post) It will cause it to die...slowing down to stop signs, or..just apllying the brakes. To retreive the codes..find the computer connector(on gm....usually down under the steering column(pedals area) the 2 upper right side terminals...the last rt one..and..next to last right one on the top row...put a liece of mechanics wire....cotter key...something between these 2 terminals(with the key off)...turn the key on..and..the check engine light will flash. Count the flashes(will be like...blink blink....pause.....blink blink blink...codes 23...ect) and ...let us know if any in there.
 
What 90 is describing w/ the lockup solenoid, it's like you're stopping and forgetting to depress the clutch on a manual trans. It's a violent bucking and die as you stop. but if you've disconnected the bat again,it may need to completely readapt. If you've messed w/the base idle screw, that may cause a problem as well. Is the rough idle/miss gone with the fouled plug? Greg
 
ok , there is no way to set the idle screw as it is a stud that is in a solid aluminum housing, i guess you could clamp a vise grip pliers and try to screw it out, but no i havn't messed with it.. i have replaced the m.a.p. sensor this morning and still have a rough idle. it is not the lockup solenoid im sure, as it dies very smoothly, my wife doesn't even know it died until she stops and finds out no power steering and hard brake pedel..lol i think im going to replace the throttle pos. sensor. if you just barely push on the throttle pedel it hesitates and then goes. that only does it when she is stopped, so i would believe it has a bad spot just after idle?? i might just take it to a shop and se what they come up with.. hate to drop a bunch of money into it and not fix anything!!!

p.s. i have a code 33 in the computer, but no service eng. soon light was on....
 
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