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Discussion Starter #1
Something new this spring....it studders and hesitates at idle...seems like it settles down after a minute or two but comes back...runs perfectly on the highway.then the same thing when I pull into the garage....I replaced the four coils 15 yrs ago when I purchased...also just now replaced the throttle control motor...no change ...think I should change the coils again?....they arent that expensive...and what about the MAP sensor....could that be an issue...thanks for any help...craig
 

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Discussion Starter #3 (Edited)
How old are your spark plugs?
Thanks for the reply...probably 15 yrs....I pulled the four up front...they looked ok to me....but then 15 yrs is a long time...the way its acting it seems like it is having trouble with the fuel mixure when coming back to idle....when I bought it I changed everything in site....I had a nice run....Thinking about it, I just ordered a new set of plugs and 4 new coils....I'm still curious about that MAP sensor and if that could be my problem....not sure exactly what it does but a rough idle is one of its indicators of a problem....any help appreciated....
 

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What are your diagnostics showing ?
Have you tried idling in the dark to see if anything is arcing ?
And something stoopid: what is the voltmeter showing at idle ?
 

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Discussion Starter #5
What are your diagnostics showing ?
Have you tried idling in the dark to see if anything is arcing ?
And something stoopid: what is the voltmeter showing at idle ?
I ran the codes this morning
PO23H
PO25H
PO83H
SO44C
SO60H

PD02 @ 99 for the MAP sensor

It's erratic...stumbles with a miss when I start it, then settles down....it starts at 1000+rpms then down to 700 rpm's in a minute or two...when I came home from the grocery store there were no issues....erratic....next week my plugs and new coils show up...I did get up at 2:30am and ran it in the dark....nothing showed up..
 

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OK codes that end in H are history. C is current. For S044 I get a lift or dive signal fault which should not affect idle.
S044 is on page 3G2-34 & P codes are in section 6E-A in the 93 FSM.
I'd clear all faults and see what comes back.

Might see what PD40 and PD41 (knock related) are saying. If mine I'd set up a display of many things. Sometimes that is the only way to troubleshoot.
583155
 

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Discussion Starter #7
Someone suggested an EGR valve might be an issue...I realize this might be like shooting darts without a mehanic looking at it....But....I'm willing to shoot a few before I take it in...
 

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If that is the same digital (triple) EGR as a 3800 you can move by hand or with a Mit-E-Vac and see if it sticks. You can also view the "EGR pintle position" PD07 on the DIC.
 

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Discussion Starter #9
I'll check that out on the DIC....thats where I got the MAP sensor number of 99....I've owned this Allante for 15 yrs and would like to keep it so I can justify some maintenance...
 

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Discussion Starter #10
Mondays results....cleared all codes...drove out to the golf course, shot a shitty round of golf and drove home....ran the dic...two codes showed up SO44history and SO60history... I also wrote down while running PD02 Map 37 and PD07 Pintle raw 38....I can't interpret that...thanks for any help...car ran perfectly ...Idled perfectly....after changing out the idle control motor does the computer take alittle time to adjust to new equipment?...wishful thinking...
 

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Yes, it takes a while to set all of the trims. GN people disconnect their battery before every run so it goes max rich.

Hate to sound like a broken record but any 25 year old car needs a service manual. Here are the values and ranges, is in section 8D.
583233
 

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Discussion Starter #12
I have a service manual I just wanted confrimation on how I was looking at PD02 and 07...my numbers are 37 and 38 so does that mean I am within an acceptable range of being ok..?....thanks for your help....appreciated....these service manuals are written for qualified mechanics...which I am not...
 

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Discussion Starter #14
Just off the highway so warmed up....Later this week I plan on replacing the plugs, four coils and the EGR valve...I've always liked new replacements to eliminate things and besides after 15 yrs it's time to freshien up...I'd like to keep this Allante....I might look for a Montana Blue one...
 

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Discussion Starter #15
Yesterday I installed new plugs, four new igntion coils and EGR valve....thats in addition to a new ICM a week ago....will use this week to test drive and report results....interesting the EGR valve had a very thin metal what I would call a gasket instread of the nomal thick paper type gasket that was on the original Valve....anyone else experience this?...thanks.....cleared all codes for a fresh start.....Anyone give me a quick reference where to find instruction in the service manual to change the date and time.....clearing the change oil I found but after an hour of looking I stopped on the date/time...thanks for any help...craig
 

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Metal gasket resists heat better. EGR can get hot.
Is in owner's manual. For my 89 press the time/temp button then press ahd hold the reset until display switches. Flashing thingies starts to right. Use arrow buttons for up/down. Press reset to move one space left. When done press one o the fuel buttons to exit.
 

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Discussion Starter #18
I drove the Allante around for a week and it seemed to run good...no issues.....today as I came into the driveway the same original problem came back...stuttering and surging to the point where I needed one foot on the brake.....after changing plugs, coils icm and egr valve, my issues are still here...I ran the codes during the week and nothing showed up...I ran them now and po36 current registered .....don't know where to go at this point....
 

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Discussion Starter #20
Thanks Padgett for helping out.....I read thru that and will start it up in the morning and see where I am....that fix seems beyond my ability ....I'll report in what happens...thanks again and best with your new project....
 
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