strange idle speed problem!
strange idle speed problem!
I flushed the cooling system of the Q today,then rinsed off engine afterward to clean up a few drops of spilled coolant,now the car is idleing at 1200 rpm when hot in park! Before,it hot idled at aprox 650 rpm in park or drive.the engine has run at least 4 hours since the procedure,so it should be dry,and sometimes,it idles at the correct speed{650rpm} sometimes 1200rpm when fully warmed up,any ideas whats going on?
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nuQ
- Posts: 1659
- Joined: Thu Jan 23, 2003 1:39 pm
- Car: 2003 Infiniti M45
2009 Dodge Caliber SXT - Location: Bethlehem PA
i would check the connection for the MAF first. i had a very similar problem with a unsteady idle when hot. took the connection of the MAF, VERY GENTLY scrapped the metal connections down, applied some bulb grease, firmly pressed together,,,problem solved. in your case, might help to make sure everything is dry around the connection point first.jeff
thanks,i wiggled the maf connector,no change in idle speed! the car idles smoothly,just way to fast!,was perfect at 650rpm before this procedure.hopefull i can resolve this ,i have a feeling if i take it to nationwide infiniti,they will just lower the idle speed without looking for the real problem.
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elwesso
- Posts: 30810
- Joined: Sun Feb 23, 2003 4:52 pm
- Car: 94 Infiniti Q45t 5 spd
2007 BMW M Coupe
2007 Infiniti G35 S 6MT - Location: Indiana
- Contact:
I have the same problem, but its probably not caused by the same thing... I have a vacuum leak, and since it just started I doubt this is your problem also....
So your saying sometimes it idles high, and sometimes low???? I would suspect a sticky IAC..... You can get it pretty clean while its still on the car, just disconnect the 4 bolts holding it on, spray carb cleaner in there, and get some canned air to really blow it out.....
So your saying sometimes it idles high, and sometimes low???? I would suspect a sticky IAC..... You can get it pretty clean while its still on the car, just disconnect the 4 bolts holding it on, spray carb cleaner in there, and get some canned air to really blow it out.....
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Q45tech
- Moderator
- Posts: 14296
- Joined: Tue Apr 30, 2002 3:19 am
- Car: 1990 Q45 342,400 miles 22 years ownership with original engine
1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl
The coolant temp sensor [the 2 terminal one] only throws a code when fully open or fully shorted [say zero to 40 ohms] .........the normal range 325 ohms at 176F to 2500 ohms at 68F..............if connector corrosion made it read 5,900 ohms [normal for 32F] the ecu just thinks the engine is cold and increase the rpm to warm it up.
1990-1995 ecu are dumb as rocks.....they do what the sensors tell them to do with out checking unlike modern OBD2 systems.
http://www.jag-lovers.org/xjlo...s.htm
Just so you know the coolant temp sensor/ecu bridge circuit cannot read beyond 225F.........this is the software limit 50F beyond normal operating temperature.As 195F starts the ignition timing decrease for overheat safety [knock reduction] but thermal runaway starts around 220F as the last reduction step is at 215F [when the maximum of 5 degrees has been taken out of the calculation]
1990-1995 ecu are dumb as rocks.....they do what the sensors tell them to do with out checking unlike modern OBD2 systems.
http://www.jag-lovers.org/xjlo...s.htm
Just so you know the coolant temp sensor/ecu bridge circuit cannot read beyond 225F.........this is the software limit 50F beyond normal operating temperature.As 195F starts the ignition timing decrease for overheat safety [knock reduction] but thermal runaway starts around 220F as the last reduction step is at 215F [when the maximum of 5 degrees has been taken out of the calculation]
[QUOTE]Originally posted by Q45tech "]The coolant temp sensor [the 2 terminal one] only throws a code when fully open or fully shorted [say zero to 40 ohms] .........the normal range 325 ohms at 176F to 2500 ohms at 68F..............if connector corrosion made it read 5,900 ohms [normal for 32F] the ecu just thinks the engine is cold and increase the rpm to warm it up.
1990-1995 ecu are dumb as rocks.....they do what the sensors tell them to do with out checking unlike modern OBD2 systems.
Q45tech,my q is a 96,with OBD2,would this problem with 1200rpm idle throw the check engine light on?another symptom I am experiencing with the fast idle is that the transmission seems to be holding upshifts till much higher in the rpm band for the amount of throttle given,compared to before this idle problem began!It wont even go into 4th gear till about 45mph,even with verry lite pressure on the accelerator,never had this happen before,HELP!!!!!!!!!!!!
1990-1995 ecu are dumb as rocks.....they do what the sensors tell them to do with out checking unlike modern OBD2 systems.
Q45tech,my q is a 96,with OBD2,would this problem with 1200rpm idle throw the check engine light on?another symptom I am experiencing with the fast idle is that the transmission seems to be holding upshifts till much higher in the rpm band for the amount of throttle given,compared to before this idle problem began!It wont even go into 4th gear till about 45mph,even with verry lite pressure on the accelerator,never had this happen before,HELP!!!!!!!!!!!!