| Author |
Message |
    
nick
| | Posted on Wednesday, July 17, 2002 - 10:53 pm: | 
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97 4.0 when idling,idle goes up and down between 750 and 1500 rpm what would cause this? |
Bill Bettridge (Billb)
| | Posted on Thursday, July 18, 2002 - 09:26 am: |
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Stepper motor (IAC) - did you check that?
Bill |
nick
| | Posted on Thursday, July 18, 2002 - 06:38 pm: |
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cleaned the stepper and it helped the erratic idle
now I would like to know how to adjust the idle besides the cable adjustment it is idling a little high,thanks in advance,nick. |
Randall Smith
| | Posted on Friday, July 19, 2002 - 02:18 pm: |
|
Nick
There is no cable adjustment for the idle...do not tamper with cables to adjust the idle. You can adjust the base idle, which is used to prevent the engine from stalling if the computer controlled idle system fails.
Idle problems:
Clean/replace stepper motor.
Check base idle.
Clean throttle plate and throttle bore.
Check for vacuum leaks.
Vacuum leaks only have an effect on engine running when the throttle is closed, causing high or erratic idle.
Randall |
nick
| | Posted on Sunday, July 21, 2002 - 11:54 am: |
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how do you adjust the base idle manually,trying to help a friend out withn 97 RR 4.0.Dealer says the only way to adjust idle is electronic setting no way to adjust manually,any truth to this? thanks again for any input. |
jp
| | Posted on Tuesday, July 23, 2002 - 04:26 am: |
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Dont know the 4.0 US Spec, but..
Clamp off the bypass hose (to stepper) so its blocked. Remove tamper plug on side of intake near throttle plate - hex adjuster inside. Fit a GOOD tacho to coil (book says dash tacho is not accurate enough) . Adjust hex to give 525rpm +- 25 is spec for D1 3.9l - clockwise is slower. I found mine barely able to sustain 550. If you go much higher, you may find that idle is too high if you coast in neutral.
good luck.
jp |
jp
| | Posted on Tuesday, July 23, 2002 - 04:28 am: |
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Unstable idle can also be caused by air leaks, leaks/problems in charcoal canister, leaking valley cover etc. Check all vacuum lines, esp pressure regulator line.
jp |
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