Engine nearly dies when stopping
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Junior Member
Joined: Dec 2002
Posts: 2
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Engine nearly dies when stopping
Have 2001 supercrew with big V8 and when I am coming to a sudden stop the engine RPMs drop to around 400 RPM, and on some rare occasions actually dies. The RPMs always drop below the regular idle RPMs, and then pops back up to normal idle if the engine stays running. Someone mentioned an "IDLE CONTOLLER" as the culprit??, --- any ideas, any suggestions.
HELP
HELP
Senior Member
Joined: Sep 2003
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From: Aggieland, TX
Probably need to clean or replace your IAC (Idle Air Control) valve.
On the 5.4 it is located just behind the throttle body (the angled part), and to the passenger's side.
It's a little tough to get to though.
You can search the forums for IAC* (include the asterisk to fulfill the 4 word minimum).
On the 5.4 it is located just behind the throttle body (the angled part), and to the passenger's side.
It's a little tough to get to though.
You can search the forums for IAC* (include the asterisk to fulfill the 4 word minimum).
Senior Member
Joined: Jun 2003
Posts: 186
Likes: 1
From: Biloxi, MS
check the IAC, but don't over look the upstream O2 sensors... if the truck does it more noticeable when it is warmed up, then the O2 sensors are the culprit... they don't always turn a light on.. and they typically start showing signs of going out around 50k or more.
Senior Member
Joined: Jun 2003
Posts: 186
Likes: 1
From: Biloxi, MS
just wanted to update my advice, there could also be a vacuum leak, and be sure to check the rubber elbow located right at the PCV valve. it becomes weak and collapses when vacuum is supplied. my truck did the rough idle thing, when it starts acting up, try putting it in neutral and see if the rpm's shoot back up...
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Junior Member
Joined: Dec 2002
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Thanks,, follow up question..
See it IAC is way back up under overhang of the firewall and wondering if all I need to do is remove the two bolts and the attached electrical?>> And then, exactly what do I clean on it and what should I use.. See some recommend WD40, and others brake fluid, etc.,,etc.. what do you think? And do you know where I should look for the best price on replacement if needed? I do thank you all for quick and good response. Thanks, looking at the symptoms I feel quite sure it is the IAC, or possibly the sensors, but don't think so.. No vacuum leaks.. APpreciate it..
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Joined: Jan 2004
Posts: 81
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From: Georgia
Had the same problem in my 97 XLT 4.6l, here is a list of things I did: replaced ECV, cleaned IAC, MAF, and throttlebody, changed downstream O2 sensor and still had problem. I finally changed upstream O2 sensor and it runs straight (600- 700RPM) although I still have a click coming from pass. side of engine (?)
Good Luck.
Good Luck.