Idle issue with my 4.7L V8

smg0413 · #1 08-27-2009, 03:48 PM

I have an 02 Quad Cab with the 4.7 V8. with about 130,000 miles

The car has been idling very rough for the last year.
When you start the car, the RPM shoots up to between 1500 and 2000 RPM's
Also, as I am slowing down, especially in traffic, as the transmission downshifts from 2nd into 1st, at about 10mph, the RPM jumps and the car slightly lunges forward, causing the brake to have to be pressed harder.

In park, especially with the AC on, the idle with bounce between 1000 and 1500rpm.

Finally, in a test, I came to a full stop at the bottom of an incline. Let go of the break, and the car idled all the way up the hill (about 1/8 mile) with out touching the gas, and it was going between 3-5mph.

When I took it to the shop last year, they checked all the lines (no probs) and cleaned the hell out of the throttle body.
Still had the problem.

Does anyone have any suggestions?
It's very frustrating.

Edit: Also have never had an engine light, or a trouble code.

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Crazy4x4RT · #2 08-28-2009, 02:50 AM

It may be the IAC Idle Air Control valve. Try cleaning it up or replacing it.

smg0413 · #3 08-28-2009, 03:40 PM

Quote:

Originally Posted by Crazy4x4RT

It may be the IAC Idle Air Control valve. Try cleaning it up or replacing it.

I believe the mechanic tried changing that last year. No luck.

donkshow · #4 09-08-2009, 01:27 AM

just fixed this issue with my 2000 4.7 5speed. I replaced the throttle position sensor and it fixed the idol issue.