Idle Drops At Idle

[2003CTMarauder]

I mean't RPM's drop at idel. When I am at idle backing up in reverse and have the wheel turned the idle goes down and goes up and down and fluctuates at little bit. Ive noticed it a couple times.

[Rider90]

My guess is the IAC.

[RR|Suki]

When I am at idle backing up in reverse and have the wheel turned the idle goes down and goes up and down and fluctuates at little bit. Ive noticed it a couple times now.


power steering (sp?)

[TripleTransAm]

When I am at idle backing up in reverse and have the wheel turned the idle goes down and goes up and down and fluctuates at little bit. Ive noticed it a couple times now.


If it happens as you're turning the wheel and applying tension on the wheel in uneven bursts, it's a "feature". The 4.6 DOHC is so testicularly challenged at low RPM that it can't handle the extra load of the power steering pump doing its thing, so there is a pressure switch on the power steering that tells the PCM to raise the idle to keep up with the extra drag. I don't know how other manufacturers do this compensation routine but this is the first automobile I've ever driven that surges so badly at idle. (and both my MMs do this). Even my brother's lo-po 1999 Accord seems to handle its power steering load at idle without flinching... I'm getting tired of having to explain the surging to all my slightly-automotively-knowledgeable passengers.

Makes for a real pain negotiating the car into a tight parking space in a parking garage, I can tell you that much.:shake:

[RR|Suki]

If it happens as you're turning the wheel and applying tension on the wheel in uneven bursts, it's a "feature". The 4.6 DOHC is so testicularly challenged at low RPM that it can't handle the extra load of the power steering pump doing its thing, so there is a pressure switch on the power steering that tells the PCM to raise the idle to keep up with the extra drag. I don't know how other manufacturers do this compensation routine but this is the first automobile I've ever driven that surges so badly at idle. (and both my MMs do this).

Makes for a real pain negotiating the car into a tight parking space in a parking garage, I can tell you that much.:shake:

I don't see how... but ok... anyway It's a ford thing my Cougar does the same thing... I really don't see how it makes it hard for you to park. All you have to do is take like a millimetre out of your lock and it'll be ok. Trust me, I've never had it any other way, hell before my cougar I drove all cars with 0 power steering.

[TripleTransAm]

All you have to do is take like a millimetre out of your lock and it'll be ok.

Not the same thing. The wheel is FAR from lock in this case.

Imagine the following scenario: you're backing into a tight spot between two pillars in a parking garage. The car is in reverse, and you are idling it while having the wheel turned. Of course, you have your foot on the brake, to keep the car always in control. The car slows to what seems like it will come to a complete stop (quite possible with the Marauder's 4.6l at factory idle) and you are releasing the brakes a bit more to keep the car moving. Of course, as you are backing into the spot (trying to keep a close eye on the pillars), you might change the amount of pressure you're putting on the wheel as you're turning it (again, FAR from lock) and then the engine will suddenly surge and the car will begin to move... if you're not quick reacting on the brakes, you might hit something.

Same scenario should occur if you're backing into a tight parallel parking situation: if you're looking back inching your way as close as possible to the guy behind you while turning the wheel to guide yourself in, better be ready to slam on the brakes... if that pressure switch goes off, the engine's going to surge and if you're close enough to that other car at that moment, BUMP!

Easy way to get around this situation: do NOT try applying any pressure on the steering wheel if you're at idle. You'll look like a Class A moron trying to park (you'll take 15 attempts) but you'll never have to worry about any unsollicited movement while moving the car at idle speed.

Sometimes I use this surge to my benefit: if I'm backing into a spot where I want the car to keep moving in a straight line, sometimes if I need a little nudge to keep the car moving, rather than remove pressure off the brake I will flick the wheel side-to-side, not enough to move the front wheels but just enough to nudge that natural pump resistance you feel back through the steering column.... the pump switch will cause my RPM to surge a bit and the car will keep moving until I get to where I really want it to stop.

Very graceful indeed.

Non-power steering cars don't have to worry about this: there's no load change on the engine as you try to turn the wheels.

Edit: try this and see for yourself. Make sure you are in a safe location to try this. Put the car in gear, make sure it's at hot idle, and hold the brake. Flick the steering wheel just enough to nudge that rubbery feedback resistance. You should see the RPM change a bit. Sometimes you can remove some of the pressure on the brake to make it easier for the pump to turn the wheels. Now, for added fun, try to time your steering flicks for when the RPM is on its way back down. As soon as you hit it just right, you'll drop the idle low enough to have the engine stumble and you'll probably see the BATT light come on in the dash momentarily, as the alternator turns too slow to provide any charge. Some have even made the engine stall this way!

Again, I've NEVER had any of my auto tranny cars behave this way, V8 or not.

[RR|Suki]

Not the same thing. The wheel is FAR from lock in this case.

Imagine the following scenario: you're backing into a tight spot between two pillars in a parking garage. The car is in reverse, and you are idling it while having the wheel turned. Of course, you have your foot on the brake, to keep the car always in control. The car slows to what seems like it will come to a complete stop (quite possible with the Marauder's 4.6l at factory idle) and you are releasing the brakes a bit more to keep the car moving. Of course, as you are backing into the spot (trying to keep a close eye on the pillars), you might change the amount of pressure you're putting on the wheel as you're turning it (again, FAR from lock) and then the engine will suddenly surge and the car will begin to move... if you're not quick reacting on the brakes, you might hit something.

Same scenario should occur if you're backing into a tight parallel parking situation: if you're looking back inching your way as close as possible to the guy behind you while turning the wheel to guide yourself in, better be ready to slam on the brakes... if that pressure switch goes off, the engine's going to surge and if you're close enough to that other car at that moment, BUMP!

Easy way to get around this situation: do NOT try applying any pressure on the steering wheel if you're at idle. You'll look like a Class A moron trying to park (you'll take 15 attempts) but you'll never have to worry about any unsollicited movement while moving the car at idle speed.

Sometimes I use this surge to my benefit: if I'm backing into a spot where I want the car to keep moving in a straight line, sometimes if I need a little nudge to keep the car moving, rather than remove pressure off the brake I will flick the wheel side-to-side, not enough to move the front wheels but just enough to nudge that natural pump resistance you feel back through the steering column.... the pump switch will cause my RPM to surge a bit and the car will keep moving until I get to where I really want it to stop.

Very graceful indeed.

Non-power steering cars don't have to worry about this: there's no load change on the engine as you try to turn the wheels.

Edit: try this and see for yourself. Make sure you are in a safe location to try this. Put the car in gear, make sure it's at hot idle, and hold the brake. Flick the steering wheel just enough to nudge that rubbery feedback resistance. You should see the RPM change a bit. Sometimes you can remove some of the pressure on the brake to make it easier for the pump to turn the wheels. Now, for added fun, try to time your steering flicks for when the RPM is on its way back down. As soon as you hit it just right, you'll drop the idle low enough to have the engine stumble and you'll probably see the BATT light come on in the dash momentarily, as the alternator turns too slow to provide any charge. Some have even made the engine stall this way!

Again, I've NEVER had any of my auto tranny cars behave this way, V8 or not.

Well I can't speak for you MM neither can I try this that you speak of, cuz my car has too much power always anyway, so my idle doesn't drop when I turn my steering... not even a little. On my cougar I've never had a problem with the surge. The revs go down a little and then the power comes back up a little. I'm still kinda confused, but I guess I must be used to it, cuz it's never given me real trouble. I even have an 01 motor in my Cougar aswell, so it makes good power, unlike the 96 motor. I've never had a surge that would make the car leap any considerable amount or make any issue of parking... perhaps your tune is off from factory :confused:

[Warpath]

Ford used to put "large" steering pumps in these vehicles to supply enough pressure during parking lot maneuvers (low rpm). Once the vehicle got some speed going, these large pumps were overkill for the application. Therefore, to save some weight and money, Ford put in smaller pumps and compensated for the size at idle by bumping rpm whenever steering pressure is required. At least that's what I've heard.

[rayjay]

So the answer for the kid is its normal.

[the_pack_rat]

I've noticed this too.

When I'm backing inside my garage all it will take is the slightest correction off center, to surge the idle up. The same goes for getting in and out of the car when it's running. When the car is parked & idling - you go to get in or out & bump the steering wheel a pinch, the same thing will happen.

A bit excessive IMHO at times, but I'm used to it.

The one quirk that I find more annoying .....

Is the slight delay in the engagement of reverse.

Trying to pull any quick "K" turn manuevers, could get really ugly if you don't figure in that slight delay and there is heavy traffic approaching.