Weird High Idle

[GrazniM]

A few days back I did about 250 miles in local and highway driving over the course of one afternoon. That evening when I pulled into my driveway and shifted into park my RPMs shot up to about 1200. I waited about a minute and then blipped the gas and RPMs shot to about 2K then settled back to 1200. (My normal idle is about 600-650). Played with windows/seat heaters (create some draw) no real effect, turned on A/C and the RPM's dropped to 700, turned off A/C and RPM's back to 1200. Shift to drive and RPM's just over 700. Turned off car and decided to check it the next morning - in the AM, all working 100% normal; no discoed hoses or wires I could find.

?? anyone see this type of thing with their ride ?

[duhtroll]

Mine is doing similar things. As soon as I have time I'm going to pull the MAF and spray it with some cleaner. Maybe IAC too. That fixed it the last time.

While doing this, disconnect your neg battery terminal for the duration of the cleaning. This will reset the CPU.

[GrazniM]

Can't hurt. A few weeks back I installed the K&N CAI, sprayed the MAF with CRC MAF cleaner and performed a reset (the owners manual reccs. turning on the A/C and placing car in drive for a minute or two to help set the idle speed). Could be the oil from the K&N element fouling the MAF a bit? Didn't think of the IAC....

[Muddflapp]

I have a similar problem.
The tach jumps to 2k every time I start the DOHC 4.6L engine.
Then it slows to 1.2k. After driving down the street it will lower the idle to normal.

The Mercury dealer said "That doesn't seem normal". Then later they said "Don't worry about it". I'm concerned that it will eventually blue smoke.

2004 Marauder 8200 miles.

[Evasfunk]

I have a similar problem.
The tach jumps to 2k every time I start the DOHC 4.6L engine.
Then it slows to 1.2k. After driving down the street it will lower the idle to normal.

The Mercury dealer said "That doesn't seem normal". Then later they said "Don't worry about it". I'm concerned that it will eventually blue smoke.

2004 Marauder 8200 miles.
Yours seems normal...mine does the exact same thing its just the engine warming up.

[fastcar]

I have a similar problem.
The tach jumps to 2k every time I start the DOHC 4.6L engine.
Then it slows to 1.2k. After driving down the street it will lower the idle to normal.

The Mercury dealer said "That doesn't seem normal". Then later they said "Don't worry about it". I'm concerned that it will eventually blue smoke.

2004 Marauder 8200 miles.

This is NORMAL. When the car is started cold, the idle goes way up, then settles back a bit, then eventually goes to 6-700. Lidio said it does this to warm up the cats.

fastcar:burnout:

P.S. DAMN, you have low mileage!

[cyclopsram]

Not good for the engine, but satisfies the EPA...so much garbage on the puter...

[Muddflapp]

Maybe I'll get one of those things that keeps the oil system pressurized between starts. It had 1273 miles when I got it 7/29/06

[CRUZTAKER]

... my RPMs shot up to about 1200. ?? anyone see this type of thing with their ride ?
Mine will do this as well. Even with an entirely different motor. Must be in the EEC. Some programmer, somewhere in the Upper Peninsula, is laughing his arse off. Eh?
:flamer:


I have a similar problem....
The tach jumps to 2k every time I start.

Normal. Stick around for some time, and you will see this presented once every 5-6 weeks or so.;):up?

[GrazniM]

I have a similar problem.
The tach jumps to 2k every time I start the DOHC 4.6L engine.
Then it slows to 1.2k. After driving down the street it will lower the idle to normal.

The Mercury dealer said "That doesn't seem normal". Then later they said "Don't worry about it". I'm concerned that it will eventually blue smoke.

2004 Marauder 8200 miles.


Fast idle is competey normal for startup and warmup, (chokes on old-time cars and outboard motors), though mine dosen't go to 2K for more that a second or two. RPM during startup in modern cars is partially dictated by conditions (temps/sensor readings, engine not run in a while, etc) The computer is going to pump enough gas and suck enough air initially to warm up the components until everything can run smoothly without stalling out. Because this is is all automated the best things you can do are to use synthetic oil, which flows better at cold temps, and a good oil filter. Give your car a few minutes warm up (ESPECIALLY in cold weather) before moving out, letting your car reach normal operating temps (fully warmed up) before punching it, and on the tranny side when you first move out in the morning put it into drive and keep it there without moving-out for at least 20-30 seconds.

Oh, and you might want to check your air filter if you have not looked at it recenty - a clogged up filter can give you abnormally high idles on startup.

[Aren Jay]

Lucky you I have the other problem.

[GrazniM]

thats weird...

[MENINBLK]

This is a normal start for any F/I engine.
When you first start your engine the ECM puts the fuel system into a
MULTI-PORT INJECTION mode where all cylinders receive fuel
spray at the same time.

When the idle settles down the ECM changes from MPI to SFI
(Sequential Port Injection) where each individual cylinder
gets fuel spray at the correct interval.

The additional fuel aides the cold/warm engine to start and run,
incidentally causing the high rpm flare, and allows
the engine to continue running until SFI can be achieved.

At 80,000 miles my Marauder does not show any signs of blue smoke.