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#4064064 - 05/21/20 12:53 PM high idle at cold start up.
SDHOUHK07 Offline
n00b

Registered: 03/22/20
Posts: 28
Loc: San Diego, CA
My 98 Crown Vic LX has this really high idle at start up, making me say "wow, she's angry!" at start for about 4-5 seconds at around 2,000-2500 rpm then quickly settles to about 1,000-1200, lol just estimated guess since it lacks a tach. It does have quite a longer crank before start up when cold so I'm thinking hmm maybe my IAC or TPS may neeed replacing..but there is no check engine light active. I did switch to 5W20 Motorcraft SB oil for my car.

Car has 126,000 miles. All original powertrain. Formerly elderly owned vehicle that they bought new since 1998 then sold to another elderly couple in 2012 and now its mine.


Edited by SDHOUHK07 (05/21/20 12:54 PM)
_________________________
My personal quotes:

"Take care of your liabilities, even if they don't go up in value over time."
"Working for an hourly wage and collecting a biweekly check is not a path to happiness and wealth, it is just a safety net to keep you from being homeless!"

1998 Ford Crown Victoria LX with Handling Performance Package dressed up in Ford factory medium wedgewood blue metallic clearcoat paint with dark denim blue leather interior. It's my first car ever bought! Stock as of now. Nothing wild put on it. Paid in FULL, because making 7 year plus interest note on a new car, SUCKS!

My cars before were "hand me downs" and were a 1995 Oldsmobile Achieva, 1996 Chevrolet Corsica, 1991 Toyota Corolla, and 2004 Chevrolet Impala. All gone and forgotten.


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#4064070 - 05/21/20 01:44 PM Re: high idle at cold start up. [Re: SDHOUHK07]
BigJon Offline

Grand Poobah

Registered: 06/30/02
Posts: 11792
Loc: Virginia
Every panther I have owned has done that.
_________________________
-Current:
2001 Crown Victoria P74

-Gone, but not forgotten:
1988 Mercury Grand Marquis
1994 Ford Crown Victoria
2000 Ford Crown Victoria HPP
2004 Ford Crown Victoria LX Sport
2004 Mercury Grand Marquis

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#4064104 - 05/21/20 05:21 PM Re: high idle at cold start up. [Re: SDHOUHK07]
RF_Overlord Offline

Poobah

Registered: 12/14/02
Posts: 7080
Loc: MA
The high idle is to get the O2 sensors warmed up and working so the engine will go into closed-loop sooner.
_________________________
'03 Mercury Marauder (The Blackbird)
Trilogy Motorsports supercharged #61
Too many mods to list / Driveway Queen

'04 Grand Marquis LS Limited Edition (Spruce Green)
Daily Driver (Thanks, Adam!)

'00 Grand Marquis GS (Silver)
Rotted frame and broken transmission crossmember
Being resurrected...slowly.

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#4064210 - 05/22/20 08:18 AM Re: high idle at cold start up. [Re: SDHOUHK07]
BigMerc96 Offline

I know nothing
Posting Addict

Registered: 06/05/10
Posts: 19688
Loc: I can see Detroit from here!
Fuel Injected Fords always idle really high on a cold start. Most cars do, but older Fords are probably most noticeable. On a cold start, these cars will usually idle at 1200rpm or so, and after 5-10 seconds it'll drop to 1k before eventually settling in at 650-800 (depending on year/model with P71s warm idle being higher). They can and will hold the high idle longer if the battery is discharged, higher idle means better charge output from the alternator, same reason P71s idle higher to start with. In fact, aside from the better shift points, the number 1 thing I noticed when I put the 1999 P71 PCM (ARA3 catch code, considered the best factory PCM tuning for the era) in my '98 HPP is that it idles higher.
_________________________
-Steve

2006 Audi A6 ~132k miles, stock.
1998 Mercury Grand Marquis LS HPP ~100k miles, slowly acquiring modifications.
1997 Town Car Cartier ~145k miles, Ported Plenum, Gutted Airbox, Contour E-fan Retrofit, Dual exhaust with Magnaflows, cats deleted, MSD Ignition, KYB Gas-A-Justs, P71 front bar, air ride reinstated, Projector retrofit, Caddy 4-note horn retrofit, Wood rim steering wheel retrofit, holistic weight reduction as the parts fall off..
1996 Mercury Grand Marquis GS 117,485mi. R.I.P. 7/14/12 frown

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#4064224 - 05/22/20 10:01 AM Re: high idle at cold start up. [Re: SDHOUHK07]
AlleyG Offline
Climber

Registered: 04/28/14
Posts: 509
Loc: Raleigh, NC
2500 is too high - especially in freezing temps. None of our late 90's/early 2000 Fords have done that, it's more like 1200.

I did have an 88 T-Bird that did that, but it was only after swapping out the clutch fan. Not sure why it did that. Probably because it was an Advance Auto part, lol!

Al
_________________________
2004 CVPI - 85k miles
1997 T-Bird LX - 85k miles
1994 Supra Turbo - 107k miles
Previous Fords:
1988 T-Bird, 1995 T-Bird, 1996 Cougar

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#4064236 - 05/22/20 10:45 AM Re: high idle at cold start up. [Re: AlleyG]
BigMerc96 Offline

I know nothing
Posting Addict

Registered: 06/05/10
Posts: 19688
Loc: I can see Detroit from here!
Originally Posted By AlleyG
2500 is too high - especially in freezing temps. None of our late 90's/early 2000 Fords have done that, it's more like 1200.

I did have an 88 T-Bird that did that, but it was only after swapping out the clutch fan. Not sure why it did that. Probably because it was an Advance Auto part, lol!

Al
I kinda highly doubt its really idling at 2500. That would be IAC at 100% open and/or a big vacuum leak. With no tach, it can be tough to judge RPMs unless you're familiar with the engine and its sound.
_________________________
-Steve

2006 Audi A6 ~132k miles, stock.
1998 Mercury Grand Marquis LS HPP ~100k miles, slowly acquiring modifications.
1997 Town Car Cartier ~145k miles, Ported Plenum, Gutted Airbox, Contour E-fan Retrofit, Dual exhaust with Magnaflows, cats deleted, MSD Ignition, KYB Gas-A-Justs, P71 front bar, air ride reinstated, Projector retrofit, Caddy 4-note horn retrofit, Wood rim steering wheel retrofit, holistic weight reduction as the parts fall off..
1996 Mercury Grand Marquis GS 117,485mi. R.I.P. 7/14/12 frown

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#4064248 - 05/22/20 11:33 AM Re: high idle at cold start up. [Re: SDHOUHK07]
Lance01 Offline
Member

Registered: 04/02/18
Posts: 304
Loc: Pa
Originally Posted By SDHOUHK07
My 98 Crown Vic LX has this really high idle at start up, making me say "wow, she's angry!" at start for about 4-5 seconds at around 2,000-2500 rpm then quickly settles to about 1,000-1200, lol just estimated guess since it lacks a tach. It does have quite a longer crank before start up when cold so I'm thinking hmm maybe my IAC or TPS may neeed replacing..but there is no check engine light active. I did switch to 5W20 Motorcraft SB oil for my car.

Car has 126,000 miles. All original powertrain. Formerly elderly owned vehicle that they bought new since 1998 then sold to another elderly couple in 2012 and now its mine.


Without knowing anything else since your car is a 1998 a new IAC, a tune up (clean out throttle body, new spark plugs, air filter , ect) and a new battery should fix your issue.

I replace car batteries every 3-4 years and about 2 weeks ago I just replaced my battery and went from 650CCA to 850CCA and noticed a difference in how quickly the car starts now.

Look at your battery and check for the sticker to see when it was manufactured. It will have the month and year like this: 5/16


Edited by Lance01 (05/22/20 11:35 AM)

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#4064272 - 05/22/20 01:18 PM Re: high idle at cold start up. [Re: SDHOUHK07]
TheCableGuy Offline
Climber

Registered: 04/08/19
Posts: 724
Loc: Far Northwest AZ
Mine idles high on startup, like 1200-1300 initially, after about 10 seconds it sits at 1K, then after about 5-8 minutes or so it drops to its normal idle rpms.
_________________________
2010 P7B 149K. 11K hours. 3.27, RKE, Cruise, Ported stock plenum, JMod
2011 Sierra 1500 155K, too many mods to list. (RIP 01-05-2019)
2001 Durango R/T 5.9. 230K. SOLD 5-1-19

I’m a classical textbook over-thinker.


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#4064420 - 05/23/20 07:09 PM Re: high idle at cold start up. [Re: SDHOUHK07]
2008interceptor Offline
Over the Hill

Registered: 09/02/02
Posts: 3100
Loc: Pennsylvania
Do try and get the OEM iac valve not worth the headache and wasted time. Also cleaning the intake throttle plate and iac bore itself can help. Sometimes you can clean the iac with electronic contact cleaner or maf cleaner. Though typically the failure is the electric motor not a mechanical one. Use air intake cleaner on the throttle body (toothbrush/cloth) and if you do it maf cleaner on the maf. Carb cleaner eats the coating on the throttle body so it'll gunk up faster. Maf can't have anything that leaves residue like intake cleaner could. Sometimes carbon gunk can cause the throttle plate to stick, worse when cold.


Edited by 2008interceptor (05/23/20 07:11 PM)
_________________________
2008 Ford Crown Victoria Police Interceptor P71 with street appearance package.

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