5.0 idles up and down when warm

westridez · 11-21-2004, 08:50 PM

anyone know why it would be ideling up and down when its warm motor is pretty much stock 88 5.0 i deleted the polution pump cats tabs ect and i left the egr plugged in and plugged the vacuum line off and its non mass air

Unit 5302 · 11-22-2004, 02:23 AM

Quote:

Originally Posted by westridez

anyone know why it would be ideling up and down when its warm motor is pretty much stock 88 5.0 i deleted the polution pump cats tabs ect and i left the egr plugged in and plugged the vacuum line off and its non mass air

Idle surge is fairly common on the SD cars. Make sure your tps is set right, and your IAC is clean. Check your vacuum lines running to the MAP sensor, and other parts of the engine.

westridez · 11-22-2004, 01:35 PM

Quote:

Originally Posted by Unit 5302

Idle surge is fairly common on the SD cars. Make sure your tps is set right, and your IAC is clean. Check your vacuum lines running to the MAP sensor, and other parts of the engine.

whats is the iac?and how do i set my tps?

Dark_5.0 · 11-23-2004, 02:29 PM

Quote:

Originally Posted by westridez

anyone know why it would be ideling up and down when its warm motor is pretty much stock 88 5.0 i deleted the polution pump cats tabs ect and i left the egr plugged in and plugged the vacuum line off and its non mass air

Its more than likely an o2 sensor IMO.

westridez · 11-23-2004, 08:14 PM

Quote:

Originally Posted by Dark_5.0

Its more than likely an o2 sensor IMO.

is there a way test the o2 sensors ?

Dark_5.0 · 11-24-2004, 09:40 AM

It takes a minute or so for the o2 sensors to get to operating temperature. When they get to temperature the ecu then starts collecting data from them, if they are faulty they can cause a serious idle surge especially on a speed density car.

last Summer my car would start up and idle perfect until the O2 sensors warmed up and kicked in, then I had a steady idle surge.

I replaced them both with Bosch O2 sensors costed about a $100.00
and now it idles like a dream.

PKRWUD · 11-24-2004, 10:00 AM

Your IAC solenoid is the can shaped item bolted to the throttle body. After the engine warms up, unplug the electrical connector going to it, and see what happens. If the idle smooths out, the IAC needs to be cleaned or replaced.

Have you checked for any codes?

westridez · 11-24-2004, 01:10 PM

i havent checked anything im not driving this car right now its not finished yet i just did a complete 88 to 84 conversion but all the drivetrain is in and working and now im having this problem how do i check the codes?

HoodStrype · 11-24-2004, 02:57 PM

Actually, I think any Autozone will do it now for free... is your check engine light on?

westridez · 11-24-2004, 03:57 PM

the check engine light aint on

~The Jester~ · 11-26-2004, 09:58 AM

Start with testing the IAC like Pkrwd said. Most of the time a good cleaning with some GOOD carb cleaner fixes them up. If that isn't it, head to the O2 sensors. Just for the record, for some unkown reason, I've had bad luck with aftermarket O2 sensors. It costs a bit more, but I always put Ford O2 sensors back in.

westridez · 11-26-2004, 11:28 AM

is there anyway i can test the o2 sensors by unpluging them when the car is running?to if its them or which one it is

Mustang Brandon · 12-08-2004, 09:27 PM

my 89 mass air does this also. doesnt affect the performance at all though

11-21-2004, 08:50 PM	#1
westridez Registered Member Join Date: Oct 2004 Posts: 48	5.0 idles up and down when warm anyone know why it would be ideling up and down when its warm motor is pretty much stock 88 5.0 i deleted the polution pump cats tabs ect and i left the egr plugged in and plugged the vacuum line off and its non mass air __________________

11-24-2004, 09:40 AM	#6
Dark_5.0 Registered Member Join Date: Apr 2001 Location: Staging lane Posts: 4,337	Re: 5.0 idles up and down when warm It takes a minute or so for the o2 sensors to get to operating temperature. When they get to temperature the ecu then starts collecting data from them, if they are faulty they can cause a serious idle surge especially on a speed density car. last Summer my car would start up and idle perfect until the O2 sensors warmed up and kicked in, then I had a steady idle surge. I replaced them both with Bosch O2 sensors costed about a $100.00 and now it idles like a dream. __________________ 92' LX-Big brakes, Lots and lots of suspension, GT40X heads, Ported cobra intake, stock cam, Vortech SC trim. 00' Lightning-Stock 88'CRX-13 second ego killer

11-24-2004, 10:00 AM	#7
PKRWUD Junior Member Join Date: Mar 1999 Location: Ventura, California Posts: 8,981	Re: 5.0 idles up and down when warm Your IAC solenoid is the can shaped item bolted to the throttle body. After the engine warms up, unplug the electrical connector going to it, and see what happens. If the idle smooths out, the IAC needs to be cleaned or replaced. Have you checked for any codes? __________________ Webmaster: Rice Haters Club Jim Porter Racing Peckerwoods Pit Stop Support Your Local RED & WHITE!

11-24-2004, 01:10 PM	#8
westridez Registered Member Join Date: Oct 2004 Posts: 48	Re: 5.0 idles up and down when warm i havent checked anything im not driving this car right now its not finished yet i just did a complete 88 to 84 conversion but all the drivetrain is in and working and now im having this problem how do i check the codes? __________________

11-24-2004, 02:57 PM	#9
HoodStrype Rearview Mirror Haze Join Date: May 1999 Location: Huntsville, Alabama...a.k.a. "HuntsVegas" Posts: 387	Re: 5.0 idles up and down when warm Actually, I think any Autozone will do it now for free... is your check engine light on? __________________ 93 lx Notch 01 GT ...the epitome of Murphy's Law

11-24-2004, 03:57 PM	#10
westridez Registered Member Join Date: Oct 2004 Posts: 48	Re: 5.0 idles up and down when warm the check engine light aint on __________________

11-26-2004, 09:58 AM	#11
~The Jester~ Rat Killer Join Date: Aug 2002 Location: Cold ass Ohio Posts: 1,143	Re: 5.0 idles up and down when warm Start with testing the IAC like Pkrwd said. Most of the time a good cleaning with some GOOD carb cleaner fixes them up. If that isn't it, head to the O2 sensors. Just for the record, for some unkown reason, I've had bad luck with aftermarket O2 sensors. It costs a bit more, but I always put Ford O2 sensors back in. __________________ d-Con Racing "Nothing fancy, just 347 inches of RAT POISON!" MICE need not apply.....

11-26-2004, 11:28 AM	#12
westridez Registered Member Join Date: Oct 2004 Posts: 48	Re: 5.0 idles up and down when warm is there anyway i can test the o2 sensors by unpluging them when the car is running?to if its them or which one it is __________________

12-08-2004, 09:27 PM	#13
Mustang Brandon Registered Member Join Date: Feb 2004 Location: louisville, kentucky Posts: 88	Re: 5.0 idles up and down when warm my 89 mass air does this also. doesnt affect the performance at all though __________________ black 89 lx hatchback 5.0, 17x9 polished Cobra R's wrapped in 215/50/17 up front and 245/40/17 out back , perfectly clean and original interior less than 1,000 miles on new t-5, throw out bearing and clutch. completly redone exaust shorty headers, custom h pipe, flowmaster 40 series, all mandrell bent 2.5 inch tubing i got all new headlight assembly for christmas with clear corners www.50resto.com