Help me create the "Surging Idle Checklist"

Prince95GT · Jul 27, 2006

sweet

Reed · Aug 5, 2006

Just a couple of questions from me. I dumped codes on my car today and the only thing that came up is a 12 (RPM at idle out of range) during the KOER test. I'd like to try and adjust the idle to 600 RPM as suggested, but where is the screw on the TB? Is it underneath the spring that has the throttle and TV cable attached?

If I follow the checklist, it should (hopefully) cure my idle problem, correct?

jrichker · Aug 6, 2006

Mine is under the TB on the side nearest the air intake. The screw head faces the back of the car.

There is a very high sucess rate with the Surging Idle checklist. It is easy to do and not expensive since it helps to reduce buying parts you don't need.

Reed · Aug 6, 2006

Thank you, I didn't have too much time yesterday, so I'll look around today. Excellent list, I'm glad you created it!

89-notchback · Aug 6, 2006

Hey Guys, I went through the surging idle checklist which helped me fix alot of stuff, Everything checks out good except i have a code for the passenger side O2 sensor. The engine is pretty much stock except for the ford B-cam which was in the car when i bought it, The car idles good around 800 when not in gear, when i put it in gear( i have an AOD) it surges about 200 to 300 RPM. The car smells rich i assume thats from the bad O2, the IAC seems to be working and i replaced the TPS cleaned all the ground wires, also when i first start it it doesn't want to idle and likes to stall till it warms up a little. I'm gonna replace both O2 sensors and go from there, any other ideas of what it might be?, could it be becuase of the B-cam?, any suggestions would greatly be appreciated.

jrichker · Aug 6, 2006

Replace the bad O2 sensor and go from there.

Kabuki_notch · Sep 6, 2006

Jrichker if you are still following this thread a got a nasty stalling problem, I have a IAC and a EGR valve coming in tommrow but before I replace them I want to know if you can tell me which code is killing me.

My car is driven mabey 30 miles a week at this point since I dont have time to drive it when I start it when I get home from work it instantly dies, second startup it idles fine. So I can drive it around after about 10-15mins check engine light pops on and whenever I get to a stop sign or light, the car dies, here are the codes I pulled, keeping in mind this car had a new motor put in and I deleted the smog and a/c

54-IAT
67-A/C (deleted)
81-Airpump (deleted)
82-???
85-Canister purge (deleted)
84-EGR solednoid

thanks for any help!

jrichker · Sep 6, 2006

Code 54 – ACT sensor out of range. Broken or damaged wiring, bad ACT sensor. Note that that if the outside air temp is below 50 degrees F that the test for the ACT can be in error.

Check the resistance of the black/white wire to battery ground. If it is less than 1 ohm, it is good. If it is more than 1 ohm, the black/white wire has bad connections or a broken wire. Always take resistance measurements with the circuit powered off.

Then check the resistance of the ACT sender located in the #5 intake runner on most 5.0 stangs.

ACT & ECT test data:

The ACT & ECT have the same thermistor, so the table values are the same

Pin 7 on the computer - ECT signal in. at 176 degrees F it should be .80 volts

Pin 25 on the computer - ACT signal in. at 50 degrees F it should be 3.5 volts. It is a good number if the ACT is mounted in the inlet airbox. If it is mounted in the lower intake manifold, the voltage readings will be lower because of the heat transfer. Here's the table :

68 degrees F = 3.02 v
86 degrees F = 2.62 v
104 degrees F = 2.16 v
122 degrees F = 1.72 v
140 degrees F = 1.35 v
158 degrees F = 1.04 v
176 degrees F = .80 v
194 degrees F = .61

Ohms measures at the computer with the computer disconnected, or at the sensor with the sensor disconnected.
50 degrees F = 58.75 K ohms
68 degrees F = 37.30 K ohms
86 degrees F = 27.27 K ohms
104 degrees F = 16.15 K ohms
122 degrees F = 10.97 K ohms
140 degrees F = 7.60 K ohms
158 degrees F = 5.37 K ohms
176 degrees F = 3.84 K ohms
194 degrees F = 2.80 K ohms

Kabuki_notch · Sep 6, 2006

I hope it's not a broken wire that would be a pain, I will try your test first. Thanks!

Kabuki_notch · Sep 24, 2006

well I replaced the Air intake temp sensor and that didnt do anything the car still after 15mins or driving shuts off at a stop, so I followed that wire to the battery ground and this happened,

I dont know what this is but it was connected to the black/white wire. I broke the stud right off it. What is this where can I get one? it was pretty rusty/grimey so I cleaned the connection and I must have over tightened it, it snapped

also I saw this was unplugged with a black/white wire not sure what this is either it may not be related.

jrichker · Sep 25, 2006

The broken part is probably the circuit breaker for the power windows. I can't identify the other wire at this time.

blackfiveoh · Oct 7, 2006

jrichker said:
Updated 17-July-2006

Ranchero5.0’s comments on engines with other than stock cams:

A little dragon slaying lore here:

99% of the time on a cammed car opening up the divider between the ports on the IAC with a dremel so the motor idles at 1000rpm with the IAC unhooked, the throttle plate shut and the TPS at .98vdc fixes all surge related problems. Found about to do that on my '93 with a very mild cam and good induction it didn't like idling below 900rpm. The IAC can't react quick enough to a lopey cam induced RPM fluctuation so instead of dampening the surge it increases it. Every E cammed car I've ever worked on needed this to keep a stable idle. Similar to Fords idle bypass plate without the cobbled look. Just dremel out a little at a time till it idles around 1k. In my experience the stock puter doesn't like to idle a cammed car down low.

what i did was cut the gasket between them because i didn't like the idea of dremeling and it worked. You could cut alittle away if it doesn't solve it completely.

thanks for the help this was killing me i tried everything on the list and it was this that worked.

my car ran cold, but as soon you warmed it up it would start to fluctuate and they shut off.

I have a 1991 GT and just added Cobra heads with factory roller rockers, cobra intake, e303 cam, 65mm throttle body, and equal lenth headers.

jrichker · Oct 7, 2006

The idle bypass plate kit would probably done the same thing. I will have to make note of you experience, thanks for the input.

Nicoleb3x3 · Nov 7, 2006

ok...fix a surging idle a long time ago and had a perfect running stang for the summer...

now; the other day to go to the car wash and get an undercarrige high pressure wash...

the surge started while in the car wash at that exact momment...I though maybe a little water maybe caused it and it would go away..but now it seems only about half the time I still have the surge if I'm in park or neutral...not when I'm in drive at a stop.

..not sure if it's related; but I pulled in to a parking spot; I think I was just moving from drive into park and the car surged forward like I steped on the gas! luckily I had my foot on the brake or I was likely going to hit the front bumper. It happend another time too; sora lunged forward when waiting ...I must have been in drive shifting to park again?

Nicoleb3x3 · Nov 7, 2006

ps. I think I hit my tv cable when flushing out my heater core...maybe I also hit my throttle cable?

could my throttle cable or something have gotten wacked to cause this crazyness?

GTOreturns · Nov 7, 2006

I thought this thread used to be a sticky?

Black1987Stang · Nov 22, 2006

Nicoleb3x3 said:
ps. I think I hit my tv cable when flushing out my heater core...maybe I also hit my throttle cable?

could my throttle cable or something have gotten wacked to cause this crazyness?

The cables shouldnt have anything to do it since it cant open up the throttle without you doing it (mechanically wise with the cable) , I vote for something with the Iac, pull codes and see what you got and post the codes here. After the car wash only think I could think of is something with the 02 sensors? Pull the codes and go from there....BTW Nice Stang

jrichker · Nov 22, 2006

Another vote to pull the codes. The one item under the car that high pressure water could affect is the O2 sensor wiring. I would inspect it very closely after dumping the codes.

jrichker · Nov 22, 2006

GTOReturns said:
I thought this thread used to be a sticky?

It still is - see the "Useful Technical Thread Index" sticky. It is gouped together with all the other neat technical stickies. Daggar had a great idea when he decided to group them all together.

Nicoleb3x3 · Nov 24, 2006

ok thx
I did notice it only surges in park...occasionally..

as far as the IAC is new, and so are the o2 sensors..I was wondering about the VSS..

but why does it only surge in park? It doesn't surge sitting in drive at a stop (ie stop lights i'm fine)

I haven't had a chance to pull the codes

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