Idle issues

[Devin]

I recently switched out my idle air bypass valve IAB/IAC/ISC with a new Delphi CV10140 due to some issues with my idle hunting and sometimes settling at 2000 RPM. Now it seems my problems are worse. When I start the car it idles around 2400 for a few seconds then slowly drops to 1500, and after about 60 seconds it drops to 1000. Then if I drive it anytime I clutch in instead of the RPMs dropping quickly as I change gears it hangs out at whatever RPM I was at for a few seconds and then slowly drops. Additionally, the RPMs will sit at 1800 or so sometimes at lights, and the only way to fix it is to shut the car off and turn it back on.

Do I have the incorrect part? Defective? Bad ECM? I have no CEL currently.

 

[zoomlater]

TPS sensor?

 

[Texas Marauder]

Did you disconnect the battery to erase the learned idle? Is the throttle body clean and working properly?

 

[Devin]

Did you disconnect the battery to erase the learned idle? Is the throttle body clean and working properly?

The process I followed was 1. Turn on headlamps 2. Disconnect negative terminal for 10 minutes, turn off headlamps, reconnect negative terminal. Start car and turn on all accessories and key idle for 10 minutes. Then I drive it for a few minutes.

 

[luigisho]

The delphi part looks correct. I think the Ford number is

E9AZ-9F715-AA​

 

[Devin]

It seems that it acts better after getting into open loop. Most of my issues appear in the morning or after it has sat for a work day.

 

[Devin]

Never mind, still acts up when warm!

 

[zoomlater]

maybe the TPS is sticking or throttle cable sticking

Please Help

V6 1989 Ford Taurus SHO. Car surges , RPM’s rev up and down, stalls, cuts off when driving, to make a long story short. I took it too ford and they told me I need a crank shaft positioning sensor, water pump and a timing chain. Is there anybody in the Charlotte NC area who knows how to repair...

shoforum.com

HIGH Engine Idle

If it isn't one problem it's another. Finally got my SHO back on the road again and now it's idling at around 1200 - 1900 RPM. It's always idled a little high since I got the car (900 - 1000) but now it is getting really high. This higher idle just started last night and I'd like to get it...

shoforum.com

 

[rubydist]

I have had several new IAC that were sticky right out of the box, and that sounds like what you have. I would get another one.

 

[Devin]

I'll try another IAC but also test the TPS.

 

[Irish Pride]

Unplug the IAC while it's running. If the throttle body is adjusted properly the car should still run with the IAC unplugged but the rpms will be lower than normal. If you unplug the IAC and the idle smooths out then it's my opinion that you need another IAC. If it doesn't smooth out then you have another issue.

Have you checked for codes? There can be stored codes without having a CEL.

-Chad

 

[zak]

One other possibility, these cars are at an age where their evaporative emission hoses, the soft rubber parts, are cracking and or crumbling. Follow the vacuum line down to the EVAP solenoid and check the lines below, and going to the evap canister. If there is a hole the mixture will become lean/idle rough.

 

[BaySHO Performance]

Sounds like you are shooting in the dark. I suggest checking the codes to see if they tell you anything: https://wiki.wikisho.com/wiki/EEC_Self_Test_Procedure

 

[Devin]

I was definitely but I an going to pull the codes once it stops raining for five minutes. Speaking of which, I got a CEL today! It popped up when my idle hit 2800.

 

[Devin]

116 ECT
122 TPS
114 ACT

I believe those are correct

 

[luigisho]

Those will all pretty much cause issues with idle. Strange that all 3 pop up.

 

[BaySHO Performance]

116 ECT
122 TPS
114 ACT

I believe those are correct

The TPS is the main possible culprit. The 116 may cause the engine to run hot or cold, and the 114 may upset the A/F ratio a little, but I doubt if either would cause idle issues. So check out the TPS.

 

[Devin]

Thanks! I had the CEL when running out earlier and popped the TPS harness off and then plugged it back in and the CEL went away and the idle dropped. I'll run through those tests next.

 

[Devin]

Picked up a replacement TPS but the bottom screw stripped out. Mike sold me a replacement TB and screws so I can just swap in the new TPS and extract the old one on my own time.

Unfortunately my relatively new tire lost all pressure on the highway today and possibly trashed my rim, so I have to pull that off and see what happened.

 

[Devin]

Just got a look at it today. Ouch.