Skip to main content ↑ ↓
Topic: idle hunts when enine is warm (Read 1846 times) previous topic - next topic

idle hunts when enine is warm

this is an 88 5.0-HO EFI motor with AOD trans. My problem is when the motor is first started and cold it runs fine but when it warms up and idling in gear the engine idle starts hunting. When shifted into neutral it levels out at about 600-700. Also, after driving the car and shutting it off, it will start hunting for a few seconds and then level off after restarting. My computer is from a 5spd car and this should be ok. Any help will be appreciated.

idle hunts when enine is warm

Reply #1 –
Quote from: larrycar78;190477
My computer is from a 5spd car and this should be ok.
Have you tried an EEC from an auto trans car?
'98 Explorer 5.0
'20 Malibu (I know, Chevy, but, 35MPG. Let's go brandon, eh)

idle hunts when enine is warm

Reply #2 –
C-o-d-e-s?
Long live the 4-eyes!  - '83 Tbird Turbo - '85 Marquis LTS - '86 LTD Wagon-  '81 Granada GL 2dr

idle hunts when enine is warm

Reply #3 –
chucks right. if you dont know how then learn to pull your codes.  If you dont have a paper clip,, find one.

see my diy link to.... instructions inside.  I suggest you follow the link to the source site for the illustrations ect.

idle hunts when enine is warm

Reply #4 –
Mine did the same thing when I dropped in the HO untill I adjusted the idle screw. I'm running speed density and I have a bigger than stock HO cam so that's what I had to do to make it run right. What cam is in it and are you running speed density or mass air?
88 Thunderbird LX: 306, Edelbrock Performer heads, Comp 266HR cam, Edelbrock Performer RPM intake, bunch of other stuff.
 

idle hunts when enine is warm

Reply #5 –
Learn to live with it.  I spent more time and effort trying to solve my idle surge on my ol' Bird than I would like to admit...everything had been gone over, every sensor, every wire, multiple ECU's...I even wasted $45 on that POS idle adjustment plate that Ford sells as a "fix" for this problem...it only worked if you jacked the friggin' idle up to 1200....however, after I cut the VSS signal wire to the ECU it did run better...but it would idle high sometimes and other times it would idle low...still surged a bit in gear though.  I know people are going to tell you fixes for it...but I've tried just about all of them and got nowhere.

Good luck,
Don
Project 3G: Grandpa Grocery Getter-'85 Crown Vic LTD 2-door, 351W with heavily ported/polished GT40 heads, heavily ported/polished Typhoon Power Plus upper & lower intake, Comp Cams 265DEH retarded 1*, FAST EZ-EFI, HD T5, 8.8" 3.73 trac lock with extra clutches, 3G alt. swap, '99 CVPI front brakes, '09 CVPI rear disc brakes, '00 CVPI booster&m/c + wilwood adj prop valve.

Parted & Gone-'88 T-bird Sport, 351W swap, ported GT40 heads

idle hunts when enine is warm

Reply #6 –
Your not goin to get much help unless you give more info!
Then you will get so much you won't know what to do.
Old Grey Cat to this.88 Cat, 5.0 HO, CW mounts, mass air, CI custom cam, afr165's, Tmoss worked cobra intake, BBK shorty's,off road h pipe, magnaflow ex. T-5,spec stage 2 clutch, 8.8 373 TC trac loc, che ajustables with bullits on the rear. 11" brakes up front. +

idle hunts when engine is warm

Reply #7 –
Thanks for all the suggestions.
1-I'm going to re-check the tps to make sure it reading .9v with the throttle body fully closed.
2-Make sure the throttle body is fully closed (check cable free play).
3-make sure idle air bypass is working properly.
4-One of the tech articles said it was O.K. to use a computer from  a  5 speed car with an AOD trans. so I'll assume that is O.K.
5-This is a speed density engine and I upgraded to a 65mm T.B. and a set of patriot headers, duals with Flowmasters. Other than the surging it runs awsome. This was a great swap if you want to pick up a lot more power for a little money.

idle hunts when enine is warm

Reply #8 –
Quote from: larrycar78;190683

5-This is a speed density engine and I upgraded to a 65mm T.B. and a set of patriot headers, duals with Flowmasters. Other than the surging it runs awsome. This was a great swap if you want to pick up a lot more power for a little money.


Ah ha. More air flow changes the vaccum signal at idle. That's why you have the surge. Mine would surge at idle and would stall when warm when I shifted from D to R or R to D. On my SD set up I've had to adjust the hot idle to 1100 rpms in park and it is happy. No more stalling or surging. It idles at 750 rpms in gear.
88 Thunderbird LX: 306, Edelbrock Performer heads, Comp 266HR cam, Edelbrock Performer RPM intake, bunch of other stuff.

idle hunts when enine is warm

Reply #9 –
thanx thunderjet, I'll try it.

idle hunts when enine is warm

Reply #10 –
Quote from: thunderjet302;190925
Ah ha. More air flow changes the vaccum signal at idle. That's why you have the surge.

That's defiantly NOT the reason... The engine requires the same amount of air to idle no matter what size TB is installed... IF you are getting increased airflow the idle will be increased...

Quote from: larrycar78;190477
My computer is from a 5spd car and this should be ok. Any help will be appreciated.

A 5 speed computer fixed most of my hot surge problems... Increasing idle to 900-1000rpm in gear should help, but not for the above reason...

idle hunts when enine is warm

Reply #11 –
Oops. I meant to say that if you change the vaccum characteristics of a SD engine you mess with the idle. My bad :crazy:
88 Thunderbird LX: 306, Edelbrock Performer heads, Comp 266HR cam, Edelbrock Performer RPM intake, bunch of other stuff.