high idle problems

[xfactortype1]

hi all,

so i finally get my car going again. it was in the shop for the past two months. it sat for 16 months and was getting work done. so i get it back and notice a high idle. the guy told me it was a little high but i think 1800 constant is a little too high. before everyone start with the iacv and fitv and vacuum leak ive checked those. i replaced all the vacuum lines with silicone ones since they were old. i even took apart the mystery box and changed those to silicone as well. that didnt help. i also took the intake tube off and when the engine fans came on i felt for suction at bottom hole which is fitv and there was no suction. the iacv however had suction. and the throttle itself is closed and i tried pulling up on the gas pedal and no idle drop. so again im stumped. i also checked the coolant level and topped it off and changed a hose that leaked.

im confused because the idle is smooth, but its just high. i still wanna say vacuum leak, but dont know. the iacv is brand new honda as is the fitv.

thanks again in advanced
x

[xfactortype1]

help?

any ideas? i bought a vacuum guage from autozone

[bruno8747]

How did you check for vaccum leak? Seems like a big leak to be idling that high. Did you check the intake manifold gasket for cracks or missing pieces.

[xfactortype1]

im going to hookup a vacuum gauge to see if its holding vacuum. loking for 17-22mmng

[bruno8747]

im going to hookup a vacuum gauge to see if its holding vacuum. loking for 17-22mmng

Try that, I always sprayed carb cleaner on all the nipples and around the intake manifold to check for leaks. If the idle drops when you spray it then thats where the leak is.

[xfactortype1]

thanks for your input

ill try that thanks

[d112crzy]

What did the shop do to your car? That's a long ass time for any repair, unless it's body. Even then, you must have not been a priority at all.

Either way, try loosening your throttle cable. A vacuum leak would lead to a surging idle. If it's constant, either your idle screw is out all the way or your throttle cable is too tight.

[accord junkie]

Either way, try loosening your throttle cable. A vacuum leak would lead to a surging idle. If it's constant, either your idle screw is out all the way or your throttle cable is too tight.

yup thats where i would start.

[xfactortype1]

thanks for the input

i told the shop to take their time i have two other vehicles. i hooked up the vacuum guage and have a rock steady 17-18 mmhg. the idle doesnt surge at all. when i first start the car it start at 1500-1600 then goes up to 2000. no coolant leaks or oil leaks. no overheating either. i disconnected the brake booster and then plugged it, and noticed no difference in idle so i know its not the brake booster.

1)- would a bad ECS prevent the engine from going from open loop to closed loop thereby not dropping the idle cuz the ecm isnt getting the signal?

2- would a bad o2 meaning corroded as well cause a similar issue with the idle.?

the car did sit for 16 months prior to getting worked on

[bruno8747]

i told the shop to take their time i have two other vehicles. i hooked up the vacuum guage and have a rock steady 17-18 mmhg. the idle doesnt surge at all. when i first start the car it start at 1500-1600 then goes up to 2000. no coolant leaks or oil leaks. no overheating either. i disconnected the brake booster and then plugged it, and noticed no difference in idle so i know its not the brake booster.

1)- would a bad ECS prevent the engine from going from open loop to closed loop thereby not dropping the idle cuz the ecm isnt getting the signal?

2- would a bad o2 meaning corroded as well cause a similar issue with the idle.?

the car did sit for 16 months prior to getting worked on

Did you change the gas prior to the work being done?
Did you try resetting the ECU?
Try adjusting the throttle cable
Try adjusting the idle screw on the Throttle body

[xfactortype1]

throttle screw is tight.
gas was changed as well as the fuel pump. walbro 255
i also rest ecu twice.
i disconnected the throttle so the plate could close completely and no difference.

no cel lights on. good idle quality again just high.

im going to order a new o2 sensor and ecs i think ..then look at the tps.

map sensor is good cuz when i disconnect it the engine stumbles and sputters and recovers when i plug it back in. same as for iacv. suction is present at warm idle. the fitv has no suction at warm idle.

[xfactortype1]

and thanks again for all inputs. its appreciated. i got to get it inspected. so i wanna figure it out

[accord91lx]

i would suggest taking something like b12 chemtool or starting fluid and spraying along gasket surfaces, at like the throttle body, iab (if applicable), and where the intake mates with the head and see if it revvs up more or not to check for leaks. You said that you unhooked the throttle cable so the plate would fully close. Maybe there is something in the throttle body physically preventing it close (debris).

[HondaFan81]

- Remove intake piping and spray throttle body cleaner to remove any debris/oil accumulated on the throttle body (it can get sticky from the crankcase ventilation being introduced into the intake, etc).

- Verify after TB cleaning and throttle cable looseness that the TB is indeed snapping closed, you can feel it. Open the TB rotor by hand, then slowly let it close and feel/listen for it fully closing.

- Check at bottom of throttle rotor if someone/your shop tampered with the TB mechanical stop screw, they may have raise it and that is why it keeps at 1800 rpm (I've seen people do this as a "quick fix" for idle instability issues (not good for stock cars).

- Check your idle adjustment screw in the TB, heck go through the idle adjustment process in the manual to set it to 750 +/- 50 rpm. It should not be fully tight, it needs to be partially open, but you need to find out where by doing the idle adjustment process. I suggest putting silicone sealant on the threads, then reinserting screw, going through process and letting the sealant setup so the screw don't backout/cause vacuum leak.

[xfactortype1]

i will check the stop screw on rotor. thanks for the idea.