my 91 accord lx 5door just installed a new tps sensor. calibrated it per the doc's thread at .480 ct and 4.5 wot. cleaned the throttle body, pcv, iac and fitv and screwed it all the way in. at cold idle it runs 2000 for 2 min then the idle surges from 1500 to 2000 to 1500 and repeat. help! someone make it stop. need help! anyone have any ideas?

 

Is the FITV adjusted correctly? Did you burp the coolant system thoroughly? Maybe a bad IAC. Maybe a vacuum leak. Are you getting any codes?

 

So you have a vacuum leak. If you pulled the throttle body, the leak could be there. Did you use a new gasket? Perhaps a vacuum hose is now torn. You need to use some carb cleaner, warm the car up, spray around the throttle body until the idle changes which will indicate where the leak is. If you sprayed inside the iacv that coulda killed the internal seals. Never spray anything inside the iacv as you only need to clean the outside metal filter when it gets clogged.

 

I turned down the fitv all the way down. I put a new gasket on the throttle body. the vacuum is 20 to 17 between the idle going up and down. burped the coolant. check engine light is not on. according to wildoutwhitegsr @ ***How-To Clean*** Your IACV a.k.a. Idle Air Control Valve 5) Take your brake cleaner or simple green and start to clean up the inside of the IACV by spray inside the two holes. Continue to do this until no more dirty fluid comes out. Should take anywhere from 5 minutes to 15 minutes. This depending on how old and dirty your IACV is. The gasket can be seen in this picture as well. conflicting info!

 

here's the latest on my surging idle 91 accord. inside the throttle body there are two holes one at 7 o'clock and one at 9. it I put my finger over the hole in the 7 o'clock position the surging idle stops. I think that hole goes to the fit valve. so I ordered a new fit valve $75. does anyone know what the name of the valve around the corner of the head and to the right of the iac valve? it has a vac hose coming from the throttle body from the rear of the valve cover.

 

nope those two holes inside the throttlebody go to the idle control valve. you just spent $75 on a part you don't need. hahaha

 

milldew, you are correct. One hole goes to the IAC valve and the other goes to the FIT valve. I can't off hand remember exactly what one is what. It's been a while since I have looked at a 90-93 TB.

As far as the valve on the side of the head/intake it could be ether the air boost valve or if you have an F22A6 you could be talking about the intake air bypass (IAB) diaphragm. I would need to see a picture of what it is that you are referring to.

 

ghost is right as usual ...and ur talking about the air boost valve ..it gives slightly more air on startup and rarely ever go bad

 

here's where I am at. as nerfgunner420 said, I installed the new fit valve and nothing changed. I set my tps at .605 ct and 4.8 wot and it stabilized the looping idle. not sure what this will do to my rice burner? first Honda I ever worked on, cut my teeth working on muscle cars.

 

If you unplug all the sensor it will probably fix the looping idle or you can

 

I have had a vac gauge on the car since it started the looping idle. I installed a new throttle body gasket the one on it tore. vac sits about 20 inches. I understand the 91 accord engine is set up differently than the rest of the accords as far as where the fit valve and other parts. my coolant fan runs when the key is in the run position and the coolant temp gauge on the dash has never worked. I removed it and the original owner had it super glued for some reason there is also a burnt spot on the back of the mother board that connects all the gauges.

 

sounds like you have more problems then a bad tps. you need to fix all the electrical first then move on to sensors. loopy idle im guessing ect sensor don't work right making it run rich and high idle. fitv for it to go out. jesus never seen one ever... that lower hole is the iacv. but you need to tackle the electrical first as you'll never know the temp of the car. it could be overheating and youll never know. reason i believe that is you said fan are on direct. bad sign already fan thermal switch might not work or a short/open in the circuit

 

you guys are a wealth of knowledge. I installed a new iac valve and I still have this hesitation, hiccup, surge . I have tried to lower the idle to the spec on the sticker under the hood 700 in gear without the a/c and the lowest I can get it is 1100 in drive or park. any idea?

 

You have a vacuum leak, have to start checking the gaskets, injector O-rings, cracked or disconnected vaccum hoses.

Have you checked for vacuum leaks as described in holmesnmanny's previous post?

 

vac sits about 20 inches

 

How many times do we have to tell you to find and fix the vacuum leak before you decide to do it ?

 

10-4, thanks