mazdaverx713b

iTrader: (91)

it seems as though i've checked everything. vaccume leaks, throttle body, bacv, p/s switch, i just can't figure out my problem. i figured i'd just post a little video and maybe someone can see something i'm not seeing.

http://www.youtube.com/watch?v=7HYjBYGsCRg

NoDOHC

Sometimes I have found the cruise control cable to get stuck and not allow the throttle to go all the way closed.

mazdaverx713b

iTrader: (91)

i did try pulling both arms where the cable slips through closed as if they were holding the throttle open. no change. bacv has no effect on the system, throttle lever is resting on the stop. thermowax is not holding the throttle open, i have no vaccume leaks as verified using the starting fluid method. bacv measures around 19 ohms with the engine off. i'm just really stumped!

scrip7

iTrader: (6)

By the sound your engine is making, I bet you have a vacuum leak. It sounds uneven, as if the vac leak were closer to one chamber than the other, such as a split vac hose at the "spider" underneath the UIM. Use a unlit propane torch to check for the leak with the engine at idle. If you put the tip of the torch in the area under the UIM and you get a response, the leak is either at the vac spider, injector seals, or the gasket between the UIM and LIM. If you put the torch down low where the LIM bolts to the block and get a response there, it is likely the gasket. Starting fluids don't catch all vac leaks, but a flammable gas will be sucked in anywhere there is a leak and it's easier to direct it and control it, and is safer than carb spray or other fluids. Look for split vac hoses and also for a hose that has been blown off under boost, such as the ones going to the nipples on the passenger side of the intercooler.

rotarymanic

"Try changing ur solenoid" haha j/k.

veedubbed

There is a definite hissing in there somewhere. That, and you have a very dead battery.

Also, try unplugging the BAC and closing the adjustment screw on it all the way. Take it out of the picture.

scrip7

iTrader: (6)

I listened to the sound of your engine while cranking, and it sounds like you may have low compression on one rotor. The pulses sounded uneven when you cranked it. I can hear misfiring at idle as well as an exhaust leak. If you don't have a compression gauge, try this:
With the engine at idle, remove the EGI fuse and let the engine stall. Crank the engine for a good 10 to 15 sec while you take a video of that so we can listen to the pulses. If you have low compression on one rotor, it will sound consistently uneven while cranking. Also there is a better way to check if the BAC is keeping the idle too high. Pinch the hose (not the coolant hose, the air inlet hose) going to the BAC with a pair of needlenose at idle. If the idle slows back down or the engine dies, then focus on the BAC. It makes more sense to do this rather than disturb any adjustment screws.

mazdaverx713b

iTrader: (91)

all vaccume hoses as well as the hoses going to the bacv are new. the intake gasket is new upper and lower. the engine is a used engine with maybe 50K. the thing starts every time and pulls hard with no flooding, so i doubt that i have low compression. i could do a compression test..... i'll try the propane approach and post back.

mazdaverx713b

iTrader: (91)

there definatly is a misfire at idle. the battery is low and the engine does crank well with a good battery. i am going to check the bacv now and check for vaccume leaks with my map gas torch. also as a note, the hissing that can be heard is coming from the power steerig idler pulley. the bearings are starting to give up the ghost. teh vaccume hoses going to the air bypass solenoid valve and to teh intercooler are new, as well as the injector seals.

mazdaverx713b

iTrader: (91)

battey is dead. i'll have to wait til later and let the battery charge for a bit. i'll post the results later this evening.

loskeezy

search around for the air compressor way to find vac. leaks. you will hear the hissing coming out of any leaks. It is definitely the easiest and safest way.

mazdaverx713b

iTrader: (91)

i tried using map gas instead of propane because thats all i had. no leaks were found(didnt observe any idle spikes)

mazdaverx713b

iTrader: (91)

any other thoughts or emissions equipemnt that i can check that may contribute to this weird condition?

scrip7

iTrader: (6)

I couldn't tell from the vid, but do you still have the air injection pump?....if so, with the engine at idle, use a pair of needlenose pliers to pinch the air pump outlet hose closed (the one between the pump and ACV, not the other going to the air filter box). If there is improvement there, you might have a valve stuck partially open on the ACV.

Did this happen suddenly, or right after any service work was done?....have you double-checked spark plug wire routing?

mazdaverx713b

iTrader: (91)

there's no air pump. i thought about reinstalling it. when i installed teh new engine i never installed the air pump because i wanted to remove the emissions. that never happened and the air pump is in my garage in a box next to the car. every other component on the engine is stock with no modifications what so ever.

the idle issue has been ongoing since i installed the engine. no change in 200 miles of use.

scrip7

iTrader: (6)

Is the ACV still on the engine or did you install a block-off plate?

mazdaverx713b

iTrader: (91)

the acv is currently on the engine

WingsofWar

funny, my car makes the same noises as yours..almost dead perfect, from the hissing, the uneven high idle, to the horrid ticking sound just like in that video. I Thought it was a vac leak too so im in the process of putting everything back together after replacing all my rubber hoses.

mazdaverx713b

iTrader: (91)

the hissing is the idler pullies' bearings. the ticking is an exhaust leak at the turbo flange, and the high idle is just driving me crazy!!!!

scrip7

iTrader: (6)

Take off the acv and block it off as your next step. If you don't have a block off plate, just use a flat piece of metal lying around and have someone hold it on the LIM temporarily while you start it back up.

mazdaverx713b

iTrader: (91)

i can do that or i can reinstall the airpump. just curious why you are mentioning the acv. could there be a problem with the acv, causing the engine to have an increased or rough idle?

Soma

Looks like your engine wasn't warmed up when you shot the video...
What does it idle at once you reach normal operating temperature???

RXJIM

iTrader: (3)

This thread should solve you problems.

https://www.rx7club.com/2nd-generation-specific-1986-1992-17/boncing-idle-686331/

Good luck

mazdaverx713b

iTrader: (91)

once warm, the engine sits around 1500rpm

scrip7

iTrader: (6)

Yes. The anti-afterburn valve (bottom part of the acv) can stick open, causing unwanted extra air to be drawn into the primary intake runner to the rear rotor. This is why I suggested the block-off plate to take the acv out of the equasion.