SonicRaT

iTrader: (6)

Alright, I've had a couple of problems with my idle, anything over 1k is always solid, yet it tends to change position anywhere from 1k to 1.3k whenever I let off the gas, it was never constant. So, I've done this enough to assume vacuum leak, bust out the cans and start spraying, none to be found. So I figure maybe I've got a vacuum line routed incorrectly, I start swapping them around, and I notice that when I leave on off, the car idles perectly 800rpm, turning any of the electrical load on doesn't affect it at all (this would cause my car to stall previously and hunt from 200-1100rpm). The BAC does function, if I pull it the idle will drop to about 100-200 (or stall). Any idea's other than the bypass on the BAC possibly being dirty, or a faulty TPS? (no leds, or mm to test it, but the idle is fine with the vac leak) This thing is boggling my mind.

RXspoof

lol... i dont understand it ether... but when i remove my Vac hose from my Pressher sensor it seems to run better too. but it lacks a lil power after that

Parastie

I'd go with either TPS or the vacuum line is maybe clogged? Start with the TPS first though.

SonicRaT

iTrader: (6)

My pressure sensor is still hooked up. I pull about 475mmHg at idle of vacuum (800rpm), the car will just idle poorly (200-300, bounce, stall with electrical load) without a vac leak. I just have one of the hoses open vented right now, and it's running great. Same ammount of power/etc. Timing is spot on.

Vacuum line plugged... Which? I've only got 3. Pressure sensor, FPR, and cruise. I just removed one of my vacuum caps, and that's when it started to get better.

RETed

Car is idling too rich to begin with.
Vacuum leak causes the car to run leaner.


-Ted

SonicRaT

iTrader: (6)

I already knew that part. It's why that's kind of boggling my mind! I checked the TPS last night and it's at .99v @ idle, no bad spots at all on either sensor. Perhaps it's time to run a gallon of techron through it.

dr.jones63

I had a similar problem after changing a alternator belt. The idle was high even when I had the adjustment screw screwed all the way in. I looked and looked for vac leaks and couldnt find any. I was showing a steady 16 lbs vac at idle on my boost gauge. I lifted up on the gas pedal and the idle dropped. I had a slight kink in the accelerator cable under the hood. I must have bent it a little when I was working on the belts. Problem solved

SonicRaT

iTrader: (6)

That's not my problem, I've checked that just about every day when I get pissed and start yanking on things trying to get it to behave. I did figure out my unstable idle (such as why it's always different from day to day) The secondary stop screw's locking nut is MIA, and the screw was threading itself from the engine vibrations causing them to hang open. I've got the car down to about a 500rpm idle at the moment, but I still have to have a vacuum leak for the car to idle at all. I'm wondering if my bypass on the AFM is clogged or plugged? Either way, I'll be doing some more digging later on today. Just put in the new fuel filter, brake pads, o2 sensor, and plugs, so I figure I might as well keep on wrenching.

Kenteth

What if your car's idle settings were calibrated for the vac leak? For instance, you calibrated idle when you had a vac leak, drove around for a couple months. Then you spot a vac leak and plug it. All the sudden your idle is crap because the car was still expecting (calibrated) for that extra unmetered air. Just a thought.

SonicRaT

iTrader: (6)

Problem is I never had a vac leak, I haven't had a vac leak since I bought the car, and I was rerouting hoses while the car was running, and I pulled one off and strangely it idled perfectly at 800rpm with no hickups, I could turn on any electrical component to try to drag the engine and it'd just stay idling happily, only after that did the set screw start causing problems, but that's taken care of and the cars still idling at 600-700 just fine with the leak. If I plug it, the damn thing stalls. I've even got a little RC car filter on the vac line so it doesn't suck up anything bad.

Kenteth

Out of curiousity, what nipple is it?

SonicRaT

iTrader: (6)

Doesn't matter which, but it's currently the bottom of the three on the firewall side.

SureShot

So - the vac leak balances the rich idle.
Problem Solved!
Maybe put a little tiny air filter on it.

Kind of like the mechanical equivalent of an SAFC.
I may try that..

vaughnc

What exactly are you referring to, the secondary injectors, fast idle adjustment screw, bac adjustment screw?

6port

I think he meant the secondary throttle plates

Kenteth

Actually I busted that nut off (ha..haha) anyhow, My idle does the same thing. Everyonce in awhile I have to screw the bolt back off a 1/10000000000 an inch to get the idle straight again. Man that thing is touchy. The fact the bolt head/nut that holts it broke off doesn't help any. i'm thinkig that screw calibrates idle too low/too far closed, and that extra vac leak gives the engine enough air to keep a decent idle.

SonicRaT

iTrader: (6)

At the moment I've got that screw completely removed, and the idle screw on the top of the TB as open as it will go, and it idles around 500-600 with the leak. Even by trying to adjust those plates with the leak plugged, I still can't get it to idle smoothly at anything below 1k, it'll just kind of sputter and stall. I do have a filter on the open nipple, I got it off an RC car.

vaughnc

Yeah I was afraid of that. The FSM doesn't mention any screw, just the "double throttle diaphram".

Kenteth

That TB rich/idle screw doesn't have a chance of coming near flowing as much air as the set screw you removed! If you remove that screw, the TB paltes are completely closed (in theory). The entire air for the engine has to then be flown through a path in the TB that is half the width of a pencil. And you wonder why your engine stalls with the vac leak capped?

Thats like a person with asthama trying to braeth through a coffee stirrer.


That vac leak is suppling a good amount of air at idle/tb plates closed. If you capped it, and propped the TB paltes open at idle with the set screw, you'ld be fine.

BTW: don't bother going to the dealer for that nut and screw, they don't have it. (stupid, but I thought I would check anyhow.) I put some gasket maker on the screw/bolt, and it doesn't seem to move much anymore. Plus I could still get it out by turning it with pliers if i had too.

SonicRaT

iTrader: (6)

I guess you declined to read more of what I wrote. I removed that screw for the sole purpose of avoiding it keeping my throttle 15% open by threading itself in, so I can go to ace and pickup a replacement nut. However, the BAC kicks in and provides extra air to help keep the idle up. But, regardless, I mentioned previously that even with the plates operating, I still can't get it to idle smoothly under 1k rpm, I can use the plates to adjust it to anything over 1k just fine (with the vac leak plugged off), but as soon as I get it under 1k, it stalls. However, with the vac leak, I can adjust the plates/and so forth to whatever speed I want and it'll idle just merrily.