Normal Vac at idle

Ok got a question, what is the normal amount of Vac. i should see at idel (800-1k)

17-19hg

Depends on what the elevation is where you live. @ sea-level it should be 14-15. I see about 12 at idel because I'm 1780 above sea-level. I see 15 when I let off the gas while crusing.

I get 18 in/hg @ idle and about 22 - 23 in/hg during deceleration.

Scottse, your's seems a little low, are you sure you don't have a vacuum leak?

Not sure in the slightest. I always figured Vac reflected Appsolute pressure. Im starting to second guess now. Durring Idel their is no possitive pressure, so the engine is running on air pressure to get air through the valves & into the cylinder durring overlap. Am i missing somthing? I know that exhaust gas causes a small draft like effect helping air into the cylinder. I didn't think it helped anywhere near that much! Humm. Crap. Another problem!

Yeah scotsee, that's a little to low for vacuum.

i live in louisiana and im getting 10-13 at 1k idle and decel is like 18-19

with 3" turbo back, i get like 21 at idol and decel is 30 or so...im in VA tho

ok well fixed a few leaks. one big leak. Thought i had it whooped. Started car, still only reads 10-12 vac at idle and 19 at decel. I dont know peps.

ok one more thing. i pressured my system to 10psi,on my joe p boost controler, you know the little hole in the controller itself, well it was leaking from there. but when i run it, it boost up to 14psi, should it be leaking at that point or what. just a question, not quit sure.

In my very limited experience with these cars, normal vacuum on stock cams is 19-22", with 264s its 14-15", and with 272s its 10-12", IIRC.

well wtf, i nknow i still have stock cams. i dont know why its only doing 10-12vac any ideas?

could the gauge be messed up at reading vac, what about that hole in the Joe P boost controller? this SUCKS

Could be vac leak after the throttle body, leak to the guage, or a shite guage. Then you get into the complicated things like timing off a tooth, etc .

im also having misfires, wouldnt that be cause by timing off a tooth?

Check your injectors and make sure there is not oil in the holes. If there is you should get a leak down test I think. Correct me if i am wrong.

A leak down test is for checkin for head gasket, intake valve seal, exhaust valve seal, or valve cover leaks. It's not a vacuum test, although it is a good test.

so im going to the shop next week sometime, whenever the damn hurricane decides to finish fucking us up lol.Im going to get him to put it on the timing light and see if thats it, if not what else should i get him to check, The leak down test?

A simple boost leak test would be the first thing I woul do.

did it already, found one at the boost gauge tie in source. and a huge one under the intake, have a little itty bitty line that was not hooked up. cant hear anything else

So I'm assuming you fixed them, did that affect the low vac? I would expect the one at the boost guage line to be the worst. Even if you cna't hear any more leaks, is the system holding pressure? The biggest leaks are the hardest to hear.

yea its boost to 14psi and holds, i do have a small one somewhere but cant find it, i put about 10psi in it with the boost leak tester and the gauge needle drops slowly. but i cant hear it. im getting a new boost gauge because the light on my old one stoipped working. so when i hook it up im hoping that fixes it. Im going to take my car to the shop and tell them to put it on the Timing light gun and see what it says. I never messed with one of those, what is the timing supposed to be at idle.

You have to ground the timing at the ECU so that it holds it at a solid 5 degrees, rather than making it bounce around all over the place as part of closed loop idle control. Luckkily for you, the 95s are the only 2Gs with the connector to do this. Its a brown plug on the firewall behind/to the right of the battery. Pull the connector/cover off, and there is one pin in there that you need to ground. Then connect the light to power/ground on the battery, and hook the pickup to the number 4 (far left) plug wire. Shoot that bitch at the crank pulley, and it should show 5 degrees. On the 2g motors it is not adjustable without a 1g CAS however, so it is very unlikely to be off...

On the 2g motors it is not adjustable without a 1g CAS however, so it is very unlikely to be off...


Do you think when he put all the belts and shit back on( he had to take all the timing stuff off and put it back together)he may have put it off a totth or two?

Ok just changed the fuel filter, and nothing. still have the miss.I dont know what. Im going to have the injectors flushed out maybe friday when i get some money.
One other question
Ok i thought i may have had the cylindars numbered wrong instead of 4321 i thought they may have been 1234 so i switched them but left the ones on th ecoil the same. well NO DIFFRENCE wtf?

Have you tried a power balance yet?

Have you tried a power balance yet?

what the hell is that?

ok i have to have a major vac leak somewhere.My S-AFC is set wierd right now to make the STFT and LTFT Stoich. it normally reads about say -5 or so and idle, now its reading likr 0% to +1% wtf. Also i think my ICS is going out. the car will idle at 1k then the next day jump up to 2k so i turn the adjustment screw on the Throttle body and get it to 1k again. well next day back to like 1.5k to 2k.

Messing up the cam timing on a 2g will still not affect ignition timing, since the signal is taken from the crank. On the 2g, the only thing the cam angle sensor is used for is ODB2 misfire detection.

If you had the piston numbering backwards, it still worlnt matter if I'm thinking of this correctly. Cylinders 1 and 4 are on the same coil, and 2 and 3 are on the same coil, so I think the end result would be the same :D

Keep in mind that the BISS is not to be used to adjust idle speed. The ECU will still over ride your adjustment with the Learnedidle and ISC Position values, much like AFC settings in closed loop are over ridden by STFT and LTFT mid/low, until you max out its range of adjustment. The BISS is only there for adjusting the position of the ISC under normal operating conditions, so it has full adjustability in unusual conditions. Same reason we use the AFC or similar to get fuel trims back to 0 (for 2g, 100 for 1g) when we upgrade injectors, etc.

so what could i do to fix this damn high idle. is my ICS broken, how hard are they to change. Also, would dirtty injectors cause me to get the P0300 misfire code. How does the ICS work on the 2gs, is it vacuum driven or something, could it have a vacuum leak and that could be causing my low vacuum reading and the car Idle messing up like it is.


PS thanks for all the help so for. I appreciate this a bunch

ISC is bolted to the TB right under the TB elbow, has the brown connector with 6 pins. Its held on with 2 8mm bolts. Takes 5 minutes to swap it out, and that icludes carefully cleaning the hole it sits in of carbon type buildup. There is a test you can do to see how your ISC is working, do it when its cold and when its warm (engined driven for a good 10 minutes should do it). Sometimes they can appear good when cold but go open when hot. www.vfaq.com or www.crebotech.com should have the procedure and resitance values.

Ok UPDATE
ok GOt my new gauge and redid a few litle hoses and the Vac is pulling about right, but with the missfiring and bad ISC it still moves around a little and varies. And as you can see my ISC is bad, did the Ohm meter check and the last check point was bad. Went to junk yards but can find one.
Ok so now i got a new turbo intake pipe also.
Ok so still having bad missfire, and starting to run really rich, but i think my o2 sensore is going out or fouled out. on the pocket logger it shows the car running about stoich, but i can smell gas and all four of my plugs were black sutted and also have unburt fuel coming out the exhaust.Is there anyway to check the o2 sensor without taking the thing out, its a pain in the ass to get to really. Im trying to go get my injectors flushed too but havnt had time to take the car to a place to do it.None are around where i live.I think that my be my missfire problem(HOPEFULLY). Oh and sometimes on my pocketlogger when the car is idling. the STFT would get stuck and wont move, at like 10 or something, anyone had this problem.

HELP!!! lol

I saw an ISC on ebay yesterday for $22....let me see if I can find the listing.

Ok people,ive got to figure this damn thing out. Ok what are yall settings on S-afcII with 16g,195pump,550 injectors. I also think maybe my o2 sensor is gone out, it shows my car running STOICH on my pocketlogger but the car is running rich. The plugs were coverd with carbon the other day when i checked them,and sometimes it spits unburnt fuel out the exhaust. And you can smell it running rich. Also the car is misfireing like a mofo and maybe its because of the richness.So my question is, could a o2 sensor be reading but reading wrong?is there any way to check it without either A. pulling it out(hard to get too) B. buying a new one. On my Afc my LTPs were at like 0% at 1k to like -3% at 2k 3k. Ive heard they should be around -18% lol so something is fucked up.

is that BISS screw supposed to be backed out flush or what.

The BISS is a little more complciated than that ;) It is used to adjust the ISC to the center of its adjustment range. If you dont have the tools to monitor ISC position or force it to the center, don't touch the BISS.

Edit> It is definitely not supposed to be backed out flush, thats all the way. Just before its flush with the bore it is completely unscrewed.

ok well with my ICS screwing up, thats the only way to get it down sometimes. im bringing it back to the man that did the work to see why this thing is still missfiring and running rich.
I also got a P000 code yesturday WTF is that one.It said description not found.
Im hoping its just something simple, or just the timig is off a tooth or two. what is timing on the pocketlogger supposed to be at idle.

Also where do you live kevin lol im off next weekend, im going to drive and let you figure this DSM problem out :)

I'm in MA, might be a good haul for you :D

yea lol. well i dropped my car off at the shop today. hopefully get it back soon running good :) or atleast get that missfire shit handled so i can start tunning it.

Ok UPDATE, well i got the car back today, he changed the water pump and redid the timing. Well car idles woundeful, still has a vvery very slight missfire. BUT THE CAR IS STILL OVERHEATING. it was running fine, when i left the shop, went warshed it off, got on the road and ran it a little and when i pulled up home, noticed the damn thing was almost at 220on my pocketlogger. Well the thermostate is out of the car from when i started overheating before i dropped it off. The water is boiiling in the over flow tank. the radiator fan is bad but the guy hooked it up to turn on when the ac fan turns on. So the car just got a head job and water pump and that didnt work. Im going to try and flush the radiator out tomorrow and see if that fixes it.

2g fans are controlled by the ECU. I'm not sure what bad fan means when it works rigged up to come on with the AC fan? The AC fan wont come on unless the AC is on, and that just makes it harder to cool the radiator. I would get the main fan to act the way it is supposed to, it's pretty important. The ECU should kick it on at about 210 degrees.

well i think the headgasket may be gone. dnt know, i noticed a little bit of light white smoke out the exhauste at idle. Im also about to hook the main fan up to a toggle switch or something and leave it on, the fan is about to go out i think. when the car is off you can spin the AC fan easy with your finger, when you try to spin the main fan it slows down fast.

I would just replace the fan. A little white smoke at idle is normal, since there is always some water in the exhaust (and water vapor is also a byproduct of combustion of course). But repeatedly overheating the motor will take out the HG eventually.

Well the fan i thought was the radiator fan is actually the AC fan so DOH!!.i felt the radiator after it was running and the ac fan side felt hot and the radiator fan side was cool. big diffreance in temp.