JCurry

iTrader: (6)

Ok well my connector on my bac valve broke off so today i made a new one, but with the bac valve plugged in at idle and normal operating temp my car idles at 1500rpms. If you unplug the bac valve it idles at like 1000rpms, well i tried adjusting the screw on the bac valve and it wont go down anymore, its already screwed all the way in. So wats the deal????My idle used to be perfect at like 750 before i set the timing,(It was wayyyy off) now its real high!! What else do i need to check...

Also If i buy the block off plates to take the bac valve and stuff off, wat do you use to control you idle speed?????? cause i dont need emissions in tx so that is another option...

Thanx

JCurry

iTrader: (6)

Also i just tested the ohms resistance between the terminals on the bac and it was 13.5ohms. And with the motor running there is only 10 volts going to the bac valve if you put the meter on both leads, but if you put in on the positive lead and ground the other its the same voltage as the battery....

Is all this normal or do i need another bac valve, would the resistance being that high make the car idle high with it plugged in??????

Please help me out here

JCurry

iTrader: (6)

Anybody? Someone has to have experienced this before, and ive been searching this site for a while now and i cant seem to find a thread that answers my question..... just alot of threads saying that the idle bounces, mine dosent bounce its just too high, and i set my tps dead on were its supposed to be and that did nothing so i dont kno what it is, i also checked for vac leaks and i didnt find any...soo?????????

crazyasu

it's normal for engine speed to decrease when you unplug the bac valve connector, that's good. As for the resistance, the DMM should read between 10.7 to 12.3 ohms.

crazyasu

a bad thermo wax pellet would also cause a high idle.

JCurry

iTrader: (6)

where is that and how do u check it?

and if my dmm is reading 13.5 does that mean my bac is bad?

SirCygnus

iTrader: (1)

also check to make sure your throtle cable isnt too tight. for some reason, mine tightened itself and the revs got hige every month till i was idling at 2 grand. suckd ***.

JCurry

iTrader: (6)

Would the resistance on the bac being to high make the idle be high?

HAILERS

The BAC is probably good.

YOUR problem is most likely in the timing. When you set the timing, the rpms MUST be below 1000 rpm or there abouts. As you know from what you've been reading, the timing advances somewhere around 1100 rom. The ECU does that.

IF you turn the a/c on to try to drop the rpms lower, that is a mistake. The ECU also advances the timing, at idle, if you turn the a/c on. So that would be a bad route to get the timing down.

The thermowax is a good place to look. You need to remove the intercooler. Then look at the left side of the throttle body. The rear of the throttle body. Tell you what, I'm going to stop right here because I don't have the time. Go look in the online FSM in the Fuel Section and find the thermowax. It has pictures and How To.

We assume you already made sure the throttle cable has some slack in it. Just a touch is all it takes. We also assume you have nothing causing the throttle to stick. Anyway, look in the FSM for the water thermowax, fast idle cam , fast idle screw etc.

ABout the BAC. Go to the auto store. Buy a roll of gasket paper. Go remove your bac. Cut out a piece of paper to match the outline of the bac and then punch/cut two holes in the paper for the attach bolts. Put the paper on the engine then the bac. You now have a temp block off plate which will eliminate any thoughts about the bac being the problem.

You NEED to get that engine at a much lower rpm before setting the timing. Heck, your problem could be another thing altogether. Who knows.

Richter12x2

iTrader: (1)

A couple of months ago, I was driving down the road and suddenly my idle was 5 grand. Then 6, then 7. Eventually I had to slip the clutch at red lights to keep it out of the red. It turned out the backup nut on my dashpot was loose, and my dashpot was vibrating loose, wedging itself under the throttle bracket, and holding my revs up.

HAILERS

Yeah. Check the dashpot too.

Anyway, attached is a jpg out of the FSM showing the thermowax, fast idle cam and the two adjustment screws. In real life you can't see it that clear. What you can see is the two screws i"ve highlighted in RED.

The most inboard of those screws is NOT so easy to see. The outboard one is below the dashpot which you going to look at anyway. If you turn the screw to the left in the picute (most outboard), and turn it IN, that will make the linkage come off the fast idle cam/roller sooner. That is desired in you case right now. So screw it all the way IN.

The other screw will be a little harder to find but it's there. Turn that screw anti clockwise quite a bit but not so far that it is about to fall out.

Both those actions will/should make the idle drop because it will make the throttle plates close more shutting the air off to the engine. Then put the intercooler back on and see if the idle is lower. By the way, COUNT the number of turns you take with each screw and write it down so that later you can put everything back as you found it if needed.

Another thought is to fully warm the engine up. Go drive it hard for fifteen minutes and come back to the house. Now turn the cas til the rpms are lower than 900 rom. Put the timing light on the pulley. Adjust the cas til the timing marks align for the LEAD mark. When you did that, did the rpms advance as you turned the CAS? And if it did, did it advance in one big chunk at one point???? IF it did, that probably was the ECU advancing the timing because the rpms got over 1100. If that did happen, then do what I wrote above this paragraph to lower the idle speed.

Heck, it could be your bac too. So try that advice about putting a piece of gasket paper b/t the bac and the intake to act as a blockoff plate. Who knows. Could be a vacuum leak also. Get some starter fluid and spray away while at *idle* and see if the rpms change. Too many things could cause your problem. JPG attached.

JayWrx7

Maybe some of this info will help:

http://rx7.subbuteoclub.com/idlecontrol.shtml

Richter12x2

iTrader: (1)

That is good info - am I to understand that if you have your BAC removed, you don't need to jump the initial set coupler before setting idle?

HAILERS

As far as I'm concered, I don't install that jumper. I just pull the plug off the bac. When you install the coupler, the bac's duty cycle is SET to a percentage that I flat forget. But the key is that with the coupler installed, the bac can't react to any input you make to the air/mixture. If you leave the coupler out and don't disconnect the bac, and then make air/fuel adjustment, then the bac will react and drive you silly as you fiddle around.

One thing that has to be done is get the idle speed below about 1100 rpm and preferably closer to 7 to 800 rpm because like I said, the ECU WILL advance the timing all on it's own at that speed, making any timing adjustment a total waste of time.

Tell you what, I'll go out to my car, fully hot engine, and put a timing light on it. Then install the coupler. When I raise the engine speed over 1100 I'll bet a hundred bucks the timing will advance just the same as if the coupler was not there. IF it does not advance, I'll write back and say so. Won't.

By the way, protect yourself. Don't believe everything you read on this forum. Go out and try it out for yourself for .....self verification.

EDIT: Did what I said I'd do. Hot engine. Timing L 5 ATDC and T 20 ATDC. If I turn the a/c on, the timing goes to L 14.7 BTDC and T 4.5 BTDC.

Now I turned the a/c off and installed the initial set coupler. Engine running L 5ATDC and T 20 ATDC. Turn the a/c on and it adcances to 14.7 and 4.5 AGAIN proving the initial set coupler has no effect on timing. It effects the bac though. Memory says the Fixed duty cycle is in the range of 40 percent. Memory there.

JCurry

iTrader: (6)

Thanx hailers your the man!!! We need to get together sometime since fort worth is only like 1 and a half hours from my house.... but yeah ill go try all that and get the idle down then check timing and see wat it is...thanx everyone...

I just go to looking at the people in this thread and there are like 3 tx people...hahah....thas cool...

JayWrx7

I just go to looking at the people in this thread and there are like 3 tx people...hahah....thas cool...[/QUOTE]


Make that 3 1/2....I'm planning on moving to TX in about a year.

JCurry

iTrader: (6)

where u moving too

JCurry

iTrader: (6)

Also yes my rpms went up as i adjusted the cas, so your saying that while im adjusting it i need to adjust something else to keep the idle at around 750 or how does that work???? im not really understanding wat your saying..... so basiclly turn the screws on the tb to get the idle to 750 then check timing and see if its on and if not adjust it right? and is there any harm in messing with those screws and not putting them back where there were to start with?

Richter12x2

iTrader: (1)

I think he's saying to adjust your CAS so that your idle drops down below the point where the computer controls it, then adjust your idle speed down using the other screws, then back up with the CAS, back and forth until the timing is right and the idle is where it's supposed to be, because the engine is trying to compensate whenever the idle is over 1200. So use the CAS to get the idle down, then creep up on the right timing and idle without getting back up to 1200 where the computer will confuse you.

Am I right?

HAILERS

Yep. Most of what I wrote is not understandable.

Your problem could be just a vacuum leak causing the rpms to be high. Spray starter fluid to find out one way or the other. IF no leaks, then do the part below.

I'm suggesting that you go to those screws and turn them anti clockwise to see if you can drop that idle below 1000 rpm preferably down below 8-900rpm. THEN, if that happens, get your timing light out and set the timing. I'm guessing that when you get that rpm down, you'll end up having to adjust the cas one way or the other and life will be tolerable once again.

If you set the timing earlier, and the rpms were up in the 1000-1100 rpm range, then it was set wrong because the ECU had already advanced the timing above the normal 5 and 20 ATDC to about 14 for lead and 4.5 for trail.

JCurry

iTrader: (6)

Thanx man ill try that out!!

JayWrx7

Looking at the Austin area. My wife lived in Lubbock for awhile...not much there though.

NJGreenBudd

iTrader: (1)

hey did this ever get fixed??

JCurry

iTrader: (6)

yeah it ended up being a bad vac leak and after i got the vac leak fixed it idled low so i just adjusted it back up with the adjustment screw on the bac valve...vac leak was the lim it was f***** up real bad....