J-Rat

iTrader: (2)

There isnt so much as a question here, its more of a play-by-play, in case others are having the same problems.

Here is the situation. My TII has developed an incredibly irritating habit of idling at 1500, no matter what I do.

Things replaced, cleaned, or tested:

TPS
BAC
Water Temp switch
Air Bypass Solenoid valve

I read the following post by Mazdaspeed...

https://www.rx7club.com/forum/showth...ight=high+idle

This is what I am going to try today.

More info as things progress (or digress).

Jarrett

J-Rat

iTrader: (2)

Well, disconnected the neutral switch (which should make the car think its in gear), but nothing happened.

All it does now is idle really high (1500-2000) and when the clutch is released, it revs up and down.

This is friggin MADDENING!!!

88 SE

I fought a 1500 rpm on my recent rebuild for months, it took a combination of things to finally bring it down

Biggest problem was vaccum leaks. Had to track all those down.

Once I fixed the leaks it went down to about 1000 rpm.

I could finally set timing, was a good amount off. that lowered it another 100 rpm.

Next was just tweaking with BAC and Mixture settings until it finally got to 800.


One thing you might try to... When I set my idle speed an mixture, i turned lights and AC on to put engine at full load. Ajusted it to spec, then pulled the initial et jumper.

This was the only way I could get it to stay under 1000 rpm even under no load.

J-Rat

iTrader: (2)

Well, I managed to beat the TPS into submission by using the light method. For some reason, the resistance method was messing things up. At full warm, with the first TPS light BARELY illuminated, I was reading 1.16 kOhms, and the car idled. Not perfectly but it idled and didnt surge.

When it was surging, on decelleration (idle) it sounded like the rear rotor was being shut down. This led me to think that the TPS was out.

The neutral switch is disconnected (more like the wires broke), and it didnt change a thing (I figured it wouldnt).

So, next on the list is a BAC cleaning, an ECU swap, and a new O2 sensors.

More to come.....

Jarrett

88 SE

Have you checked for vacuum leaks? I felt 100% sure that mine had none but it turned out it was leaking in some wierd places.. mainly intake to engine gasket and the EGR valve (EGR valve would be worth a look since most of em are leaking by now)

HAILERS

Turbo inlet ducts like to leak where it connects to the turbo. Usually a hairline crack around the clamp. Hard area to spray with fluid.

J-Rat

iTrader: (2)

This is a possibility, but it is not a new motor. I am, however, going to inspect all the hoses..Etc. I was spraying carb cleaner all over the damn place trying to get the thing to surge, but that didnt work.

Jarrett

J-Rat

iTrader: (2)

Oh yeah? Hmm...May have to look at that too. Of course, on the drive to work, the damn thing started idling back up. But it will idle down if I put it in neutral and fully release the clutch. WTF is up with that? Is this a normal symptom of a cracked TID?

So, now to add to my list:

Check all hoses
Check TID (what if its bad? Time for a new intake system?)

Clean BAC (I used lithium grease inside of it...Probably not smart)
R2 (thats remove/replace) the O2 sensor
And R2 the ECU

Sounds like a fun evening to me!

Jarrett

*edit* and check the EGR valve...

J-Rat

iTrader: (2)

Well, I fixed several cracked lines. This includes the TID. I can get the car to idle at 750, but after some driving, it seems to creep back up to 1500. The idle will drop if the clutch pedal is let all the way out.

Man, this is starting to suck...

Jarrett

88 SE

Try resetting the idle again, but set it with engine on full load. adjust the BAC and idle mixture with all your lights on and the AC on, it helped alot with mine.

If i tried to set mine with no load it would do a fine 750 idle with the initial set jumper in, but when i pulled it, it would creep back up to 1200-1300 rpm with no load.


I dunno if its normal for hte idle to drop when you let the clutch out, I know mine does it though. It idles higher if the car is in gear or clutch is in.


As for the starting to suck part.. i totally feel your pain hehe, i spent so so long and put in so many hours fixing little leaks. It blows.

GLHS

Use starting fluid to check for vacuum leaks.. its works better than carb cleaner...

HAILERS

Putting the car in gear while idling can/might/will change the idle. Part of the way Mazda designed the fuel system. Neutral switch making a ground/not making a ground to the ECU.

I watched my primary injector with a Fluke meter last weekend, and even on a 87 you will see a change in duration of the injector in ms. Something like 2.8 ms at idle, out of gear, then if you turn the lights on and the heater fan etc, the duration will get into the 3.5 area (from memory). So the ECU even on a 87 makes adjustments for load. The same change happens to the bac if watching its duration in ms while turning electrical things on/off.

Almost sounds like a bac problem when you said that after you pulled the initial set coupler that the rpm went up. Maybe pull the plug on the bac and see what happens? I posted a while back about how the bac on my turbo went screwy. Would make the car idle at 1000rpm, but if I let the clutch out a touch to load the engine it would return to 750, but then again if I slightly reved over 1000-1200 and then let go , it would do the 1000 idle again unless I put a clutch load on it to pull it below that figure, then 750 again. Swapped bac's out. Had a spare. The original is still soaking in some super lubricant (forgot about it til now).

I'll put the Fluke on the car today and watch as the car is put into and out of neutral and let you know.

Cavernkid

Well give you a little tip. On my 7 when i got it the little screw was tightened all the way down and this caused the adjustment to be way off cause the little tangs were bent slightly. So i took out the screw and spring and tweaked them until they would work while bearly pushing on the spring and ever since i had no problems with idle.

J-Rat

iTrader: (2)

What screw?

J-Rat

iTrader: (2)

Okay:


Neutral switch is disconnected (it broke). But I have another one I can install tonight.

I tried swapping BACs but the results were inconclusive. Mine comes off tonight for cleaning.

Pulling the plug on the BAC does absolutely NOTHING...Nada, ZIP....That cant possibly be right.

As far as the neutral switch goes. With the plug disconnected, the car thinks its always in gear. This is a POSSIBLE problem, and I will re-install the Neutral switch tonight.

Jarrett

J-Rat

iTrader: (2)

that damn thing is a few seconds away from the dealer...I cant figure this out...

Jarrett

J-Rat

iTrader: (2)

Well, here is the latest:

Found that unplugging the BAC did nothing for the idle, and I couldnt figure out why... So I checked the plug. The connectors had migrated back out, so it looked like it was plugged in, but it wasnt...

So now I have to re-adjust everything and try again.

Jarrett

HAILERS

I'd concentrate on the throttle stop screw and see if it's making contact or not. It's that little tiny screw with the 8mm size jamnut that holds it in place. You've probably done that already. Then there's the thermowax and the fast idle cam. Making sure the cam is off the roll pin when the car is hot.

That's good info on the bac socket being pushed back. Seems to happen often. Usually you WON'T see a difference if the bac plug is taken off when the rpms are over 750. For some reason the bac I mentioned did react to god knows what.

I know you've read this http://www.teamfc3s.org/info/articles/idle.html right?

J-Rat

iTrader: (2)

Well, I came across that particular thread earlier this evening, after an exhaustive search through all the idle problem threads. There seems to be a common thing to each thread. NOBODY POSTS WHAT FIXED THE PROBLEM!! How rude is that?

Anyways, I got the car good and hot today, after fixing the BAC connector, and adjusted the TPS and the air/mix again. Now here is what it does. It idles at 1500 rpm (thats bad), but its a steady 1500 (thats good). I can drag the RPMs down to 1000 by using the clutch. And there it will stay, unless the throttle is used again. Interestingly enough, when in neutral, and idling at 1500, when the clutch is released ALL THE WAY, the car starts stuttering. When the idle is manually brought down, the clutch pedal can be released with no adverse affects. My theory? Its because my neutral switch is broken, and the car is trying to compensate (right now the ECU thinks its in gear all the time).

So thats getting fixed tonight.

No, I didnt look at the cam and throttle stop. I am a little dumb in that dept. Should the throttles be touching the stop? And whats this cam all about?

Jarrett

*edit* I sprayed enough carb cleaner around the engine to kill of a small country. Nothing seems to make the RPMs change at all.

HAILERS

Yo. With that pvc outfit you should be able to see the throttle stop screw at the left/rear of the throttle body. If it's touching when the car is fully warm, and the idle is still running high, back the 8mm wrench size nut off, and screw the throttle stop screw until it does not touch anything.

I'll see if I can did up a picture of the fast idle cam, roll pin and thermowax device and fast idle screw. You need a small mirror to look at them with the throttle body on the car.

The long and the short of it, is, that when the engine is fully hot, the cam should come off a roll pin. If it does not then adjustments need to be made to the fast idle screw and the screw that determines the rate the cam falls off the roll pin. I forget its name at the moment.

I'm betting the throttle linkage is touching the throttle stop screw and you can back it off to close the throttle plates to lower the idle.

jacobcartmill

iTrader: (6)

i agree with this. i had to do that to my TII to get the idle anywhere close to 1000.

at the beginning of this thread, your car was sounding exactly like what my TII was doing. but mine owuld od the vroom fall thing til the car got totally hot and driven for 15 minutes. it would even vroom fall when i would put it in gear and try to take off, making me buck. my car was also running very rich.

have you checked your water thermo sensor? it seems to be a sneaky little bitch (you have an S4 right? should be on the back of the water pump elbow almost under the alternator) and can cause a lot of problems. if dont have this water thermo sensor and your car is cold (under 80 degrees F i believe?) it makes your car run really really rich in the cold and lean in the hot weather because the ECU doesnt know the temp that this sensor is suposed to be sending it.

i'd try checking those throttle plates and see if you can close them off a little more to cut off some air and maybe lower the idle a little bit.
(i think your problem may have something to do with this idle switch stuff)
but check into some of the more "unchartered territories" by getting into the sensors that could be making the ECU make your car run retarded.
get back with us.

J-Rat

iTrader: (2)

Just for ***** and grins, here is the Home Depot intercooler bypass assembly. AKA $3 worth of PVC and elbows.

J-Rat

iTrader: (2)

Okay, here is what I did:

I removed the intercooler and capped off the 2 lines that go to it. These are the (I think) the Air Bypass Solenoid Valve (for startup) and the Air Supply Valve (for power steering). Then I put the Home Depot intercooler bypass in. Still ran high, but not as high as before. Looked at the idle screw. Wasnt even touching the throttle assembly... Throttle wasnt resting on the dashpot, nothing. So I ran that screw down (or up, I cant remember which) to lower the idle. Then I had to re-adjust the TPS. Re-adjusted TPS, and adjusted initial idle mix. Things were still a little high, so I adjusted a combination of the TPS, Variable Resistor, Air Screw (BAC) and Idle stop screw.

The result?

Rock solid 850 idle. WOOO HOO!!!

I left the 2 lines capped off, and put plugs on the intercooler because I removed the power steering, and I dont need a 3000 RPM startup in Arizona. With the intercooler re-installed, idle was even lower. Now its 850, sometimes higher coming to a stop, then it drops. What a relief.

Now here is my question...How the hell did that screw get backed all the way out?

Jarrett

Oh, and THANKS!!!! You guys are great. My FCs wouldnt run if it wasnt for this site.

88 SE

I dunno about on turbos, but I know on the non turbos the idle screw is covered with a JB-weld type substance that prevents tampering. If it was gone on your T2... it might be a sign that someone put it all the way out like that.

Its amazing what readjusting your idle settings 1000 times will do for your idle lol.

Took me a good 10 or 12 times of readjusting everything before it was finally perfect 800rpm at load and with no load.

J-Rat

iTrader: (2)

Yeah, I had considered the possibility that someone had tampered with the vehicle.. Who knows?

Jarrett