My stock '87 TII with has been running perfectly. I drove normally about 6mi; stopped for about an hour or hour and a half. Engine wouldn't start easily, so I put gas pedal to the floor to clear out gas. Engine caught and immediately charged for the redline. I turned off ignition before it reached the redline. Each time I restarted - same result. Had it towed home. Same result when cold, except it doesn't rev up as fast. I removed the intercooler and verified that the throttle shafts operate normally and return fully to their stops when accelerator cable is slack (cruise control cable is also slack). I don't see any vacuum hoses that popped off, though I have only looked from above, so far. Car starts with intercooler removed but dies immediately. Someone in our MA club said it could be the BAC valve. I disconnected the vac hose and plugged it - no effect on my problem. By the way, when removing the short vac hose on the BAC, I broke the plastic inlet nipple on another part. I have the FSM and Haynes but can't make out the part. Is it the Accellerated Warm Up System valve that is immediately downstream of the BAC - it sits on top of the dynamic chamger? Is it safe to buy a used one?

Any suggestions? I looked in the archive but only found high idle problems. If the answer is in the archives, please tell me how to find it. I haven't pulled the cover off the throttle body, since it looks like a major operation. Am I missing something. One nut is inaccessible under the bracket that supports the intercooler.

 

is the throttle stuck or not.. your post is not clear.

Can you (by hand) turn the throttle at the throttle body?

 

The plates have to be staying open. If they were closed there's no way it could rev up like that.

That's my off the cuff opinion.

 

I agree, but he wasn't clear on if it was the cable or part of the linkage.

 

Sorry about the confusion. The throttle shafts turn normally as the pedal is depressed: first the primary and then the secondary. And the throttle shafts return fully to their stops when the pedal is released. When the pedal is released, the cable that attaches to the throttle shafts is loose, as it is supposed to be.

Is it possible for the shafts to turn without the throttle valves closing? Seems really unlikely.

 

It's got to be an intake leak you have not found yet.
I sympathize - I'm still looking for one on my NA.

 

Only time I've seen that in person was my neighbor who had her oil injector rod hang up and hold the plates open. When I looked at the linkage, it looked like they were closing, but in hindsight they werent.

Umm.. Thats probably not it as you say the linkage is closing fully, but hey may as well check it anyway.

I just dont think the front linkage can move seperate from the rear linkage. .. or can it??


** EDIT.. I just looked at a spare TB i have laying around. It looks like the front linkage (i.e. oil rod) can hold open the plates while that back connections (gas and cruise) look closed. WHile the car is off, is the linkage where those gas and cruise cable connect all floppy and loose?

Umm.. if you have an s5, I dont know if its different. i.e., electric oil metering pump

 

yeah I was thinking bent or damaged linkage to the OMP as well (since he posted that he has a 87 T2), but I wouldn't think that the throttle plates would be moving still

 

Icemark, I agree. I was just kinda tossing it out there as that was the prob they only time I ever saw it on a rotary in real life. It was an N/A though.

She was a little dumb about it though. I heard her pull up, went outside and saw steam coming from the engine, could smell cooking brakes and clutch.. Apparently she had drivin it about 5 miles home in the city at full throttle..

Oh well.. needless to say, she blew a few seals - lol - The car is still sitting in her driveway 2 years later.

 

Please keep those suggestions coming. The oil injector rod is free and not stopping the throttle shaft from returning to its stop.
Where can a big supply of air be entering downstream of the throttle valve? And how would it happen suddenly?
Can you answer my other question? I broke the plastic intake of a device downstream of the BAC valve - the short vac hose from the BAC valve goes to this intake - and that's how I broke it, trying to remove the hose to test the BAC valve. Is it the Air Bypass Solenoid Valve?

 

May I suggest you get the Factory Service Manual chapter about 'fuel and emissions systems (turbo)"
from www.fc3s.org under how-to's-<manual

You will find a troubleshooting guide for when idle speed is too high

Hope this helps a little bit,
Hugues -

 

If you want some info general info about idle operations,
read this:

idle operation

Unfortunately, I don't know what happened to all the pics

hugues -

 

Thanks guys, but this is NOT a high idle problem, unless you consider 7+grand a high idle. The engine acts as though it is under WOT when I turn on the ignition, even though I am not touching the gas pedal.

I have the FSM and Haynes - neither deals with this problem.

 

It has to be something to do with the tb. Air cant get into the engine and it cant rev that high if its not open.

 

try having your friend physically hold the throttle down when you start. If it still revs, then your problem is not with the tb

 

I agree.. Triple check that TB.. Its got to be stuck open. A vacuum leek will (in my opinion) never cause that.

A couple things.. Does your gas pedal have a normal feel to it, or does it just sorts drop to the floor?

Go to where your throttle cables go into there little notches on the linkage. When your sitting there with the car off, does it take effort to twist them, or are they all loosy goosy. If there all loose, and can twist back and forth, your throttle is stuck open somehow.

There is a lot of crap on our tb's.

I guess to tell for sure. The very last little tab on the backside of the tb where it touches a screw, is that tab touching the screw when the car is off?

 

Yes, the throttle shafts operate smoothly and return completely to their stops - that's what's so weird about the problem. The pedal and accelerator cable operate smoothly - the pedal does not drop to the floor; there is slack in the cable when the pedal is released. The throttle valves should be fully closed.
Is there any way for air to bypass the throttle valves when the valve are fully closed? Can the throttle plates break loose from the throttle shaft?

 

have you checked the fast idle cam on the back of the TB. Although it should make the idle any faster than about 3000 RPM, I suppose that it could be jammed/ broken and sitting higher.

 

I'd suggest removing the TB if nothing else works, look at the plates them self when moving the linkage, or maybe you could let off the gas once the car is running j/k.........try to unflood it by pulling the egi fuse before you start it and don't touch the gas peddle, it should start after you pull the fuse crank it a few time, plug it back in and fire her up with no gas pedal....hope this helps

 

I agree with these guys, it has to be the throttle plates.

I've had the same thing happen to me after having my TB off and sitting at a weird angle. I just slammed my throttle open/closed a few times by hand and it was good.

I don't think it is a leak somewhere after the throttle plates because your AFM wouldn't be moving any air, and it would cut fuel and shutdown.

How fast does it try to rev? I would pull the TB off and verify the throttle plates are closing all the way.

 

Did you find out what the problem was??? I am curious to know...

 

AN INJECTOR GONE STATIC???

 

Thanks again for the suggestions. A mechanic friend is hoping to come by tomorrow and help me sort it out. From my phone description, he thinks air must be entering downstream of the throttle valves. That makes sense, in theory, since the throttle shafts appear to be operating normally and closing fully. I will post a message as soon as I learn more.