1badFB

iTrader: (1)

Ok, so ive read the "GSL-SE IDLE PROBLEMS" writeup sevral times, and I think Im prety comfortable with how the EGI componants work and how the system should regulate the idle. My problem seems somewhat uncommon.

Thing is, my idle nearly always sits at a perfect 800 rpm once its warmed up but every once and a while I start up my car instead of going into its warm up mode with a bit of an increased idle (choked) It will just immediately come back down to 800 rpm. The weird part is that if I push the gas in a bit it seems to stay at 1100 rpm when I let off the gas until its warmed up like its supposed to.
I checked the TPS and it is in perfect adjustment, so unless it is faulty that isnt the problem.

Another small issue I have had is that occasionally (not very often) after its warmed up, if I get the revs up past about 4-5 grand, when it comes back down it will drop below 800 rpm and feel like its going to stall (although it stays running). Ive checked to make sure when that happens that the throttle plates arent closing any further than normal, and from what I can tell the throttle plates are in the perfect closed position regardless of this problem happening or not.

Im a bit confused at what to look for now, so if anyone can help it would be great. The car is so close to being perfect, that even though the problem isnt causing my car to stall or leaving me stranded Id just love for it to be perfect.


Final question is: when the car is idling it seems to have a tiny bit of a shakey feeling to it. The vibration/shake completely vanishes once it hits 1000 rpm, and hasnt ever seemed bad enough to worry about. I have been told its just how the 13b runs due to the overlap of the ports??? Im just not sure if its normal since it runs so smooth above 1000 rpm.
I looked back at the previous owners maintainence paperwork and apparently when he bought it in 1999 it was taken into a mazda dealership and the same issue was noted, and there is a written report from a mazda tech saying its normal for the rotary and that the engine was in great condition. There was even a proper mazda style compression test done and everything looked great. Is this normal or is there something I should look for?
Thanks

trochoid

iTrader: (6)

Sounds like the linkage may have a minor bind in it. I would clean and lube all of the linkage and springs on the throttle body. If that doesn't take care of it, you may have an intermittent vacuum leak or a slightly corroded conection.

Rogue_Wulff

BAC may be a little sluggish at responding. This could explain both the low RPM during warmup, and the low idle, both being intermitant.
As for the mild vibration, it could be normal, or it could be a small vacuum leak. This could also be a contributing factor in the idle issues.

XLR8

iTrader: (52)

Lube up your linkage and BAC with some WD40

LongDuck

Actually, my response would be that you need to calm down! These cars are 23 years old!

Both issues that you described are operating as normal for an -SE, even in NEW condition - that's right, I said in *NEW* condition, they would do what you describe, and here's why;

1) Starting it without pressing down on the accelerator pedal completely ONCE, then turning the starter...

This start sequence on the -SE's is *specifically* to reset the Cold Start Cam which is on the throttle body main shaft which controls the primaries. If you look at the rear of the TB from the passenger side, there's the green-colored Thermowax Pellet which controls the cold-start throttle setting. The idea behind pushing the gas pedal down complete ONCE before you turn the key is so that the throttle body cam can get set against the Thermowax piston, setting a higher throttle position during the cold start. When you just get in and start it up (without pressing the gas pedal down once), it does not reset this cam, and thus, the throttle is set for a lower idle position for the cold start. Once you start driving it and push the pedal past the cam position, it resets the cam position so the engine runs at a higher RPM until it warms up. Once the Thermowax pellet melts from hot coolant coming from the back of the waterpump, the cam is rotated out of the way of the TB rod, allowing for normal 800 RPM idle.

So what you described is PERFECTLY normal.

2) Idle dropping down below 800 when cold and almost dying...

Probably linked to the above condition when you DON'T reset the cam; When you allow a cold engine to return to idle, the fuel/air mixture is not yet being stabilized in the intake due to the cold engine condition. This means that idle return will tend to overcompensate in drop before your BACV idle controls can kick in from vacuum pressure and return the idle to a smooth 800 RPM. Once the engine heats up, your TB is warmed from the coolant hose described above as it goes to the Thermowax Pellet, and this higher TB temperature allows for more consistent air metering through the BACV and Throttle Plates.

So, again - it's behaving PERFECTLY normal for an -SE.

If these things bother you that much, I'd suggest sticking to the tried-and-true, Factory-recommended method of pushing the gas pedal down to the floor completely ONCE, and then turning the key to kick the starter. This will prevent most of the 'problems' you're describing here.

That, and enjoy your car. There are plenty of real problems endemic to -SE's that you can focus on if you're just looking for something to fix!