In parting, I've owned 4 Miatas. My 99, in particular, idles between 500 - 1500. Or are they not related? Some owners have reported better performance by using Bosch Platinum plugs, but any difference would be miniscule - under 1hp. The throttle cable goes to it. Be careful not to drop any foreign matter into the wells. Also how long and hard are these taps on the gas? It runs badly only under certain load conditions, especially 30 mph in third gear, on a level road or a slight grade downhill.
The point is, don't do a compression check without either pulling the connectors from the coils or keeping a spark plug in the wire while turning over the engine. That's not 13-W80 in the drawing is it? Yesterday I read the article about advancing the timing to 14 or 16 degrees and decided to try it. Ambient temperature also plays a role--the hotter the weather, the less timing your engine will tolerate. On October 15, I will take my 99 Miata to the dealership for the 3rd time, after which I will invoke the Lemon Law for the State of Florida. If it pings just sneak back towards stock 'til it stops.
There is a slight smell of gasoline also. I have a '94 Taurus that had the same problems and here is how I fixed them: Start by changing the motor oil and filter with a top synthetic oil like Mobil 1. Electrical loading of the alternator sucks horsepower, drag on the motor - slows it down. More likely a wire problem that is causing the engine to run rough and create the vacuum reading. I expected the dealer to be able to hook it up to some sort of scanning equipment, see what was going at various speeds and various load conditions 30 mph in 3rd in particular , then diagnose and fix the problem. Uses a 7mm nut and tiny allen wrench to adjust. Magnecor is considered a high performance wire.
After adjusting the idle improperly, without the jumper to compensate for the current draw of the Hella H4's, my timing was retarded by about 3 degrees! If so something to keep in mind. I also think maye it's only happened within the first five to ten minutes of driving. Setting timing Note: The timing on the '99 Miata is not settable. If grounded out it will still not work because they need lots of heat for it to produce voltage. I have the same type of thing happening except in my case its when the car is cold. There are sensors all over the car, especially involving the fuel monitoring systems and pollution controls.
To check if engine timing is off, have your mechanic check the timing between the crankshaft and camshaft by pulling the cam sprocket plastic cover off, and checking camshaft index mark against the top dead center mark on the crankshaft. If it is before a leak shouldn't matter but if it is after a leak can cause a lean condition. Tech spotted loose clamp on intake end of snorkel. The stock Miata is designed to run on 87 octane fuel. Intermittants are hard to find. A low or rough idle on a style engine can be cause by any vacuum leaks in the intake. Since the battery is not in the engine compartment, you should use the provided for this purpose.
I have not fortunately , had the car stall as a result of this however. Folks at Firestone, where I buy most of my tires, suggested that cleaning solution used to clean intake manifold might have damaged a sensor in the intake. Although the wires are the most common cause, if you have a '96 model, you might try this solution: Last April I purchased a 1996 Miata. The consequence of setting it at this point is when you are on the open road at speed the fan usually won't be running as much and the timing will be higher than what you thought it was set to. I didn't have this problem until a few weeks after the coldside kit was installed. Bill Cardell from Flyin' Miata shares his method: The stock tach is close enough for what you are doing. The piston is already beginning to travel back down the cylinder when the combustion occurrs.
It is almost as bad as the bottom pivot bolt on the alternator not being tight. You may want to share this on the site. Is there a sensor in the intake that could be causing all my problems? It should be around 850. You may need to blast the water out with high pressure air. As a result, the rubber boots on the spark plug wires sometimes grabs the ceramic insulator so tightly that the boots stay behind when the wires are removed.
. Connect the timing light ground connection the black wire to a suitable grounding point such as one of the unpainted bolts or other unpainted metal connected directly to the body. The far right one is oil burning. Remove the ignition wires by firmly grabbing the boot that seals the spark plug well. An easy way to check is, pull 1 spark plug, and drop the dipstick down the hole. There should be a very small amount of slack with the throttle plates closed.