So I made a thread a few months back of my car getting a feeling of it missing. I hit a bump a few months back, last year, and since then I have been feeling this engine miss feeling. This feeling used to only happen when I hit 3 or 4k rpm in third gear, but now I am getting it in all gears and while accelerating and occasionally at highway speeds.

the problem is that its only intermittent. So I was thinking that it was the Gas. I filled up with some good gas, like a gas station that I always got good MPG from and was off the highway so I knew it would be fresh. Plus it wasn't the cheapest in the whole area by an absurd amount like the stations that I have been getting it at previously. So after I did that it seemed to have worked. From what I observed I didn't get any hiccups or engine miss feeling whatsoever.

So I was wondering, would a bad fuel filter cause this feeling. Maybe there is crap in the gas and the filter is plugged so the filter is just being bypassed? The whole electrical system is New. With less then 15k on everything.

 

or maybe it's the cheap gas you where using that was per-igniting/detonating? higher octane gas is more stable and less prone to per-ignition/detonating.

 

I thought about it...but it ran fine with 87 octane before...plus it did it with 89. So no sense in wasting money

I just think that Valero Gas is crap, thats why its cheaper.

Also the car is stock, everything from the Exhaust to the stock air intake. D15b2 engine.

 

When was the last time you did a tune up. Cap, rotor, plugs and wires. Also, cheap gas contains very little or no detergents to help keep injectors and valves clean.

 

last year with about 20kmiles on it. And the whole distributor was replaced, cap rotor, plugs, wires, and everything.

Shouldn't the fuel station be following gov't specification?

 

Cheap gas is probably within spec. Chevron, Shell and the like place additives in the gas with equal higher cost. East cost gas is all the same. All manufactures pump gas into the pipeline. At local distribution centers chevron will take gas from the pipeline and and in their additives. I use cheap gas as well but it occasionally put some fuel additives to help keep things clean. Like sea foam

 

I put this redline cleaner in it. But I still get a minor miss.

The thing is, I am wondering if it is even a miss.

 

I would go back and check the rotor and cap. Check the points to see if they have any buildup. Check the condition of your plugs. Are they wet, what color. Check to see if all your ground wires have good contact with the chassis. The fuel filter? The only way to know is to change it. Also I'm not sure how you drive but and occasional WOT doesn't hurt. It helps loosen deposits. I read that some where in a BMW manual a while back.

 

Yeah I will have to get it up higher in the RPM rev range sometime soon. Oil is leaking into one of my plug sockets...that could be happening, but I cleaned it off really good and it still did it.

I am going to cycle through this crappy gas and see what happens.

 

wouldn't matter if you cleaned it. the oil would have leaked into the spark plug hole again. looks like you might need new rubber grommets.

 

No, It was dry when I did that run, I made sure. It didnt fill back up.
A new valve cover gasket is on the things to do list.

 

I am wondering if this problem is being caused by a main relay. The car DOES start fine.

But today I went out for a ride up this parkway in my state, it was hot and hilly and I was missing, bad. So when I got to my destination and it sat for a few hours it only missed maybe once. Then a few hours after that, which would be night time, I only got a miss which I knew was an actual miss once. Thats it.

So I wonder if temperature has something to do with this.

 

I know this is an old thread but I have been chasing this problem for weeks now. I unplugged the o2 sesnor and tested the voltage and the voltage was low...but what concerns me is that I did not get a check engine light when I pulled it.

 

Since this thread isn't getting anywhere I will decide to post an update.

I did some testing around and the plug wires seem to be in good shape resistance wise, they all tested at about 8k ohms give or take. The tube portion made of a harder material, maybe like metal? But that had some scratches on it. I wondered about it... The IAT sensor tested to be within specs and the IACV tested to be within spec. I tested those because I thought it had something to do with temperature...but it did it today and it was quite cold today.

However reading in the shop manual I noticed that there was a fail-safe option in the ECU. For when the ECU is getting a bad signal from the sensor it just swaps in a known good signal for it.