My car has recently developed a random miss. Drove it to work this morning and everything was fine. Drove it to get breakfast a couple hours later and while I was idling in the parking lot it started missing. The check engine light has been on because of my high flow cats (I've had the codes scanned just to make sure) but I went ahead and reset the ECU and proceeded to beat the crap out of it. Everything cleared up for a little while. Left work to come home and sitting at a light it missed twice and hasn't done it since. The check engine light hasn't come back on since I reset the ECU this morning even after it missed on me tonight. You can feel it in the car, hear it in the exhaust, and watch the rpm's dip about a 100 or so. It only does it at idle. Can't feel it while driving.

I'm running pop chargers that haven't been cleaned in 30k miles, berk HFC, and magnaflow cat back. I'm thinking maybe clean the MAF sensor and throttle bodies and run some injector cleaner through it and see what happens.

Yall got any ideas?

 

Does the idle drop, car shakes a little and then go back up? Does it only happen when the car is fully warmed up?

 

It drops about a 100rpm, the car shakes just a tiny bit, and then it goes back to normal for a few seconds. The car isn't fully warmed up when it does this but pretty close.

 

Sounds exactly like my car when my TB's needed to be cleaned. Try cleaning them and see if it helps.

https://www.myg37.com/forums/d-i-y-i...le-bodies.html

 

That's what I was reading yesterday but figured I'd post and gather a few ideas. Any idea on how to keep the throttle bodies from getting dirty? Maybe switching to a dry filter instead of an oiled one.

 

Actually it has little to do with the air filters. The carbon deposits come from the crankcase ventilation system, specifically from the tube that goes from the passenger side valve cover to the rear of the plenum. The oil vapors load up inside the plenum, lower intake manifold, valves and behind the throttle body valves. The only way to stop the vapors is to install a catch can between the valve cover and plenum.

 

That was my next question. I'm assuming a few site vendors sell them?

 

This is the one I'm using

home online store ...

There's a lot of different brands and styles to choose from.

 

Nice piece but for $100 ill build my own. Thanks.

 

Possible bad gas as well. How full is the tank?

 

Empty. The tank gets run down to empty weekly. I usually get about 400-460 miles out of the tank and end up putting 17.5gal in it. Right now I've got about 19 miles left in the tank.

 

Running your car til it gets that dry is not good. I bet your fuel filter is nasty as hell.

 

Doubt it. Unless the fuel going in is nasty then there's no way the tank can get nasty. I dropped the tank on my diesel after 200k miles and it looked brand new and I fill that thing up anywhere.

 

I'm not so much worried about gunk rather than water in the gas. That is a typical issue in older gas stations. The fuel filter is pretty big for the amount of fuel it has to take in. It can get pretty gunky and still allow enough fuel in.

 

True. That's why I only fill up at the same stations. Valero by my house and stripes by work.