My WK started bucking really bad after I had a mechanic look at it. I noticed that he pulled a vacuum line while it was running.
After he looked at it, the check engine light was on but I didn't pay it any attention. After driving it for a while, the engine light began to flash and that when I started to worry.
I then noticed that when I accelerate heavily, I get very bad surging/bucking at around 40mpg @ 3,000rpm.
I checked the hoses. They are connected. He only pulled on hose and immediately put it back on.
You will get a very good look at it towards the end of the video.
Funny thing is that it's not doing it anymore. The engine light is still on but it's not in flash mod anymore (it's not continuously flashing like it was when I had the problem).
Some mechanics are aholes and will do something stupid so you can take it to them, seen it done many times! Did you keep an eye on him the whole time he was in the engine bay?
I don't trust mechanics one bit!
I wanted to see if I needed manifold gaskets. We were looking for a source for my slight tick and he noticed a slight hissing sound. That's when he checked the vacuum line.
Come to find out, I have no exhaust leak because there isn't any black residue anywhere around the gaskets.
Well if ya go to the trusty ol Air/Fuel/Spark.... Im guessing if his codes are showing a misfire i'd check plugs, ignition coils. Im not sure how you'd check the actual fuel. Any chance someone put water or something else in your gas tank?
P0339 is the crankshaft position, so look for that sensor and make sure it's secure.
P0300 is multiple cylander misfire.
Sounds to me like your mechanic can't keep his hands off wires. betchya he was tugging. Go make sure every wire on the coil packs is secure, and all your wire connectors are secure.
The intermittent issue is probably because they are loose but not completely un done.... so they might be working one minute, then after a bump, not.
The crankshaft position sensor is used by the PCM to determine proper timing. So my guess is if the connection keeps going in and out the PCM will have trouble getting the timing right hence the misfires. If the sensor itself is bad it can cause those issues too. When the sensor went out on my BMW it wouldn't even start.
The guy in that link was think it was the battery.
I do have very little corrosion on the + terminal that just started to happen.
I think I might buy a red top Optima tomorrow. It's what the guys at Advance Auto suggested because the yellow tops they have on the shelf have too little cranking amps. The red tops they have in stock have a little more cranking amps than stock.
My wife's 3.7L Laredo was bucking like that...running like crap. I changed the plugs and it cleared it right up. Good luck figuring it out man. My XJ did that once too and I believe it was bad gas. I know a lot of people don't believe in not running the tank dry, but it can't hurt to fill it up and see if the problem goes away. There could be sediment at the bottom of the tank, or you could have gotten moisture in the tank and with it almost empty, any moisture would be now getting sucked in by the fuel pump. Water floats on gas...
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