Check engine light/oil light

[Lewis_17]

I have a '95 Jetta, with the 2.0 liter and a 5-speed. I noticed that under hard acceleration (like getting onto the freeway) at about 3,500 to 4,000 rpms, the check engine light comes on, and I feel a loss of power. Someone told me that it was the rev limiter kicking in, but a tech at the dealership I work at told me that what's happening shouldn't be. So what would be causing this? And another question I have is, after I've been driving around for about 20 minutes and the engine's at the normal operating temperature, and I'm cruising along in 4th gear, right around 2,000 rpms, the oil light comes on and I hear a beeping, so I usually shift so my rpms go down, but why does that oil light come on? Do I need to change my oil? Or is the cause something more than that?

[Doug Tatham]

If the 95 is same as the 91, you have two oil sensors. One on the cylinder head (lower set point) and one is attached to the oil filter holder and has a higher set point. The one on the oil filter is designed to give an alarm when the pressure is too low and the RPM's are above 2000. The other sensor gives a light (but not audible) at idle and above. It could be that the high setpoint sensor is bad (happens all the time) and causing the alarm. I don't know how smart the car is, but it may limit the RPM's when the sensor is reading low pressure. Senors cost a few bucks online. An oil change (and oil filter) certainly couldn't hurt. It's been awhile since I trouble shot this type error, but try disconnecting the sensor and grounding the plug. If I remember right, it should give you an alarm. The fact that you get the alarm when the engine is hot (oil thin) could also indicate that you have an oil pump problem or some of your engine bearings are worn. If I had to bet, I'd go with the sensor.

[Lewis_17]

Thanks a lot! I'll probably check it out tomorrow because I'm going into town, and I can swing by the dealership I work at and give it an oil change. I'll post again after I get a chance to check it out. And the thing with the check engine light and loss of power happens anytime I accelerate hard, like if the engine's cold, or if I've been driving around for awhile.

[Lewis_17]

I had to do some work on my car, and part of this work included removing the valve cover, while it was off, some dirt fell under my camshaft, so I decided to change the oil again, and after I was all done with the oil change, I left it running, and it was still running hella rich, like it has been doing for awhile, and just for shits and giggles, I unplugged my m.a.f. sensor, and it started running like a champ. I plugged it back in, and it ran crappy, I unplugged it, ran like a champ. So now I'm thinking I have a bad m.a.f. sensor. Is there a way I can test it? Or should I just pull one from a junkyard and see if that helps?

[Doug Tatham]

Use a can of carburetor cleaner or electrical contact cleaner and clean it out. They build up serious dust despite the air cleaner.

[Lewis_17]

After what I did not long ago, it'll be pointless to post about this car. I was driving home, in dense fog, and in the middle of a curve, like an idiot I decided to look down for a second, and when I looked up, all I saw was a ditch. It was too late to pull out of it, and I slid into a raised part of the ditch, where you can drive into the field and whatnot, and flipped my car through a fence. I pretty much totalled it, so it's going to the junkyard tomorrow. Surprisingly, I walked away with little more than a small cut on my head, and a bruised thumb. I'll try to post pics tomorrow.

[Lewis_17]

[Doug Tatham]

I got T-boned by a tractor trailer truck in my 91 jetta and thrown off the road sideways. The passenger side was caved in and I had to get a new body for the car from a salvage yard. I walked away with a minor lower back injury.