96 Jetta GL 2.0 - CEL - Cylinder Misfire

jiveabillion · #1 (**permalink**) 05-29-2010, 09:43 AM

My 96 Jetta GL runs like crap, especially when it's cold. It gets about 17mpg and the CEL comes on after driving it a short distance.

If I drive it for a while, then clear the engine codes, the codes don't usually come back until I park it again long enough for it to cool down and then drive it again.

It has new plugs, wires, distributor cap and rotary button, PCV valve and hoses, Catalytic Converter, MAF sensor and Temperature sensor. AND brand new Ignition Coil
I've also cleaned the throttle body (which got rid of one engine code)

Now I am left with 2 frequent engine codes and one intermittent engine code
The two frequent ones say Cylinder 1 misfire and Random Cylinder misfire.
The other one has something to do with the O2 sensor not reading anything, but it only throws this code once every long while.

What could be the root cause of my troubles?
Could it have jumped time? How difficult is it to change the timing belt in one of these?

perrib · #2 (**permalink**) 05-29-2010, 10:48 AM

Youi need to find out why #1 is misfiring. Compresion, worn cam, weak valve spring, defective injector, etc. Chances are all that unburned fuel is driving the O-2 sensor crazy.

mcrow · #3 (**permalink**) 05-29-2010, 11:46 AM

When the random misfire comes on its either the ignition coil or camshaft position sensor. The cylinder #1 misfire and random misfire are most likely connected problems.

jiveabillion · #4 (**permalink**) 05-29-2010, 11:52 AM

Quote:

Originally Posted by perrib

Youi need to find out why #1 is misfiring. Compresion, worn cam, weak valve spring, defective injector, etc. Chances are all that unburned fuel is driving the O-2 sensor crazy.

When I first got this car, it was in terrible shape. Your suggestion reminds one of one thing that was wrong in particular.

The wires going to cylinder 1 fuel injector were sparking out on the intake manifold. I put some electrical tape on it as it was one of a slew of problems I had to fix just to get it running. I have a whole fuel rail I got off a junker complete with all 4 injectors. I could try swapping it with those to see if it improves anything. I will also inspect the wires to see if there is anything I can do to improve the situation. Is the wiring harness for the injectors part of the whole electrical harness? Where can I get a new one?

jiveabillion · #5 (**permalink**) 05-29-2010, 11:53 AM

Quote:

Originally Posted by mcrow

When the random misfire comes on its either the ignition coil or camshaft position sensor. The cylinder #1 misfire and random misfire are most likely connected problems.

I forgot to mention it also has a brand new ignition coil. It runs exactly the same as it did before I replaced the old one ( I was very disappointed).

mcrow · #6 (**permalink**) 05-29-2010, 11:58 AM

Well that is important information to know haha. Well i would start by repairing those wires the right way, electrical tape isnt water tight or anything like that just temperary.

I would cut the bad part of the wire, strip the insulation till you have nice clean wires, twist them together, solder them, and then heat shrink insulate them. If you dont have a soldering tool you can just twist them together and crimp it.

jiveabillion · #7 (**permalink**) 05-30-2010, 04:01 PM

I replaced the #1 Cylinder injector today and the CEL light has stayed off since. It seems to run smoother too. It still doesn't run as well as I think it should. I haven't been in any other 96 Jettas, so I don't really have anything to compare it to. Hopefully, I will at least get better gas mileage now.