Random Misfire - can't solve the problem 2000 Jetta 2.0
I have just joined the site // forums and need some real good ideas on how to moved forward with an ongoing problem that I can not solve.
Vehicle: 2000 VW Jetta 2.0 4-cylinder non-turbo. Base Model.
The background story// details:
- In the very beginning the issue started by showing up during accelerations from side road speed to high way speed... during a normal acceleration.
- The car would lose quite a bit of power and check engine light would start to flash at me.
- I immediately release foot off accelerator and coast // for 15+ seconds.
- Power would be restored, car run 100% again - check engine light would stay on BUT stop flashing allowing me to drive.
- Check engine light would cycle through and after about 100 miles of driving it would actually shut off on it's own.
- This progressively got worse over 2 weeks to point where at stop signs, red lights etc... at idle, it would mis-fire and I could feel the engine shake and I could feel it sitting in the driver's seat.
- I was getting a few codes:
- P300 - Random Mis-Fire
- P301 - Random Mis-Fire Cylinder 1
- P303 - Random Mis-Fire Cylinder 3
- P1200 OR P1250 I can not remember - (Coolant Temp Sensor Ground)
With this in mind, at this point I Decided it was time to do something about it. I bought an ignition coil. 1 coil for all cylinders and it's the style that is one plug in each corner // square.
I replaced it and started the car. No improvement. In fact it was almost worse. So now at this point to me it sounds and feels as though it is running on maybe 2 cylinders. Check engine is flashing at me and it wants to stall out when applying any throttle. So, now I felt like I have wasted my money on a coil for this and need back at square one.
I now moved onto spark plugs. I should have done this first but I was told they were replaced when buying the vehicle. I pulled them out and they were 110% the original spark plugs. Worst condition I've seen. I replaced these with brand new BOSCH ones either Platinum or Iridium. (I forget, 4-prong)
While doing the plugs I also cleaned my MAF sensor. Took it out and cleaned it along with my air filter.
This, I thought anyways, fixed it. I was able to drive 30-40 miles before it cut out on me again like it originally was. (Felt like running on 2 cylinders, engine shake, no power, Check engine light flashing. Had to get it towed home. After getting it home and off the flat bed, I started it to try to move it into the heated garage and it started right up no problem and seemed to be runnin like a champ. No issues. Pulled it in the garage.
Replaced thermostat and coolant temp sensor. The thermo. was stuck open and did needed to be replaced anyways.. But everything that seems logical to me I've replaced or tested.
I decided to pull the "new" coil back out and look at it and after close examination one of the plug tabs was recessed half way into the coil and kind of broken off. I again, was sure this was the issue. So since the issue was so much more minor before I replaced the coil than after I decided to put the original 'Old'' coil back in and try to see if it made a difference.
I was able to drive it so far about 250 miles in the last 2-3 days with only MINOR symptoms showing. Example, getting on the highway the high RPM range it will cut out and misfire a bit and also going slow in a high gear and giving it a little throttle and riding that gear out as I speed up it will cut out and mis fire as well. So slow and low rpm in a high gear or higher rpm in a lower gear trying to speed up is when I get the minor buck and choke .. I let off the accelerator momentarily and power returns and no check engine light comes on (I'm sure it would come on if I was to hold the accelerator where it is when the symptoms present themselves.
I ended up getting a new - new coil after bringing the damaged new coil back and getting it replaced. so I did end up with a good coil in the end. I put that on and it is the EXACT same characteristics as if it was still the original coil I just pulled out again.
new coil is installed.
Please help - I need to fix this asap. I've spent over a week almost every night out in the garage after work trying to get it right.
What do I need to test or replace?
I was almost at the point wondering if it was a fuel issue. Fuel quality? Fuel filter clogged up that doesn't allow fuel to pass through ... starving the cylinders for fuel?
Thank you in advance... I tried to be as specific as possible.