Coolant Thermostat/Valve Temperature below control range
Cyl.1 Misfire Detected
Cyl.2 Misfire Detected
Cyl.3 Misfire Detected
p0128 is a common problem with vw beetles as the engine is quite sufficient actually and the beetle has a heater module that heats the coolant enough to allow for interior car heating. It can be cleared with no problems. If it comes back you can try running with the temperature switch slightly on (not all the way cold) or replacing the auxillary heater, or thermostat switch. If you are missing the plastic engine covers underneath (noise dampers) you are getting more cooling action from the outside. IF you can find a new beetle in a junk yard you can try to find these. They're several hundred dollars to replace new and are a dealer part.
P0301 - P0303 can be caused by any of several problems, or a combination of any of them.
- First, what quality wires did you install? cheap wires can cause rough cold starts and/or difficult starts during rainy seasons due to poor quality insulation materials. on high energy systems even good quality wires can occasionally cause this. This is generally more common on dodge and chrysler vehicles than others but it still happens on others.
After you've driven the vehicle, let the engine cool. dampen a rag with non-conductive oil and wipe the wires liberally with the oil. See if this lessens the problems any. If so, buy some high quality wires, buy some wire shields. install the wire shields and seal/insulate them with heat resistant electrical tape (belt and suspenders type deal) and install the wires in a fashion that keeps them off the heated areas.
- what quality plugs did you use? even with 3 plugs misfiring, it is possible (not probable though) that it could be a bad set of plugs from a bad stock run.
clear the codes, install better quality plugs and see if this lessens the issue
- Ignition module might be acting up or going bad. this runs about 150 online from after market suppliers and is an expensive test but just might be the issue. the ignition module is in place of the cap and rotor if you're old enough to remember those, (and "points" of even older systems)
- combustion, fuel, or exhaust issues. These are just some issues, several highly UNlikely. There are a few INexpensive things you can try for them I'll list as well. I won't go into detail with these but they can cause misfires even on multiple plugs, but mechanics will usually focus on electrical before looking at these, Especially given how UNlikely some of them would actually be the cause (some of the exhaust issues for example)
- valve corrosion
- plugged fuel line
- water in fuel
- fuel filter
- fuel pump
- oxygen sensor
- catalytic converter
- exhaust leak/ worn out muffler
- replace the oxygen sensor and any air filters
- add something to remove water from your system in a couple tanks of gas, replace filter and run another tank with additive for water removal. replacing the fuel filter would be a good idea regardless.
- run an additive for cleaning your valves, etc. with 2 tanks of fuel. octane booster can do this but run it with something like lucas fuel treatment. Once you've gotten the valves sufficiently cleaned, run a decent additive that will keep the valves and such clean. I run lucas in my vehicles (vw and dodge) and it's done a great job so far. I don't own stock and it's just my personal opinion
- check for exhaust leaks and fix accordingly
- check the converter. It CAN cause problems though many mechanics will say it's "unlikely"
These are just ideas to consider based off personal experience from several model vehicles ranging from 1968 to 2002. I hope it gives you something solid (and INexpensive) that will work for you. I have no idea of your level of expertise so I just posted in a general manner that I hope would help a variety of levels of experience. I hope it's not offensive in any manner. If so, please forgive me.
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