Check Engine Light

[Montenegro]

Hello,

I have a 95 Mazda Millenia with 124K miles. Recently I had problem with my water pump and had to replace it.
Since I plan to keep this car, I bought new timing belt, other 2 belts, new spark plugs and new NGK wires.

My mechanic was on vacation at that time, so my car was parked for about 5 weeks.

After we replaced water pump, all the belts, spark plugs and wires, my engine works strange. It does not sound smooth as before. I was afraid that we maybe messed up the timing for "one tooth", but we checked and everything works fine.

Current symptoms:

- Car runs, but with noticablly less power
- Check Engine Light is flashing. Sometimes stops to flash, and stays still.
- when in D or R, rpms are pretty low, and car shakes
- when in P rpm go up to 1500 rpm
- 3 upper spark plugs were noticably wet after we ran a car for the first time after 5 weeks of sitting.

I had similar problem last year, after car was sitting outside for 2-3 weeks, only the check engine light was still, no flashing. At that time, after few weeks of trying different things, I replaced Wire 5 and it worked great up to now when I installed brand new NGK cables.

My mechanic says that few different things can cause this problem:
- problem on fuel injectors
- bad Air Mass Flow sensor
- bad sensor that controls opening of throtle.

He is not sure what it is, and does not want me to spend money fixing all these parts. I am meeting with him in a day or two to read current codes.

Things I did to try to fix this so far:

- installed new spark plugs
- tryied ti replace wire 5 with another new wire
- add 2 cans of fuel injector cleaner in my tank
- cleaned inside the throhtle body with carburator cleaner ( interesting is that Check engine light stopped flashing for 2 days after I did this)

I plan to go to read codes again this weekend, but I am affraid that will give me a code for a wrong part, or maybe for multiple electronic parts.

I do not want to replace parts that may be O.K., so I'd like to see if any of you guys had similar problems.

Alos do you know a good source for a affordable Air Mas sensor or RPM sensor, in the case I need to fix them.

Thanks

[TrueNorthMilly]

Your problem might well be overly sensitive rear oxygen sensors. This is covered in Technical Service Bulletin 01-003/01. If your mechanic pulls codes P0420, P0421, P0430 or P0431, this indicates problems with the rear oxygen sensors.

420/421 refers to the right side sensor and 430/431 refers to the left side sensor. If the failure of these causes operability problems is not clear to me, but anything is possible.

The TSB directs the mechanic to replace the sensor at fault, but not both if only one one code is shown.

When you get the codes, let us know what they are.

[DJ Hellfire]

You said that there was water in one of the spark plug banks, right? Well, did you guys thoroughly clean out and dry the wet spark plug wells before adding the new plugs and wires? Did you gap your plugs properly or did you by pre-gapped plugs? And did you make sure your reconnected the spark plug wires to the right spots/order?

[casapro]

If the milly was running fine before you had the work done, check for loose vacume hoses and electrical conections, before replacing any expensive parts. Same thing happened to me. There has been many threads about this in the past! When going in to replace the timing belt, plugs, and water pump, anything could inadvertently get knocked loose or disconnected. When this happens, your computer could start throwing all sorts of codes!!! The blinking light means something is seriously wrong. Good Luck, and let us know the outcome.

[Montenegro]

Thank you for your responses and advices.

First just to make clear that when I said spark plug was wet, it was not water it was fuel. Looks like spark plug was not working properly at that time.

I played little bit with my milly this weekend, but still have the same problem.

The codes I got:
- multiple cylindar misfire
- idle speed sensor

I adjusted a timing little bit, checked all electric connections and car was running little bit better. Check engine was still ON, but I had more power than before.
After all that, codes were reading only:
- multiple cylindar misfire

Yesterday I cleaned fuel injectors with a special kit that you connect straight to the engine. Check engine is still ON.

I talked with some friends and they suggested to change spark plugs again, but to use NGK or Dyno plugs instead of Bosh Platinum. Sometimes computer reads time of spark plug fire wrong, and then it starts to give wrong codes and signals.

What do you think what are the best spark plugs to use?

Also, I think that my catalyc convertor maybe prety dirty, so that could cause problem with not having enough power.

My mechanic suggested to replace convertor and spark plugs and then to go from there.

All advices are welcome.

Thank you.

[Tallahassee]

I recently used a fuel additive and had my Check Engine light come on as a response to this. Diagnosis revealed sensitivity with the Catalyic Converter, but mechanic couldn't find anything wrong with mine. I've since flushed all of the old fuel out of my car, and I won't be going back to fuel additives anytime soon. This could possibly be your converters. Although I must ask, who did your tune-up?

[Renboy]

If you're getting multiple misfires, the I would suggest you look at the distributor. First make sure you put the wires back the way they are supposed to go, and sit properly on the spark plugs. Then look to the distributor, if the plugs are wet and not firing properly then that sounds like what the problem is.

[Tallahassee]

Originally posted by Renboy@Jun 30 2004, 01:25 PM
If you're getting multiple misfires, the I would suggest you look at the distributor. First make sure you put the wires back the way they are supposed to go, and sit properly on the spark plugs. Then look to the distributor, if the plugs are wet and not firing properly then that sounds like what the problem is.

This dude is awesome!