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Terry S. Trent
Terry S. Trent, Auto Mechanic
Category: Car
Satisfied Customers: 378
Experience:  Associates Degree Automotive Technologies
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Customer Question

95 Mazda millennia 2.5 L. Problem is a slight miss when idle, moving forward or reverse and when traveling about 40 mph. Problem came on sudden no warning. Had diagnostics check done here are the codes: P0100: P0110: P0134: P0160: P0325: P0510: P1170: P1173:P1402. P0325 code I know about its the wire inside the engine was not connected properly. Replaced spark plugs and wire set. Check rotor and distributor cap added Sea foam gas treatment. Checked all vacuum connection Things I checked for: Check all or most connection going to the sensors related to the codes. Using ohm meter checking voltage / resistance and grounds. Replaced plug on o2 sensor on the bottom front of engine wires exposed and touching each other at the connection plug: Replaced o2 sensor before the Catalytic converter 3 wire connection, and after the converter 4 wire connection. (Universal replacement parts). Running better but problem still there. Don’t know what else to try???
Submitted: 7 years ago.
Category: Car
Expert:  Terry S. Trent replied 7 years ago.

Check out this factory bulletin i found...



Customer: replied 7 years ago.


Further along in the progress I had the codes rechecked all of the codes are clear except for the P0325 knock sensor. When I had my engine replaced my mechanic had to modify the knock sensor wire the side that goes into the engine. The cable shielding does not have a good connection but the car after two year still runs good no problem with the knock sensor issue. The check engine light stays on because of it. About three week ago my wife started complaining of a gas smell about the same time that's when the car started to stutter a little when the car was backing out of the garage at slow idle. or pulling into the garage at slow idle. I've explained to you all the diagnostic I have done and the parts I have replaced. the car is running better I suppose changing out some of the parts helped clear the codes but it still has a slight stutter in the park position when you first step lightly on the gas pedal. My mechanic thinks that it could be a stuck valve or a fuel injector is going out.

Expert:  Terry S. Trent replied 7 years ago.

Well it sounds to me like you have it covered and just wanted to chit chat a little, hehe


Your initial post is nothing like your second reply, so I really dont know what to say other than it was nice to taking to you and it sounds like everything's ok...

Customer: replied 7 years ago.


Its not OK. I wanted to know if you have experienced this type of problem. The problem being the slight stutter my car is doing. and how to fix it. It feels like the engine has a miss not a spark miss but an engine miss???

Expert:  Terry S. Trent replied 7 years ago.
Ususaly it's secondary ignition when you get a stutter on slight acceleration? IE plugs, plug wires, etc? That would be first thoughts, honestly, I have done driveability many many years, if I went and started thevehicle and slightly raise the rpms and get a little stutter I would look first consider secondory ignition...
Customer: replied 7 years ago.

What is secondary ignition? My wife states this same stutter happens at or around 45MPH.and goes away if she goes faster then 45MPH??.

Expert:  Terry S. Trent replied 7 years ago.
Ok, so, you cleared all of the fault codes and 1 specific fault reamains correct?
Customer: replied 7 years ago.
Yes. The knock sensor code still remains,its been there for over two years.
Expert:  Terry S. Trent replied 7 years ago.

The final step is replace ECM?


If you had 02 sensor wires gounding out, lots of fault codes, lots of issues, I would just get a replacement ECM because it's most likely damaged. I mean even in the shop if I ran into this issue with grounded wires and 10 faults and nothing else fixes it I would replace the ECM. Get a used or reman computer, that is what I would do myself...

Customer: replied 7 years ago.

What about the Idle Control Valve. The ECM would be trying to do this without having to spend too much money. Out of work, I have more time than money.

Expert:  Terry S. Trent replied 7 years ago.

It does not even mention idle speed control ISC in relation to mis-fire or anything other than does it back-fire through exhaust. Since you have had a knock sensor fault for two years which alters the timing, and wires directly to the ECM grounded out, I really don't think ISC relevent.


A (used ECM) for this thing is most likely pretty inexpensive. Basicaly it says if all wiring is good, connections are good, you clear the codes and it reurns which it has (for two years) straight replace ECM...




Customer: replied 7 years ago.


The knock sensor wires are not grounding out it the opposite the braided shielded cable is not thoroughly attached to the remaining cable. (it acts like an open) if I was to remove the engines head cover and solder the braided cable then I would have a good complete connection. The shielded cable is just that it act like a ground covering one insolated wire that runs through it.


I'll continue to look for the problem. I'm sorry you could not help me at this time.



Expert:  Terry S. Trent replied 7 years ago.

No you said the (oxygen sensor) wires were touching ground... I was just showing you no matter how you look at it, the amount of codes, wires touching ground going directly to computer and a knock sensor code that returns after being cleared numerous times and it returns even after repairs are made. That is what wrote. That is my basis for justifying replacing the COMPUTER. Due to the fact the Knock Sensor code has been repaired and cleared is still on after two years...


No problem my freind, but putting a used Computer in this vehicle is a valid answer...