Took My Car In For a Rear Motor Mount Replacement, Now It Barely Runs!!!

[PowrSlave]

I was having trouble getting the rear motor mount swapped out, so I took it to what is apparently a reputable mechanic and when I went to pick it up it barely idled and ran very rough. His scanner said P0300 but he couldn't determine which cylinder was missing. I have since replaced the coils, plug wires and plugs. Didn't fix the problem.

I think the mechanic might have damaged something while doing the motor mount removal/install, but he is playing dumb about it. This problem wasn't happening before I took it in to him. Does anyone have any ideas what I should be looking for? I am having trouble dealing with the guy and am probably better off trying to figure it out myself.

 

[pcb]

Did you give your car 100 miles for the computer to relearn itself ??

My car idles like complete crap while the ECU relearns the car after a battery disconnect.

(although I won't think your car should throw that code while learning)

 

[kms1990]

could be a disconnected fuel injector harness, could be a tear in the intake boot. could be could be a loose air filter intake box. could be a loose wire on something he had to disconnect when doing the work. i would fight it and get him to pay for the repair, but at a shop of your choosing, if you can.

 

[hornsfan10609]

The mount is near the main engine harness on the firewall, I would check the wiring and make sure nothing is damaged or pinched.

 

[lowlevel]

I also guess its an air leak in your intake path... after 12 years all that stuff is brittle and easily damaged... assuming some thing plastic broke that's not exactly the mechanics fault, but he probably should have warned you up front that going in there something was bound to break.

 

[PowrSlave]

I'm running an Injen CAI system so I will check the elbows for some leaks I suppose. I'm actually the one that removed the two electrical harness nuts to make it easier to get to the top motor mount bolts for when I took it into him and I didn't notice any trouble when I was driving it prior to dropping it off.

I honestly have no idea how I'd ever trace an electrical issue from that wiring harness considering where that bastard is located.

Would an injector electrical issue fire a P0300 on a code reader?

I am going to call the mechanic tomorrow and inform him. This is a complete pain in the ass.

 

[lowlevel]

EGR could be sticking open... this will cause rough idle, set P0300 first... then after a while of it staying open P0401 will get set and CEL will light up. It could be anything from fuel injector, low compression, ignition issues or air leaks ...

 

[kms1990]

EGR could be sticking open... this will cause rough idle, set P0300 first... then after a while of it staying open P0401 will get set and CEL will light up. It could be anything from fuel injector, low compression, ignition issues or air leaks ...

The mount is near the main engine harness on the firewall, I would check the wiring and make sure nothing is damaged or pinched.

also very distinct possibilities. it is the mechanics fault if they break anything while working and had not given you the advanced warning when estimating the repair. this is why many shops go out and look at your car now, so that they can see any potential liabilities before starting work, and if any are found price can go up on estimate. this covers their arse. but it being 12 years old makes it more prone to that. it may not have been his fault directly, as that part could have been on the verge of breaking, but he still owes you at least the decency of a free diagnosis to find your issue. the mechanic at least owes you a full explinantion and the time to dig down to the real issue. whether or not he pays to fix it, or reduces costs after the thorough diagnosis is between you and him.

 

[lowlevel]

I agree that the mechanic should at least figure out what the problem is for free since it seemed to happen while he had it... but yeah, sometimes they're not very easy to deal with.

 

[rit14623]

Check your EGR valve. It's back there near the rear motor mount. He may have removed it to get better access and didn't put it back on tightly or something. There's a plug in the EGR where a wiring harness goes into. Check if there's a loose harness.

 

[hornsfan10609]

I'm running an Injen CAI system so I will check the elbows for some leaks I suppose. I'm actually the one that removed the two electrical harness nuts to make it easier to get to the top motor mount bolts for when I took it into him and I didn't notice any trouble when I was driving it prior to dropping it off.

I honestly have no idea how I'd ever trace an electrical issue from that wiring harness considering where that bastard is located.

Would an injector electrical issue fire a P0300 on a code reader?

I am going to call the mechanic tomorrow and inform him. This is a complete pain in the ass.

If any of the COP wires were pinched or broken then yes a misfire code is entirely possible.

 

[P-Funk!]

Did mechanic remove the intake manifold? If so - t/b gasket or others could be leaking...

 

[PowrSlave]

If any of the COP wires were pinched or broken then yes a misfire code is entirely possible.

You called it. Someone must have bumped the ignition coil wiring terminal since one of the wires was sticking out on one of the coils. The car would only start as long as the left coil was plugged in, so I checked the wiring on the right coil and sure enough one of the pins in the end connector was barely sticking out. Almost not noticeable at all had I not tried the single-coil start test. At least I have new coils, plugs and wires now huh.

 

[kms1990]

glad you got it, he must have bumped it, or unplugged it and just didnt seat it right when going back in

 

[rit14623]

You called it. Someone must have bumped the ignition coil wiring terminal since one of the wires was sticking out on one of the coils. The car would only start as long as the left coil was plugged in, so I checked the wiring on the right coil and sure enough one of the pins in the end connector was barely sticking out. Almost not noticeable at all had I not tried the single-coil start test. At least I have new coils, plugs and wires now huh.

That's good for you. Was this a Mazda dealership service dept?

 

[PowrSlave]

That's good for you. Was this a Mazda dealership service dept?

No it was an independent shop. They usually have really down to earth prices and are pretty honest, but they aren't the best at diagnosing technical problems sometimes as we have seen, but overall I'm happy with them.