Any car mechanics?

[BrianKesler]

My girlfriend has a 2005 Mazda 6 with the 3.0 v6. A few months back, the check engine light came on and i took it to the local parts store, they will use the little computer and pull the codes for free. It said EGR valve had some issues. The car was running fine, and she didnt have the $200 to buy a new one. Now, the car is running like crap, it hesitates, almost like its runninng on 4 cyl instead of 6. The check engine light even started to flash so i had her park it. Got it back to the parts store, to see if it threw any new codes, and sure enough...still has the original EGR code, but now it has another EGR code, and a "random misfire" code.

I dont know anything about EGR valves, so my question is, can a bad EGR valve cause these types of issued for a car?

Anyone who can help gets a beer on me!

 

[Rainbow7]

Try disconnecting/removing it and then see how the car runs. Lots of people do that.

 

[bigworm]

not so sure the egr caused the random misfire but its possible. i'd pull the plugs and or check for a damaged plug wire. most the time the code will specify which cylinder. as for the egr code, it could be hung open(excessive flow) or hung shut(inadequate flow). sometimes you can take them off and clean it with some carb cleaner, also it could be the port inside the intake is clogged up

heres a place thats helped me since i don't work at a dealership anymore. OBD-II Trouble Codes - DTC Codes Car Repair

also if your a DIY'er you might like this you can buy the information just for your car https://checkout.alldatadiy.com/adecomm/diyecomm/ymme?execution=e1s1

you can get the OBD2 code readers for cheap at the parts store.

 

[GsxrBots]

Yes, I believe an EGR valve can definitely make a car run like crap! I don't know a whole lot about it though, but I do think that could be causing the problem. I had a car a billion years ago that the EGR valve went in, and it idled like crap, and had a very odd acceleration feel to it when you decided to take off.
You also might want to call the dealer. MOST new cars are required to have an Emissions warranty. They are usually for like 10 years, 100K miles, and if anything Emissions related fails in that time, its covered under warranty. I would think the EGR valve is DEFINITELY emissions related.
Just a thought...

 

[bigworm]

also unpluging it like stated above, it'll definitely set a malfunctioning egr code but won't hurt anything.

 

[Warputer]

Straight from the lovely world wide web..........although this guy is talking about Mazda RX-7's, yours seems to have the same symptoms.




EGR VALVE

Difficulty? Medium

Total time: Couple hours.

Applications: 86-88 NA/Turbo, 89-91 NA/Turbo

DISCUSSION:

The purpose of the Exhaust Gas Re-circulation System is to help the engine reduce exhaust emissions. It does this by feeding a small amount of the exhaust gases back into the intake to be re-burned in the combustion process.

The system is controlled by two of the four solenoid valves found right above the spark plugs. These valves open and close, allowing intake manifold pressure to open and close the EGR valve.

The problem with the system is that the EGR valve eventually fails in one of two ways: 1) The rubber diaphragm used to open and close the valve dry rots and cracks. 2) The valve gets clogged from carbon build up.

This problem is pretty much guaranteed to happen to every RX-7 owner at one time or another. The symptoms of a bad EGR valve are:

* Rough idle

* A "miss" or slight "popping" in the exhaust at all RPM's

* Large amount of backfiring

* The car runs rich, and the spark plugs are black when you pull them out.

DIAGNOSIS:

To determine if your valve has failed, you need to perform a vacuum test on the valve:





The valve itself is located directly under the intake manifold. If you have a turbo car, you should have pretty easy access to the valve. If you have a non-turbo then your going to need some small hands. There is one vacuum hose that leads to the valve. Remove that line and attach a vacuum pump to the valve. Then warm up the car completely, and allow it to idle. Once the car is warm, apply pressure from the pump to the EGR valve. (about 200 mmHg / 7.87 inHg)

Once you apply pressure to the valve, the car should run very rough and want to stall. This means the valve is working properly. If it does not want to stall or the pump can not hold any pressure, then the rubber diaphragm has failed.

If you can get the pump to hold pressure but there is no change in the idle of the car, then the valve is probably stuck partially open and needs to be removed and cleaned.

REPAIR:

If your valve has failed, you can do two things: Buy a new valve for ~$300 from Mazda, or you can remove the valve and make a block off plate. The plate method works very well, but it will effect your emissions. So be careful if your in a smog testing area.

My solution to fix my leaky diaphragm was to remove the valve, Clean all the carbon out of it so the valve closed properly, and JB Weld the valve shut. I then placed a ball bearing in the vacuum hose that leads to the switching solenoid. The ball bearing was necessary because without it, you have a major intake leak coming from the cracks in the EGR diaphragm.

The hardest part about doing this was that I had to remove the intake manifold from the engine to get at the valve. Like I said earlier though, if you have a turbo model, you should be able to access valve without removing the intake.

 

[RPGonzo]

The Mazdas (primarily the 6) is known to have EGR issues as you creep higher in mileage from what I have read, we bought my wife a Mazda 3 and I was researching known issues with the car before buying and I found more about the 6 than the 3.

From what I saw a 'cleaning' of the EGR valve fixed many peoples issues, it tends to get clogged with carbon and it effects the AFR so if it seems like its missing it could be a contributing factor.

Another thing is to check the spark plugs, if the EGR valve is causing issues the plugs could be on their way to being fouled if not already there. With the car running lean/rich because of the faulty/clogged EGR valve would be the contributing factor to fouled plugs.

My 2 cents anyways

EDIT: HA! Many posts before i hit submit that state the same lol

 

[bigworm]

usually the egr is pretty easy to get too, i have a ford taurus and its pretty much a 6 and i'm having the same egr problems. cleaning it fixed it for 50k somthing miles. theres also a sensor called the "bpfe" or something close to them letters that goes bad and sets an egr code. i know the part for the taurus is 150$

 

[ditchdr]

SOunds like the EGR is hung open. Carbon build us causes this. What the EGR valve does is allow spent exhaust gas back into the engine in small amount to have it "reburned" to give cleaner tail pipe emissions. With the carbon build up the valve it will not allow it to close off, there by sending excessive exhaust into the engine causing it to run rough, or even like it is miss firing. If you think about it, if you put 1200 degree air into a mix of fresh air and gas, the fuel will burn before the spark plug can light it off causing the missfire code.

Now the fix lol. As stated above, you can sometimes clean the EGR valve and it will fix the problem. However if the carbon build up is real bad it might be better to replace it with a new or known good part. Once that is done, give the car some love and throw a new tune up at it. New plugs, air filter, fuel filter, belts, hoses, oil change etc etc. Also most dealers have a EGR cleaning service. It is more of a 2 fold system. 1 the clean the fuel system, by shutting off the furl pump and running a solution through the injectors that will clean out any trash in the injectors. Then the throtle body is cleaned out. Step 2 is the remove the EGR valve and run a cleaning through the EGR system removing all carbon deposits from the system.

I know it was wordy and long winded but I hope it helped.

 

[MR Felt]

If any of the above doesn't work...go to a general repair shop. The auto parts stores don't know how to fix cars.

 

[theskaz]

interesting i have the 07 mazda 6 and my CEL is on... but its something about fuel evap something or another.

 

[BrianKesler]

Thanks a lot guys! Seems the EGR is bad, and it caused the plug closest to it to foul out. I replaced the plugs and wires, and the car runs good now, but the check engine light is still on because of the bad EGR.

Now for the bad part....in the process of ripping all that apart, somehow one of those little plastic nipples that a hose attached to broke, so now when i start the car there is a red fluid (possibly tranny fluid) all over. Have to wait til the morning to get it off and take it to the dealership to figure out what the part is even called.

 

[bigworm]

interesting i have the 07 mazda 6 and my CEL is on... but its something about fuel evap something or another.

most cases that means the gas cap has malfunctioned or someone put gas in the car with it still running. i'd have the codes cleared and see if the light comes back on. if it does come back on the cheapest and easiest thing will be to get a new gas cap. make sure the cap "clicks" when you tighten it up or replace the cap.

 

[BrianKesler]

Ok guys so after the new EGR valve, the car still has a "random misfire". Thought maybe it had a bad coil, so bought a new one and swapped it one at a time, but no luck. Only other thing i can think of is more than one coil is bad? Goodyear worked on the car for three hours, and couldnt figure it out either....fortunately for me, they didnt charge anything since they couldnt fix it, that was nice of them. Sooooo, tomorrow morning im gonna get up and take it to Mada to have a diagnostics test run on it, hopefully i can get more of a specific answer other than random misfire....unlesss of course you guys have any ideas??

 

[MO-BUSA]

interesting i have the 07 mazda 6 and my CEL is on... but its something about fuel evap something or another.

fuel cap i bet

 

[1Falcon989]

Absolutely will cause this. Had a problem on a similar engine design(taurus 3.0) which has a nearly identical egr design.

 

[rubbersidedown]

Ok guys so after the new EGR valve, the car still has a "random misfire". Thought maybe it had a bad coil, so bought a new one and swapped it one at a time, but no luck. Only other thing i can think of is more than one coil is bad? Goodyear worked on the car for three hours, and couldnt figure it out either....fortunately for me, they didnt charge anything since they couldnt fix it, that was nice of them. Sooooo, tomorrow morning im gonna get up and take it to Mada to have a diagnostics test run on it, hopefully i can get more of a specific answer other than random misfire....unlesss of course you guys have any ideas??

This car sure has you jumping thru the hoops.
I used to love diagnostics...now I dont have the patience usually.

Good luck with it. RSD.

 

[outlawbusa]

Gas is a little different, but I had an issue and ruled out the EGR valve on diesel a while back...about $300 the dealership wanted.

Anyway, you can take the valve out and clean it (google clean EGR valve) for a temp fix, may last a while.

I purchased one off Ebay (same OEM as dealership had) still in the box brand new for less than $50 and replaced. Even though that wasn't my issue, through investigation and research they say it can make an engine run like total crap~!~

 

[BrianKesler]

So Mazda runs their test on it...misfire bank 3, sounds easy enough right? WRONG! We put a new coil pack on that bank, and try it again. The misfire then moves to bank 1..... I am lost....i guess im gonna just replace them all and hope for the best, dont know what else to do

 

[RPGonzo]

If its moving around after the coil has been replaced sounds like its in the ECU, have you by chance reset the ECU since you made the changes??

A simple fuse pull for about 10 minutes should do the trick. Had a issue once with a car holding the CEL even though it was not tripped and that was AFTER we cleared the CELS with the hand held diagnostic device. But when the ECU, for this car anyways, has a registered CEL it would put itself into a "fail-safe" mode altering fuel/ignition maps.

Just a thought