[ducksoup18]

Exhaust Smells

Hey all,

I just did my plugs and the EGR mod on my 03 6s and now im getting an exhaust smell in my cabin after driving a while and coming to a stop. Anyone else get this? It smells terrible and im worried i F-ed up something in the process. I put new air intake gaskets on and i've heard they may smell while getting broken in but this seems much worse.

Thanks,

DS18

 

[andrewschenk]

when lifting the IM off, how are you guys getting it past the EGR nozzle? i can lift it up about 1/2" then the EGR gets in the way and stops it from lifting off. I pushed on the EGR a little but the steel tube(exhaust gas line?) stops it from moving far enough out of the way so the IM can clear

 

[ctmazda]

I was able to push the EGR module back far enough to squeeze the IM off once I removed all the bolts holding them together. It took a little force, but it's manageable.

 

[andrewschenk]

yea i got it, thanks for the quick reply though!

 

[Trillo]

just did this mod the other day, i feel as tho i have better throttle response not sure on the gas mileage i will be able to tell in a couple days when i get home to see if it jumped up have an 05 6 S hatch with 118k and get 28 mpg on the highway

 

[justsomeguy]

just did this finally..... after taking the im off do gap my plugs ....man did that tube ever get in the way of the flow wat a poor design

 

[Chwriting]

No offense meant to anyone here--I'm all for modding a vehicle. In this thread I see all kinds of "in theory" and "feels better", but has anyone actually performed any tests (dyno, A/F, etc) to verify what's happening after this mod? Like I said, no offense but having worked for an OEM in the past, engineers always have something in mind for their designs and it's not like they just pull stuff from their behinds. Months or years of development take place, and I just don't see them going with a taller EGR tube "just because", especially if a smaller tube had benefits.

It all reminds me of the old V6 Taurus SHO and the "air horns" in the big intake manifold that had owners going nuts. Someone took apart their intake and found these metal tubes mounted in the front and rear sections of the mainfold directing air into the intake runners. This person thought "wow, those horns really restrict airflow... that's a stupid design!" and took them out. Other people started to do it, and each said how much harder the car pulled, etc. An engineer and SHO owner finally did a before/after comparison and found that removing the tubes added maybe 1-2 horsepower at the very end of the rev range (which on that motor was north of 7k) but lost 5-7 horsepower and similar torque figures (don't remember exact) down low. Those horns were there to better optimize a/f going into the engine at lower speeds, giving more usable power down low instead of a couple wasted ponies way up high. Obviously they had a very specific purpose.

I'd love to hear from anyone with some actual data on this mod? I've got some scheduled maintenance on the 6 coming up... I'm not opposed to doing this but I need more than "feels better" before I second guess the engineer that designed this setup

 

[Mr.Smoke]

Dont know about any before & after testing but it seems very logical to me. Stick your arm out the window while driving down the highway. Same idea. Its something in the path of air flow which will hinder flow & create turbulance. Aside from that, it makes removal & install of the plenum much easier.


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[justsomeguy]

I have came across a dyno/logs charts a long time ago and it was very minimal like .25hp iirc but thats all i can remember

 

[The Great NY]

ok, where in this DIY has it been stated that this mod is done to make power? please read the first post again. this mod is done to fix an airflow differential between the front and rear banks. YES there were MONITORED tests done to justify this mod. and the differences are listed in the first post.

thanks

 

[Chwriting]

Again, not trying to offend anyone. Just not seeing any answers to my questions. Yes I did read the first post, and actually, you mention power right away (see #2 below..."restricted airflow = power loss"). As I mentioned in my post above, what may seem like a restriction isn't always a restriction. I'm not an engineer so I readily admit I don't have the knowledge to determine what may or may not be effective, even if it seems obvious.

But I've worked with enough engineers over the years to know there's usually some method to the madness. All I'm asking for are some actual, verifiable results in performing this mod aside from balancing a small A/F difference between banks.

AGAIN, I'm not calling you or anyone out. I'm just seeking something more than "feels better" or "seems different" before I take a saw to my engine. I've been tweaking my vehicles for 20 years, and if I've learned anything in that time it's that most of the "free" mods do more harm than good. Not always, but often.

What I'm really interested in with this mod is upping my fuel economy. I saw some mention throughout the discussion but nothing more than speculation. Thus far I'm struggling to break 18 MPG and I'm driving easy with a mix of city and highway. Right now it's winter and my commute is only about 7 miles so I know the car is barely warmed up by the time I get to work, so that figure will certainly go up in spring. But my 5.0 would get 21 MPG with granny 2:73 gears in the winter--I know these Mazdas aren't the greatest on fuel, but I was expecting better than 20 at least.

And if there aren't any verifiable answers, that's fine too. Not trying to start a war :hide: Just making sure I look before I leap.

Ok.........i was asked make a how to on how to do this mod. But first here is a quick explaination of what this mod if for and what it does.

REASON FOR DOING THE EGR MOD:

the Mazda 6s from the factory has a few flaws that may be small and some that can even lead to detrimental damage to the car itself. some of these flaws and/or shortcomings can usually but not always be fixed. But of course the manufactureer wont do it.

Anyway, the design of the Mazda 6s EGR system puts the tube of the EGR directly in the middle of the intake tract. Thats bad business. Basically it blocks the airflow to the cylinders. This compounded with a decently bad design of an Intake Manifold causes 2 issues.

1. one of the 2 cylinder banks will run significantly leaner than the other. How significant are we talking here?
--it has been documented that there is about a 5%-7% difference in fuel trims between the front and rear banks.

******now on a stock motor it probably wont hurt it in the long run. but most of us owners tend to enjoy modding our rides and getting more power. and if this is left stock it could cause engine failure when dealing with power adders such as turbos, superchargers, and nitrous. again 5-7% may not sound like a lot. but that could be the difference of you keeping your 12.2 AFR in one bank......and leaning out to 13.0AFR+ in the other. then boom******

2. it blocks some airflow all together. restricted airflow=power lost

*****drive about 50mph.......stick your hand out the window. feel the pressure on your hand. you get my point*****

 

[The Great NY]

Again, not trying to offend anyone. Just not seeing any answers to my questions. Yes I did read the first post, and actually, you mention power right away (see #2 below..."restricted airflow = power loss"). As I mentioned in my post above, what may seem like a restriction isn't always a restriction. I'm not an engineer so I readily admit I don't have the knowledge to determine what may or may not be effective, even if it seems obvious.

But I've worked with enough engineers over the years to know there's usually some method to the madness. All I'm asking for are some actual, verifiable results in performing this mod aside from balancing a small A/F difference between banks.

AGAIN, I'm not calling you or anyone out. I'm just seeking something more than "feels better" or "seems different" before I take a saw to my engine. I've been tweaking my vehicles for 20 years, and if I've learned anything in that time it's that most of the "free" mods do more harm than good. Not always, but often.

What I'm really interested in with this mod is upping my fuel economy. I saw some mention throughout the discussion but nothing more than speculation. Thus far I'm struggling to break 18 MPG and I'm driving easy with a mix of city and highway. Right now it's winter and my commute is only about 7 miles so I know the car is barely warmed up by the time I get to work, so that figure will certainly go up in spring. But my 5.0 would get 21 MPG with granny 2:73 gears in the winter--I know these Mazdas aren't the greatest on fuel, but I was expecting better than 20 at least.

And if there aren't any verifiable answers, that's fine too. Not trying to start a war :hide: Just making sure I look before I leap.

i dont monitor MPG's. because MPG's dont matter to me. if you read the first post. you will see the main reason AS STATED for doing this mod is to promote EQUAL airflow to both the front and rear banks of the engine. and if you read the first post you with see DOCUMENTED numbers of how much the mod EQUALS out Airflow AS STATED in the first post it brings the Front and rear bank differential down from 5-7% to within 1% differential. DOCUMENTED and STATED. AND VERIFIED.

The above considering how engines work. Power production and efficiency has a lot to do with Airflow. the only thing not DOCUMENTED is a DYNO run before and after the mod. but given the effect of this mod on the engines airflow to the front and rear banks. there IS a significant change. while how much HP and/or TQ is gained or lost is not DOCUMENTED. Mainly because no one is going to spend $100 to see if something that was done to even the airflow to the engine lost or gained 1hp. Especially when its already DOCUMENTED and VERIFIED that the mod fixes an Airflow issue that the car had.

the restricted airflow= power loss was put in the first post due it being true 97% of the time. especially dealing with an internal combustion engine. if you want to question the other 3% of the time that it may not lose power, lol. Then have at it. Not trying to be a dick, but the info is there. the rest is common sense in terms on gas engines

 

[The Great NY]

if you have the V6, 18mpg city is average. you can get more city miles by doing a tuneup. getting injectors serviced and the usual. and also, take a look at driving habits. i have seen some people in the low to mid 20's in mpg for the v6 in city.

whens the last time you had a tuneup? whats your spark plug age? and ignition coil age? what kind of oil do you use? all that will effect mileage. Do you drive around with a full trunk or a bunch of stuff in the car all the time.

Mileage will also be lower on winter mix gasoline.

 

[Chwriting]

So in other words, the only thing known for sure is that the mod balances the A/F difference between banks. Which I already stated. Twice. If nobody else has anything to offer, then it looks like my question is answered. Seems like a lot of work to correct something that's for all intents and purposes a non-issue, with no other indication that it makes any difference at all. But that's just my .02. I appreciate the extra insight and the effort you put into this write-up.

My 6 is new to me, only had it about a month. Haven't even put 1000 miles on it. It came with quick-oil change receipts that show the OEM weight was used, don't think it was synthetic (can't remember off the top of my head what that is). Just rolled 54,000 miles so no tune-up has been done. Just had the fan control module recall done. Sometime in the next 6000 miles I'm planning to dig into the engine a bit, look at the plugs, etc. which is why I was asking about this mod. Would be nice to find a couple extra MPG while I'm nosing around. I live in the county so I'm not doing city stop-and-go, but I'll still drive a couple miles, stop, drive a couple miles, stop again, so it's not like I'm just crusing for an hour.

 

[The Great NY]

Lol, if you think unequal airflow to the engine is a non issue. Then by all means forget about the mod. But i will say you are the first person i have met that deals with cars that think unequal airflow is cool and a non issues.

I have no clue at all what makes you think its a lot of work for nothing. It takes all of 20-30minutes to do. But ok, drive on dude.

 

[MoonRoc]

Thanks to The Great NY forum contributors

I did the EGR modification today. Just wanted to say thanks for the great info. I was changing the sparkplugs and the coils because of a couple of misfiring cylinders, so I did the mod. Only trouble I had was removing the wiring harness from the throttle body. The car feels good. Thanks again

 

[elhefa]

did this yesterday while changing plugs and coils...quick,easy. reading this thread made me want to do this. I just makes sense. thanks for the info...

 

[Modbug]

Did this this morning. Notice the power instantly now since I have ALL 6 running properly (better then they were) thanks man!

 

[FrankMazda6]

Collapsed EGR Tube?

Any thoughts on this:

http://forum.mazda6club.com/3362388-post48.html

Look the image, basically his EGR tube into the intake manifold collapsed, he says he did this mod. Does the mod make the tube structurally weaker and unable to handle vacuum?

 

[JimiJak]

I just did the optimization...along with the re-route last week. Before the mod, I was able to get 24-26mpg average (70% highway) with some very eco conscientious driving. (MTX)
I haven't checked after the mod, but I also regapped plugs, changes COPs, Installed a CAI, new PCV and did the optimization / re-route.
Some of the pics have made it up already here.

Everything runs great...now.
As for the collapsed dip tube above, anything that messes with the flow / vacuum to the EGR will likely result in throwing a CEL...luckily, a broken EGR doesn't do anything beneficial or more detrimental than a stock EGR sooo...if you don't mind the light, I don't know how much I would worry about the tube.