Car is "bogging down" going down the road if the engine has to pull at all, "stumbles, misses" when running at 50-60 down the highway. Have to let the car kinda idle up to cruising speed or it falls on it's face.

Car idles really low (compared to the last year or so).


(So much detail for the people that will ask what I did exactly)

Last week the car started "missing" when driving down the road at around 60. You could just feel a little "shudder", but there was no real loss in power.

The check engine light was on, had been on for a few months. It was reading "lean bank one" and I was told that it needed spark plugs, but may have been due to an aftermarket air filter issue with that year. (according to the guy at the parts store)

I got a set of ACDelco plugs, and installed them. All proper steps were followed. I unplugged the battery, then I labeled the new plug boxes 1,2,3, and 4. Then I removed the old plugs one at a time, put them in the correct box. One at a time so I wouldn't confuse the wire order even though the wires only reach to where they go, and are numbered and cannot go in the wrong hole.

I put on anti-seize, making sure to get plenty on my hands, used the socket to carefully place each plug into the correct location, and turned counter-clockwise until I could feel the tiny click, and then clockwise until hand tight. I then placed the socket wrench on and carefully tightened the plug.

I then placed the boot into the hole, and onto the spark plug, pressed down until I felt the click of it seating.

Then I plugged the battery back in.

After I was finished with the plugs I started the car to make sure nothing was wrong, it started and immediately idled really low (around 500, usually it idles around 1k). Shut it off. I did not rev the engine, etc.

Then I decided to clean the engine off a bit. First I got the air hose, and with the nozzle blew the dust and leaves off of the engine. Then I took the garden hose, and using the "mist" setting sprayed parts of the engine bay, then I took dawn and water, and an old rag and wiped down the engine bay, being careful to avoid the top of the engine, distributor, and other electronic parts the entire time. Then I rinsed the water off and used the air hose to dry the engine/engine bay off.

Next I got a can of carb cleaner and cleaned off the throttle body, and other metal parts, I sprayed, and used a paint brush to loosen any grease (only one spot by the power steering fluid reservoir). Then I wiped with a paper towel, replaced the engine cover (why is that needed?) and went inside to cool off.

About an hour later I went and got in the car, started it, it idled around 500 again. Went to go down the driveway, hit the gas, and it fell on it's face. I thought perhaps the computer was having to relearn "stuff" as stated on various websites.

I drove home and the car was gutless, if I tried to accelerate too quickly the car would "bog down" and fall on it's face. Something was not right at all. Any pull on the engine would make it bog down.

I limped it home, opened the hood, took off the darn cover, and checked connections to make sure I didn't bump something during the repair. then I pulled all four boots off to let the holes around the plugs "breath" in case I got water in there.

Went out about 3 hours later, hooked everything back up (boots, engine cover) and took it around the block, still stumbling, and bogging down.

I went in and told my wife that I would take it to work Tuesday, and if it didn't get better by Wednesday I would put the old plugs back in.

Well, last night I cleaned the old plugs, and put them back in, same as above, including getting the anti-seize on my hands.

Still running like crap, BUT now revs on startup, and then works back down to the 1k idle we are used to. It has to be something else. Any ideas?

I've checked fluids, no check engine light (yet), and all the tires have proper pressure.

Brad

The only thing that really pops out in my walnut brain, is fuel filter? We had a 04 Mazda 6, and it was so completely issue free, that I actually miss that car.

Check your MAF sensor. They seem to be the Achilles heel on newer Asian stuff. Been replacing a bunch lately. It will definitely throw a lean code. I don't believe it will have a vacuum leak, you would probably hear it. Could also be the O2 sensor on that "lean" bank causing it too dump fuel and flood, but you would notice it running rich. That 1000 rpm idle is kinda high.... I'd still start with the MAF sensor.

The exhaust doesn't smell rich at all.

It does however if I run for awhile smell like a match burning, that sulfur smell. I think the Catalytic converter may be plugging up, would that cause similar problems?

Crap, I'm gonna have to get another Chilton manual. Fuel filter can't be that hard though. Should be pretty simple and inexpensive to change just to see if it is the problem.

Brad

Coolant temp. Sensor, fuel pump, timing belt, ign coils. First thing I would do is check fuel pressure, then scope the secondary ign. I just went to my tech site and found one just like yours, The fix was the PCV hose. check for oil contamanition, soft spots, holes.

[This message has been edited by Kekipi (edited 08-12-2010).]

quote Originally posted by twofatguys: The exhaust doesn't smell rich at all. It does however if I run for awhile smell like a match burning, that sulfur smell. I think the Catalytic converter may be plugging up, would that cause similar problems? Crap, I'm gonna have to get another Chilton manual. Fuel filter can't be that hard though. Should be pretty simple and inexpensive to change just to see if it is the problem. Brad

A bad cat can cause the bogging and stumbling issue. So can a bad EGR valve (although one would expect a code for at), o2 sensors, MAF sensor, etc...

Were there any codes before you swapped the spark plugs? What kind of mileage is on the car?

quote Originally posted by Xerces_Blackthorne: A bad cat can cause the bogging and stumbling issue. So can a bad EGR valve (although one would expect a code for at), o2 sensors, MAF sensor, etc... Were there any codes before you swapped the spark plugs? What kind of mileage is on the car?

The only code prior to changing the spark plugs was the Lean bank 1 code.

Brad

Edit: The lean Bank 1 code I was told was because I had changed to an K&N air filter, and the computer was having "issues" reading more air flow. According to what I found online the problem was fixed for model year 2004.

[This message has been edited by twofatguys (edited 08-12-2010).]

Ok. That could be multiple things and not just plugs. How do the old plugs look? Did you re-gap them when you cleaned them up? New wires when you did the plugs?

Try putting an inline spark checker on each plug on the coil side (I assume this is a 4 cyl?) and see if the light flashes (harbor freight sells em for about $4). If any of them don't flash, it will narrow down to either coil or wire.

You can also unplug your MAF and see if it runs better or gets worse. if it gets worse with the MAF unplugged, then you can rule out the MAF (usually).

Try pushing up on the diaphragm on the EGR valve and see if it returns to normal position. That'll give ya an idea of whether the EGR is good or not (if it doesnt return, it needs replaced).

And you could try the fuel filter as well. Swap it out with a good one before you go replacing anything else (even if its not needed, its still cheap enough and its basic maintenance anyhow)

Yea, I should note I can't afford groceries this week, let alone a bunch of expensive tests. I'll just leave it be until I can afford to do something in a few weeks.

I went and checked the intake rubber, just to make sure with my memory, and it was fine as far as I could feel.
I gapped the plugs, checked each one at the store, and the ones I cleaned after I cleaned each one of them.

It's turning into another reminder of why I hate living. Every ****ing thing is too damned expensive, and in the end it's a crap shoot on if it'll work.

Thanks for the help though guys.

Brad

I know how ya feel Brad...

Most of the stuff I listed is free to do yourself All but fuel filter and spark plug tester that is.

First thing I'd suggest trying in your case is to unplug the MAF and see if the car runs better. In all reality, you shouldn't be having issues with the K&N filter. My mom has an 03 Mazda 6i and it has a full blown cold air intake that the previous owner installed, no CEL on...

Fuel, Air, Spark, the 3 things you need to run the engine.

Fuel--Fuel filter as others have suggested.

Spark--unless you have a bad wire, or coil pack (I'm unsure if the MZ6 is coil on plug or anything exotic like that), you've already eliminated the plugs.

Air--
Did you disturb any of the induction plumbing when you did the spark plugs?

It sounds possible that you could have an air leak between the throttle body and the engine. This could be allowing extra, un-metered air into the engine, with the same amount of fuel, causing stumbling, and also a lean condition. (the ECU is metering a proper amount of fuel for the air going through the throttle body, if extra air is getting in downrange of the throttle body, you will have a leaner mixture than the ECU intended)

The classic way I've checked for this is to take an unlit propane torch, and with the valve on the torch opened slightly, move the the tip of the torch around the intake. If you hear the engine increase RPM's, you have found where the induction leak is. Obviously, a visual inspection of the intake plumbing is a wise idea as well.

Good luck

------------------
66 Chevrolet C10 250 cid, Powerglide
00 Ford Focus 2.0L 5spd
04 Suzuki GSX-R600
09 Mazda5 2.3L, 5spd

Just so I am clear, I didn't mean anything against the guys that were helping at all. I appreciate every bit I can get.

I was really hoping for a "Oh, I had that same problem, you have to tap the steering wheel once before you start it and that permanently fixes it" type of deal. You know how it is. Money is really tight, like I am sweating meals for the next week tight, let's try the "inexpensive" diagnoses for now, I just called work and begged them for more humiliation, and filled up my weekend. Can't even afford the beer to ward of the suicidal thoughts that come with this job. BTW. The "pay freeze" cut half of my "extreme" pay out, and all of my weekend "bonus", so really I am doing more work for a lot less now, and I didn't get a ****ing lot before.

quote Originally posted by WrenchingPilot: Air-- Did you disturb any of the induction plumbing when you did the spark plugs?

nope, I didn't have to go anywhere near that stuff, I did wash it off.

quote The classic way I've checked for this is to take an unlit propane torch, and with the valve on the torch opened slightly, move the the tip of the torch around the intake. If you hear the engine increase RPM's, you have found where the induction leak is. Obviously, a visual inspection of the intake plumbing is a wise idea as well.

Everything up to the throttle body itself looks to be fine.
I have a propane torch, I can check it when I get to the house.

quote Originally posted by Xerces_Blackthorne: Ok. That could be multiple things and not just plugs. How do the old plugs look? Did you re-gap them when you cleaned them up? New wires when you did the plugs?

The old plugs looked browned, but not bad at all. no real carbon build up, I think I changed them just a few months ago, but my memory won't let me know when it was.

I 'll try a few of the other things and see if that points me anywhere. Does anyone see an issue with me pulling the Cat (if I am able) to see if that clears it up? I know it'll be loud, but around here that won't be a problem.

I'd say if ya got a welder and a large pry bar, pull the cat and gut it for now. Sure, it'll be loud like ya said, but it'll clear up any restrictions (possible bad cat, etc) and net ya an extra hp or 2 Who needs beer money when you can drive fast Plus that'll keep ya looking legal for any emissions testing or whatnot that you may (or may not) have around there in the future.

Here's a chart you can use to compare your old plugs to. It'll give ya an idea of whats really goin on inside the engine

http://www.gnttype.org/techarea/engine/plugs.html

[This message has been edited by Xerces_Blackthorne (edited 08-12-2010).]

So after searching online I have found that the fuel filter is built into the pump, making it the most expensive fix at the moment,
Price:
$474.99

So we can bet that is the problem.

I'm going to run to a buddy's shop after work and see if he will let me borrow is fuel system tester thingy. (that's the technical name)

Brad

quote Originally posted by twofatguys: Price: $474.99 Brad

I pray for you that is not the issue. Wish I was there to help you out Brad. Hold your head up man.

quote Originally posted by WrenchingPilot: Fuel, Air, Spark, the 3 things you need to run the engine. Fuel--Fuel filter as others have suggested. Spark--unless you have a bad wire, or coil pack (I'm unsure if the MZ6 is coil on plug or anything exotic like that), you've already eliminated the plugs. Air-- Did you disturb any of the induction plumbing when you did the spark plugs? It sounds possible that you could have an air leak between the throttle body and the engine. This could be allowing extra, un-metered air into the engine, with the same amount of fuel, causing stumbling, and also a lean condition. (the ECU is metering a proper amount of fuel for the air going through the throttle body, if extra air is getting in downrange of the throttle body, you will have a leaner mixture than the ECU intended) The classic way I've checked for this is to take an unlit propane torch, and with the valve on the torch opened slightly, move the the tip of the torch around the intake. If you hear the engine increase RPM's, you have found where the induction leak is. Obviously, a visual inspection of the intake plumbing is a wise idea as well. Good luck

And Timing, compression.

Went to the shop to check the fuel pump and see how the pressure was, and he didn't have the correct adapter to check it.

He did go over everything else (except the exhaust system) and said it all seemed to be in order. I may have a bad oxygen sensor, well, he's pretty sure the first one is bad, but it is a special order item as well, and not cheap. I'm starting to think I'm repairing some high end German car, and not a Mazda.

We put a can of Sea Foam in the tank, and filled it up. A member on here that I trust said half a can, but the mechanic said to use the entire thing and not cheap out on this step. Since the half a can wont hurt anything, and theoretically could only help. Why not.

Now we drive and see if it helps at all. And I worry.

Thanks guys for all the help so far.

If it's a fuel filter it's less expensive to finish out the 4.9 and drive it.

Brad

I just ordered new plugs and wires.

OEM NGK TR7IX (ok, two steps cooler running than OEM) iridium plugs.

And OEM plug wires.

Here is my theory.

I changed nothing when I changed the plugs, I did move the wires. And the car is running like it has bad plugs. So I think that the wires are bad, and when I moved them out of the way I uncovered a short. It's a shot in the dark, but I have a feeling that it's in the right direction. The wires in the car are original

We have went through fuel, computer, and other various things, so right now I'm back where I started.

Brad