Help me with Mazda 6 surging please

Good Day!

My wifes car is a 2006 Mazda 6 2.3L manual.

In every gear at any speed (including idle) the car surges. When you apply a little bit of gas, the car acts like somebody is driving it that is just learning how to drive a stick. Ya know, the buck, buck, buck motion.

It still pulls pretty well (it just surges while pulling).

Searching the 6 forum made me think it might be the PCV valve. I replaced it (a 4 berkeleying hour job! <-- its behind / underneath the intake manifold). That was not the problem.

I would think if it was fuel related, it would not pull as hard as it does. If you wring out 3rd gear and shift into fourth and stay on it, it never "falls on it's face". This would lead me to believe it is not a fuel issue.

Because the car is DBW, I would think a bad throttle position sensor would not allow it rev at all. (there is nothing to tell the throttle plate to open)

I checked for vacuum leaks. I replaced the spark plugs and the oil (my wifes idea). No change.

Any help is appreciated!

Thanks!

Rob R.

Thanks for the help!

The engine does this at all RPM. Even ripping on it in 3rd gear to redline. If the car is not under load, you don't notice it. (except you can hear it at idle AND any throttle application causes it to buck).

97,000 miles on the car

EGR?

CEL on? Have you put a scanner on it?

No CEL.

I assume, probably incorrectly, that if there is no CEL, there are no codes.

If that is incorrect, let me know! I would love to be able to scan for codes.

Thanks,

Rob R.

P.S. I like that all of us in this thread have rotaries or had rotaries.

Mazda berkeley yeah!

In reply to wvumtnbkr:

I'm all but certain there are instances where there WILL be codes, but no CEL. Not all codes turn the CEL on.

TPS? I've never heard of those going wrong specifically in the mzr and its kin- but anything is possible.

Definitely check for codes.

When did it start? Have you gone through multiple tanks of gasoline with this problem?

It started 2 or 3 days ago. My wife was driving to work and it did the surging thing. She had less than an 1/8 tank of gas at the time. She filled up on her way home. The car did the same thing and has continued to do the same thing for the next 75 or so miles (still does it).

The gas was from a reputable gas station that was not currently getting refilled (I have heard this can stir up debris, so I asked her if this was the case).

Can a place like advance auto check codes with no CEL?

Thanks,

Rob R.

Do the NA 2.3s have the same motor mounts problems that the turbo 2.3s have? And if so, could the movement of the engine 'tug' on hoses/wires to make it buck?

I've not heard of the NA ones having slappy MM's like the turbos. The one thing I have heard about the turbo ones is the MM's go bad a lot faster due to the 100 extra torques and the additional stress of the hi-po motor. My RMM actually failed in my ms3- it was unpleasant. I do know of several other mz3's with the 2.3 na having bad motor mounts at a relatively early age... so I suppose it's possible, just not the severity the ms3 and its friends suffered.

Ehhh... one of the engine mounts on my 2.3 Mazda3 went bad. I know a 3 isn't a 6, but it might be worth checking out, anyhow.

Anyplace with an OBD-II scanner can run a diagnostic, even if there are no CELs.

Yay! I will check that out.

The mazda6 forums seem to be a bit light on tech.

They generally throw parts at it.

I realize that I have throwna few parts at this as well, but they were items that SHOULD be done anyway.

I would rather find the issue than replace the MAF and or the Throttle Body (which is what the 6 forum says to do).

Thanks Guys!

Rob R.

Wonkothesane wrote: It could be a lot of things, of course, but in times like these (if there's no codes) fall back to the basics before guessing at major problems (MAF/Throttlebody/etc). I'd check (well, to be honest, I'd just replace because the car has almost 100k on it and it should be done anyway): * Plugs - normally these or coils would cause higher end rev problems, not lower, though. (Plugs changed two days ago - right after the problem started) * fuel filter - No one remembers to change these, and they can cause all kinds of fun problems to diagnose. (I will do that next) * air filter (changed 1 month ago) * spray starter fluid around on the engine while it's running, if there's any vacuum leaks it will suck it in and change the idle. (Did this with propane) And of course, the motor mount should be inspected. I had an eclipse once that had a rip on the intake tube accordion, and when you first hit the gas to start moving and the engine torqued, it would sputter like all-get-out, once the engine settled in, it would accelerate normally. If you have a smart phone, now is a great time to buy a Bluetooth OBD II scanner from Ebay (Less than $20) and the app called "torque" and do your electronic diagnosis yourself.

I added my responses in ( ).

I agree that throwing parts at it isnt the solution. however, the fuel filter COULD be it. I just have a hard time figuring our how the fuel pump / filter / injectors could cause this surge all the time. You would think it would effect higher rpm worse than it does at idle if it was fuel related.

Thanks again!

Rob R.

Why can't I just get a FSM printout of the sensors / ECU and check the values at the pins of the computer (like my 2nd gen)?

I haven't been able to find a pinout yet.

That makes it so easy to find out whats going on!

For example.....

Ohhh, I don't have voltage on pin 2J. Let me check out the sensor on that. Hmmmmm, it is hooked up and has teh correct resistance accross the wires. Maybe if I make jumper wires. Yep, I have a short in my 30 year old harness. New wires run to pin 2J. Car runs like a champ! Yay!

Rob R.

i have heard that the 1st-gen mazda6 fuel pumps can get fubar'd by running low on fuel. i know that my '03 would run kinda the way you're describing when going around a right turn with less than 1/4-tank. i think the problem started around 80k (while the PO still had it). i got the car at 125k, and i finally got sick of it at 164k. i replaced the fuel pump and it's all good now. in fact, i haven't put fuel in the car since replacing the pump, just waiting to see the low fuel light for the first time LOL.

Check for good grounding, de-crud the battery terminals, and lastly, suspect the coils.

Caution, I just changed the coils on my RX-8 so I may be suffering from coil-centricity.

RX Reven' wrote: Check for good grounding, de-crud the battery terminals, and lastly, suspect the coils. Caution, I just changed the coils on my RX-8 so I may be suffering from coil-centricity.

The symptoms do not seem the same as they did when my RX8 coils started going bad. However, that is something to check!

Thanks!

Rob R.

P.S. I read on the Mazda6 forums that it could be a bad tensioner. I have no idea how that could cause this issue. However, it is free to take the belt off the car and drive around the block.

Normal operation of the automatic transmission.

Vacuum leak

restricted fuel filter or lines

erratic fuel presure

secondary ignition

visual inspection : coolant level, hoses,coolant and vacuum,battery and cable conditions,alternator and accessory drive belts, electrical and elelctronic connections, cleanliness

All of the above taken from my old fuel injection book.

It is a manual

I checked with propane and then with brake cleaner

Seems weird it would do it all the time AND pull to redline in every gear (except 5th - WAYY too fast)

Same

I have no idea what secondary ignition is

Everything looks to be in good shape. having the intake off requires you to touch alot of parts.

Keep the ideas coming people!

Thanks! Rob R.

I still have not scanned the car. I will do that tonight.

wvumtnbkr wrote: It is a manual I checked with propane and then with brake cleaner Seems weird it would do it all the time AND pull to redline in every gear (except 5th - WAYY too fast) Same I have no idea what secondary ignition is Ignition has two parts, primary is the low voltage part, secondary is what fires the spark plugs. Everything looks to be in good shape. having the intake off requires you to touch alot of parts. Keep the ideas coming people! Thanks! Rob R. I still have not scanned the car. I will do that tonight.

I checked for codes.

There was a code P0113 for a IAT sensor. I was at advance Auto and they had one on the shelf (it is part of the MAF sensor). I installed it and the symptom remained. The weird thing was that the cel immediately lit up when I started the car with the new sensor.

I also checked to see if it was the belt tensioner (somebody suggested this on the Mazda 6 forums). I took the belt off and drove around the block. Same symptoms.

I cleaned teh Throttle Body and MAF with the appropriate cleaners. No difference.

While I had the scanner plugged into the car, I checked the output on the TPS. it was reading steady at any throttle position. For example, with the pedal half way down, it read 50% without any variation. I think I can rule-out TPS.

The Throttle body only made noise for 20 seconds after shutting the car off (this is what is supposed to happen).

At this point, I guess the only thing I have left to track down is the fuel pressure. I will check that tonight.

Thanks for the help!

Rob R.

At this point, you'll have to consider the possibility that there are demons that need to be exorcised.

Sure,

Thanks for the help!

Also, the IAT is reading around 218 degreee T. The code is specifically related to reading high on the IAT.

Thanks again,

Rob R.

IAT 218 degrees ? How did it get so high ? sounds more like coolant temperature.

In reply to iceracer:

It is not really that high. That is what the output is.

I thinks it might be brokes.