TR Forums

i have OBD2 wifi.
no code mean no diagnostic code with odb reader

Well only things I can think of that wont toss a code, but still cause issues would be EGR valve, or idle air valve. One or both of those could be sticking in the wrong position, and both can cause drivability issues.

Also, even if has no problem codes, does your reader show the emissions tests as all passed?

Starfalcon wrote:

Well only things I can think of that wont toss a code, but still cause issues would be EGR valve, or idle air valve. One or both of those could be sticking in the wrong position, and both can cause drivability issues.

Both will throw a code (one some cars, not sure about an early 2k Mazda).

Idle air control valve would make sense if it idled badly when cold, but well when warm though (since they're generally open for warmup but close at runtime). EGR potentially, but I'd expect that to throw a code as well since it messes with the A/F ratios.

Does a 2003 Mazda 3 have a MAF?

in emissions tests all passed except o2 = Failed. (cuz i drill the catalytic converter ).
its have MAF and MAP . i clean the MAF.

i think this problem coming from bad map sensor or maybe wire broken on map sensor . im going to check that with a mechanic.

mostafarez wrote:

i clean the MAF.

MAFs are exceedingly delicate. Pretty sure you'll be buying a new one.

today i double check everything.
check this video
https://www.youtube.com/watch?v=zVGk5Xc28Dg
my Throttle Body is not close/open smooth. its feel lag when pressing pedal slowly. or its okay? what you think? (i guess my problem coming from this. i'm not sure.)

If it's a mechanical linkage (which it appears to be, since you're moving it without the engine running), you might just need to clean it out / lightly lube the shaft.

Waco wrote:

If it's a mechanical linkage (which it appears to be, since you're moving it without the engine running), you might just need to clean it out / lightly lube the shaft.

its electronic throttle body.

Could be your throttle pedal sensor needs cleaned, or the servo on the throttle body is going out. The former might be cheap enough to simply replace as a test.

Throttle Body replaced with new one. but still have lag in open/close. is it normal? or its definitely a problem from somewhere else

mostafarez wrote:

Throttle Body replaced with new one. but still have lag in open/close. is it normal? or its definitely a problem from somewhere else

Someone mentioned the pedal position sensor. An electronic throttle body is controlled by a position sensor at the accelerator pedal. Have you checked that?

after replacing with new TB i got another wired problem. when the engine reach to operation temp the (A/T) on and P0123 P233 come and the gas pedal get out of the radar . -- also is bad with my old TB - My car get die :O -- (i will investigate and update this topic surly)

++ my new TB are lagging when open/close too.
*TB = Throttle Body

Please stop buying and swapping parts. This shotgun approach is not financially sound.

Waco wrote:

Please stop buying and swapping parts. This shotgun approach is not financially sound.

Depends if your other option is a mechanic at US standard labor rates (who may end up doing some of the same motions in the case of mysterious, electrical-related gremlins). Been there, done that a couple times.

In one case it was a wiring harness that had been improperly secured after an engine replacement, hence was occasionally touching the EGR tube deep behind the intake manifold. Wasn't completely burned through but the intermittent shorts made the troubleshooting downright maddening. Ended up with a couple new sensors I didn't need but which broke when I was accessing them due to age and heat, a couple others I was able to access and test without breaking and replacing, and eventually, a dawning realization that all the problems I was chasing eventually converged back to the same electrical harness. Pulled out enough of it to discover the root cause after, dunno, three weeks and $300?

And that was on an older car with the benefit of factory wiring diagrams. Finding that same problem on a new vehicle would be a nightmare.

I was just going to suggest getting a multimeter or scope of some type to avoid parts shotgunning. Swapping parts without any real testing is a great way to lose a lot of money.

Waco wrote:

I was just going to suggest getting a multimeter or scope of some type to avoid parts shotgunning. Swapping parts without any real testing is a great way to lose a lot of money.

True.

Captain Ned wrote:

mostafarez wrote:

i clean the MAF.

MAFs are exceedingly delicate. Pretty sure you'll be buying a new one.

Cleaning a MAF is exceedingly simple. Step 1 - buy unreasonably expensive spray can of MAF sensor cleaner. Step 2 - spray MAF sensor until it's shiny clean (one little blast should do it). Job done.

Unplug the MAF and test, the car should run in closed loop. If it still runs rough you can do the same for the MAP. I would test one sensor at a time.

Finally i found the problem. all the problem came from bad gauge Cluster :O

the official dealership replace my torque cluster and everything work perfect after the replacement


i still don't know whats the connection between bad idle / bad performance and display gauge.
i bought the car for 60k and spend 20k for diagnosing jerking rpm.