RPMs problem

[Vitaliy]

Hi.
I'm facing the following problems. Very long delay when switch from R to D 5-10sec. When stop on trffic light on D holding brake the RPMs drops to ~500 and engine vibrates. After 5-10sec RPM raises to ~850 and works normal. If during the driving switch to N RPM goes low holds it until switch to D. Sometimes (usually on cold engine) all problems disappear. OBD reads P0421. With regular gas engine detonates under load. With gas grade 91 no any detonates but all problems are same.
What can I start from? I have ELM327.

 

[lolwut]

Read through this and see if it helps. Good luck

http://www.mazdas247.com/forum/show...2-Mazda-Protege-5-P0421-amp-P0300-OBDII-CODES

 

[Vitaliy]

P0421 I have about 3 years from the time I had problem with ignition coil and don't want to spend money for catalitic convertor. Idle RPM problem I have about 4 months.

 

[tweety2300]

Search for the non fouler, $10 and will get rid of the cel

 

[Vitaliy]

Could you explain it with more words?
Does it related to idle RPM problem?

 

[tweety2300]

It made mine mess up a little bit till I fixed it but I fixed a few things at once

The non fouler restricts airflow to the downstream o2 sensor that ministers the precat. It will make the ecu think the precat is good

 

[Vitaliy]

So practically need extention to put O2 sensor out from the cat chamber? Do you know part # of the non-fouler?

 

[tweety2300]

http://www.mazdas247.com/forum/show...ure-Cel-Mil-from-removing-cat-with-Non-Fouler

Everything you need to know about it

 

[Vitaliy]

Is it possible I have idle RPM problem due to dead catalytic convertor.

 

[tweety2300]

Yes because the ecu puts its self into a certain mode and the car won't run right. If it doesn't think anything is wrong with it, it should run fine

 

[Vitaliy]

I put extention on post cat, cleaned EGR and IAC valves. Nothing changed with RPMs problem. And engine is defenatelly not as powerfull as before. What to check next? Can it be something with pre-cat O2 sensor or flow meter? I can post some OBD graphs.

 

[tweety2300]

What cel do you have?

 

[Vitaliy]

None.

 

[tweety2300]

Which o2 sensor did you put the non fouler on?

 

[Vitaliy]

Post cat

 

[tweety2300]

Have you cleaned the maf sensor? Check for vaccume leaks

 

[Vitaliy]

MAF sensor is clean. No vac leak.
Some times all problems just disappeare. Like some sensor or actuator start to work properly.

MAF reading shows 2.3g/s on "P" idle. When fan runs 3.6g/s.

 

[Vitaliy]

Replaced pre-cat O2 sensor. Nothing changed. Any ideas?

 

[dbMazda]

Is your VTCS, "Variable Tumble Control System." etc working right?
The one close to the injectors should shut on a cold engine then open when warm.

The other valve when the engine is warm should open at higher rpms.
If they both do something, move then they work good on your car.

You might have a air leak? With no cats a Mazda gets very picky!
Check all your vacuum lines. There is a secret one under the manifold.
It's the white & green thing. Seen here! ( http://www.mazdas247.com/forum/showthread.php?123784387-what-is-a-vtcs-removal )

With no cats you have to run on 91. There is more fuel being read as being rich, so the ECU will turn down the fuel. Better combustion will help to burn more of the fuel so less will be read. My spark plug mod! ( http://www.angelfire.com/me4/dugbugwap/images/SplugMod.JPG )

Chevron techroline fuel additive is good.
To me it has good cleaning stuff.
PolyEther Amine, Distillates, hydrotreated light, Stoddard solvent, Solvent naphtha, light aromatic, Benzene,
1,2,4-trimethyl- & Xylene.
CAS # 999999-51-7,64742-47-8, 8052-41-3, 64742-95-6, 95-63-6 & 1330-20-7.

You get the point, I have info on my page. ( http://www.angelfire.com/me4/dugbugwap/cartips.html )

 

[Installshield 2]

Is your VTCS, "Variable Tumble Control System." etc working right?
The one close to the injectors should shut on a cold engine then open when warm.

The other valve when the engine is warm should open at higher rpms.
If they both do something, move then they work good on your car.

You might have a air leak? With no cats a Mazda gets very picky!
Check all your vacuum lines. There is a secret one under the manifold.
It's the white & green thing. Seen here! ( http://www.mazdas247.com/forum/showthread.php?123784387-what-is-a-vtcs-removal )

With no cats you have to run on 91. There is more fuel being read as being rich, so the ECU will turn down the fuel. Better combustion will help to burn more of the fuel so less will be read. My spark plug mod! ( http://www.angelfire.com/me4/dugbugwap/images/SplugMod.JPG )

Chevron techroline fuel additive is good.
To me it has good cleaning stuff.
PolyEther Amine, Distillates, hydrotreated light, Stoddard solvent, Solvent naphtha, light aromatic, Benzene,
1,2,4-trimethyl- & Xylene.
CAS # 999999-51-7,64742-47-8, 8052-41-3, 64742-95-6, 95-63-6 & 1330-20-7.

You get the point, I have info on my page. ( http://www.angelfire.com/me4/dugbugwap/cartips.html )

Sorry, but that isn't accurate. I've been running a JDM mazdaspeed 4-2-1 header for nearly 5 years...never switched from 87 octane, and live at a relatively low altitude...never had any problems with using no pre-cat for nearly 80,000 miles. But how the system works is as follows:

The protege's ecu, like most OBD-II systems, seamlessly switches between a 'closed' loop mode...and open loop...closed loop is a 'reactive' engine mapping program that adjusts fuel based on readings from the PRIMARY O2 sensor...NOT the secondary. closed loop is only used for low load, low rpm engine operation...once the engine is up to operation temp (there is a 'cold start' open loop program, but thats beyond the scope of this). The system NEVER takes any calculative data from exhaust after a catalyst (this is why the primary O2 sensor, in stock condition, is located before the primary catalyst). Because of this, the actual fuel being pumped into the engine is never influenced by whether or not a catalyst (be it the primary or secondary) is attached to the exhaust system. Closed loop requires a reading just a few cycles off of the current condition, also. This is why the factory O2 sensor is mounted very close to the cylinder head, and only taking a reading from a single cylinder. If a primary O2 sensor would be relocated to an area reading all cylinders (after a collector or something), closed loop operation would often run problematically. Some early cheap Header systems for FS engines caused this by poor O2 bung locations...but most available with any reputation work properly.

Also, after revs and load rise under normal driving conditions...the system then uses open loop mode based on pre-set AFR maps built into a database in the computer. In this case the primary O2 sensor is no longer being used at all.

Now the secondary O2 sensor. That only serves a single purpose, which is primary catalyst performance. It is checked every so often by the computer in both closed and open loop. The O2 sensor outputs two signals. One is to determine proper exhaust heat up (which luckily is a very broad reading, if the exhaust is getting 'hot', you're fine)...the other is a reading on the exhaust gas oxygen ppm...which is correlated with AFR data to determine if the catalyst is working properly. When you remove the primary catalyst from the exhaust system...You will create a reading from the secondary O2 sensor 'knowing' that the catalyst 'isn't working', as its no longer in the system...but 'heat up' readings will remain ok.

The non-fouler basically blocks the O2 sensors ability to read oxygen levels in the exhaust...yet keeps the sensor on the piping enough for it to heat up...no oxygen reading means it won't know the catalyst is gone...and never trip the ecu's MIL. Been running the non-fouler set up the entire time. for the most part, its great...but i've tripped 2 or 3 cel's over the years, where it managed to get a pocket of dirty exhaust gas...it usually checks again then within 50 or so miles, doesn't get the same reading, and resets itself.