RPM does not go beyond 2500

[mazdacxseven]

Hi All,

Have a 2008 Mazda CX-7 AWD Turbo, that very recently started acting up. The CEL has been on for a while and I was told it was the spark plugs, which I changed them today.

When I floor the gas, there is a lot of misfire. The RPM goes to 3000 and then drops dead back to 2000 and if it did go beyond 3000, the gear would be stuck in 2 or 3 and the vehicle won't speed as expected.

What could the possible reasons be?

Also when changing the spark plugs today, I saw this weird part all taped up, looks like an o2 sensor to me. Looks like the pipe was busted and the previous owner just glued it and taped it back together. I don't know if this it related to the above issue. Had the car for couple of years and only started having problems 2-3 months ago.


Any pointers much appreciated.

[Vansquish]

It could be related. That appears to be part of the purge valve system and could cause a vacuum leak.

However, it would help to know what the ID of the CEL is. Could you post that for us?

[mazdacxseven]

Originally Posted by Vansquish It could be related. That appears to be part of the purge valve system and could cause a vacuum leak. However, it would help to know what the ID of the CEL is. Could you post that for us?

Dont have the exact codes, but I did get the car scanned and was told I had a lot of codes around misfires, which the mechanic told could be around o2 sensor or spark plugs. Hence the spark plug change today.

[smurugby12]

That appears to be the check valve for the purge system. I am not too familiar with the CX7 layout though. I did attach a picture and circled what we are looking at to give some perspective.

Like Vansquich said, give us a CEL. Specific engine codes it's throwing.

[mazdacxseven]

Originally Posted by smurugby12 That appears to be the check valve for the purge system. I am not too familiar with the CX7 layout though. I did attach a picture and circled what we are looking at to give some perspective. Like Vansquich said, give us a CEL. Specific engine codes it's throwing.

Would that cause the engine misfire and RPM to not exceed 3000 when I accelarate quickly? Or is it completely unrelated?

[smurugby12]

Could be, sounds like a vacuum leak so it's a possibility. Really need to ask the guys at the auto parts store what engine codes it has after they run a diagnostic on it, should be free right? Report back here. Your car also may be in limp mode to protect itself.

[mazdacxseven]

Originally Posted by smurugby12 Could be, sounds like a vacuum leak so it's a possibility. Really need to ask the guys at the auto parts store what engine codes it has after they run a diagnostic on it, should be free right? Report back here. Your car also may be in limp mode to protect itself.

Thank-you.

I will try to get codes tomorrow. On a side note, how can I reset the limp mode (remove the limp mode)?

[mazdacxseven]

Update:

Replaced the egr check valve, cleared all the codes most were around egr and o2 sensors and drove around 50 kms and none of the codes came back online.

But the limp mode seems to be still on. When I hit the gas the car misfires a lot and the rpm keeps dropping back to 2000 like drop dead back.

The problem is even more persistent during the start of the day, the first start. The first 15 mins of drive is very rough, lots of misfires and hesitation. Smooths out a bit later on. But acts up as soon as I floor the gas again.

[smurugby12]

Did you get the specific engine code it was throwing? Did it say a specific cylinder was misfiring that you know of? It could be a number of things. A vacuum leak somewhere, o2 sensor issue, coilpack issue, ect.

[mazdacxseven]

Originally Posted by smurugby12 Did you get the specific engine code it was throwing? Did it say a specific cylinder was misfiring that you know of? It could be a number of things. A vacuum leak somewhere, o2 sensor issue, coilpack issue, ect.

The codes were mostly engine running too lean, engine running too rich, both o2 sensor related. And also a code around EGR valve, which was fixed.

Btw, my oxygen sensor was out a long long time ago, never did the car behave the way it is doing currently. Also it misfires even more when the engine is cold.

I got all the spark plugs changed and the valve replaced and cleared the codes and none of them have come back online (drove 100+ kms). I wonder if the limp mode just hasn't been reset? Maybe re-setting the limp mode after all the above fixed would fix the issue?

If so, how would I reset the limp mode?

[SofaKingAwesome]

Post the fucking code numbers.
Any AutoZone, Advanced, etc. does this for free and will give you a print out.

[mazdacxseven]

Originally Posted by SofaKingAwesome Post the fucking code numbers. Any AutoZone, Advanced, etc. does this for free and will give you a print out.

UPDATE:

After the codes were cleared, this time the CEL light turned back on with just the follwing 2 codes:

P0300
P0301

I disconnected the battery and drained it to reset the ECU and inturn the "limp" mode. As my engine was warm by the time I drained the battery, did not notice a difference yet as the engine was responsive. It is usually during cold start it splutters a lot.

Now that I have the codes, what could be wrong?

[smurugby12]

P0301

Check that link ^^^ How much have you searched? I'm literally just spitting out what old threads have talked about.

Try some of these steps first. Run injector cleaner through the gas for a few tanks, but read what this guy went though. Also google, " p0300 p0301 www.mazdaspeedforum.org/forum" and see the dozens of other threads that come up with questions on those codes. Come back and post results once you figure out whats wrong. GL!