rpm dropping to 0, rough idle and now CEL

D

davemsc

Member
:
mazda protege5
hey all...

Have a P5 manual with 224,000km on it.

Everything was fairly good until last week.

I was on the highway and went to go on the offramp. It's a long one so I basically put the car in neutral and just coasted. I've done this before without problems but this time the rpms dropped to 0 and all the dashboard lights lit up - it almost stalled. This now happens if I put it in neutral at higher speeds (like the example I just mentioned), but not around town at lower speeds.

Also, I am getting a rough idle at stop now and the CEL came on after starting the car one morning.

My buddy has a scanner which I will use this weekend (he's in the city 100km away) - the CEL isn't blinking so I should be ok on the highway.

Anyway, any immediate guesses?

thanks,
Dave
 
Have you searched "rough idle" and ruled out EGR, spark plugs, wires, and coils? Also the car idles rough for a bit if the battery has been disconnected.


Sent from my iPhone using Tapatalk
 
good point.....i was well below the regular idle rpm, but i can't say for certain it was 0.
I was thinking th EGR valve, but this seems to be like a switch was flipped - I would think the EGR valve would be more gradual?
it has new plugs....but not new wires and coils....I guess that might be where to start

Battery wasn't disconnected.

Thanks man
 
The ECU might have switched from open loop to closed loop control when you start to cruise in neutral or idle. I think that's how it works.


Sent from my iPhone using Tapatalk
 
The EGR is only active while cruising at higher speeds. Sounds like it could be sticking.

Coils are another common issue, although the CEL usually blinks when they act up.
 
Not long ago I had a MAF that went bad and it pretty much happened exactly like what you describe. I luckily had a replacement laying around and that fixed the problem perhaps you should check yours?
 
Well, got the code. My buddy had a scanner. P0171 System too lean.

I have read that alot of these codes are caused by a crack or something in the hose from the intake to the engine. I don't see or feel anything obvious. Any tricks I can do to narrow it down?

ANy suggestions? Would a dirty MAF cause this? If so, how do you clean it? I'm not too car saavy.

Thanks,
Dave
 
davemsc said:
Well, got the code. My buddy had a scanner. P0171 System too lean.

I have read that alot of these codes are caused by a crack or something in the hose from the intake to the engine. I don't see or feel anything obvious. Any tricks I can do to narrow it down?

ANy suggestions? Would a dirty MAF cause this? If so, how do you clean it? I'm not too car saavy.

Thanks,
Dave
Click to expand...

bump?
 
dirty MAF? Idk... I didn't notice that my hose was cracked until I took it off, then it started to fall apart. You can clean the MAF by spraying it with a MAF cleaner. If you google it, you'll find a lot of information.
 
gilella said:
dirty MAF? Idk... I didn't notice that my hose was cracked until I took it off, then it started to fall apart. You can clean the MAF by spraying it with a MAF cleaner. If you google it, you'll find a lot of information.
Click to expand...

You are talking about the round, almost plastic, tube or hose coming from the air filter housing to the engine right?
 
Yes.

P0171 can also be caused by vacuum leaks. Get a can of carb cleaner and spray around all of the connections. The idle will change if you spray a leaking area.
 
Yup, it's that hose from the air filter box to the engine. Right where it is bumpy, there are cracks in the bottom of the ridges.
OK so I need a new house. What are they called so I don't look like s tool when I go to Napa tomorrow lol?

For installation, looks like a simple clamp on either end and that's it?
Thanks
Dave
 
I had a similar hose-related sudden performance issue when I bought my car. I replaced the air filter and suddenly the car ran like s***. It was like riding a bucking bronco in low gear - like I didn't know how to drive standard... LOL. After researching the forums in complete puzzlement I found a great troubleshooting write-up and the first thing on the list was the air hose. When I disturbed the hose to install the new air filter, the dirt that was keeping everything together let go and voila - instant rodeo. Bought my air hose from Mazda and the price was reasonable. I think it was somewhere between $20-30 CAD. I get a trade discount though.
 
Rock Auto has them...

(they're a lot cheaper in US dollars... so is shipping)



 
pcb said:
Rock Auto has them...

(they're a lot cheaper in US dollars... so is shipping)



Click to expand...

Yeah, I paid $65 all in with tax and shipping. I'm in Canada so I would have gotten killed anyway with the exchange. Should be here today or tomorrow. Duct tape is fixing the issue right now. Maybe I should have just kept it taped and save $65
 
davemsc said:
Yeah, I paid $65 all in with tax and shipping. I'm in Canada so I would have gotten killed anyway with the exchange. Should be here today or tomorrow. Duct tape is fixing the issue right now. Maybe I should have just kept it taped and save $65
Click to expand...

Just installed it. Took 15 minutes.
Thanks for pointing me in the right direction everyone!!
 
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