HELP ! Idle low on decel...

[LittleRedWagon5]

HELP ! Idle Crashes coming off throttle.

Ok the last couple days my idle has been acting up. When I let off the gas and push in the clutch it goes way down to where it stubmbles and wants to almost quit running. And tonight with the help of a friend discovered that the infamous "cold-rattle" isn't there anymore. Anyway it runs fine and still gets up and goes and doesn't miss at all. But the idle is wacked. Could it be the cold weather, it's been cold here in MD lately. Below freezing. Or is it an electronics problem, should i reset the ECU ? Last week I cleaned my air filter, a K&N and re-oiled it. Could I have put to much oil on and fouled up the MAF sensor. The car only has 16K miles on it. Any help would be greatly appreciated.

 

[LittleRedWagon5]

well since no one wants to reply I took it upon myself to do some investigating. As usual i couldn't reproduce the problem this morning until I turned on the headlights. So now I think it could be a charging problem. Anyhow I Unhooked the battery to reset the ECU and let it sit disconnected for an hour, while it was sitting i checked the MAF sensor. It looked clean, I mean there was no dirt or filter oil on it. So i reinstalled it, after that I checked all the vaccum lines and made sure the VIS and the tumble controls were working freely and weren't seized up. Everything was good.
So I hooked up the battery, started it and let it idle till it warmed up and then gave it a quick stab of the throttle, it revved evry fast, and didn't idle rough.....Until I started to drive it with the lights on. It's not as bad as it was before, but I think its the charging system. I tested it with a multimeter, it puts out about 15 volts. with or without the lights on. It only acted up once and the voltage went down to about 5 volts for about 15 seconds.

Any ideas ? (quit reading and reply )

 

[Jim Frye]

Re: HELP ! Idle Crashes coming off throttle.

Any help would be greatly appreciated.

What's the rpm at idle normally and when this situation occurs. Turn off all of your "other" electricals (neons, stereo, etc). If the ECU can't hold the idle properly with the just the headlights on at idle, I'd be making an appointment with the service folks. Jim

 

[LittleRedWagon5]

Normally the idle is 750. No A/C, No Radio, No Lights, No acces. When I turn on the lights it drops to like 725-700 and fluctuates.

 

[Jim Frye]

Mine Don't

2003 P5 with automatic, warm idle at 750. turn on the headlights and no change, even with the high beams. I'm wondering if the alternator has a problem. I don't know the Mazda, but I had one of the four diodes go out on the alternator in my Saturn and it caused a similar problem. This essentially halved the output of the alternator, but didn't trigger any error codes. Eventually, I ran the battery down to the point where it went below 10 volts and the transaxle would not shift out of second. That's when the CEL finally came on. I'd be calling the service department first thing Monday for an appointment. Jim

 

[1sty]

I am having a very similar problem with my car. The lights crash the idle. I actualy have an aftermarket alternator so the 15 volts didn't startle me but I have never seen a stock alternator pump out 15 volts before.

 

[LittleRedWagon5]

I'll have to do some more checking in the morning. I'll start the car and then disconnect the battery. If the alternator is working properly when i turn the lights the car should still run decent. the only other possibility is that the battery may be going bad already.

 

[1sty]

Just to inform you of my antics.

I had originaly thought it could be a charging problem but I get 12.7 volts on the battery and 15 rom the alternator. That s about the most I can troucle shoot a charging system so I moved on.

With help from some board member I have been trying to se if its the IAC valve. Basicly if you pull the frey clip from the cylinder atop the throatle body the cars idle should crash or stall. When I did it nothing happened. You may want to check out my post in the performance section to read all that I have tries thus far.

Next up is metering the IAC vavle wire to the ECU to ensure no shorts or open circuits.

Unfortunitly becuase of the turbo I can't go to a dealer so if you find out anything please let me know ASAP.

 

[1sty]

Oh and if you reset the ECu do it alone, with nothing else.
I did it after cleaning the IAC and now the car barely runs. Hopefully its the computer reset that did this and not me killing the IAC.

 

[FuNwaGoN]

finally someone else is having the same problems as me ...I'm not going crazy afteral

Ok guys check out my posts. I have been having the same problems that you all have described. meaning the flucuating idle(alot worse than yours because mine would almost die. I have had the ECU reset 4 times and Reprogrammed once, I also had the IAC valve replaced, and the base idle reset 6 times. Problems are still there. the dealer actually says that they have never been able to recreate the problem but it happens to me everyday and is really pissing me off. Anyway I don't feel like going through the whole explanation again so I will just post links to the threads. Read them and let me know what you think. I am awaiting a Special Mazda technician to look at my car. The result of that will determine wether or not my car goes back on lemon law. BTW my car is bone stock with 6800 miles on it and I have been having this problem since about 2500. My idle jumps about 100- 200 rpms when it flucuates though. and the idle is around 450-500.

Sorry if I sound happy about this but it just means that I am not crazy afterall because others out there are having my same problem.

not sure if it will help you guys out or not but I am waiting for Mazda Corporate to call me back about a switch to fix my idle problems that my dealer called me about. Will let you know what they say when I talk to them.

http://www.protege5.com/vbb225/showthread.php?s=&threadid=11153

http://www.protege5.com/vbb225/showthread.php?s=&threadid=11270

http://www.protege5.com/vbb225/showthread.php?s=&threadid=10749

http://www.protege5.com/vbb225/showthread.php?s=&threadid=9701

http://www.protege5.com/vbb225/showthread.php?s=&threadid=9190

I know thats alot but this has pretty much been going on since I got my car. It was fine for the first month and then the first day the temp got cold it went all screwy.

It has actually gotten to the point where you can see my headlights dim when at speed on the road. there is this like 1-2 second hesitation that happens about every other minute and my lights dim whenever the hesitation happens. DO YOU GUYS HAVE THIS????