98 Protege, low idle and idle air system check engine light, how to fix?
#1
11-26-2012, 03:27 PM
98 Protege, low idle and idle air system check engine light, how to fix?
My friend bought a 98 Protege with a 5 speed stick and the 1.5 engine. When she bought it, it was idling low and slightly rough and then would jump up to around 2k and back down to 500 and up and down. But it was idling more around 500rpm than jumping up.
She didn't have a check engine light so she went though emissions and while there, they said that the computer wasn't ready and she needed to go through a few drive cycles. At that point, the check engine light went on and threw a code, the cryptic Idle Air system problem check code. (p0505?, can't remember exactly).
I checked most common things. I looked for an air leak somewhere along the intake system. Checked the intake hose (looks great). Took the IAC valve off the throttle body and cleaned it. It looked pretty clean to begin with.
Put it all back together and now the engine was no longer idling low but was rather idling at around a constant 1900 rpms. Check engine light came back on again (same code).
Took the IAC valve off again and tried cleaning it out some more. Same problem but now the engine was hunting. Was mainly idling around 1900 but then would drop down momentarily to 500-600 rpm and then back up to the 1900rpm.
Got fed up and went to junkyard and got another throttle body with intact TPS and IAC valve. Just did a straight swap. reset the computer. The engine now idles again at 500-550rpm but no longer hunts, it just idles along happily at 500-600rpm but that is a pain, it is still just too low. She hasn't gotten a check engine light since Friday when we replaced the throttle body (that is a good thing I guess).
The low idle is a problem though because she has a hard time taking off from a dead stop and it feels like it wants to die.
Just for giggles, I folded up a piece of normal paper 3 times so it was the thickness of 3 sheets of paper. I then inserted that strip in between the throttle stop and the throttle adjustment screw (I did NOT alter that screw). The idle raises up a tad but only to about 600rpm. The odd thing was that if I added one more thickness of paper to the shim so that it was 4 pieces thick, and put it in place, the idle then jumps up to 1900rpm and doesn't want to settle down.
Any ideas on what the heck is going on with this and how to possibly fix it cheaply? My friend is rather broke and needs to get this car to pass emissions since she can't register it otherwise.
She didn't have a check engine light so she went though emissions and while there, they said that the computer wasn't ready and she needed to go through a few drive cycles. At that point, the check engine light went on and threw a code, the cryptic Idle Air system problem check code. (p0505?, can't remember exactly).
I checked most common things. I looked for an air leak somewhere along the intake system. Checked the intake hose (looks great). Took the IAC valve off the throttle body and cleaned it. It looked pretty clean to begin with.
Put it all back together and now the engine was no longer idling low but was rather idling at around a constant 1900 rpms. Check engine light came back on again (same code).
Took the IAC valve off again and tried cleaning it out some more. Same problem but now the engine was hunting. Was mainly idling around 1900 but then would drop down momentarily to 500-600 rpm and then back up to the 1900rpm.
Got fed up and went to junkyard and got another throttle body with intact TPS and IAC valve. Just did a straight swap. reset the computer. The engine now idles again at 500-550rpm but no longer hunts, it just idles along happily at 500-600rpm but that is a pain, it is still just too low. She hasn't gotten a check engine light since Friday when we replaced the throttle body (that is a good thing I guess).
The low idle is a problem though because she has a hard time taking off from a dead stop and it feels like it wants to die.
Just for giggles, I folded up a piece of normal paper 3 times so it was the thickness of 3 sheets of paper. I then inserted that strip in between the throttle stop and the throttle adjustment screw (I did NOT alter that screw). The idle raises up a tad but only to about 600rpm. The odd thing was that if I added one more thickness of paper to the shim so that it was 4 pieces thick, and put it in place, the idle then jumps up to 1900rpm and doesn't want to settle down.
Any ideas on what the heck is going on with this and how to possibly fix it cheaply? My friend is rather broke and needs to get this car to pass emissions since she can't register it otherwise.
#3
11-27-2012, 09:41 AM
Have you tried using starting fluid to see if there is a potential leak at the intake manifold itself?
#5
11-27-2012, 05:25 PM
bobotech: I have the very same model protege and I have had a good bunch of deferred maintenance to deal with. You did a nice job so far. Here are some steps that I took (the list will repeat some of your steps):
1. Check for vacuum leaks: intake hose, all small hoses, pcv and connections, etc. I took off all hoses and replaced the small ones with new hoses from the reel.
2. Checked for clogs in the vacuum lines: The vacuum hose to the fuel pressure regulator was plugged. The nipple for the EGR boost sensor was clogged. I opened it with a 3" piece of strong wire (bicycle spoke).
3. Cleaned throttle body with throttle body cleaner, inside and out.
4. Removed and cleaned out EGR valve and opened the EGR ports at the mouth of the the intake manifold (2 holes, 6 o'clock and 12 o'clock).
5. Cleaned MAF sensor and IAT sensor (intake air temperature) with MAF sensor cleaner.
6. Lubed the throttle cable.
7. Replaced the air filter.
8. Replaced the spark plugs, wires, distributor cap and rotor.
9. Gave it the infamous "Seafoam" treatment. Don't do it in the neighborhood, go into an industrial area for this.
10. Switched from regular gas to mid-grade, 89 octane. (In your case I would switch to 91 octane until I'd pass inspection.)
11. You also can test:
a. the throttle position sensor.
b. the fuel pressure
c. compression
d. battery and charging system because voltage drops can affect the computer.
Once you are done with the things you choose to do, disconnect the battery negative and then step on the brake to drain all voltage from the memories.
The computer will have to relearn stuff. So drive in town and drive on the highway. Make a few stops, turn off the engine and turn it on again.
I had the light out for about a year. My problems center around the EGR system and the heated O2 sensors. But I live in a state without inspections......
Good luck to you!
1. Check for vacuum leaks: intake hose, all small hoses, pcv and connections, etc. I took off all hoses and replaced the small ones with new hoses from the reel.
2. Checked for clogs in the vacuum lines: The vacuum hose to the fuel pressure regulator was plugged. The nipple for the EGR boost sensor was clogged. I opened it with a 3" piece of strong wire (bicycle spoke).
3. Cleaned throttle body with throttle body cleaner, inside and out.
4. Removed and cleaned out EGR valve and opened the EGR ports at the mouth of the the intake manifold (2 holes, 6 o'clock and 12 o'clock).
5. Cleaned MAF sensor and IAT sensor (intake air temperature) with MAF sensor cleaner.
6. Lubed the throttle cable.
7. Replaced the air filter.
8. Replaced the spark plugs, wires, distributor cap and rotor.
9. Gave it the infamous "Seafoam" treatment. Don't do it in the neighborhood, go into an industrial area for this.
10. Switched from regular gas to mid-grade, 89 octane. (In your case I would switch to 91 octane until I'd pass inspection.)
11. You also can test:
a. the throttle position sensor.
b. the fuel pressure
c. compression
d. battery and charging system because voltage drops can affect the computer.
Once you are done with the things you choose to do, disconnect the battery negative and then step on the brake to drain all voltage from the memories.
The computer will have to relearn stuff. So drive in town and drive on the highway. Make a few stops, turn off the engine and turn it on again.
I had the light out for about a year. My problems center around the EGR system and the heated O2 sensors. But I live in a state without inspections......
Good luck to you!
Last edited by tanprotege; 11-27-2012 at 05:35 PM.
#6
11-28-2012, 11:27 AM
Awesome info. My friend brought by the failure printout from the emissions station today.
In a nutshell, it didn't show any "fails" for each of the computer statuses, but what it did show was 3 not ready and a few passes. So even though she drove the car for 4 days with no failure code, ODB didn't go to full ready.
I'm not so sure that there is a failure at this point but rather trying to figure out why the computer won't go ready for all of the ODB tests.
I"m stiill going to follow your info in the above posts but I'm wondering if its more an issue of getting the computer to go ready.
In a nutshell, it didn't show any "fails" for each of the computer statuses, but what it did show was 3 not ready and a few passes. So even though she drove the car for 4 days with no failure code, ODB didn't go to full ready.
I'm not so sure that there is a failure at this point but rather trying to figure out why the computer won't go ready for all of the ODB tests.
I"m stiill going to follow your info in the above posts but I'm wondering if its more an issue of getting the computer to go ready.
#7
11-28-2012, 11:44 AM
In a nutshell, it didn't show any "fails" for each of the computer statuses, but what it did show was 3 not ready and a few passes. So even though she drove the car for 4 days with no failure code, ODB didn't go to full ready.
I'm not so sure that there is a failure at this point but rather trying to figure out why the computer won't go ready for all of the ODB tests.
I"m stiill going to follow your info in the above posts but I'm wondering if its more an issue of getting the computer to go ready.
I'm not so sure that there is a failure at this point but rather trying to figure out why the computer won't go ready for all of the ODB tests.
I"m stiill going to follow your info in the above posts but I'm wondering if its more an issue of getting the computer to go ready.
#8
11-28-2012, 12:10 PM
Its not just a 15 minute ride before going to the test. That trick was good for the older pre-odb 2 systems where they did the sniffer. That would heat the catalytic converter good and hot and clear out the crap int he car.
ODB2 emissions testing is done with no sniffers at all unless there is a problem. Its all though the computer. If the ODB2 computer senses a failure at any point, it throws a code that is stored but that is currently not an issue here.
What caused my friend's car to fail was the readiness monitors not being ready:
I just don't know the proper procedure to get a complete drive cycle to occur and just how long does it take for the drive cycle to occur?
ODB2 emissions testing is done with no sniffers at all unless there is a problem. Its all though the computer. If the ODB2 computer senses a failure at any point, it throws a code that is stored but that is currently not an issue here.
What caused my friend's car to fail was the readiness monitors not being ready:
OBDII (Non -Continuous)
Readiness Monitors check
These monitors are like self checks of each emissions component (EGR, O2 sensor, etc) within the OBDII system. These non-continuous monitors are considered Ready until either DTC's have been cleared with a scan tool or if battery power has been disconnected, then the monitors will reset back to Not Ready.
In order to get the monitors set back to Ready, the vehicle must be driven through a drive cycle, which is a combination of city/highway driving for a set period of time. This drive cycle relearns the OBDII system and rechecks all of the emissions component's individual systems. As each system completes its own self test, the monitor will set back to Ready.
Readiness Monitors check
These monitors are like self checks of each emissions component (EGR, O2 sensor, etc) within the OBDII system. These non-continuous monitors are considered Ready until either DTC's have been cleared with a scan tool or if battery power has been disconnected, then the monitors will reset back to Not Ready.
In order to get the monitors set back to Ready, the vehicle must be driven through a drive cycle, which is a combination of city/highway driving for a set period of time. This drive cycle relearns the OBDII system and rechecks all of the emissions component's individual systems. As each system completes its own self test, the monitor will set back to Ready.
#9
11-28-2012, 01:52 PM
From a google search:
"Here is a Mazda drive cycle:
Pre-requisites: MIL off and no DTCs present (this is where clearing your codes comes in); fuel level between 15 and 85%; all accessories OFF; cold start (preferred 8 hour cold soak w/ engine between 68 and 86 deg F at start-up)
1) Start vehicle and idle 5 min.
2) Rev engine in neutral or park to 2300-2700 rpm for 15 seconds
3)Rev engine in neutral or park to 3800-4200 rpm for 15 seconds
4)Idle engine for 20 seconds with cooling fan stopped.
5)Accelerate to 52-55 mph, maintain speed (in high gear) for 1 1/2 minutes
6) Decelerate to 15 mph, and then drive for 13 minutes at speeds ranging from 15 to 35 mph
7) maintain steady 25 mph for 50 seconds.
Each step of the drive cycle indicates a test for a different monitor on the vehicle (catalyst, o2 sensor, evap, etc) so each step is important. Some vehicles are a pain and may require a few drive cycles. "
"Here is a Mazda drive cycle:
Pre-requisites: MIL off and no DTCs present (this is where clearing your codes comes in); fuel level between 15 and 85%; all accessories OFF; cold start (preferred 8 hour cold soak w/ engine between 68 and 86 deg F at start-up)
1) Start vehicle and idle 5 min.
2) Rev engine in neutral or park to 2300-2700 rpm for 15 seconds
3)Rev engine in neutral or park to 3800-4200 rpm for 15 seconds
4)Idle engine for 20 seconds with cooling fan stopped.
5)Accelerate to 52-55 mph, maintain speed (in high gear) for 1 1/2 minutes
6) Decelerate to 15 mph, and then drive for 13 minutes at speeds ranging from 15 to 35 mph
7) maintain steady 25 mph for 50 seconds.
Each step of the drive cycle indicates a test for a different monitor on the vehicle (catalyst, o2 sensor, evap, etc) so each step is important. Some vehicles are a pain and may require a few drive cycles. "
#10
11-28-2012, 03:40 PM
Pain in the A.S.S.
That is a pain in the A.S.S.
Nice find though!
