2003 Mazdaspeed Protege High Idle Issue...Any ideas?

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cygnus_x1

Member
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Mazdaspeed Protege
Hi guys,

I have a 2003 MSP with about 170k miles. About 3 months ago I was having an issue with the car idling low, about 400-600 rpm. I cleaned the egr valve, throttle body, IACV, and MAF. The idle got smoother and stayed around 600 rpm. A few months after, I drove about 60 miles on the interstate, and suddenly the car began idling high - about 1000 rpm.

Shortly after, it threw codes for the VICS and O2 sensor. I replaced the VICS solenoid and O2 sensor to no avail (I know the VICS wouldn't cause it). When I swapped the O2 sensor I noticed my exhaust manifold had a crack that recently spread to the O2 bung. I replaced the manifold with the Pope Performance one last week. I swapped my plugs, coil packs, and wires as well.

The idle still sits between 900-1100. If I drive then take my foot off the accelerator with the car in gear it pulls forward rather than decelerating normally. The idle also stays around 1500 when rolling to a stop then drops a few seconds after fully stopping.

Any ideas are appreciated!
 
I didn't make any changes when I cleaned the throttle body. How do I adjust it? Thanks for the reply!
 
Last edited:
I pulled the white retainer clip on the cable, but can't get the black adjuster to budge with my fingers. Should it require tools? It doesnt seem terribly sturdy and I dont want to force it.
 
Leave the cable alone don't try to adjust it. It is likely a vacuum leak causing your high idle
 
***DO SO AT YOUR OWN RISK, BRAKE PARTS CLEANER WILL IGNITE IF EXPOSED TO A SPARK***
Take some brake parts cleaner (I prefer Advance Auto's Wearever brand because it evaporates quickly) and lightly spray in the area around the throttle body and intake manifold while running to see if the idle changes to indicate the source of the leak. If spraying in one area dramatically decreases the idle, even possibly to the point to stall it if the leaks is large enough and you've used liberal amounts of parts cleaner, that's a good indicator as to where your leak is at. If you have a leak.



You didn't mention if there were any other DTCs stored, but just to make certain: There aren't any other DTCs, right?

Does the idle decrease if you depress the clutch?

Just asking as things that you may have left out that would help in diagnosing the problem. If not, then I'd agree that's it's likely a post-throttle body leak.
 
Thanks for the replies. I pulled the intake pipe off of the throttle body to make sure that it was returning to it's zero position before messing with the throttle cable. It is, so that's not the problem. I'll give the brake parts cleaner method a try.

The only codes it had were p0031 (O2 sensor) and p0660. Replacing the VICS solenoid took care of p0660, and the crack in the exhaust manifold was seemingly what was causing the O2 sensor misread. I'll take it by a shop tomorrow and see if anything new has come up since I put the manifold on.

Idle doesn't change when I depress the clutch. The idle is consistent, just high.

Are there any common culprits for a post-TB leak?
 
There aren't many options, really. You have your brake booster hose, a hose on the bottom of the manifold, a hose on the center of the manifold, throttle body gasket, injector seals, intake manifold gasket, plenum gasket, and.... I think that's about it....
 
Ever determine anything? My RX7 has an unusually high idle at times. Completely different vehicle I know, but just curios on how this turns out.
 
I sprayed some brake cleaner around the throttle body and intake manifold. Nothing. I noticed that the bracket holding a solenoid on the pipe to the throttle body was looking a bit strange. It started to peel (not really the right word) off and there was a little leak there. I hit it with some JB weld and it sits very smooth at 900 now. I reset the ecu so I'll see if it comes down at all in the next few days.

If there are any other ideas feel free to share them. Maybe it's just going to idle a touch high now?
 
Does sound like it could've been a vacuum leak. I can't find any such leaks on my RX7 but have adjusted the idle on the carburetor and it now idles at about 1400rpm which is still a bit high. Curious to see if your car maintains a good idle after you reset the ecu.
 
The high idle seems to be fixed. Must have been that vacuum leak.

New issue:

The exhaust manifold flange/turbo flange connection came loose and started leaking. The studs rattled themselves loose from the new manifold. I used red Loctite and let it set before tightening the nuts on. I pulled the assembly on Sunday and replaced the studs with new ones (not a perfect replacement, but extremely close from Carquest). After driving for awhile, the leak is there again. I've never set studs before. Do I need a stud driver or something to get them nice and tight initially? I'm thinking about ordering the street unit set of studs and nuts so that I don't have to question the hardware. What am I doing wrong?

Thanks for all the help so far!
 
The hardware you have should be fine they don't need to be as tight as you would think, try using a lock washer. The factory nuts are 'pinched' to keep them from coming loose.
 
Hey guys,

Sorry to keep reviving this thread. I got the manifold issue taken care of. I bit more muscle when setting the studs and some lock washers seemed to do the trick. Thanks for the advice hornsfan.

High idle is still present. I unplugged my IACV and it dropped to 700 with no issues. I replaced it thinking it was the issue. It seemed to help at first but the idle was back at 1100 after a few days.

When I start the car, it turns over just fine, then has a little hiccup at about 1k rpm before jumping up to about 1700, then slowly dropping as it should on a cold start. It doesn't do this when the car is warm. Before it's warmed up, it will often idle perfectly with no accessory loads on the engine. Once warmed up, the idle is high again.

I've also noticed in the last week that if the AC is turned on, the idle drops dramatically (not quite stalling, but very close) then jumps up to 1200 rpm. It repeats that cycle over and over. Every few drives, I can kick the AC on and it actually brings the idle to 800 or so like it should. If I turn my steering wheel the idle will go up considerably.

Is it something on that belt? I replaced the alternator awhile back with one from a yard. Each pulley seems to be spinning without any issues.

Any more ideas?
 
Sounds like a vacuum leak to me, that's usually what causes a high idle, or a dirty MAF sensor.
 
I've searched for vacuum leaks like crazy. I'll try the MAF again. I metered it and the reading was higher than what I've read it should be. I'll try that out after work today. The TPS sensor reading was a little high when I tested it as well. Could a bad/dirty MAF sensor influence the TPS reading?
 
Yes but it's most likely a vacuum leak or even a dirty throttle body. Do you have a boost gauge to check the vacuum at idle?
 
The throttle body is definitely clean. I cleaned it a few months ago and wiped it again when I did the IACV the other day. It seems like a vacuum leak to me as well, but there's no reaction to carb cleaner. I've sprayed everywhere from the intake hoses all the way to the intake manifold gasket. I don't have a boost gauge. I'm open to going to a shop and having them test it though. The day it first idled high I changed my oil. I used a different brand filter but the same type of oil as it's had since day one according to the original owner. It would be borderline comical if that had anything to do with it, but I'm not an expert and strange things happen.
 
Also, if I grab the TB linkage and give it a little torque toward the closed position, the idle goes down. I'm not sure if the AC issue is fixed when doing that though.
 
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