Help with Idle Issue 03 P5

jamieson456

Member
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Mazda, Protege5, 2003
Quick apology for lengthiness, I want to be specific and every detail counts when trying to diagnose a problem.

So over the course of a couple weeks I noticed that my P5 seemed to be hesitating slightly on hard accelerations, as if the car was just not putting out all of its power. No check engine light either.

So over the course of these past weeks I replaced spark plugs, fuel pump, full synth oil change, valve cover gasket, new radiator, brakes, and even both CV axles.

Well today I decided to replace the intake manifold gasket, not a difficult job but certainly not an easy one either. Long story short I removed the manifold and throttle body and carb cleaned everything. replaced the manifold gasket with a fresh Felpro one (no RTV) and torqued everything to 16 ft-lbs.

Here's where my problem begins, I start it up and it instantly revs to about 3 grand. I freak out and shut it off. Start it again thinking maybe some extra carb cleaner was being burned off? It starts and revs to 2 grand (normal its been doing that since I got it, however it usually drops to 750 after a minute or two). It stays at 2000 for a little so I rev it myself, the throttle response was so instantaneous now I thought I fixed a huge problem. But it continued to rev higher even with my foot off the gas. It stayed at 3000 and then came slowly falling back to 1500 but surging up and down the whole time.

I checked the codes with the Torque app and it showed a cylinder 4 misfire. Still no check engine light. Now I have work tomorrow and my car currently seems to be unsafe to drive with these surges in throttle. I wasn't able to do a test drive because it was late and I didn't want to annoy my neighbors anymore than I already had with the car going up to 3 grand!!

So I need some help, anything I can do to pinpoint what sensor might be the culprit? Since I cleaned the throttle body could it be a sensor in there? Any insight would be greatly appreciated.
 
It sounds like you have a vacuum leak. Get a can of carb or brake cleaner and start shooting it around the intake area. If you find an area that changes the idle when sprayed, you have found a leak. Check the injector seals as well, they leaked on my car. Check all vacuum hoses too.

Check the intake tube for cracks around the bellows.
 
I'm going out to do that right now. I don't think the intake hose has any cracks but I will take a good look at it. The injector seals are fine I was looking at them last night and the intake is bone dry along with the area around the injectors. I'll reply with an update when I do the carb cleaner test. Thanks!
 
Update: found out my throttle cable wasnt seated right and it was causing a weird throttle response. I also replace the intake hose and everything is all good, car send fine!
 
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