Idle speed problem
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Professional
Joined: Jun 2007
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From: Miami
Replaced MAP sensor. Same voltage measures. Trip from Miami to Key Largo. 60.6 highway miles at 70 mph almost all time. 3.2 gallons . Almost 20 mpg but still the same problem. When stop, RPM are between 1000~1500. If I wait at "idle" speed around 10 minutes, then RPM drops to 600 RPM.
I heard a vacuum leak at passenger side inside hood but is only at the moment I stopped but disapears inmediatly
I heard a vacuum leak at passenger side inside hood but is only at the moment I stopped but disapears inmediatly
Champion
Joined: Oct 2009
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I don't know if this will help, but try disconnecting the big vac line to the brake booster and plug it, Check the hose for cracks, test. remember you will have "NO" power brakes with the vac line disconnected.
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Professional
Joined: Jun 2007
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From: Miami
Checked voltage from the O2 sensors: between the normal range.
Scan tool: still showing P0505 idle control malfunction, both O2 sensors showing "inc"
I don't know where to troubleshoot now??? I need some help
Scan tool: still showing P0505 idle control malfunction, both O2 sensors showing "inc"
I don't know where to troubleshoot now??? I need some help
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Professional
Joined: Jun 2007
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From: Miami
Noticed it doesn't matter how long is running at idle, never increases the RPM (600 RPM) even at operation temp.
When is running at high RPM, then, when you stop, RPM will increase to 1000~1500. Passed 10 minutes, star to decrease until 600 RPM again.
Heard some vacuum leak but tested lines with a vacuum pump and didn't find it...
When is running at high RPM, then, when you stop, RPM will increase to 1000~1500. Passed 10 minutes, star to decrease until 600 RPM again.
Heard some vacuum leak but tested lines with a vacuum pump and didn't find it...
Captain
Joined: Nov 2007
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The only correct way to test a MAP is with a manual vacuum pump that has a gauge.
I still believe you have a vacuum leak. Did you check that port I mentioned before?
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Professional
Joined: Jun 2007
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From: Miami
.... you need to start looking for vacuum leaks. 1,000 is very high for a warm engine. There's a vacuum port on the side of the manifold that is capped from factory on most engines, but that cap deteriorates (or gets eaten my rodents), and causes a leak. And there are other places that it could be leaking vacuum as well. The easiest way to find a vacuum leak is with a can of carb clean or brake clean sprayed around the intake and vacuum hoses while the eninge is idling. If it has a leak, pulling in the cleaner will cause an over rich condition and drop engine RPM.
However, before you do that, you mentioned a whistle at part throttle. Sounds like your air horn gasket is shot. Replace that before you go looking for vacuum leaks, as it'll give you a false symptom and send you on a wild goose chase.
However, before you do that, you mentioned a whistle at part throttle. Sounds like your air horn gasket is shot. Replace that before you go looking for vacuum leaks, as it'll give you a false symptom and send you on a wild goose chase.
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Professional
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From: Miami
I did it yesterday with a vacuum pump and holds the pression.Then, I installed back the original part ( I installed a new MAP sensor but is $68, if mine is OK I'm planning to keep it)
Captain
Joined: Nov 2007
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I don't mean checking it for a leak, I mean voltage sweeping it. You watch the signal volts on a scanner or a DVOM while you slowly increse vacuum. As vacuum goes up, voltage goes down.
Captain
Joined: Nov 2007
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The fact that they still function fine just means that the leak isn't the vacuum line into the cab or to the CC module.
I couldn't find any images that actually show that port I'm talking about, but snagged this one and put an arrow where you need to look:
