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Car wants to die at a stop

Tiny
GATERTAMER
  • MEMBER
  • 1993 MAZDA MX3
  • 220,000 MILES
Car wants to die at a stop. When accessories are turned at idle like heater, lights, or touching brake pedal rpm's drop so low it dies. Recently tuned up, new vacuum hoses, new maf, no codes, tested iac valve and tps both react how their supposed to when unplugged and resistance is in correct range, injectors are clicking fine, cleaned throttle body and air boot, alternator is putting out 14.5 volts, new fuel pump and filter. Pressure is good, vacuum guage reads about 20 steady. Any ideas?
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Saturday, January 5th, 2013 AT 11:54 PM

30 Replies

Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Go here: https://www.2carpros.com/articles/engine-idles-too-low
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Sunday, January 6th, 2013 AT 3:05 AM
Tiny
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Neglected to say it was 1993 mx3.1.6L. Sohc. Manual. According to chiltons it says if you unplug IAC when warm rpm's should drop. Instead. They go up about 600. Did resistance check and its within spec and thoroughly cleaned. What do you think?
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Sunday, January 6th, 2013 AT 3:45 AM
Tiny
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Should IAC valve move either in or out for this model with key on?
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Sunday, January 6th, 2013 AT 5:08 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,164 POSTS
The IAC should move in and out when the key it turned on and off.
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+1
Sunday, January 6th, 2013 AT 6:06 AM
Tiny
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Why don't you just open it up and clean it out with a bore brush and carb cleaner and see what happens-appreciate the B/U Joe-hope the holidays when well-TY
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Sunday, January 6th, 2013 AT 10:51 AM
Tiny
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Thank you. Done it a couple times. Took off IAC and turned key on it's gettin 12.5 V to it and it starts to spin rapidly and moves a little too. Plus the RES is right on guessin it works ok. On to something else.
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Sunday, January 6th, 2013 AT 3:46 PM
Tiny
KHLOW2008
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Did you try adjusting the idling speed?
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Sunday, January 6th, 2013 AT 8:29 PM
Tiny
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Thing is it idles pretty well. Rpm's drop a little when you turn on heater then a little more when you turn on lights then a little more when you hit brake pedal til it dies or almost dies. Is there another way to adjust idle than messing with TPS. ALT is putting out 14.5V same as what batt reads.
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Sunday, January 6th, 2013 AT 9:33 PM
Tiny
RASMATAZ
  • MECHANIC
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Try doing this:

Connect Diagnostic Tester (49 B019 9A0) to diagnostic connector and select SELF-TEST mode, or connect jumper wire between diagnostic connector terminals TEN and GND. Connect tachometer to diagnostic connector terminal IG (-).
If idle speed is not within specification, rotate idle air adjusting screw on throttle body.

Adjust to 700rpm
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Sunday, January 6th, 2013 AT 10:14 PM
Tiny
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Code 03 is appearing. Dist no g1 or g2 signal. Is there a simple way for a backyard mechanic to figure it out?
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Monday, January 7th, 2013 AT 12:43 AM
Tiny
KHLOW2008
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  • 41,815 POSTS
Refer to chart
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Monday, January 7th, 2013 AT 12:47 PM
Tiny
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Thank you for diagrams. Not quite sure about step 6 what is voltage supposed to be. With key on or off. Dist connected or not. And step 5 how do you check for ground. Step 8 with dist disconnected but is key on or off. Thank you
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Tuesday, January 8th, 2013 AT 11:13 AM
Tiny
KHLOW2008
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When checking voltage, the ignition must be ON.

When checking for ground it means check for shorts. One end of ohmmeter to wire/terminals and the other to body.

Is your vehicle Federal or California Specifications?
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Tuesday, January 8th, 2013 AT 1:39 PM
Tiny
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Its federal. Just dont know when it says is voltage ok what is voltage supposed to be?
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Friday, January 11th, 2013 AT 11:28 AM
Tiny
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Is there an easy way to check and see if internal voltage regulator is working correctly?
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Friday, January 18th, 2013 AT 8:56 AM
Tiny
KHLOW2008
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Sorry for the delay in replying. Was away for the past week.

Here are the pin voltage chart.
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Tuesday, January 22nd, 2013 AT 2:44 PM
Tiny
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Thanks for diagrams. Did step 6.(Tested ecu terminal voltage from dist.). It was 5 volts with key on but stayed 5 volts at idle it didnt drop to 1.5V like it should. The 2E terminal was at 5V with key on and dropped to 2V at idle. Like it should. There is continuity between dist. Wire and ecu. Step 7 tested at 5V and it says replace dist. However when performing step 8 there is no voltage and it says replace ecu. Does step 7 superceed step 8 because it tested at 5V and it says replace dist. If it were you which one would you replace?
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Saturday, January 26th, 2013 AT 10:49 PM
Tiny
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Any fault with the ECU takes precedence over others.
Anyway step 6 showed voltage, why does the voltage disappears when measured at ECU?
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Sunday, January 27th, 2013 AT 6:22 AM
Tiny
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It asks for the dist. Connector to be disconnected. Im assuming thats why there is no voltage. Also distributors are sold with or without modules what does that mean? And could it be just a bad module in dist. And I dont need to replace entire thing?
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Sunday, January 27th, 2013 AT 9:12 AM
Tiny
KHLOW2008
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If the module comes separately, you can just replace that because the problem is only within the module circuit. However you need to check/test the wiring circuit within the distributor as it could be bad wires as they become brittle over time and any movement of them can result in breakages/poor continuuity.
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Sunday, January 27th, 2013 AT 7:18 PM

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