Shakes bad at 1000 RPM gas pedal on floor

Tiny
DRMALOY
  • 1998 MAZDA 626
  • 112,500 MILES

Car will only start if I hold gas pedal to the floor and runs only for a short bit. It shakes bad and is maybe at 1000 rpm gas pedal to the floor

Engine had a tune up and told IAC valve needs replaced. Car began making noise in engine by belt side. Was driven 1 mile following day and it died while driving. Unable to restart. Installed a new IAC valve and checked plugs they were wet. Checked for spark and had good spark. Fuel pumped humms for couple seconds when key goes to start.

fuel pressure seems good. Engine ran okay then all this the next day. Any help would be greatly appreciated.

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Tuesday, September 18th, 2012 AT 6:49 AM

21 Replies

Tiny
KHLOW2008
  • EXPERT
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Have the battery and alternator charging checked. The belt noise could be a fault with the harmonic damper and this can result in improper charging.

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Tuesday, September 18th, 2012 AT 7:46 AM
Tiny
DRMALOY
  • MEMBER

Engine turns over fine its not the charging system. When it fires up it shakes the engine and now barely reaches 500-600 rpm
going to do a fuel pressure test today and see if there is a leak.
Will the fuel pressure regulator hold vacuum. Or if it leaks is there a problem with it.

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Tuesday, September 18th, 2012 AT 4:47 PM
Tiny
KHLOW2008
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It shuld hold vacuum. Idling speed is to low. Have the throttle body and IAC cleaned.

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Tuesday, September 18th, 2012 AT 5:57 PM
Tiny
DRMALOY
  • MEMBER

Did A Fuel pressure test and it seems good.
Cleaned the throttle body with some spray. I got the car to stay idle but it has a slight surge. Any attempt to give it gas it surges more and shakes but will only get to 1000rpm and then want to die. It idles with the air mass sensor removed. At idle I put it back on and it died. Any ideas, thanks

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Tuesday, September 18th, 2012 AT 7:26 PM
Tiny
KHLOW2008
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Did you check for trouble codes?
Is the Malfunction Indicator Light indicating?

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Tuesday, September 18th, 2012 AT 8:09 PM
Tiny
DRMALOY
  • MEMBER

Engine light has not come back on. Had a p1506, & changed idle air control and cleared it.

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Tuesday, September 18th, 2012 AT 8:24 PM
Tiny
KHLOW2008
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Was it a new or used IAC that was replaced?
Are you still having difficulty starting?

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Wednesday, September 19th, 2012 AT 1:09 PM
Tiny
DRMALOY
  • MEMBER

It was a new IAC. It starts but has erratic idle and you have to hold gas pedal sometimes to get it to start. Unable to rev engine at all. Any ideas.

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Wednesday, September 19th, 2012 AT 7:33 PM
Tiny
KHLOW2008
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No trouble codes with symptom description. I can only think of the following that can cause that.

1. Throttle Position Sensor.
2. Mass Air Flow Sensor.
3. Valve clearances.
4. Engine Coolant Temperature Sensor.

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Wednesday, September 19th, 2012 AT 8:11 PM
Tiny
DRMALOY
  • MEMBER

My fuel pressure test was 60_70 specs are 35_45psi
I am going to redo pressure test to make sure and check vacuum to fuel regulator
Should the fuel regulator hold vacuum with key off.
Will also check throttle position sensor and position.
Changed engine coolant temp sensor and when starting cooling fans came on
Immediately. Is that normal?

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Thursday, September 20th, 2012 AT 2:51 AM

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