Slow Return To Idle; Engine Runs Rough/Rolling Idle - Mazda B-Series 1997 Workshop Manual

TROUBLESHOOTlNG GUIDE
FT
r - 2
'
Remove PCV valve and shake it.
6
1
Does PCV valve rattle?
- -
SLOW RETURN TO tDLE
Yes Install PCV valve
GO to next step
1
No Replace PCV valve
DESCRIPTION
Englne takes more tlme than normal to return to Idle speed
I Start engine. Disconnect crankcase ventilation hose
1
from the throttle body. Place a stiff piece of paper
over the hose end.
Does vacuum hold the paper?
Is the throttle body free of contamination?
=
page FT-146
- -
ACTION
-
Diagnostic trouble code displayed
Check for cause (refer to Diagnostic Trouble Code
chart)
- -
w
page FT-77
No diagnostic trouble codes tlisplayed
Go to next step
Are any dlagnostlc trouble codes displayed dur~ng
Key On Englne Off, Key On Eng~ne Running or
Cont~nuous Memory inspection?
=
page FT-71
Is air leakage felt or heard at intake air system
components while racing engine to higher speed?
Yes
If yes, check evaporative emission system
=
page FT-160
cap, PCV valve, rocker cover for bolt torquetgasket
- -
~ o / G o t o n - ; x t i i & - - - - -
No
- V e r i f y i t results. If OK, return to diagnostic index to service any additional symptoms
ENGINE RUNS ROUGHIROLLING IDLE ATIDLE
DESCRIPTION Engine speed fluctuates between specified idle
shake
Idle speed too slow and excessive engine shake
INSPECTION
1
ACTION
1
Are any diagnostic trouble codes displayed during
Key On Engine Off or Continuous Memory
inspection?
w
page FT-71
-
-
- - - -
- -
Start engine and let it idle to bring to normal
operating temperature.
Does engine stall or RPM drop with idle air control
solenoid disconnected?
Disconnect vacuum hose from EGR valve and
plug it.
Is drive symptom eliminated?
Yes
I
Yes
No
4
- -
Yes
Does EGR valve seat properly?
-
No
Yes
No
Diagnostic trouble code displayed
Check for cause (refer to Diagnostic Trouble Code
chart)
=
page FT-77
No diagnostic trouble codes displayed
Go to next step
Go to next step
Check idle air control solenoid and wiring harness
=
page FT-147
Check EGR vent on vacuum hose to EGR valve for
obstruction or leak
If OK, replace EGR vacuum regulator solenoid
If not OK, repair or replace vacuum line
Go to next step
Go to next step
Check EGR valve and EGR vacuum regulator
solenoid
=
page FT-158,159