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1994 b4000 idle/rev issue


Jothomo

New Member
Joined
Apr 4, 2014
Messages
1
Reaction score
0
Points
0
Vehicle Year
1994
Make / Model
Mazda(ford)
Transmission
Automatic
1994
Mazda b4000
4x4
216,xxx

No mechanical issues other than a leaky break hose and one I can't figure out, on occasion when stopped or on neutral the rpms jumps and the engine revs, like if the brake weren't depressed or it was out of gear it would lurch forward, like...vuh! Buhbuhbuhbuh vuh! Buhbuhbuh and so on. What causes this and how do I fix it
 


Rock Auto 5% Discount Code: F9A1A579ACFAD1: October 1st, 2021

RonD

Well-Known Member
Joined
Jun 2, 2012
Messages
20,128
Reaction score
3,951
Points
113
Location
canada
Vehicle Year
1994
Make / Model
Ford
Transmission
Manual
Does the Check Engine Light(CEL) work?
Comes on with key and then goes off.

If it is working I assume it is not on and there are no "codes" to check.

Could be an intermittent vacuum leak.
Leaking power brake booster.
Dirty PCV Valve
Leak in EVAP system would probably turn on CEL

Cleaning IAC valve and MAF sensor would be good general maintenance, not sure they could cause this issue but IAC valve could be getting sticky and computer can't hold idle steady.
 


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