rough idle any help is appreciated.

[slammedmazda]

i have a 97 mazda b2300 4cyl. if u let it idle for about 10 minutes it will start missing really bad. sometimes while driving it will do the same and barely pull its self then it goes away. i replaced the timing belt and the cam was out of place by 2 teeth. after i did that it was significantly better. actually pulled its self down the road. but if u pass someone and hold it floored for a few seconds after u let off it misses real bad like it is getting to much fuel. if u hold it floored at about 70 it quits pulling for a second and starts to again. i know this thing isnt fast at all. i just think it should run better and not act so funny. idk if this stuff links together or if it has multiple problems. where should i start?

 

[MountainMike]

Did you check you plugs/wires and clean you MAF?

Sometimes it is just simple things you overlook.

 

[modelageek]

as MountainMike said. if you dont have an codes or other symptoms. I would start with the easiest maintenance issues and work my way thru it. Air filter, pcv, clean maf, clean iacv, clean throttle body,fuel filter, run techron thru it, replace plugs and wires with Motorcraft parts..look for broken vacuum lines/leaks, etc. I did the airbox mod on mine (takes 10 mins) and it helpd out some.

*it would not hurt to do a fuel pressure test on it at the fuel rail. should be about 40

 

[slammedmazda]

thanks guys.


it throws lean codes all across the board. so that means to much air. i have fixed a couple air leaks. iac valve was leaking really bad and a few vacum lines where dry cracked replaced them and new gasket on iac valve helped. base timing is suppost to be at 0 and +12 for leading and trailing. not sure on order. thats with the plug connector pulled on fire wall. but mine is at -12 and 0. with the plug conector in it makes 0 and +12 each tooth on the crank pulley is 10 degrees. i belive the timing is off one tooth on the crank. i could be right or wrong. i get my info from ondemand5.com


im gonna recheck timing belt marks and see what happens then. i have sprayed break clean on all the intake gaskets and vacum lines becuase if there was a leak it would rev a little and hear idle change nothing is leaking now.

 

[slammedmazda]

what would cause it to rev to 3000 rpm when its cold first start up. after that it goes down to about 2200 2500 until it warms up. idles at about 9 to a 1000.


and i have replaced plugs wires cleaned maf i havent checked fuel pressure but i belive its a timing issue becuase i have checked it with a light and it has no power curve jus pulls through. acts as if it has no timing advance.

 

[slammedmazda]

help is greatly appreciated

 

[94twodoor]

Sounds like my issue. Check the vaccuum line going to the intake. Make sure no cracks or dry rot.

 

[slammedmazda]

i know this thing isnt gonna be fast. but truthfully it barely pulls itself down the dam road. timing is dead on and has no advance when u rev it. maybe pcm?

 

[slammedmazda]

it throws bank 1 lean code. fuel pressure is at 40. at an idle

 

[locknar]

I don't have specific experience with your truck but basic design says that the ECU checks the temperature at start, if the engine is cold it goes to idle mode and increases gas. Idle typically increases. Once the engine is at operating temperature it goes to run mode monitors air/fuel mixture. So long story short check the temperature sensor, not the one that goes to the gauge but the two wire one that is part of the ignition.
If it is stuck in a cold loop you will never get the right readings. There is usually resistance values based on temperature for testing or you can say for $22 the hell with testing.