1994 Mazda B3000 high idle - cold.

[Auger]

Recently purchased a 1994 Mazda B3000. Not driven a lot last couple years. Had a hard lifter tick when cold, but once it warmed up, that disappeared. Ran ok, but lacked power.

So, I replaced the following:
MAF Sensor
Throttle position Sensor
Idle Air Control Valve

Disconnected the battery for the whole process. (Over 30 minutes to reset computer).

Now when started cold, RPM jumps to 3100 for a while (scares me). Still ticks, not hard/loud like before, higher/milder tick. As soon as RPM drops to normal, tick is gone. I know its not a carb, but if i tap the gas after a 30-40 seconds, the RPM's drop to 700-800. Nice and smooth running, no ticks. Still lacks power above 45 MPH. Bringing in for tune up, but can't get it seen for a few weeks yet.

I'm wondering if I missed something special I should have done installing those 3 items. Throttle cable is smooth, no sticking.

Any assistance would be greatly appreciated.

Thank you !!

 

[franklin2]

Run it and drive it for a few days. Or start it up and let it run in the yard a few times, turning it off and then starting it again cold. Let the computer re-learn as you have changed some things. I have a battle with these Ford systems each time I change something that affects the idle.

If that doesn't do it, there is always a chance someone has messed with the idle stop screw to compensate for something else. If you suspect this, let the engine fully warm up. While it's idling slow like it should, unplug the wiring plug on the idle control valve. The rpms should drop down very slow. If it just keeps idling like it was with the plug plugged in there are two things that could be wrong;

1. A vacuum leak that is letting air into the engine somewhere or

2. Someone has messed with the idle stop screw on the throttle body.

If you are confident you do not have a vacuum leak, with it idling slow and the IAC unplugged, turn the idle stop screw back till the engine is idling very slow, barely running. Then plug the connector back in, it will rev high and then you have to do the start and stop several times for the computer to relearn again.

 

[RonD]

Maybe throttle plate is sticking a bit

Tap gas pedal a few times BEFORE cold start

 

[Auger]

Thank you both for the fast replies. I will give both suggestions a try. Since it's been sitting a bit, I think it just needs a good driving. I will be adding seafoam in the tank on my next fill up. Will you keep informed on progress. But being it's 11F outside, gonna wait til I get warm.

**edit** Was real hard starting cold. When it finally started, it went to 2100 RPM, then slowly back down to 700-800 (20-30 seconds). Smooth idle.

 

[Auger]

Update from mechanic. Did a tuneup, replacing plugs, points, etc. Eliminated a misfire (didn't know I had). 5 cylinders compression 170. #4 cylinder @160. They suspect the cause of the high rev @startup to be a bad ECM. Parts for this thing are almost impossible up here.

After further inspection it was determined I got screwed, bad, and not to spend another penny on this thing. Guess it was sitting in the Alaska elements longer then I was led to believe.

Final solution is to drive it til it drops and don't spend any more time or money on it.

 

[RonD]

Well at 29 years old.................

You generally don't get new computers for a 1994 Ranger/Mazda, just replace the 3 capacitors inside computer, easy to do if you or a friend can solder
The 3 blue capacitors seen in this picture: http://www.auto-diagnostics.info/ford_eec_iv

They are not always in the same place as above, and different values are used so you need to open the computer and look at each one and get the uF and V(volt) values, and remember which side is NEGATIVE, has the line, so take pictures

Must match the uF exactly
But V can be higher, but never lower

16uF 20v can be replaced with 16uF 50v, but not 16uF 10v