b2.6 liter stumbles on acceleration any1 know Y?

seems like when I stomp on the accelerater pedal my truck starts boggin out,but if I barely push the pedal it starts to pick up speed as if any other vehicle would only do if the acc. pedal where depressed. does any1 know what the cause of this might be i have replaced the distributer cap,roter,plugs,wires,fuel filter and trottle body gasket the truck is a 91' MAZDA B2600i 2.6 liter with a 4wd 5-speed Manual Transmission.

gonna say your timing is off. my mazda was doing that same thing, reset the timing and has been working great since then

You need to have a look at the ECU which is located behind the passenger side kick panel. These have a history of the original 2 capacitors on the board leaking and causing a corrosion below them (as it is mounted on the truck) which happens to be the fuel injection circuits, or something to do with them.
Your symptoms are dead on for this.
Disconnect the neg. side on the battery, remove the plastic kick panel, remove the ECU, and pull the steel cover off (4 screws) and have a look inside.


This is the one that was in my truck (1991 B2600i 2WD auto) when I bought it. It's been repaired, but a rough job doing it.......I have since replaced it with a perfect looking ECU I found in the local JY.





Rough repair area......



Here's my pristine one!







If you can, take some good pics with a camera (phones don't do good for this) and post them here........if it has leaked, it may be possible to fix it yourself, or you could have a electronics repair shop do it for you.

just read this post i went out to my truck to my ECU out took the cover off and the cap to the left had corosion under and all around it my truck is smoking white smoke using way to much gas and sounds like it has a miss could this be my problem or one of them

White smoke can also be that its burning coolant. That could be the sign if a bitten head gasket. have you checked your coolant level lately?

yes i checked it this mprning it was i lil low but not bad low

Sorry to bring up an old thread.
But do you know what the blue oval parts are on the ecu? Are they another kind of resistors (cause mine are leaking and the guys at the electronic shop didn't know what they are as well.)
I already replaced my capacitors. Thanks for that info.

Google didn't help much. Maybe I'm using the wrong keywords.

Hey Hollywood, if your talking about the blue device at the top of this picture.......



then it is a Capacitor also. Look at the circuit board and it will have the letter "C" followed by a series of numbers........the "C" designates that is a Capacitor.

Now, there are other devices that are blue also, but they usually lay flat on the circuit board (not always though!) but if you look at the symbols printed on the board, you will see they start with an "R" and that means they are a Resistor.

This got me to thinking.......usually the Electrolytic capacitors are the ones that leak and there are only 2 of them on the board........I think they were just bad caps when Mazda (Mitsubishi really) built them, but who knows......the blue one though is a ceramic capacitor I'm pretty sure and I was thinking, maybe they go bad also?

How about if you put one of those aftermarket alternators on your truck and it's putting out 18-20 volts instead of 13-14 like it should because the internal voltage regulator is screwed!! I've experienced this before......on a 1999 Buick Park Avenue.....it wreaked havoc on the Body Control Module that is basically the ECM for the interior lights/controls in the newer cars.........

SO, the question I am asking you.......have you installed an aftermarket Alternator in the truck? Did the previous owner? Have a look at the alt. and see, then when the truck is idling, check the voltage at the battery with a voltmeter and make sure you have 12-14 volts there.......then increase the engine speed to around 2000 rpm and see if the voltage stays there and doesn't go up above 14 volts..........if it does, get that alt off of the engine and replace it with a better one.

Now, if your sure the blue cap is leaking (keep in mind the position of the ECM when mounted in the truck, as the acid will flow downward with gravity!) then replace it and see what you have then.

(Little blue guys towards the left side)

Like Penitr8r, I'm having the same problem with mine. That's why it's been sitting for 2yrs.

I see from the board it's got R### so it be resistors. I used a continuity test on them, some beep (which i believe is good) and then others have a value (no beep). Should that be of concern?

Already replaced the leaky capacitor. Only had one.

The battery is good. Alternator is still original still good.
Replaced with new fuel pump and new gas tank, fuel filter, new ignition unit in the engine bay (the one connecting to the distributor)

my board

So, you have replaced the C103 (black one on your board) capacitor? The reason those blue resistors to the left of C103 cap. look like they are leaking, is because the original cap leaked acid and it flowed down to their connections on the circuit board.......keep in mind, they are below that cap when it's mounted in the truck.

If you did replace that cap, are you sure you got the polarity correct before soldering it into the board.......those caps have (+) and (-) terminals to them.

Also, look immediately to the left of the printed numbers/letters, "C103".......do you see the 5 traces right next to one another that have been turned a black color? Those are being eaten by the acid that was on the board unless it has been neutralized.....you need to look very closely at that area.....there's another trace above those also that has turned black, right under the printed "D7"........if those are broken, they need to be fixed.......that will be your problem if they are broken!

Last, did you clean the acid from the board when you replaced the cap? If not it WILL continue to eat away at the copper traces on the board.