b2600i 4x4 misfire and low power
 

Bought a 1993 b2600i 4x4 from a used carlot. 141k miles. Test drove it, only up to 35mph (in-town. It ran a bit sluggish. I told the dealer it felt as if the timing was bad. Took it home, dad hit it with a timing light. According to him timing was retarded. However, still lacks power and backfires if it gets too much gas. Have to rev to about 4200rpm just to get out of 3rd gear. Then there is very little power from 4th.

So far I have changed the plugs, fuel filter, pre-filter in tank. The distributor is new with new plug wires. There was a rather large amount of rust colored sediment in the fuel filter. I installed a universal clear filter to monitor the gas coming into the fuel rail. Removed the intake manifold and checked the injectors. The plastic caps on 2 of the four injectors are cracked. Not falling apart, but has very noticeable cracks. Likely due to heat.

I cleaned the screen on the injectors with some denatured alcohol. Blew them out with the compressor.

Still no change.

I have the Haynes manual but it is focused more on the 2000/2200. Nonetheless, it is still very useful, but it does not mention an egr or vacuum advance. So, it must be an electronic advance. Yes?

I cannot find clear reference as to whether this has an EGR valve. Does it?

I am going to test all solenoids tomorrow but as far as I can tell most if not all the systems appear to be in proper order. The check engine light does not come on. It's blowin through fuel like crazy. It idles pretty nice, although a little noisy. Personally I think the previous owner was a numbskull for drilling 2 1/4" holes in the muffler.

If any of you awesome mazda nuts could give a hand in bringing this sweet little truck back to life you'd be doing a great service. I need this truck fir school this winter.

Thanks guys!

Also, when looking at the distributor there appears to be a nipple for a vacuum hose. The distributor does not have vacuum advance, so is this a hose I should be concerned about?

The distributor does not sound correct. Might be a distributor from an older model. To set the timing you must jump grd and ten with a wire in the little black test box under the hood. That takes the computer out of the equation. Those trucks are prone to MAF failure also. A lot of rust is bad. Add some Marvins Mystery Oil to the gas tank to lube the pump.

Thank you for the reply,

Did some testing today. Used the timing light to measure pulse on each plug wire. Cylinders 1 and 2 fire consistently at idle. Cylinder 3 only fired intermittently and cylinder 4 didn't fire at all. I pulled the cap and rotor and cleaned the contacts. Reassembled and now cylinder 3 fires almost consistently. Cylinder 4 fires occasionally at idle and starts firing more when I hit the accelerator.

At this point I am inclined to think that it is an ignition coil problem. Can I get an amen?

Also, I have been having one hell of a time figuring out the specifics on proper timing adjustment. I know it's supposed to be 5° BTDC @ 770 rpm. My manual says something about grounding the green test plug on the right side of the engine. Does that mean passenger side?

Second to location how is it meant to be ground? Simply to a ground on the engine? Or ground to timing light?

It's probably simple but I get so smart sometimes simple makes me look stupid, LoL.

Thanks for the help!

Yes, passenger side, the single pin green connector. Use a jumper wire to ground it. This bypass's the computer so that does not keep trying to adjust the timing while you set the base timing/idle speed. That is however the wrong distributor for that truck.

Well it's fixed. Took it back to the dealer I got it from and apparently the #3 & #4 plug wires were reversed. Not really sure how I missed it. I checked firing order and I thought it checked out. But hell, Ocams razor got me!

Thanks for the help guys!

This is a pretty zippy little truck. Time to hit some trails!

Great. Sometimes it takes "a second pair of eyes" to note something "obvious".

I have B2200, painted the numbers onto the distributor cap.

Be aware with a B2600i that the distributor rotor can go on the shaft three different orientations. And only one will be correct, and work. Don't blame me, I didn't design it !

I think it was the rotor. Cause it still looks like the wires are still in the same order. Pretty hard not to automatically place the by their successive lengths. 1-3-2-4 smallest to biggest placement on wires and, done. But it's cool, fixed and that's all I care about