Just bought a new 4.0L

[Firebird]

Hi everyone, I just bought a 94' Mazda B4000. It has the same engine as the ranger, so I wanted to ask some questions here. First off, this thing wont rev over about 3000rpms, any idea why? It feels like it just wont get any fuel past that point.

Second question, is there a write up, or does anyone have a walk through on changing the gears in the front axle?

Thanks for any help, I look forward to any help I can get.

[Wicked_Sludge]

welcome to the boards.

more then the engine is the same between your mazda and a ranger, if you lifted the body off of both, you wouldnt know which was which.

what does the engine do when you try to rev higher then 3k? does it sputter and stumble? or does it just rev up to 3k and stay there?

setting up a ring and pinion isnt as simple as throwing the gears in and going. it takes some special tools and special skills to know how to set them up properly. HERE (http://www.pirate4x4.com/articles/tech/billavista/Gear_Setup) is a good article on R&P setup.

[Firebird]

Thank you very much for your reply.

As for the rev problem, it depends on the gear, in 1st it just revs up to 3K and stays there, same in with the clutch in. In 2nd and higher it does the same thing but stumbles a little. Any ideas?

Thank you for the article on the axle, looks like I better do my homework before I jump into it.

[Wicked_Sludge]

as always, start with checking basic tune-up items. check spark plugs, wires, and fuel and air filters. you might try pulling codes on it. even if the CEL isnt on, there may be codes stored in the PCM that could help point us in the right direction.

[woodyedmiston]

You might try something real basic first - pull the hose to the air cleaner (air channel) off and see if you are getting full open throttle when you depress the pedal.

[MAKG]

The best ring & pinion setup article I've seen is Randy's. http://www.differentials.com/install.html (http://www.differentials.com)

They really are all just about the same. And it is NOT easy. You have to be really anal about the settings or your gears won't last.

The easiest way to swap gears in the front is to swap the whole front pig.

[Bob Ayers]

Thank you very much for your reply.

As for the rev problem, it depends on the gear, in 1st it just revs up to 3K and stays there, same in with the clutch in. In 2nd and higher it does the same thing but stumbles a little. Any ideas?

Thank you for the article on the axle, looks like I better do my homework before I jump into it.

The PCM has a rev limiter, as well as a speed limiter. If you are driving, the RPMs will go higher than 3K, but not sitting still with the clutch pushed in.

[fastpakr]

The PCM has a rev limiter, as well as a speed limiter. If you are driving, the RPMs will go higher than 3K, but not sitting still with the clutch pushed in.

Since when does the ECM limit engine speed on a manual transmission vehicle based on the clutch safety switch? It certainly doesn't on my '94. It may on an auto in neutral/park, but not on the manual transmission vehicles.

[MAKG]

The best ring & pinion setup article I've seen is Randy's. http://www.differentials.com/install.html (http://www.differentials.com)


OK, I take this back.

Randy's is definitely usable, but I read the Pirate article, and it's very well written and the figures are amazing. It particularly shines with the gear marking interpretation. Randy's discusses this in detail, but the figures are not easy to read.

[Bob Ayers]

Since when does the ECM limit engine speed on a manual transmission vehicle based on the clutch safety switch? It certainly doesn't on my '94. It may on an auto in neutral/park, but not on the manual transmission vehicles.

You may be correct, I thought the rev. limiter came into play with the clutch disengauged also.

[Wicked_Sludge]

You may be correct, I thought the rev. limiter came into play with the clutch disengauged also.

its a moot point because a '94 doesnt have a nuetral rev limiter anyway. the rev limiter is about 6500 on his truck, whether its in motion or not.

[Bird]

You may be correct, I thought the rev. limiter came into play with the clutch disengauged also.

No Bob, you were correct - the later models all have a 3000 rpm rev limiter when in park (auto) or neutral (auto/manual). A good tuner can take it out, but for a daily driver, why bother.


Bird

[Wicked_Sludge]

yep, starting in '95.

since this is a '94, it doesnt matter.

[Firebird]

Thanks everyone for your replies. I actually bought the truck last night, so I didn't get to test it out very well. Tonight I took it for a drive and noticed it would rev all the way to redline as long as i didn't go over about 3/4th throttle. So I figured maybe the throttle position sensor might be bad. Sure enough, I unplugged this:
http://picsorban.com/upload/dsc00044.jpg
Which is what I thought was the right one, and the truck revs straight up in gear now at full throttle. Does anyone have a part number for this? What are the adverse affects of just leaving it unplugged? It feels a little sluggish now.

For the gear question, I have an almost full front axle sitting in the bed with the original gearing, please look at these pictures.
http://picsorban.com/upload/dsc00046.jpg
http://picsorban.com/upload/dsc00049.jpg
http://picsorban.com/upload/dsc00047.jpg

It has 4517 stamped on it. It looks like the center differential could be disconnected from the axles and main housing which acts as the cover, and be directly bolted into my new one. If so, this would be great so I wouldn't have to set up the gear and pinion myself.

Thanks again everyone for your help, I look forward to ANY info I can get.

[Wicked_Sludge]

good call. thats a bad throttle position sensor. any of your local parts stores should be able to get one for you at a reasonable price. unplugging it should have tripped the CEL...which means your truck is now running in open loop. it'll hurt your power, mileage, and overall dirveability.

your right about the differential being removable from the main housing. thats the easiest way to swap in new gears. you need to match them with the gears that are already in the truck, however, or else your 4wd will be very much useless. if you have the passenger side beam that matches the drivers side one (pictured), then it should have a large plastic sticker on it that will tell you the gear ratio. if not, you'll have to pull the diff. off and count the teeth.

to determine the current ratio in the truck, you can read the axle code off the drivers door sticker and compair it to the codes in the tech library.

[Firebird]

good call. thats a bad throttle position sensor. any of your local parts stores should be able to get one for you at a reasonable price. unplugging it should have tripped the CEL...which means your truck is now running in open loop. it'll hurt your power, mileage, and overall dirveability.

your right about the differential being removable from the main housing. thats the easiest way to swap in new gears. you need to match them with the gears that are already in the truck, however, or else your 4wd will be very much useless. if you have the passenger side beam that matches the drivers side one (pictured), then it should have a large plastic sticker on it that will tell you the gear ratio. if not, you'll have to pull the diff. off and count the teeth.

to determine the current ratio in the truck, you can read the axle code off the drivers door sticker and compair it to the codes in the tech library.


Thanks for your input. It did trip the CEL light right away. I will try to pick one up this weekend.

As for the diff, I had no idea it would be this easy. The truck was previously in an accident that bent the front driver side control arm, and rather than replace that they replaced the entire front axle, but with the wrong gear ratio. The one in the bed that I posted pictures of is the original. I looked at the page in your signature and saw this http://memimage.cardomain.net/member_images/10/web/526000-526999/526265_73_full.jpg
how do I strip it down to this point? Can I do this with the front axle still in the truck? I just looked at it but didn't see a way to pop the axles out. Is there a write up to do it this way, or can you walk me through it? I very much appreciate the info, I bought this truck to be my 4X4 winter truck(I live in colorado) and as a good work truck that can off road as can take on hunting trips.

I got it pretty cheap, but it defiantly needs some work. This is my first ford(ive been a GM guy until now) and I am kind of lost.

[Firebird]

Edit: Didn't mean to double post.

[MAKG]

Unplugging the TPS puts the computer into limp mode which can mask a large number of problems, many of them unrelated. CELs can be tripped by wiring (very easily). Confirm the TPS is bad. It's just a standard potentiometer. You should get 0V at one pin, 5V at another (both all the time), and a varying signal on the third. Open the throttle and make sure the signal is smooth and never drops out. If it passes the last test, the TPS is good. If it fails either of the first two, the fault is in wiring (even if it also blows the last test).

Voltage tests should be performed fully assembled. Probe the wires with straight pins and be very careful not to short them together.

[Wicked_Sludge]

getting the differential out of the truck with the axle beams in place is possible...but not very much fun. you have to remove both spindles. once you crawl under the truck, you'll probably see what needs to be done. if not, i can give you more exact directions.

if you plan on keeping the truck for a while, you might consider getting yourself a chiltons manual for it. it'll help you out with a lot of mild/moderate repair jobs.

[Firebird]

getting the differential out of the truck with the axle beams in place is possible...but not very much fun. you have to remove both spindles. once you crawl under the truck, you'll probably see what needs to be done. if not, i can give you more exact directions.

if you plan on keeping the truck for a while, you might consider getting yourself a chiltons manual for it. it'll help you out with a lot of mild/moderate repair jobs.

If you could give me instructions, that would be very appreciated. I have done much more intensive auto projects, but I am pretty new to trucks and have never done much with drive lines besides replace a few clutches.

I can see most of what needs to be done, but only owning f-bodies untill this truck, everything looks completely foreign. I am looking to get it done this Saturday, but really don't want to dive into it blind like I do most projects.

I will have to get a chiltons, but my local auto parts store didn't have one, so I resorted online and got much better info.

While not pretty I am going to have to depend on this truck, and snow is coming soon in Colorado so I really need to get the 4WD up and going. Thanks for any help, again.

[MAKG]

If time is an issue, don't change the gears until the snow is over.

Or remove the front pig and rear end and take both to a rear end shop for setup.

You do know you have to do front and rear at the same time if you want to use 4WD, right?

[Firebird]

If time is an issue, don't change the gears until the snow is over.

Or remove the front pig and rear end and take both to a rear end shop for setup.

You do know you have to do front and rear at the same time if you want to use 4WD, right?

I dont have to change the gears, just the front diff. The back is stock, the entire front axle was replaced after an accident with the wrong gear ratio, but when I bought the truck he sent the entire original front axle, including everything that is bent that has the diff in perfect condition along with it. I am just looking to change that out because the thing is undriveable in 4wd, and I really need that for work.

[MAKG]

Oh, then just swap the front pigs. Much easier that way.

Pick up a couple of old manual hub nuts (junk) off a Dana 35 or Dana 44 and thread them onto the spindles so you can whang them off with whatever is handy (I use a hand sledge) and not damage the spindles.

It's not too hard to remove the front pig. Messy and not kid-friendly (swearing), but not THAT bad.

[Firebird]

Oh, then just swap the front pigs. Much easier that way.

Pick up a couple of old manual hub nuts (junk) off a Dana 35 or Dana 44 and thread them onto the spindles so you can whang them off with whatever is handy (I use a hand sledge) and not damage the spindles.

It's not too hard to remove the front pig. Messy and not kid-friendly (swearing), but not THAT bad.

Anywhere I can find a walk through? Unfortunately I have the auto locking hubs, but I could probably pick up some manuals from a junk yard for this. Maybe a second set to put on it for when its done. The only axle I have worked on is a chevy 12 bolt, and this thing is completely greek to me.

[Wicked_Sludge]

from memory:

first, remove spindles:

1. remove front tires, hubs, brake calipers. remove the plastic cam which is part of the auto hubs.

2. use magnetic pickup tool to remove pin in channel of spindle. remove spindle nut. pull rotor and bearings off spindle.

3. remove 5 spindle bolts. figure out how to remove siezed-on spindles (mikes idea is a good one).

second, remove axles:

1. drivers side will slide right out through hole in knuckle.

2. for the passenger side, you'll need to snip one of the metal clamps that hold the slip yoke dust boot on and pull the outer axle out through the knuckle (the inner is held on with a c-clip inside the diff.).

third, pull the diff:

1. undo front driveline.

2. undo diff. bolts and loosen pinch bolt. diff should pivot (it'll be stuck to the axle beam with silicone) out of the way, then slide off the pivot bolt. you may need to remove the c-clip and inner passenger side axle before you can completely remove the diff.

mike, fill me in if i missed anything.

[MAKG]

Nope, the only thing missing is step 0: buy a Haynes book.

You only need the spindle nuts, not the hubs. Dana 35 manual locking hubs are somewhat hard to find in the junkyard (though I just scored a pair on Saturday). Dana 44's less so; the NUTS will fit, but the hubs won't.

Banging on spindle nuts will destroy them. They MUST be manual type because the auto nuts are not flat (and there is only one of them per side).