explorer engine in mazda b4000

[2stroke]

Well with my 94 explorer pretty well gone for road use, and my 2002 mercury cougar being a car, I traded the cougar for a good condition 94 mazda b4000. The car had minor transmission problems, and some other issues, but was otherwise perfectly reliable. This truck has a perfect transmission, but runs a little rough, but is also perfectly reliable. Plus I have the explorer for parts. Here's the thing, the truck engine was replaced with an explorer's engine which has 160,000 miles on it. The stock one was the same thing anyway, so I figured I would ask here.

Anyway, here is the problem as I know it now. At idle it has miss, and it is fairly consistent. Whether hot or cold, it idles on 5 cylinders, and rarely clears out. When cold, the engine almost always has a miss when driving. When the engine warms up, it starts to clear out. Sometimes it runs great for a minute, then, sometimes it misses and clears out at above 2000 rpm, sometimes it always misses. It has a normal idle rpm, never stalls, and otherwise runs good. Gas mileage is poor. I'm not sure what it is, but I have about 120 miles on it, and the tank is 2/3 gone. My guess is around 12 mpg. What I do know is that there is very possibly a vacuum leak, and sometimes I can hear it, but never at idle. It doesn't seem to affect how it runs when I hear it. The EGR was deleted, and I have a feeling that vaccume sound I hear could be the egr trying to open. It still has the valve and other components. The pipe rusted off, and both ends were blocked off. An aftermarket air intake was installed, and I may put it back to stock. I don't see how it would do anything as it's not installed as a cold air intake. Spark plug wires are new, coil is new, spark plugs are new, but with the NGK iridium. I would much rather have standard NGK $2 a plug ones, but I don't see how iridium would cause a problem like this.

The check engine light has come on. I was told it was for an O2 sensor. When I put in my radio, I disconnected the batter, and all memory was erased. The check engine light has not come back since for me to check it. I suppose now would be a good time to ask that these trucks can uses the "paper clip" method to check codes just like an explorer. I have thrown around the idea of a dirty fuel injector, but I would think that would cause a totally dead cylinder.

I guess the real question as I wait for the check engine light to come back on is could an 02 sensor (or both) cause a problem like this?

Also, as cheapo as this sounds, what do you guys think of "universal" O2 sensors. I am at a very poor point in life right now, and cost is a huge factor. I can't get OEM, and even parts store bosch is $50 each. On Ebay, I can bet bosch for $25 buck each, and I may go that route. Also on the bay, I found a brand I have never heard of for $13 each. At that price I could easily replace both.

 

[natenkiki2004]

The O2 would only cause problems when the engine is warmed up. It's a heated O2 sensor but still takes time to heat up and until that happens, the computer ignores it's input. Personally, I would only use Motorcraft for that part. I've heard bad things about Bosch and the sensor is enough of a pain in the ass to replace that I would only want to do it once. I picked up one for my 1991 on eBay, part number F4UZ-9F472-C. There's Ford part number decoders online but the jist of it is that the F4UZ means it was made in 1994 and the 9F472 is the part number, which you can get off your old unit, but that's probably it.

I doubt the plugs are the problem, NGK is good and the iridium would just mean they would last longer. Did you get new wires as well?

 

[2stroke]

Yep, new wires. I was just reading something about disconnecting the MAF sensor. If it started running better at that point, it would most certainly be some kind of sensor. I am still not ruling out a fuel injector. I think my next step would be to put the stock air intake back on and look for vacuum leaks.

 

[natenkiki2004]

A malfunctioning sensor can be worse than none at all, that's the theory behind disconnecting them. That takes little time and is free.

 

[2stroke]

I think I can pretty much rule out fuel injector at this point, but might run a fuel system cleaner through the gas just for good measure and see if it makes any difference. The engine does clear out sometimes, and runs strong when it does. I just don't see how a fuel injector could cause this issue. I'm about to go unplug the MAF to see if it makes a difference. I still think a vacuum leak is high on the list, and very possibly around the EGR. I simply haven't gotten around to trying to find one yet. I ended up getting surprisingly good gas mileage for how it is running. I got about 15 mpg highway. I do expect 20 when it is running good. The only bad thing about that is you can't just swipe the pipe to see if its running rich or lean. My guess would be just rich enough to cause a miss. The check engine light never did come back on, and I have not checked to see which cylinder is misfiring. If I don't find a problem in 2 weeks, I'll have access to all my tools again, and can compression test it at that time. I doubt its an internal problem though, as it runs reasonably strong as it is, and very strong when it clears out. That and the engine does not make a tick or a knock at all. I even went through with a screwdriver listening to the engine, and it sounds smooth.

 

[2stroke]

So I unpluged the MAF and started it and noticed no difference. It did throw an engine light for that right away, however. The weird thing is when I went to check it, the only code it gave me was 522, and as far as I can tell, that just means it wasn't in park, or in my case, the clutch wasn't in. No code for a disconnected MAF.

I'm really not sure how I should look at this. I was under the impression that unplugging the MAF would put the engine in safe mode, and disable all sensors. Since there was no change, I guess a sensor is not the problem. Either that or I need to run it longer, or maybe actually drive it.

I guess the next step is to get under the hood with some spray and look for air leaks. I'll wait for daylight for that.

 

[2stroke]

I didn't have carb cleaner with me, but I got in there as good as I could with electrical cleaner. I assume it would act the same as carb cleaner. I checked everywhere I could, and paid special attention to the upper intake manifold, and around the egr. I could not locate any vacuum leaks at all. One thing I did notice, is the EGR might not be properly deleted. Where the tube goes into the engine is blocked off, but where it comes out still appears to be intact. All the other components are still there including the EGR valve, part of the tube, DPFE, etc. I'm wondering if this may be the problem. There is no exhaust at all coming through the pipe, so its possible there is something blocking it off. I am wondering if I should just take off the tube/valve, DPFE, and put a plate to block it. The DPFE is still plugged in, but the tubes are not hooked to anything, and no engine light has come on for it.

I also pulled the vacuum line for the fuel pressure regulator. It had a negative affect on the engine, it seemed like it made it run richer, and there was no fuel in the line that I could tell. I would think this means that is working.

The one time I want the engine light on, it does nothing. I guess there isn't anything else I can do but drive it until it does. Any other ideas of things I can check quick? It just seems so strange how it can clear out and run great for a few seconds until I shift gears. It is just so inconsistent. The only consistent thing is that it runs on 5 cylinders 99% of the time at idle. It would be nice if it was just a restricted fuel filter, but I don't keep a fuel pressure tester, or those quick disconnect tools with me, so that has to wait.

 

[2stroke]

After thinking for a little bit, what would the chances be of this being an electrical problem? I know the wiring is not perfect in this truck, it took me a while to figure out why the blinkers didn't always work. It turned out to be a bad ground. It would make sense, but I still don't see how a miss like this doesn't throw a CEL. Its still not a bad idea to follow the wiring and clean up/grease all connections, including sensors and grounds.

 

[2stroke]

Ok, so I finally got some tangible evidence. I took codes and here is what I got. The only weird thing is I thought I saw 22 in there, but I might have just been seeing things. I was taking codes by the check engine light method. What I thought I saw was 114, 552, pause, 114, 552, pause, 22, 157, 332, pause, 157, 332, but that wouldn't make much sense to me. I must be getting tired.

114 (O,R) IAT sensor out of range - IAT
552 (O) AIRB solenoid/circuit failure - Solenoids
157 (R,M) Mass Air Flow signal is/was low or grounded - MAF
332 (R,M) EGR did not open/respond during test or if memory code, did not open intermittently - EVR or PFE

332 was expected, as I found that the EGR valve was still connected, and I pulled the vacuum line off. Strangely doing this has made the biggest difference in how it runs of the things I've tried so far. I plan on doing a proper EGR delete next weekend. 114 and 157 I kind of figured would come up as the guy before me put an aftermarket air intake on it. I'm not sure if its the intake, or the sensor is actually bad. I plan on putting the stock intake back on saturday, also I have a spare MAF sensor in the yard to try. As far as I can tell, the IAT sensor is right next to the MAF sensor in the same body correct? I'll just swap the whole thing and see if it does anything. The only thing that has me confused is 552. I don't even know what an AIRB solenoid is, and there is not a lot of info on the internet for it or code 552. I'm hoping it is a wiring problem, which will be solved when I go through the whole wiring harness, and all connections. Anything you can tell me about code 552 would be greatly appreciated.

 

[2stroke]

Nevermind, I read it wrong, and it was code 522 which basically means I had it in gear when I tested it. So it all comes down to the MAF and IAT. I would be really pleased if this was the problem. Isn't it great when technology comes though?

 

[2stroke]

It seems I am the only one adding anything to this topic, which is fine. Sometimes I just need to write it down to really think about the problem. Plus its there If I ever need to go back and see what I have thought of, and tested. So here is a different direction. A warped valve. Its kind of worst case scenario, but I put my hand on the pipe, and I was almost sure I felt some kind of suction. It wouldn't make sense with how the engine acts, but I have seen crazier things. I guess the only thing to check would be compression without and with oil, and compare the results. Still, I would think it would cause a completely dead cylinder much like a fuel injector. The engine does seem to run good at times, especially under low load. Often 2nd gear it runs good, but then I shift, and its has a miss again. Its not anything in the driveline, as it relates to rpm, not speed. Plus It misses almost constantly at idle, and I can hear it as I accelerate.

 

[2stroke]

As an update, I have done the things I mentioned. I took a good MAF, cleaned it, and put it on. Put the air intake back to stock. Properly deleted the EGR. Then I tried to clean and grease the wiring. Half way through I was interupted, and when I came back, I hooked something up wrong. I tested for hours before finding the problem. After all that, it still runs like it used to. The check engine lights are gone, and if anything it got worse. Now it misses almost all the time. I figured out what cylinder isn't firing, and pulled the plug. To me it looks like it is running lean. At this point a Fuel injector is the prime suspect. I plan to clean all of them this weekend. I just hope its clogged, I don't really feel like buying a $40+ injector. I do have a parts truck I could steal one from, but that would mean completely disabling that vehicle. The parts truck runs fine now, and I use it around the yard. Maybe I should have kept trying to figure out the problem with it, and got it road worthy. This Mazda is turning out to be a real pain. Now the Transmission is giving me problems. I will change the fluid as soon as I can, and I hope its not a bearing or slave cylinder. Mine sometimes shifts absolutely perfect, and sometimes I cant get it into gear at all. When the engine is off, it always shifts fine. It is not using fluid, and pumping the clutch does nothing. I noticed that when at a complete stop and it wont go into 1st, I can usually put it in reverse and quickly into 1st fine. Maybe someone can give me some hope that its just old or low tranny fluid.

 

[2stroke]

So now I am really confused. I replaced the bad fuel injector, as well as cleaned the others and put on new o rings. The first thing I noticed was the fuel injector on the bad cylinder looked ok. I got it back together and wouldn't you know, absolutely no change. I double checked everything, I even tried changing around the wires, and no go. Cylinder 1 is still completely dead. I just don't understand. I can hold a screwdriver up to the injector and hear it pulsing, so its getting fuel. I haven't put a compression tester on it yet, but it would at least fire sometimes. If it was a valve, the engine would make noise, or the exhaust would have suction. All that is left is ignition. This is where I am stuck, and hope someone can point me in the right direction. Without a CEL, I don't have much to go on. I plan on swapping coils today with my parts truck. Other than that, I guess I'll find all the ignition parts I can and start swapping.

 

[natenkiki2004]

Did you ever fix the IAT? That will cause issues in any running condition.

You can test the coils with a multimeter but the way it's designed, if 1 dies, another goes with it. There's 3 pairs in the coils. It shoots through 1 spark plug, through the block and out the other spark plug back into the coil. It's a waste spark system. It still could be an ignition issue. A broken plug wire that's arching to ground or a broken ceramic on a spark plug, both of those issues would still keep continuity in the ignition circuit and not kill another cylinder. It would probably be a good idea to pull all the plugs and wires, take a look at them and ohm test them.

A compression test would tell you a lot, whether or not you're wasting time chasing down this issue.

It's possible that the intake for that cylinder is leaking. There's 3 gaskets on the way down and any one of them could be toast. The lower intake gasket is notorious for leaking coolant, I imagine an air leak isn't too far out there.

 

[2stroke]

I'm not sure whether or not I fixed the IAT, and to be honest, I'm not even sure where it is. No CEL has ever came back on for it. I assumed that it was with the MAF. Its not a plug, they are all new again. The one I pulled out of cylinder 1 looked like it was running lean. No deposits, and the electrode was white colored. I replaced the upper intake gaskets, and saw no sign of a coolant leak, and I looked carefully. I never replaced the lower's, but have checked for an air leak in the past. It doesn't use coolant at all. In the last 1000 miles I've driven, it is still right on the full mark in the overflow. One thing I haven't tried is switching plug wires and seeing if the problem moves, but they are new wires, and there is no visible arching. I will give it a compression test tomorrow, but I just don't see how that could be possible at all. With only 160,000 miles, runs strong for only running on 5 cylinders, starts great, engine is silent, no suction at the exhaust. I just can't imagine how one cylinder could possibly have such a low compression that it won't fire at all and yet the rest of the motor runs fine.

Assuming it has spark, what would have to go wrong to have it sparking on the wrong stroke and yet have that coil ignite the other cylinder fine?

I mean this is getting ridiculous now. With all the testing I have done, its still one of 15 possible things? I don't get it. It has fuel, I'll check but I'm sure it has compression, so that leaves ignition.

 

[2stroke]

I figured I should do a follow up to help others in the future. As it turns out, the previous owner was not totally honest. I went back to the beginning and changed out all the plugs for NGK TR55's, my first choice. Other than spark plugs being one of the biggest pains in the butt, it did not take me long to know the problem. By the way, the explorer is way easier to do plugs on than this Mazda. The real problem is the AC crap is in the way of cylinder 3. It took my a couple feet of extensions, a wobble socket, and about 30 minutes just for that one cylinder. 5 of them looked fine. Cylinder 5 was completely fouled. At that point, I was almost certain of a stuck fuel injector. Strangely, we have had a 94 explorer, 94 ranger, 00 explorer, and now this 94 mazda with a 94 explorer engine. Every single one of them has had the cylinder 5 injector fail, and no others. I have no idea why its a vulnerable one, but it seems like a strong pattern to me. I went to the junk yard and pulled the injectors out of an explorer, and took the best looking one for $10 (I also cleaned it out with a battery and carb cleaner). I also got some fel-pro gaskets, and the cheapest o ring set. so one night I got a few hours and already had the parts. It only took me about 45 minutes to change the injector. It is far from my first time, but it was dark, and -15 F, and I was tired. I got it together, and wouldn't you know it ran great. I found no leaks, it idled fine, and I drove it with no problems. Anyway, the next day after seeing no problem I took it 20 miles on a lake fishing. I spent the night, and the next day I started it to find it pissing gas like no tomorrow on the ice. I drove it to shore with fire extinguisher in hand and parked it. I rode with my dad who I had been fishing with back home to get a couple tools. I found the bad injector, pulled it apart, and sure enough the o ring was all screwed up. I checked the others and they seemed fine, so I put it together, and wouldn't you know, it leaks from another one. At this point I had used all the new o rings, but had a stock one. I pulled it all apart, and again the same problem. This time I used a TON of petroleum jelly on each, top and bottom. I was extra careful when putting the fuel rail back on, and got it back together. This time it didn't leak. The only thing that has me concerned is that technically the fuel rail and plenum gaskets were used three times. Not only that, but I didn't use a torque wrench in the parking lot. I just know that the second time was more than it should have been, and the third time was as tight as I dared to in aluminum. Now it seems to idle high, but I wonder if its the computer resetting after I disconnected the battery. It's not too bad, it idles at about 900 rpm once warmed up, but I might just go back and replace the o rings with good ones (not the cheap brand I got at first), and gaskets. I hate to buy more, but at $10 a set, $5 for o rings, and a 30-45 minute job, its not too bad. There is a couple things I learned in this ordeal I hope others can learn from.

1. these 4.0 seem to have a self destructing cylinder 5.
2. use LOTS of petroleum jelly on injectors. Lube is always a good thing.
3. you should be able to pop injectors in by hand. If you can't push the fuel rail down flush by hand, take it apart and use more lube. Cylinder 1 injector is kind of hard to line up due to the fuel pressure regulator.
4. replacing fuel injectors is easier than replacing one spark plug.
5. when your engine intermittently misses, the spark test is not a valid one to find the bad cylinder. Reading spark plugs is the best way.


Also as far as the transmission, it is ok now. I bled the clutch line a couple times, and it improved it a lot. I also changed the fluid, along with the transfer case. If anyone is wondering, the best fluid you can get for a reasonable amount of money IMO (there is no real "best" in any oil) is Valvoline Maxlife ATF. $16 a gallon where I got it. Its full synthetic, and compatible with a whole heap of ATF types.

 

[RangerX]

This Mazda is turning out to be a real pain. Now the Transmission is giving me problems. I will change the fluid as soon as I can, and I hope its not a bearing or slave cylinder. Mine sometimes shifts absolutely perfect, and sometimes I cant get it into gear at all. When the engine is off, it always shifts fine. It is not using fluid, and pumping the clutch does nothing. I noticed that when at a complete stop and it wont go into 1st, I can usually put it in reverse and quickly into 1st fine. Maybe someone can give me some hope that its just old or low tranny fluid.

I know you updated in a more recent post that you bled it and it's better, I just wanted to mention that the first gear issue you had is very common, and the sometimes shifts good/sometimes not is common too. It's all symptoms of slave issues.
When mine started going years ago, it was seasonal. I had the first gear trouble in the warm months, and when temps went down for the SoCal winter, it would be fine. Took me two years to see the pattern.

 

[2stroke]

Yep, I still suspect the slave. The reason being is it is not 100%, but to me it doesn't need to be. I'm ok bleeding the clutch every couple of months, it only takes a few minutes the way the manual says to do it. When I drop the tranny I plan on replacing the slave, the input shaft bearing, and upgrade those plugs on top to metal. I don't mind leaving a clutch if it looks in good shape. It's not easy, but its not the end of the world to drop a tranny on these, and with the price of clutch plates, I am willing to pass. Is there any slave cylinder that is considered to be best, or maybe some kind of upgrade?

 

[RangerX]

Yes, popular knowledgable consensus here is to only use a slave from Ford. Too many reports of parts store slaves ceiling after a few months.

 

[2stroke]

Its too bad my parts truck (or the one at the junk yard) is not a manual, because I like having cheap parts at my disposal. I got a check engine light today, and got the idle air temp sensor, as well as the coolant temp sensor. Both I can swap from my parts truck, and I know they work. I'll wait a while for that slave, as its not a pressing issue. It doesn't grind into gear, so its not causing damage to the tranny, its just annoying a rare amount of the time. I am waiting for pay day, as I plan on making a big order (well, for me atleast) to rock auto. I want to get the plenum/fuel rail gaskets ($3 from rock auto), new injector o rings (fel-pro this time), as well as a non-AC serpentine belt and a new tensioner. I want to delete all of the AC junk.

I don't think this thread is so much asking a question anymore. Its more or less a build log for my Ford-Mazda hybrid that is some how stock, yet made of many different vehicles. I just thought of a name for my truck, the canibal.