Hello all, first off, this is part engine and part suspension, so I'm going to drop it in both. Feel free to answer each part accordingly, or admins, to delete whichever thread is not at home. Thank you.

My truck is a 1999 Mazda B4000 (4.0L) v6 4x4.

Three or four weeks ago, I broke down. Got towed home via flatbed. Knew the engine wasn't getting fuel, so I started with replacing the fuel filter. It started right up, so I figured I was good to go. No. Broke down 15 minutes from home. Tried cleaning the iac with Brakleen, didn't change a thing. Got towed again, also a flatbed. Since the truck couldn't start, I had to force the steering wheel to move the tires. Get the truck back home, replaced the fuel pump, started up, drove it back the hour to school. That was Wednesday. Driving to work and class during the week felt a little strange, but I had been driving a family member's Honda CRV, which rides much smoother than my truck, so I figured that that was why it felt off.

Yesterday, I noticed that I had a high idle, around 900 RPM. Figured the truck might just be figuring itself out(battery was disconnected for a max of 8 hours during fuel filter/pump fix). Rough idle didn't go away, and now whenever I start the truck, it shoots up to 1800 RPM, then lessens to 1150 after a few seconds, then eventually goes down to 900, where it stays. So, idle is an issue.

Something else, when I am driving, the truck gets shaky when it needs to jump up a gear. I either need to get it up to the mph threshold where the gears need to catch up, or jam my foot down and force it up a gear. Spark plugs were replaced recently, so I would be surprised if those were the issue. That being said, I heard that cleaning the iac could cause spark plugs to die sooner, but 8000 miles still seems too soon.

When I am driving, I've also noticed that when I hit a bump, the steering wheel jumps more than it used to, and it seems like it has more play. I looked into this and a lot of people said it was due to needing a tire alignment. Could this be due to forcing the steering wheel to get the truck on and off of the flatbed? I have not replaced any front end suspension components, and I bought the truck around 8000 miles ago, so they may be bad, but what could have caused them to go bad?

I think that's all I've got, I'm in disbelief that this is all happening at once, I feel like these little things were all issues with my old truck. That being said, I have an idea of how to fix each problem, but I really want to get down to knowing what caused these issues, and if anything other than replacing the parts can be done to fix the problems.

Per usual, thank you for any help, you guys have always been my primary source of information.

 

I assume no CEL(check engine light)?

Fuel pump dying on a 1999 is not unexpected, and I assume that solved the no start issue.

During this time, when engine died, I would also assume you looked at things in the engine bay.

So you could now have a small vacuum leak.

After engine is fully warmed up, and idling, unplug the 2 wires on IAC Valve
RPMs should drop to 500 or engine may even stall, either is GOOD, it means no vacuum leak.

If idle stays high then there is a leak

Simple free test, do that first

Cleaning IAC can't hurt spark plugs or anything else in the engine, not sure who or why someone would say that???

When you start any fuel injected engine(hot or cold) the IAC Valve should be fully opened, so RPMs should go high 1,500+ RPMs is normal
Then if engine is cold idle should drop to about 1,100, depends on outside temperature, colder temp = higher idle.
Then as coolant warms up idle will go down

If you engine didn't do this before then something was wrong then, reads back to normal now, except that it is higher then 'normal'

When you work on fuel systems you can get dirt and debris in it, the 1998 and up Rangers have Returnless fuel system so no way for this debris to get out.
Best bet is to run a can of Seafoam in the tank to help clean system out.


Flatbed towing requires vehicle to be chained down, that could have damaged front end parts
Turning wheel without power assist is hard but won't hurt any thing
Start engine and turn steering wheel lock to lock a few times, that should clear out any air trap in the system.

 

I noticed after I replaced my front end links, the steering wheel shook on bumps until everything got seated in and whatnot. Perhaps give those a look and see if they're damaged or worn.

 

Thank you for the replies!

As for the engine and shifting issues, I drove my truck Saturday morning, and nothing was wrong. Not one thing. I'm assuming the PCM was re-learning how to be a truck after the battery being unplugged for a short time and electrical components being replaced? My old truck had to re-learn how to run when I replaced my transmission, but then the battery was unplugged for weeks at a time. I'm not sure what else to think about as to why.

The front end seems less shaky, but again that may be because I'm getting used to driving again. Although, at 65 mph+, the truck definitely vibrates more than it used to, that is the sign I need an alignment, right? I have to do a wheel bearing, if I get an alignment first would me replacing the wheel bearings be reason to get another alignment? I know tie rods demand one.

 

In a 2 wheel drive setup, the front rotors and bearings are changed together. In a 4x4 setup (like mine), the rotor and bearing are seperate.

In either case, replacing the bearing shouldn't have any affect on alignment. I'm no expert, but never have I heard people who know more than myself say this (and I've heard quite a bit), so I'd venture to say that wheelbearings and alignments aren't related.

Alignments refer to caster, camber, and toe angle. In short, how the wheel/tire is angled on the various axis's. This affects tire wear (tread life) as well as which way the wheels are positioned in relationship to the steering wheel.

Vibration occurs when a wheel (or more) is not balanced well/correctly, usually. Either a weight has come off, or it wasn't balanced well to begin with and you're noticing it now after driving something else.

A vibration could also be caused by a mishapen tire or wheel as well, but I believe you'd see that before feeling it.

My local walmart balances tires for 9 bucks a pop, but that doesn't mean they'll do it right. Only one person at mine seems to know (or care) how to do it right, and she does it fantastically. YMMV.


About the computer, while it is possible that it was the ECU relearning, maybe. The ECU is a specialized computer, and like with computers of all kinds, they all have capacitors. Think of capacitors like low-capacity batteries. These capacitors hold energy and allow the ECU to retain its 'memory', including the adjustments it's made over time.

If I were in your shoes, I would disconnect both battery terminals and short the cables together through a jumper wire. Make sure they can't touch the battery, or very obviously bad things happen. Best to remove the battery all together. Go and have dinner or whatever, come back and reconnect. What this has done is drained the capacitors in the ECU and made it 'forget', kind of like hitting a reset switch.

I did this to my 99 and my father's 03 with great results. Both shift so smooth that you can't feel it. Of course that won't fix everything, but it'll help. The fewer bad habits the ECU has, the easier diagnosis will be. For example, my father's 03 used to hang in one gear and stay at about 3 grand or so on the highway. Doesn't do that anymore.

 

I'll bring the truck to my tire guys and ask if they could balance and inspect them for me. I'll also see if they can take a look under the front end and tell if anything is bad or worn.

For tying the two cables together, should I wait until a similar issue returns, or do that now anyways? So that essentially drains whatever power is left in the capacitor?

 

Do it whenever you like. I can be done at any time. Yes, it drains out the capacitors and forces the computer to forget anything it had learned beyond it's factory programming. Consider it to be the equivalent of a 'factory reset'.