Evening fellas,

I've got a 2000 Ford Ranger 4-cyl 2wd..
Sometimes when I cold start it, it struggles to get to idle RPMs for like a second er two then idles normally. Other times it fires right up perfectly, hits the high rev (what every car does when you start it) and idles out.
More than often while putting the truck in gear (R/D) from park it bogs down to like 100-200 rpms, the goes back to idle normally. Other times the truck just stalls out completely; then after getting it started back up it operates normally like nothing ever happened. All issues vanish.
Just today for the first time it stalled while pulling off from a red light; normally just feels like it's bogging down, shaking, struggling for a second or two, It drops RPMs pretty low, and then returns to normal. Very similar to shifting it into gear while cold. But not all the time.
It has ZERO issues shifting while driving. Every shift is perfect, no jerking, shuddering etc....
And I believe it has a fuel efficiency issue; 2 days driving about 25 minutes to work then home, the truck is down a 1/4 tank (basing this off the stated 30mpg online) and I drive like a grandpa 95% of the time. speeds anywhere from 25-55 mph.
No smoke out of the exhaust.
No engine codes on the dash, haven't been able to scan it yet for a deeper check.

I've replaced TPS, AIP sensor, spark plugs, wires, coil packs, and a mass of other non-related parts since I purchased the truck at 225k miles 6 months ago. Currently sitting at 228k now.

I would like to assume that this is all caused by one part that is nearing the end of it's life span, or the truck finally had it's fun and wants to rest permanently since all of the issues kind of have the same effects. Bogging down, stalling, struggling etc....

I need the truck to be reliable since my wife also works, end result would be to get rid of the truck since I've already put nearly 3k or more into repairing it. Not a fan of money pits....

What say you? All and any help is greatly appreciated.

 

Welcome to FTE.

Given the mileage & symptoms without any trouble code clues I'd guess the IAC = Idle Air Control belongs on the suspect list. If dirty / mucked up internally with gum, varnish, carbon,or just worn out, it can act out intermittently & cause the posted symptoms. If cleaning the IAC with a plastic safe product like CRC MAFsensor cleaner stops the problem, replace the IAC as it'll soon act out again like mine did, but cleaning was a good trouble-shooting step for my intermittent idle problems before replacing mine with a BWD brand part as the Motorcraft is expensive & other brands soon have quality problems. BWD also makes OEM parts so has a good quality program in place. Look for discount codes, I found a 40% off but was years ago.
Also if the engine intermittently has under load idle up problems, like when the AC is switched on, or when you shift the auto tranny into gear, the IAC belongs higher up on the suspect list.

I agree with getting a deeper scan for trouble codes & I like the inexpensive ELM scan-tool & FORScan diagnostic freeware on your choice of viewing device as discussed here Low Cost ELM Scantool - Ford Truck Enthusiasts Forums.This combo can access all of the vehicle computer / controllers.for trouble-code clues & put up live data in several formats, so is a good investment for our electronic tool box as you seem to like turning your own wrenches..
A bunch of initial thoughts that came to mind, let us know what you find.

 

I certainly agree on checking/cleaning the IAC. I would also check the cleanliness level of the throttle plate. If it is grungy, it can affect stability. Check also for any leaks to the intake manifold as a weak mix caused by a leak can cause stalling.
Do you get a good fast idle when starting from cold? It should be fast, above 1,000 and then step down as the coolant warms. If not, causes can be a mis-reporting coolant temp sensor or a funky IAC for two suggested causes.
tom

 

@pawpaw
Sorry! I messed that post up.... After looking up the IAC; the AIP (air intake pressure sensor) that I replaced was actually the IAC you've mentioned. That's my fault, I got it confused

So, after replacing the IAC roughly a few months ago since the issue started, it never went away. Could that be the result of a vacuume leak?
I'm going to run back through and clean up the TB and MAF just to be safe as well.
I plan to take the truck to Auto Zone or the like to see what their scanners say.. Got one about 5 minutes up the road.

&& I do enjoy turning wrenches! Been a mechanic for 10 years so far in the Army and my family is full of mechanics lol.


@tomw
Yeah, when the truck gets over it's bipolar start in the morning / before heading home from work, the idle rpms are right where they're supposed to be at the 1,000, and step down as normal.
&I'm going to clean up the insides and see what happens for a good short term troubleshooting..

 

Never thought I'd be happy to see a check engine light, but the truck finally showed it today. Going to get it scanned tomorrow too, perfect timing. Funnily enough, all today the truck has been acting normal aside from a slight rough idle. Will send an update on what I find tomorrow.

 

Codes read to be the O2 sensor, I wasn't fully aware that it could cause the entire vehicle to go haywire like that. I've got the part already, not the tool. So I'll have it fixed tomorrow at work and see what she does.