2.3 intermittent chug/bog when cold

[RobertISaar]

fuel filter is probably the factory one, so it needs replaced anyways, but i don't see how it would cause something that is consistently intermittent.

MAF.... probably could use cleaning, the truck appears to have been run for quite some time with no air filter.

 

[modelageek]

fuel filter is probably the factory one, so it needs replaced anyways, but i don't see how it would cause something that is consistently intermittent.

MAF.... probably could use cleaning, the truck appears to have been run for quite some time with no air filter.

Don't take this the wrong way but it sounds like you are trying to bring back to life one of the rougher Rangers. I would change the ff and clean the MAF as well as the other TuneUp stuff. Then you have a baseline to work with. I agree about inconsistancy. I am not sure what will happen when you disconnect the o2 but for $30 I would replace it. It is a maintenance item
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sent from DROID Bionic using tapatalk-2. (Ranger, 1999, reg cab, 2.5, 5 speed, 2WD) (2006, Vibe, 1ZZ, Auto, AWD)

 

[RobertISaar]

rough might be an understatement....

i ASSUME when the O2 is unplugged, the SES light will come one and closed loop will be disabled. not sure if it will automatically command the AFR in one direction or another due to it, but it should at least rule out it's sensor data.

i did the plugs/wires in the summer, along with a basic ohm test of the coils(seemed to be well within the specs alldata gave). PCV valve definitely needs replaced. timing belt was done last summer.... i can't think of many more wear items

 

[wp23n]

could be a bad or sticking IAC valve.

 

[PetesPonies]

I may have missed it . . have you checked the fuel pressure regulator? Certainly can foul things up. With the engine running, pull the vacuum line off and see if the RPMs raise and see if any fuel comes out the vacuum port.

 

[RobertISaar]

not yet.... i was hoping to find a fuel pressure guage and test pressure before messing with it.

 

[PetesPonies]

no pressure gauge needed to at least do as I suggest. When you floor it, the engine vacuum drops and pressure increases to max. If your pressure is low, it will do as you are experiencing.

 

[RobertISaar]

okay, more info:

pretty sure it is the O2 sensor now...

taking off after very short warmups, the problem either doesn't happen at all or it takes a few minutes and shows up while at relatively low load.

i assume either the heating element isn't quite heating as well as it should or is completely dead. i'll have to put my multimeter to it to see what kind of amperage it's drawing when cold. if that's not it, i guess the sensing element itself is the problem. either way, i kind of expect to need to replace it.

 

[PetesPonies]

Understand that an O2 sensor is a feedback sensor. It is not a front line sensor that is involved in determining the A/F initially. But, it is a determining factor in the computer switching from closed loop to open loop. When it heats and is operational, the computer will go full open loop and listen to what "feedback" the O2 says for triming the A/F. If all is well when in closed loop, that helps determine where the issue is.

 

[RobertISaar]

you seem to have those backwards...

open loop = no O2 feedback
closed loop = O2 feedback

if i had a way of connecting to the ECM to monitor fuel loop status, i would, but based on what i've been experiencing, when the ECM attempts to go into closed loop, if there hasn't been a significant amount of heat put into the sensor from the engine from actually driving it around or idling a REALLY long time, that seems to be when it acts up.

oddly, it doesn't seem to effect the engine at an idle very much, so i'm not sure if corrections based on O2 feedback at idle are very limited???

also, noticed that the SES light doesn't actually light up anymore at any time.... so if there is a code set and the light being commanded on, i wouldn't know about it.

 

[PetesPonies]

I read back over my post and yes, I got it backwards If my students would have ever seen me making a mistake . . I taught it for many years, but when you are sitting and typing . . . . well things happen. Good catch.

 

[PetesPonies]

Well, the ECM is expecting voltages from the O2 within a certain range. When they are out of range, a code should be stored. So you must not have a completely wacky sensor. I personally had an O2 do that and it looked like I was spraying for bugs. I drove it home 20 miles with a top speed of about 45. I should have crawled under and just unplugged it, I would have been better off. But most times an O2 just becomes unresponsive and slow in reacting. So the output may be within range, but it isn't be accurate. Those conditions will not pull a code and is why an O2 sensor is one of those things that should be replaced every 50K miles or so. Even, if you do not think something is wrong with it. It degrades over time.

 

[RobertISaar]

well, that's the thing.... i MIGHT have a code since i just recently discovered that the service engine light never comes on... i assume it's supposed to light up at key-on like pretty much eveything else from the era?

probably a burned bulb... or maybe the cluster itself, the high beam indicator seems to work on it's own schedule.

i will admit, it needs replaced.... it would actually explain why a couple of the plugs(i think 2 of the 8) i replaced had indications of running lean.

 

[PetesPonies]

No EECIV scanner? No light needed with a scanner.

 

[RobertISaar]

i come from the GM world, where we can make our own ALDL cables.

i have no knowledge of ford OBD1.