hi all,had a look through this topic and couldnt quite see my problem,
i have an 88 2+4 ranger with no mods on the engine,have just replaced all top end gaskets and checked all that, except i forgot to take out the lifters
but all the other top end components looked fine. now the truck runs perfectly untill the tempreture gauge starts to move then as it warms up
it feels like it is gonna stall and is missing like crazy when it does this it produces black smoke,not blue. and the power keeps cutting in and out,
before i did the top end, the lower intake manifold gasket failed due to incorect torque settings on the rear,err hand tight to be correct and it was letting oil
into the rear passenger cylinder,ie when you parked up hill and came back it would smoke on start up, but if you parked down hill it would not smoke untill it got going, now at does not smoke at all,untill it starts missing and cutting the power in and out. today i replaced all the leads with no effect ,cleaned all the plugs,which were a little black,could be from cutting in and out or running rich? distributor cap and rotor are new. the timing is set spout out, to 10deg btdc then goes to 31 spout in.when i went to set the timing ,as the distributor had been out, at tdc the roter was pointing slightly towards the driver and not straight back and in line with motor ,but the distributor went in after a few wobbles and i could turn the distributor so that the rotor was pointing at # wire at was at the middle of its travel,
and the timing set up fine on the pully marks under the timing light.and it runs fine when cold, oh yeah and in order to get it through emmisions testing,the o2 sensor was changed so now it has an after market sensor,as put in by a pro tech trained in emmission tests, sorry to go on but i read a few post and folks say,what year is it? whats it do blah blah.
oh and it has 130k on a pro rebuilt motor,i have the bill from the previous owner.....phew... many thanks Roy

 

2 things I would check:

1) pull codes. I wouldn't be surprised to see some ignition codes there, which could indicate a dying TFI (aka ignition) module.
2) fuel pressure regulator. Is there gas in the vacuum line to the FPR? What does the fuel pressure do if you put a gauge on it?

 

Mr. Shorty,
Is there anyway that the o2 could have caused this, or is there something already ruling this out?

The reason I ask, is because I was told at some point, the o2 is not used until it's warmed up, and it uses it's own built in table.

I guess the question is, "How much effect does the o2 sensor have on the air fuel mixture?"

Could he have the wrong o2 or a bad one by chance? He stated it is an aftermarket o2 sensor.

Wouldn't a low voltage signal from the o2 cause it to run rich?

If I were you, I would go ahead and check what Mr. Shorty says to check, he knows his ECC-IV. If you can't find anything else, I would begin testing the o2 sensor, and make sure that they didn't give you an o2 that has 3 wires where your engine requires 4. (And vise versa) Although I am pretty sure the (3/4) wiring is probably not the problem, but it's something to look into.

Pete

 

At this point, I would say that the O2 sensor as a possible cause isn't ruled out. Much (notice I said "much" and not "all") of the time, a faulty O2 sensor (or other conditions) will trigger a trouble code in the computer. If I suspected an O2 sensor, the first thing I would do is pull codes from the computer to see if the computer can see the fault. It's also important to remember that an O2 sensor code doesn't necessarily mean a bad sensor.
The primary sensor input used to determine fuel mixture is the MAP sensor. The O2 sensor is used to make corrections to the mixture calculated using the data from the MAP sensor.
Yes, it is possible to get the incorrect O2 sensor or get a bad one off the shelf. Yes, a constant low voltage signal from the O2 sensor does cause it to run rich. Like I said, I prefer to at least ask the computer what problem it sees before randomly chasing bad sensors. If the computer comes back with all pass codes, fuel pressure looks good, and the FPR isn't leaking, then it wouldn't be a bad idea to investigate the O2 sensor in more detail.

 

thank you very much, i will check the codes and check the other avenues
that you have suggested and report back when i discover anything

yours roy

by the way i learnt something else to day as i splutterd my up a big hill in north vancouver, as it splutters and misses, which it did not for the first
cold engine driving,any way when the problem arises if you floor it, the the thing seems to go like hell, you would have laughed to day as i was over taken by "grandma" ,to my truck i said please come on not now put my foot down and the thing ran like top flat out,then as i backed of the power it went
through the chitty bang bang zone. i must sound nuts!
thanks again Roy

 

sorry i havent been back here for a bit,pulled out the o2 sensorby disconecting at the conector,took the whole lot into the shop and checked
it like you guys suggested ,and one of the wires was not quite tight in
one of the crimp conectors,the tech said on the phone that he had a new o2 sensor for me as some of the ones he sold where iffy,so i soldierd and heat srhrunk taped the conection and the truck seems much better,but i'm still not 100% sure that the wire on the old one was not conected.but when i pulled out the old o2 sensor it was black as were the plugs,im not sure if the sensor went black cause it was not working and running rich or if it was working ,then stopped cause it was running rich and went black?, in which case the new one will deteriorate to the same point as the last one,sorry to go on and not get back sooner but i was waiting to bump into the tech with my free o2 sensor
plus my kid has bought me a digital code reader for christmas,so il know more tommorrow,so thanks to you two im feeling pretty positive,have a great christmas guys, roy

 

The problem you will find is a bad ground in the HEUGO (O2) sensor harness.

I had the same problem on a B2 I picked up from a coworker. It just had a transmission rebuild. It ran beautifully cold, but was over rich to the point of having heavy black smoke when it warmed up

I traced the problem to a ground wire not being reconnected after the transmission rebuild. I had to pull the wires out of the harness to fint the problem.

Alan

 

thanks folks! changed the 02 sensor and the truck is like happy kitten!
pulled the codes with the digital coder reader my kid got me for xmas,and passed on all koeo and koeo codes,the was a few in the memory but only
stuff from rough running due to ploblems caused by o2 sensor.
i am happy again, boy i hate to lose to this stuff, thanks again roy!

 

I had the same deal with my 2.9 running like crap when it warmed up,,, took it to the mechanic and had it scoped,,, turned out to be the #6 plug wire,,, thats all it was,,, whew,,, threw on a new set of Niehoffs, runs great now!, however I did read you changed your plug wires though I believe,,, but this maybe helpful to others,,, good luck