Hiccup/Stumble

[camper4lyfe]

I've got an 03 FX4 (with the 4.0, obviously) that's developed something along the lines of a hiccup or stumble. I've got a touch over 96,000 miles on it, and most likely the original plugs. I'm noticing this lurching sensation when I'm at a steady speed, as if the back end hit a bump. I've noticed it anywhere between 35mph and 70mph, so it doesn't seem to be speed related, and it happens every time I drive it, but at intermittent intervals.. I don't notice it idling rough, and it has plenty of power. It seems as though my fuel mileage has dropped, but I don't know if that's another symptom or just from the change in weather and gas formulation.

I did a search and I do plan to replace plugs and wires once I can come up with some cash and time. The searches gave me some ideas, but very few actually came back after the problem was potentially fixed to say what it was.

I'm also seeing the MAF sensor may be dirty. Where IS the MAF? I'm assuming somewhere between the air filter and the intake.

Like I said, I do plan to replace plugs and wires, and while I'm at Advance Auto, I'll probably have them see if there are any codes stored up, and grab a bottle of Sea Foam.

Any thoughts would be greatly appreciated.

 

[Original_Ranger84]

I would start with a basic tune up and see if that helps any... you know plugs/wires, fuel filter, oil ect... Then start gettin into other things.

The MAF sensor is the Mass Airflow Sensor and its located on your air filter box. its the alloy tube section right off the box and should have a plug coming off the top. Thish could be your problem as at a certain RPM range could not be getting enough air to fuel or the otherway because the MAF isn't working properly but I would imagine you would notice something at idle. It could be dirty, do you have a K&N filter or an oiled filter in your box?

 

[camper4lyfe]

I would start with a basic tune up and see if that helps any... you know plugs/wires, fuel filter, oil ect... Then start gettin into other things.

The MAF sensor is the Mass Airflow Sensor and its located on your air filter box. its the alloy tube section right off the box and should have a plug coming off the top. Thish could be your problem as at a certain RPM range could not be getting enough air to fuel or the otherway because the MAF isn't working properly but I would imagine you would notice something at idle. It could be dirty, do you have a K&N filter or an oiled filter in your box?

I'm going to at least pull a couple plugs tonight to see how they look (pretty bad, I'm going to guess), as well as run it in the dark and watch for any arcing that may be present from anything.

I'm running a regular paper filter. I'm not sold on the K&N's/oiled filters, to be honest.

 

[camper4lyfe]

Just a quick update. I swung through the parts store Tuesday night and dumped 2 cans of Sea Foam into a 1/4 tank of gas then topped it off. It stumbled once on the way home (mild compared to some of them), and didn't do it at all on the way to work today.

I still plan to do plugs and wires, but I'm thinking that this may have possibly fixed "it". We'll see though.

 

[Original_Ranger84]

Well since you sea foamed it I really recommend changing out the plugs. The paper filters are good, I got a K&N (actaully the PO did), they aren't bad you just have to oil them right.

 

[exotic_4x4]

Replace your idle air control clean throttlebody and maf along w. Pl

ugs

 

[camper4lyfe]

Another update:

Like I said, I dumped 2 cans of Sea Foam into a fresh tank of gas. This coincided with an increase in temperature into the 40's, and the hiccup/stumble stopped.

Now that it's cold again, in the teens, the hiccup's back. I plan to get plugs and wires tomorrow, and hopefully change them this weekend.

If anyone has any suggestions on how to get to the 3 on the passenger side, I'm all ears!

 

[Blueox]

Not easy but....

Jack it up, remove tire, then shrouding, and you should get better access.

 

[powerranger262]

^Definately the easiest way

 

[camper4lyfe]

I finally had enough time (and day light) to change out my plugs this morning.

I hope I never have to change them again. It took me 3 hours to get them out and changed.

Here's what I found:
1, 2, and 3

1, 2, and 3 by camper4lyfe, on Flickr

4, 5, and 6

4, 5, and 6 by camper4lyfe, on Flickr

The sticker on the radiator support says to gap at .060-.068. These measured around .080. I'm thinking this was my problem. Once the temps drop back down into the teens, I'll know for sure.

 

[camper4lyfe]

The temps dropped back down and of course, the hiccup returned.

I've replaced plugs, wires, and cleaned the MAF sensor.

I'm going to swing through Advance Auto tomorrow to see about pulling codes. I'll also give cleaning the IAC a shot.

I'm getting sick of this hiccup thing going on. Unfortunately, I have to wait for the weather to get cold in order to test anything, so it's taking forever.

 

[camper4lyfe]

I went and checked for codes, and got nothing. The guys at the store said that if the CEL wasn't on, there wouldn't be any codes. But I checked anyway, both KOEO and KOER.

I'm actually thinking now that it may be the transmission. I've got just shy of 97k on the original fluid. Next up will be a fluid and filter change.

 

[feellnfroggy]

Its most likely an emissions problem. MAF is broke not dirty or, IAC, or TPS. All my vehicles at one point had problems like these and its was emissions related garbage. A good can of seafoam, and pull all the parts off the upper end of the intake manifold and just clean the shyt out of them, maybe check fuel filter to if you havent already.

 

[camper4lyfe]

Its most likely an emissions problem. MAF is broke not dirty or, IAC, or TPS. All my vehicles at one point had problems like these and its was emissions related garbage. A good can of seafoam, and pull all the parts off the upper end of the intake manifold and just clean the shyt out of them, maybe check fuel filter to if you havent already.

If the MAF was broken, I'd imagine it would run poorly all the time, not just occasionally. I don't think it's the IAC because it idles and runs just fine.

I've already dumped to cans of sea form through it.