random shakey/rough running (very long)...

[ozzwoman9]

random shakey/rough running **updated**

ok, so a few weeks ago I was driving along and all the sudden my truck started running really rough. It was shaking like when on a gravel road and going over a "washboard". This is engine related as I stopped and it was also idling rough. I shut the truck off at the time and checked to make sure a plug wire or something hadn't come loose (found nothing). Started it up and it ran fine. I went ahead and changed the plugs/wire and had no problem for weeks.

So today, I had been driving along for about 40 miles or so and suddenly it started shaking bad again. It seems to do it worse at lower rpms. I was doing 40mph in 4th gear and had to grab hold of the stick as it was shaking so bad that I thought it was gonna pop out of gear. So I pull over, check everything over, nothing (even tapped the IAC) and nothing changed or appeared messed up. So I shut it off and start it back up twice and it still ran rough. I had no choice but to drive it another 20 miles like that (which there seems to be no lack in power when this happens). So I get to the store, was in there for like 30 mins, come back out, start it up and it runs a-ok!! FYI, I have done tuneup, plugs, wires, filters all within the last year or so...so that should not be the prob (coil pack is still original though).

I just put some fuel treatment in and topped off the gas tank to see if that helps. I have also been running E85 most of the time and I know when switching from E85 to pump gas to mix a 1/2 tank as I know people have had problems when switching directly from one to the other. But when my problem occurs it doesn't seem to happen specifically on one type of gas or the other.

Anyone have any ideas on where to look next? BTW, there is no check engine light or anything that comes on when this happens.

 

[macarchie]

I had a similar problem about 2 years ago... On my '91, there is a MAF or MAP (?) sensor that is located at the top of the firewall directly above the engine. I think it measures the ambient air pressure. On mine there is a plastic cover that you have to remove to pull it out. If I remember correctly, there is only one wire that has to be disconnected - it is a pretty easy fix. After that, I disconnected the battery for about 30 minutes, then started the engine and drove it for about 15 minutes. The manual says to drive it without the A/C or lights on. This will reset the environmental parameters in the computer. It ran like a champ afterwards.

Hope this helps, Jimmy

 

[Wicked_Sludge]

its a BAP (barometric air pressure) sensor, her '00 shouldnt have one.

even though the CEL doesnt light, there may still be stored codes that can point us in the right direction. id have a shop plug into the truck and see if anything comes up.

it sounds like an intermittent electrical issue, and those are the most difficult to track down.

 

[ozzwoman9]

*UPDATE*

There are no codes coming up on this. I am still having the problem. Is there any way to test the coil pack? I'm thinking that it may be running off 3 cylinders sometimes as I am now noticing a loss in power.

 

[Wicked_Sludge]

a dead coil pack is a good pissibility. there is a way to test the pack using an ohmeter, but i dont have my manuals with my ATM.

 

[ozzwoman9]

anyone? I'd really like to fix this this weekend if I can find the source. I obviously can't do a search as all the material was lost in the server change (I tried RPS, but they seem to stop responding to posts with similar issues and no resolve has been posted that I found).

 

[ozzwoman9]

ok, I replaced the coil pack (which tested fine, but I replaced any way as I'm at wits end on this). The truck ran fine for about 250 miles and now it's running shittier then ever again. No codes are popping up as I have scanned it. Anyone have any other ideas?

 

[macarchie]

A few thoughts...
1) vacuum leak
2) spark plug wires (broken or burned?)
3) try starting it up in a dark garage or at night and look for sparks in the ignition system.
4) fuel injector cleaner

- I usually go for the cheap fixes first.

Good luck.

 

[ozzwoman9]

*UPDATE*

I FINALLY GOT A CODE!!!
I was on my way to a job interview (truck had been running crappy since I started it). I get over 1/2 way there. I was on the hwy doing about 80 (in this part of MO there are hills) and by the time I would get to the top of the hills it was all I could do to keep the truck at 70 mph. After the 2nd hill it started "chugging". At this point I was almost convince it had to be fuel related. So it does this a few more times. Luckily I was able to get off the hwy, which it died as I was coming to a stop. I started it up and drove it about 30 ft to a gas station. I called my bro to come get me, he has a code scanner at his work. We went back to the truck and it's getting a P0176 (fuel compensation sensor circuit malfunction). I was able to drive it 30 miles back home as it ran fine all the way back. So where do I go from here? Is there a fuel pressure regulator and where may it be located? I'm thinking it is a sensor of sorts as it doesn't do it all the time and sometimes I can stop/restart the truck and it will run fine. ANYONE?

P.S. I got hired on the spot! I am going to start out making more then I did when I was let go from my previous job (which was outsourced to India)!!!

 

[skippy]

sorry,can't help with your truck.but congrats on the new job!

 

[ozzwoman9]

Hey thanks, I've had bad luck...this will be my 4th one this year. I quit one and it seems as though 2 of my jobs have made changes and let me go, not my fault. In fact I just basically lost one yesterday (they said they would call me within 2 wks to see if they have another position), got one today already....so I hope this one goes well.

AS FOR THE TRUCK
Seems to be the code for the flexible fuel sensor. The part is a special order and costs about $600....luckily my bro can get a discount for me, but it still ain't cheap! I sure hope that fixes it.

 

[skippy]

i'm not familiar with that part as i have older truck and different engine,but that seems like a hell of a lot for a sensor.must be solid gold?have you shopped it around?

 

[Wicked_Sludge]

you nailed it ozz.

the sensor tells the computer the ethanol content of the fuel so it can adjust timing, injector pulse width, ect accordingly. this isnt the first one ive heard of failing and, unfortunatly, they arent cheap.

i hope this fixes your problem.

 

[ozzwoman9]

Yeah I kinda pulled some prices from online and such. Seems as most places want $588 for it and I have a way to get it for about $470 or so. I think that's a heck of a discount considering. I'm lucky I have some decent connections with people around here cause it's really helped out so far.

I sure hope this solves it. I can get the part hopefully by friday and since it was doing this randomly it may take a few wks to know for sure that it was the cause.

 

[Wicked_Sludge]

ya, having an "in" for parts is always nice. i tell people that since i have 3 fords, i have to work at a parts store or shop so i can afford to keep eating

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