gman72

My '94 has always had a bit of a stutter ... idles smoothly, but rev it and try to hold RPM's it stutters slightly (always has ever since I bought it at 65K mi). I've got 180K mi. now, and curious if this stutter is something simple?

Basically, say I rev it to 2000 RPM and try to hold it there, I can't. It will fluctuate about 50 RPM either direction (sometimes as much as 100 or so RPM), randomly. Sometimes worse than others. I can only assume this is the same stutter I feel on acceleration as well, which makes it feel sluggish. Full throttle seems to give me all it's got, smoothly ... but this stutter has been a pet peeve from day 1.

Any words of advice on things to check first? I've had 2 mechanics look at it over the years and from what I recall their analysis was "it's fine ... just leave it as is...." ... but I still don't think this is normal.

Thanks for any help --- BTW, new to the forums here, already found a ton of great info - you guys rock!

gwhayduke

50 rpm ain't bad, but the stuttering on acceleration is. I'd swap out two things...fuel filter first and oxygen sensor second. If it's still there, then it's probably your throttle position sensor.

Although....another guy here on the board had problems with his cutting out and found plastic and metal pieces in his distributor.

gman72

Picked up a new fuel filter - will put it in today.

On the O2 sensor, I read they should be replaced every ~100K mi ... so I guess I'm due anyway. But I checked prices on 'em and they range from like $70 to $150 at my local parts store (www.kragen.com) ... Normally I'd just get the more expensive stuff, but that much of a price difference thought I'd ask for advice first...........

(couple of the "cheaper" ones say "Except Calif" in the description ... I'm assuming for CA emissions I need a different O2 sensor?)

ChickenLover

If she's still stutterin' after the fuel filter, try running some quality gas (chevron). When I run the cheap stuff my runner chokes and stutters. Nothing but Chevron for me.



Edit: The stuttering may also be caused by a vacuum leak.

gwhayduke

I bought my O2 sensor from 1st Toy Parts but "Strap22" is a member here and he's been real good to a lot of folks on pricing for OME and SDORI. I would assume he'd give you a good price on an O2 sensor as well. Mine ran me about $100 with shipping. Stick with Toy if you don't want headaches. It will take you about 15 minutes to swap out since you aren't in the rust-belt.

And yes, there is a different sensor for CA. Not sure what's different. Probably just painted it blue.

gman72

Well - nice Sunday afternoon with a couple hours of daylight left I figured I'd pop that shiny new fuel filter in .... didn't realize what a PITA I was in for...

It's not rusty or anything --- but 180K mi and never been replaced so it's been on there a while. Took some muscle but finally got the rear nut loose & drained the gas in the line.

Then the fun part started - the FRONT nut. Tried regular wrench 14mm - no go, pull too hard & it will definitely strip. OK - how 'bout a crows foot. Nope - same thing, I can see a strippin' a comin. OK - so I then put a line wrench on it ... yank it hard with the whopping 1/2" of room to turn the wrench ... and THAT starts stripping the nut!!! The entire wrench spun on the nut. AHHHHHHHHHH. :cry: I figured screw it and use vice grips, but there ain't enough room to turn 'em once clamped on.

Any additional suggestions here? I really don't wanna pay the stinkin' dealer to do this, but I really don't want to strip that nut out either. Thanks!

gwhayduke

180K and never been replaced? I think you'll find a lot more power and no stuttering after you manage to get the new one in. I find that at about 60K mine starts acting up.

As for replacing it, remove the nuts from the crossmember on the FF side and let the crossmember drop down a couple inches. You'll find that a nice space opens up that allows you more room to work.

As for stripping the nut, once it's stripped, you probably should to either order a new replacement from the dealer or plumb in a new copper line. Yes, a lot of the guys have said that theirs were pretty tight. Try soaking it with WD-40, PB Blaster or Liquid Wrench for a day or so and see if that doesn't help.

gman72

UPDATE: Finally got that fuel filter off and the new one on. Thanks much for the tips. But MAN!!!! that was more of a chore than putting new axles in!

Annnnnnnnnnnyway - bottom line, drove it for a about 50 mi so far --- I don't really notice much of a change at all. The stutter on acceleration is still there and the fluctuation of 50-100 RPM is still there when trying to hold at say, 2000 RPM. Actually, I even notice a fluctuation on idle ... looking very closely at it ... probably 10-20 RPM or so when just idling, up or down.

Will put in the new O2 sensor tomorrow and let you know if it helped, but it really seems like it's something with the fuel flow or mix that's doin' that stutter. Already replaced spark plugs & wires (plugs indicated normal firing - no probs there). Even checked compression on all 6 cyl and all was good there (yay! 180K mi. and still 170 or so on the compression check!).

As I mentioned earlier, it's always run this way since I bought it at ~60K mi... just now that I'm finally spending the time to work on it it's bugging me more and more hehe. Perhaps it's the TPS or something to do with the fuel injection causing this problem? I'm sure once I get this fixed my fuel mileage will improve since I won't have to have as heavy a right foot to get 'er up to speed... Oh well, back to the drawing board.

BTW - if you're interested, here's a mini write-up on what I did to get that damned fuel filter off ...

- Soaked it in LW for a day - that may have helped some.
- Removed the cross member bolts to get that extra couple of inches (stuck a prybar inbetween it and the frame to crank it open as far as I could w/o unbolting the tranny and removing the whole thing LOL).
- Removed the metal guard around the fuel filter (had to bend it slightly to get if off there with the tight space and all)
- Loosened the rear fuel line nut (which was the easy one) ...
- Manage to get a 19mm wrench on the filter itself (to the rear) and a 14mm flare wrench on the front fuel nut ... and just cranked hard --- finally came loose!!!!!
- Mucked up the nut a bit, it's almost stripped, but was able to get the new filter back on, fuel lines attached and hopefully tight enough (at least it ain't leakin' yet).
- Had tin snippers in my hand at one point and was ready to just cut the damn thing off and buy or build a new fuel line because the frustration got sooooo much. Fortunately I didn't have to use 'em, but the next person to replace the fuel filter on this truck will almost surely have to (oh wait, that's ME!!! LOL).
- I rank this about a 6 beer job. Having the thing up on 4 Ramps also helps out CONSIDERABLY with leverage, etc...

dragon564

Okay in some sort of random mutterings...
are thier any hole or cracks in the air line pipes after the vafm
vaccum leak
the signal gen inside the dis cap. that is the part that sends the signal to the tack, I do not know what the correct name is I just know where it is. If can be going bad or just be dirty and cause the tach to flutter
Air bubble in the cooling system
any of those things can also cause sputtering

gman72

I visually inspected the vac lines - all look in excellent shape, although I haven't put a stetho up to anything yet to listen for any leaks.

On the signal gen, or whatever it's called - if that just sends the signal to tell the tach what RPM to display, I don't think that's it. I mean, it's not just the tachometer fluttering, I can hear the actual motor stumbling slightly, and definitely feel it on acceleration. Unless that signal gen actually would make the motor stumble, not just the tach?

Air bubble in the cooling sys? Never heard of that before? I know my radiator is shot and due to be replaced --- but this stuttering has been happening way before the radiator had any issues....

crazycubano

try cleaning your throttle body, could just be some build up in the TB and could be causing it to have restrictive airflow of some type. to see if it needs cleaning just remove the hose from the inlet to the TB and look inside. if it looks black id suggest removing it and cleaning it with laquer thinner. this stuff works better than chike cleaner trust me just did it this weekend