Stutter at Highway Speed ?

[trekker9]

Hey all, I was on the way home from work this morning and my truck (94) started to stutter very roughly. It would do it and then be fine for a few minutes and then do it again. Once I got into town, it seemed to run fine at lower speeds. All the dash gauges looked fine.

I've been searching the forum for like threads, but couldn't find anything.

Where should I start looking?

Thanks.

 

[SmokingRocks]

fusible links. When you say stutter, was it like coughing? like it was getting a little bit of fuel or was it on and off like a light switch?

 

[elhombre]

First thing that comes to mind is the fuel system. Next time it happens throw it into Neutral and coast. If the shudder goes away, I would think first the fuel pump relay is sticking and causing a possible problem. If the shudder doesn't go away, then I would think drive line. Drive line problem I would check first are the u-joints. Then possible front spindle bearings not greased. Is the CEL on?

 

[izzyandsue]

Sounds like my old Bronco from college days, fuel filter was the culprit, just time and dirty gas over the decades and miles. Elhombre has a great tip to test it, neutral test it downhill.

 

[gofast]

Had a similar problem last year. If you haven't done this for a while change your plugs, cap, wires and rotor. Amazing how many sins disappear

 

[alia176]

Check for the obvious, like tune up parts, air leak on the accordion style intake air tube, vac leaks. It's been cold so old items are shrinking, tearing, breaking, etc.

And try to be more specific if you want more accurate feedback. What were the circumstances when this happened - accelerating into hwy merger, going uphill, decelling, etc.

 

[bicycleagent003]

Fuel filter in the tank or under the intake manifold. I had the same problem. If it's more frequent under load or uphill or when trying to accelerate on the freeway, I would think fuel filter.

 

[RS6tofj80]

I had the 6th injector hang up and go wide open - but before it did it acted like this....

 

[trekker9]

fusible links. When you say stutter, was it like coughing? like it was getting a little bit of fuel or was it on and off like a light switch?

It seemed like it was getting a little bit of fuel.

First thing that comes to mind is the fuel system. Next time it happens throw it into Neutral and coast. If the shudder goes away, I would think first the fuel pump relay is sticking and causing a possible problem. If the shudder doesn't go away, then I would think drive line. Drive line problem I would check first are the u-joints. Then possible front spindle bearings not greased. Is the CEL on?

I did notice that if I put it in coast and rev it up, then throw it back in drive, the problem would go away for a bit.

 

[SmokingRocks]

fuel filter

 

[trekker9]

Ordered a Filter. Hopefully, that will solve it.

 

[4G63 POWER]

Bad gas or a clogged injector. Or an injector going bad.

 

[theluckettslad]

Mine was doing the exact same but normally after a few miles. Until last weekend I went to the store and it immediately started missing and finally threw a miss fire in cylinder 6 code. Can't wait to get it in the garage this weekend to see what's going on. At first I thought it was a driveline vibration.

 

[4G63 POWER]

Swap in a known good injector and see what happens.

 

[trekker9]

It will go up to about 2500 RPM's and then dive back to 1500 or so. Does this repeatedly, and wont go above 35MPH.

 

[trekker9]

Well, I spent some more time driving it, and found I could get it up to 55 MPH as long as I accelerated very slowly. Right around 55 MPH, I would lose all power from the engine.

I took it to a local mechanic and He said he thinks it is the catalytic convertor. He said he crawled under it and it was glowing red.

Does this sound like a plausible explanation considering the symptoms?

 

[SmokingRocks]

could be, but if its cutting out at 2500rpms like its hitting a limiter then its in limp mode.

 

[blkprj80]

I'd wonder if the red cat converter is a result of something else being wrong like too much fuel. It might be junk now though. I hope not.

Did your fuel consumption spike when this happened?

 

[trekker9]

could be, but if its cutting out at 2500rpms like its hitting a limiter then its in limp mode.

Uh oh. What's limp mode?

I'd wonder if the red cat converter is a result of something else being wrong like too much fuel. It might be junk now though. I hope not.

Did your fuel consumption spike when this happened?

I can't say for sure on the fuel consumption.

 

[SmokingRocks]

limp mode is when the ECU detects an issue and limits the engine to 2.5k revs or whatever the preset is (Mine cuts at 2.5k when in limp mode). The reason it does this is because it detects an issue and is trying to protect the engine. Mine did this when I got water in the TPS connector, I blew it out with compressed air and it was fine.

I'd pull connectors apart blow them out make sure there is no water in them then reconnect. Also disconnect the batter and reconnect after 10 seconds or so. Then let me know if it still is doing this.