I have a problem

[CaptainStomp]

After driving my truck for about an hour, my truck starts losing power and starts running rough. After I let my truck cool for a little bit it will run fine again. Sometimes the "Check Engine" light comes on, but it's never on by the time I get to the mechanic. The mechanic had already replaced a couple sensors and fixed the problem somewhat. The problem used to be the same thing, but only more severe even to the point, that when I came to a stop light it would be running so rough it would sometimes stall, then took a while to start back up, until it cooled a little bit. My truck usually runs better in the cooler months and gets worst in the summer months, so it sounds like somethings overheating but I don't know what. My mechanic recently checked it even though the "Check Engine" light wasn't on. Nothing shown up when it was running, but when he checked it with the engine off, the EGR Valve was triggered. Do you think the EGR valve could be the problem?

 

[MAKG]

I suppose it could be sticking open. It's supposed to be closed at idle and at full throttle.

It's easy to test, and your mechanic should do so before replacing it.

I suspect you may need a new mechanic if he's guessing.

 

[CaptainStomp]

I replaced the EGR Valve today, anyways. The old one was pretty damn crusty, but I doubt it was the problem. It triggered that tester thing, it was very corroded, and for the price of a new one(Made In USA), I figured that was enough motivation to change it out. I haven't ran my engine long enough to see if I fixed the problem or not, but if I didn't fix the problem, what else at high temperatures could trigger my "Check Engine" light, loss of power and rough engine? Oh yeah and when the problem starts happening after being heating up, it's an intermittent problem. So it'll lose power and run rough, then it'll run normal, then lose power and rough again. It really burns up the gas, from the constant acceleration and deceleration, when the problems start up.

 

[ish474]

This is a really general answer but usually problems like that are caused by an electrical connection that is cracked and opens up when hot. The VLP pumps on cummins 24 valves are notorious for that. The circuit board cracks and sometimes the heat will cause the crack to get wide enough that contact is lost, then you get dead pedal. It seems like your problem is different but also similar. Something controlling the fuel mix is changing due to the heat. I am not sure what it could be but anything with control over the fuel should be checked. The worst case would be that the truck runs lean and burns a piston because of this. If it starts to make black smoke then maybe it's running rich. Sorry I couldn't be more specific

 

[Stonerman33]

On my old POS oldsmobile, I had similar issues with rough idle, stalling at a stop and what not, as it happens, the cat was overheating to the point it was red hot. It must have melted all the innards and clogged it up so the exhaust wouldn't be able to get through. At times though, it would run just fine. Ate gas like a v-10 superduty. $80 later, my problem was solved.

 

[CaptainStomp]

My cat was replaced last year, during the time the mechanic changed out some sensors and other stuff, that triggered in the diagnostics test. My muffler and tail pipe on the other hand is still the original, and is making a high frequency squealing or rattling sound, the higher RPM the engine is at. There's some holes that ate through the baffling, and the mounts for the baffling are completely corroded through. I was thinking about replacing it until I heard a new one would be in the $300-450 range, I guess I had thought a new set up would be around $150 or so. My plan "B' is to take if off and bang it on the ground to knock anything lose in it out, for a temporary fix, for the crappy sound it makes. If the other problem, that I'm having is laying within the muffler or pipe, then I may change it after all. What do you all think?

 

[kpbyrom]

How does your temp guage read when your motor is doing this? Cause if its something craming up your exhaust, usually it'll run hot. Also check your fuel system. My ranger would run rough and stall on startup until it got warm. It was starving, so I checked everything and eventually put a new fuel filter on it just to see of that made a difference. That was the problem, now it runs fine. Anyway hope this helps a little, just throwing some suggestions out there.

 

[footee]

You should be able to get the muffler and tailpipe work done at a local shop for less than a hundred bucks. Cats are what's expensive in the system. When they get clogged, it'll run like crap all the time and smell like rotten eggs which will probably burn up your o2 sensors. I doubt that's your problem if you just got a new cat last year. When's the last time it had a tune up? Plugs, wires, filters?

 

[ish474]

anything exhaust related wouldn't change when it got hot though. any obstruction would be there from start up to shut down. does it diesel when you shut it off when it losses power? If it runs for an hour it's not normal engine heat but heat soak somewhere.

 

[CaptainStomp]

Within the time from when I got the new cat, last year, this is everything that has been replaced: Plugs, Wires, Fuel Filter, PCV Valve, Catalytic Converter, O2 Sensors, AC Compressor, ,1 Wheel, 1 4x4 Hub, All 4 Tires, Windshield, EGR Valve, Front Seal for the Clutch, some solinoid for the 4x4, the belt and Fuel Vapor Canister. Then the preventative stuff like For the Transmission System, Engine Oil, and Coolant System, Brake Fluid, Power Steering Fluid and Air Filter. Oh yeah a heat sensor was changed too. My truck has 146,000 miles on it, I'm unsure of the miles before the high 80,000 range, when I bought it, but everything past that, has been pretty hard miles. The problem I'm having started before all this was done, but has reduced drastically after the new cat, o2 sensors, and heat sensor were installed. But the problem is still there, just not so severe, and still happens about the same time after about an hour of driving. Besides the symptoms I described in an earlier message, that's just about all the information I have on it. Oh yeah, one thing, I don't know if it's related to the problem, but I used to have the problem with a dirty MAF, and had used the fix, of cleaning off the sensors with o2 safe Gumout Carberator Cleaner. A great fix! But hopefully it's not related my new problem.

 

[MAKG]

Well, I'll repeat what I said earlier.

I suspect you need a new mechanic.

I'd encourage you to avoid the "new = good" assumption. It's not even close....

There really isn't any point to guessing. And the CEL doesn't have to be on at the moment for the tech to read it (though it's better if it is). The computer has this stuff called "memory."

As for the exhaust, I replaced my entire exhaust system from the Y-pipe back, with new factory bolt-ons (except for the Y-pipe, which was from a junkyard), for less than you were quoted for the muffler alone. My original had been perforated by an idiot with a welder.

 

[was_shaggy]

My cat was replaced last year, during the time the mechanic changed out some sensors and other stuff, that triggered in the diagnostics test. My muffler and tail pipe on the other hand is still the original, and is making a high frequency squealing or rattling sound, the higher RPM the engine is at. There's some holes that ate through the baffling, and the mounts for the baffling are completely corroded through. I was thinking about replacing it until I heard a new one would be in the $300-450 range, I guess I had thought a new set up would be around $150 or so. My plan "B' is to take if off and bang it on the ground to knock anything lose in it out, for a temporary fix, for the crappy sound it makes. If the other problem, that I'm having is laying within the muffler or pipe, then I may change it after all. What do you all think?

300-450$ sounds like someone misspoke or missheard. Drop the zero at the end sounds more like it. $30-45 will get just a muffler replaced at most local shops around here. Unless they were planning on installing a stainless steel system.

About your plan B.......well, if you can get the old muffler off to bang it around...........you're over half way to replacing one. Getting a muffler off is the hardest part for most people.

A suggestion - when you hear an astromonical price do some research online at auto stores. It can pay out well. I just replaced a Fuel Pressure Reg. O' Rielly's wanted $102. Nope sorry. Not until I go home and have a look see online. Autozone had one for $64, unfortunately it had a quick disconnect. Advance had the threaded one I needed for $84


My first thought was a colapsing muffler but I'd think that would show up sooner than an hour of driving. 10 -15 minutes is more like it.

Fuel pressure reg have been known to get get *soft* during heat as they age. They drop below spec when hot but they still work when cool.
There won't be a code since it's mech not elec.

ish474 makes a good point, makes me wonder about the relay for the fuel system.
Good luck, be interesting to know what the fix is. Let us know, would ya?

 

[CaptainStomp]

MAKG, do you know any good mechanics on the central coast and are you up in the north end of the central coast, near Monterey or on the south end near SLO. I'm pretty much in the middle so I'm always up near Monterey and also down near SLO, depending what I'm doing, and usually the drive to either is when the problem I have starts up.

 

[MAKG]

Hmm, didn't notice that.

I live in Santa Cruz County (so, far north), and I tend to use mechanics only for things I can't do myself like wheels & tires, smog sniffs, and machine work. I have no idea who is good in Monterey or SLO County. I don't even go to Santa Cruz for stuff like that, but try to stay very local.

If you have a regular parts house you go to for everything, and have some rapport with the staff, that would be a good place to go for advice. BTDT.