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Hey everyone. I have a 1997 f250 light duty with the 5.4, it idles very poorly, and I’m trying to figure out what it is/what to do with it. I’ve already cleaned the MAF and the IAC valve, and it stills glug glug glugs at idle. Now, the tailpipe is chock full of soot, and it’s steady blowing it out ever since I got it running again the other day (It’s been out of service for about a year). It threw a code last time I scanned it about an O2 sensor problem, so I already assumed that was part of the issue. Anyways, I’m looking at cats because I’m wondering if that’s not the main problem I’m having. Is this logical, or should I look somewhere else first? I can get a really good deal on some new cats but they’re 2 inch and I’m not sure just yet what size is already on it, but I think it’s stock. If 2” is too small, is that gonna be a big problem or can I work with it? Sorry if these are silly questions. Thanks in advance!
Hey everyone. I have a 1997 f250 light duty with the 5.4,
the tailpipe is chock full of soot, and it’s steady blowing it out ever since I got it running again the other day (It’s been out of service for about a year).
A clogged exhaust sysyem will have problems at high RPM, high exhaust flow, more than low. Poor acceleration, inability to reach speed. Poor idle doesn't really fit with bad converters. The sooty exhaust suggests other problems (that might actually ruin the converters if you don't fix it).
Need more clues. Why was it out of service in the first place?
Actually, I think that you have flipped the cause/effect rationale. You're answering a question he didn't ask. He didn't ask if his converters were bad, he asked if his converters could cause a rough idle. Beside that, he's not reporting a performance problem, just an idle problem. Which implies that the converters aren't bad. He's trying to fix a rough idle.
There's really not much to go on. An old O2 sensor code that is gone now, apparently. And a sooty tail pipe.
I'd get a scanner that does live data and see what's happening. Might have a pending code. Look at fuel trims. Blown fuel pressure regulator seems possible. Which could ruin the converters, of course.
Sorry for the absence guys. Supposedly, according to a VIN search, the truck has over 350,000 miles on it but I’m not certain of that. The odometer stopped at 255,221. My tools at home are limited and I’m in the process of getting the tag and insurance ironed out, so I haven’t been able to take it to a parts house or shop or anything to get it tested yet.
It’s been out of commission over a blown plug, #8, which had blown out after I already fixed it the year prior. I just hadn’t got around to fixing it the second time until just recently.
It’s been a while since I really drove it around, but for as long as I’ve had it, it struggles to go uphill without sputtering and jerking me all around. But just revving it in the driveway after I got it running again, high RPM didn’t seem to have any issues, it’s just when it’s under load I think. Sorry again for the absence and for the vague questions lol. Thank you all for responding though.
Alright, now between yesterday and today I’ve driven about 60 miles and everything checks out besides the idle. I’m in the NC hills and drive up and down a bunch of them during my commute, and it’s doing great as far as the stuttering/jittering uphill or under load. I think my next task is going to be checking the pressure coming from the fuel pressure regulator like y’all suggested and see how that goes. And I’ll get it scanned as well, and maybe I’ll get something figured out from there.
Converter failure will not cause a miss at idle
The miss will plug the cats
Pull codes first
Inspect cats
Sometimes for testing
I drill a 1/2 inch hole in each headpipe that can be easily welded up later
Last Corvette I had, the converter substrate would flip over with me driving it
Caused the engine to die and not restart it was plugged so bad
I used a 1/2 inch hole saw on the Y pipe cat on that Corvette and was able to drive it home
Plan on putting a long block in your truck and a new cheap catalytic converter
I figured out my problem, at least most of it. My cats are stopped up, and I have an appointment to get them changed out, but while I was rooting around the engine yesterday I realized the PCV tube didn’t go anywhere.
It’s kinda tricky to tell what’s happening in the picture but the two black pieces closest to the middle of the screen are the backside of the PCV tube, and somehow it looks like it melted right off. So for however long now, I guess air was just barely passing through that gap just enough for the truck to run. But now, I have a hose bridging that gap for the time being, and it runs like brand new. Thank you all for the help
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