5.0 Surging When Warm

[RandomNerd2000]

So, my 2000 5.0, which just rolled 283K, has developed a newer issue lately, seems to be slowly progressing, I have my hunches on what it likely is but I'll ask input beforehand.

Sitting at a stop, in gear or out of gear, it's hunting, it'll go up to about 1500, get down to it's literally about to stall, then back up again, in gear or out of gear. Out of gear it's slower but it'll do it.

It also, if you crank it up and put it in gear warm, acts like it's trying to stall out. It did get new plugs, Autolite Plats, at 272K miles, new fuel filter, new air filter, cleaned the IAC and cleaned the throttle body.

I'm sorta lost on it, last I checked the CEL back when it did it to begin with, it didn't show much, showed a evap system leak, that was it. Only other thing I've noticed is restarting the truck solves it for anywhere from an hour to a day.

 

[RandomNerd2000]

Update, issue is progressing, it takes a minimum of 20 minutes of driving to get it to show so a fuel pressure test is near impossible. It's getting worse though because the truck now has a rough warm idle along with the sure and a hesitation on takeoff.

 

[RandomNerd2000]

Any ideas? Anybody? I'm lost on this one, still no codes.

 

[Mr. Alligator]

Random, What about fuel pump? Maybe change fuel filter first?

 

[RandomNerd2000]

Fuel filter was done less than 10K ago, replaced factory. I'm not having lean codes, but I'd imagine it'd help to replace the pump, the hesitation on takeoff reminds me of a lean condition.

 

[RandomNerd2000]

So, it set a CEL, I also got my better code reader working again, which was productive, I got a decent list though. Most are related to electrical stuff for the windows or doors, so I'm not worried there. The codes that are worth mentioning though are, I got a bank one lean, bank one sensor one fault code, a code for the EGR valve, don't remember which one, and a code for the evap system on it. I looked at the live data, the trims do show a bit of a lean condition on both sides when warm, driver's side sits at 8% and passenger side at 11%. Considering that it had a fuel filter 11K ago, bets on the pump being tired.

 

[RandomNerd2000]

Bump again, issue went away until this week, and it's BAD now, it's surging and HARD on gas, I'm pulling a solid 8 to the gallon now. Take off from a red light on the floor and the road is full of black smoke, it'll barely pull my 5x8 trailer so it's definitely weakened and runs visibly rough. It smells really rich at the back too. I'm going to pull codes tomorrow and if it doesn't say what's wrong, just start going through what's under the hood in sensors and TPS and such. Going to also get my extra pump out and have that on standby.

I've heard a variety of things but they all relate to cold idle, this is a warm issue. I've debated a bad upstream catalytic converter, which at 289,2xx miles is plenty fair, and will be deleted if there's no sensors in it. There a way to tell if they're bad with no sensors in them? I know about the bump them with a hammer trick and listen for a rattle.

 

[RandomNerd2000]

So the rattling I've had develop is the AC compressor, that was both great (I'm getting ready to be EPA certified to handle refrigerant), and annoying. I checked and the truck didn't act like a bad cat, so I was poking around and noticed a driver side lean code, which was weird to me, so I checked and the passenger side was running rich. The driver's side? The fuel trim was +43.3%, and there was no long term trim set in the PCM. So, I took a used sensor and crawled underneath.

With that said, truck gets 21 to the gallon again, it's bad as heck too, it'll burn 265s like they aren't even there. The old sensor was actually still good excluding the sensor, it checked with a meter and was somewhat switching. It was actually stopped up, like the carbon had built up until it was simply not getting exhaust inside of it.