1997 lean condition

[crowncrazy87]

1997 model with 4.6. Running extremely rough, no power, pinging. Shows lean code for both banks but no actual misfire code. I've checked all vacuum lines, intake gaskets, pcv valves, fuel pressure. Full tune up with plugs, wires, fuel filter, air filter, cleaned MAF.

I did have it running and one by one pulled injector connectors. Some made a difference in running others not so much. Clogged injectors? I did check resistance on them and all were almost identical readings and you can hear them all clicking.

Just kind of at a loss here on what to check or do next.

Just bought this rig and want to get it right!

 

[Killer Ride]

Have you checked the Cops or the O'2 sensors? How bout fuel trims?

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[crowncrazy87]

97 4.6 doesn't have COP set up. Has the two coil packs each with 4 wires. I can check the fuel trims. Where should they be running at?

 

[Killer Ride]

Sorry bout that I would check the 2 coil packs then and the O'2 sensors. There's 4 02's right? I actually like it better than 8 Cops but a little less tunable. The trim levels don't run at a set level they are constantly changing but you want to look for vast differences from bank to bank and also from long term to short term. For '97 I would buy 1 of each the upper and the lower then you could swap them out to troubleshoot which side it is. They are different so make sure Ther is an upstream and a downstream. Usually there is 1 lazy one that responds but not as quick as it should.With it being 22yrs old I would probably replace both sides or when I could afford it. They are not too bad at Rockauto.com.

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[crowncrazy87]

I got some good o2 sensors on my currently down (fuel pump) 98 f150 4.6. I could borrow those first and see what happens. Heck I could borrow a lot of stuff to help trouble shoot lmao

 

[Killer Ride]

There you go, now your cooking! I would do exactly the same thing. Why buy to troubleshoot? Good luck

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[Killer Ride]

Post back up here if you figure it out

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[TobyU]

I don't think it's young to be O2 sensors. You could cut the wires off all 4 and it would still run pretty well.
Both banks lean points to vacuum leak. The intake manifold likes to learn on these. Try some spray around it... Carb cleaner wd-40 etc to see if it smoothes out when liquid hits leak.
Try the cylinder cancelling out with the spark plug wires. Use a rag or glove and pull one up one at a time to see the difference.
All should make a solid miss. Sometimes you will get one that as soon as you connect it, it fires smoothly for about 2 seconds then back to missing. This can be cool pack or wire. On COPs it's a weak one.

 

[1955moose]

2 things on top of what Toby said, I'd actually smoke the Motor rather than spraying it for intake leaks. Also look for smoke coming out leaking exaust manifolds. 02 sensors actually last a long time, the wires get damaged is the biggest problem with them. Do the other tests before swapping the ones from your F150. If you do remove the known good ones, from your pickup, don't touch the tip that reads info with a greasy hand. Their like halogen bulbs, they don't like human fingers touching them. As far as fuel trim readings, theirs charts online. Theirs short term, and long term readings. When reading these you ideally want to see close to 0, but they fluctuate a little plus or minus. When you have a intake leak or malfunctioning cat or 02, that's when the readings are way off. You will need Forscan or a reader that can do fuel trims. The cheaper ones only usually do codes. Let us know what you come up with.

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[Killer Ride]

I forgot to ask but if you have stock exhaust it could be same issue I'm having with clogged Cats. On my '98 Expy that I bought a few months ago it had no power. And when I would gas it over half way it would make a sound like air escaping a compressor. I took it to an exhaust guy and had him back pressure test it sure enough that's what it was. This isn't my 1st time dealing with the same issues as you I also have an F150 I installed a '02 Lightning motor/trans in and I was getting random lean codes on both banks, again it was clogged Cats. Drove around for 7months before I figured it out.

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[crowncrazy87]

Yea I've sprayed carb cleaner all around the thing already. A couple of times lol. Didn't do anything that I noticed. Checked fuel trims today. Bank 1 trims never went over 10 either way but the long term on bank 2 stayed between 18 and 26! Truck isn't really drivable so this was done at idle.

 

[Killer Ride]

Another way to check for clogged cats is with a digital thermal temperature sensor. Point it at the headers on both sides. The hotter side will be the clog

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[TobyU]

Sounds like a massive vacuum leak to me. I had one that i did the plugs on a 6.8 in a van and knocked the big hose that goes to air bypass valve off. It wouldn't run for crap of stay running...Massive leak. I thought I was screwed until I saw the hose off.

 

[1955moose]

Actually when using a heat gun, you want to aim it at the front and rear of cat. A good cat will be hotter on the exit side, by at least 100 degrees. When clogged the exit is same or colder.

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[Killer Ride]

Actually when using a heat gun, you want to aim it at the front and rear of cat. A good cat will be hotter on the exit side, by at least 100 degrees. When clogged the exit is same or colder.

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Actually the opposite is true, and the cats are directly bolted to the headers hence the reason to point the thermal sensor there nif there is a clog believe me it will be hotter above the cat

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[1955moose]

Well killer your the first in almost 5 years that made a statement like that. Think about it, exaust flows off each manifold, runs through header, then through each cat. If theirs a blockage in one or more cat, heat is going to get trapped within the honeycombs, or whatever material. If you've ever seen a really stuffed up one, they glow red. Go online, and you'll see that a proper functional catalytic system will be about 275 front, and 350-375 rear. Anybody else want to jump in here? When using a 02 gauge to read back pressure, you want a low #, closer to 0 the better. Usually a plugged one reads 10 or higher.

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[Killer Ride]

Yea thought about It,first off the heat stays trapped above the cat and usually it's the first one that gets clogged. I can put my hand on anything after that and it is only warm. Agree with you on the back pressure readings just did mine it reads 9

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[1955moose]

Was their a loss of power? Did you replace cat's? Common sense would dictate that temp should reduce down the exaust trail, not go up. Engine headers can get close to 1200 degrees Fahrenheit, as the spent exaust makes it's way to the tailpipe it's dropped way down, put your hand there at tailpipe gases, feels no more than 150 degrees. I think the reason the cat temp goes up instead of down, is the conversion process of breaking all the bad stuff down, like nitric oxide, carbon monoxide, and other nasty things, and make them breathable. Anybody here old enough to remember the 70's remember that bad smog in Los Angeles, and other metro areas. In theory it sounds backwards like you said. I did read an answer from advanced Auto parts that confirmed your theory. But all the rest said higher not lower exiting towards rear. This weekend I'm going to check my Eddie Bauer, and see what temps I get. My Suv runs fine, with no misfires or fuel dumping, so I'm assuming mine are ok. As long as we don't get too much rain this weekend, I'll post my findings.

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[Killer Ride]

Yes definitely lack of power can't wait to get them replaced it will be like brand new. Trust if your cats are plugged you will see high heat at it and above it downstream will be cool. I put my hand at end of tailpipe 5 min after start and it was cold and hardly anything was coming out

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[1955moose]

See then the theory makes sense. All the heat is being trapped in the honeycombs of cat. When unburned gasses from say a bad exaust valve or misfiring coil or plug, gets stuck in the cat, and fuses in there. It's like soldering your passages in there. As expensive as catalytic converters are, it's amazing how many individuals don't fix a simple misfire, and then cry when they've got to plunk down a grand or more for exaust work!

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