Runs rough after revving *Video*

[5.0]

.
1997 2.3 with a manual.


The engine idles fine, although a bit high at around 1,000 rpm, but then runs real rough after revving. The problem is much worse when the engine is cold, but still happens at all temps. After revving, it will idle rough and run rough at higher rpm's, like when I try to drive it misses out real bad. The higher it revs = the worse it will run. The engine returns to normal after a few minutes.

The only codes are P1443 and P0303.

P1443 = Evap problems
P0303 = Cylinder 3 misfire.

Where should I start?

 

[john112deere]

Have you checked basic stuff like plugs and wires?


As to the EVAP code- did you look over the vacuum lines from the canister to the intake?

 

[5.0]

.

Evap code: I replaced the lines except for the one from the charcoal can to the first valve (it's a special size). I have a new valve and solenoid from the junkyard that I need to try.

I just recently bought the truck... the plug wires look fairly new and the plugs don't look real old either. The dealer I bought it from replaced one of the coils.

Could a bad plug/wire/coil allow it to run fine until the engine is revved, then run rough and return to normal after a few minutes?

The problem happens every time, and the same way every time. It's not intermittent. I can make it do it, or not do it. When I accelerate, if I go easy on the gas it will run fine. If I nail the gas, like to get out into traffic, then the engine will start missing. It will accelerate fine, then start missing when I shift into the next gear.

.

 

[O'Rattlecan]

Are you getting any lean/rich codes? I could visably see smoke, but not which color it was.

Ryan

 

[5.0]

.

Nope, no other codes other than the evap code and cylinder 3 misfire.

The engine has a bit over 180,000 miles...

In the video, the smoke seems to happen after it is missing out, but still no other codes.



Edit: I may go out and (electrically) test the maf sensor for proper operation. It's been cleaned, but made no difference. I think I'm going to pick up a fuel pressure tester today on my way to work and see what the fuel pressure is when it's messing up.



.

 

[john112deere]

Evap code: I replaced the lines except for the one from the charcoal can to the first valve (it's a special size). I have a new valve and solenoid from the junkyard that I need to try.

Yeah...I chased that flippin' thing all over the city, never did find one. Finally found a little plastic fitting that let me join two pieces of hose to make the right sizes...cost me about $6, including the hose.

I just recently bought the truck... the plug wires look fairly new and the plugs don't look real old either. The dealer I bought it from replaced one of the coils.

Could a bad plug/wire/coil allow it to run fine until the engine is revved, then run rough and return to normal after a few minutes?

The problem happens every time, and the same way every time. It's not intermittent. I can make it do it, or not do it. When I accelerate, if I go easy on the gas it will run fine. If I nail the gas, like to get out into traffic, then the engine will start missing. It will accelerate fine, then start missing when I shift into the next gear.

These trucks are known for being fussy about plugs...Motorcraft dual-platinum seem to last the best, from what I've heard. It's a waste-spark design (fires at the top of the exhaust stroke, too), and one "bank" of plugs fires "backwards" or something...I'm not an expert in how these ignition systems work.

I've often wondered how these things would behave under the failure of one coil pack/one plug (dual-plug head), but never really gotten a clear answer.


I've got a somewhat similar, though not the same, stumble/flat spot/miss/something going on with my truck...I need to either do some serious diagnostics on it or start throwing parts at it, but it's just too dang cold, so I'm living with it. It's not quite as bad, either. I'll be sure to let you know if I ever do get it solved, though.

 

[5.0]

.

Alright, let me know hat you find on yours.

The plugs and wires cost about $100, so I don't want to buy them if there's nothing wrong with what I have. The #3 plug on the driver side looks like a pain to get to, so I need to wait until I have plenty of time before that plug. I'm going to get the plugs and wires sometime anyway... when I can afford them.

When my engine is still cold, I can rev it and then it will die instantly. I have to crank and crank for about a minute to get it started again, then it runs REALLY rough.


.

 

[5.0]

.

Ok, I tried some new plugs and wires... no help. It had some autolite 764 plugs in it that smelled like gas.

Here's what I've tried:

plugs and wires
cleaned maf
checked maf voltage
cleaned some ground wires


The problem happens if/when:

engine cold, rev it high and the engine will die instantly when returning to idle
once engine warms, it will not die after revving, but run real rough
after revving, it runs rough idling and at rpm
idle will return to normal after a while
happens in open loop and closed loop




.

 

[CowboyBilly9Mile]

What color were the plugs when you pulled them out, and were they the same across all cyl's or was any one or two or three cyls different?

 

[TexasNomad]

My friends Bronco was doing the same thing, it turned out to be a vac line was bad.

 

[5.0]

.

The plugs looked kinda like new ones to me. I'll take some pics and post them late tonight when I get home from work.

I still need to check for a vacuum leak too. I've replaced a couple lines and looked for anything obvious, but haven't checked any farther. It's cold outside...



.

 

[TexasNomad]

Well if its any thing like my friends Bronco II it has about 30 miles of vac lines and the thermostat is on the bottom on the engine..

 

[CowboyBilly9Mile]

.

The plugs looked kinda like new ones to me. I'll take some pics and post them late tonight when I get home from work.

.

If there is a noticeable difference in color, then it would possibly be of benefit to know what cyl they were in.

 

[5.0]

.

Ok, I did plugs and wires last night, and I'm still getting P0303 (cylinder #3 misfire). After it warmed up today it seemed to run fine.

.