Diagnostic advice needed, 97 7.4

[Smokinthehippies]

Need help chasing an issue guys

This past few days took the burb camping up in the Sierra Nevadas. Went from like 12' above sea level to about 8k' and back again.

Driving around yesterday just to the store and what not truck felt a little doggy. Didn't worry because I thought it was the elevation.
Anyways coming back home today. I noticed the truck won't let me push past 3k rpm. The truck will get louder like I'm pushing it harder but the tach will not go up past 3k. Now at idle it's very rough. Shaking and bucking.

Hooked up a code reader even though no lights were showing. Said nothing out of the ordinary.

Recent changes were
Fuel filter
Optima battery
K&n intake

All of these were done few days before and it drove fine after.
I did top off with gas up at a shack on the mountain and I'm getting the impression maybe the gas was bad. But the truck seems to be running rich? Seems like a lot of extra soot in the tailpipe and definitely not sounding hot.

I also was thinking o2 sensor but the scanner showed them as fine also (I know that's not conclusive but it's all I have at this point)

Any ideas I can do a quick diag on over the next two days before work time?


Other than this truck was magnificent as a camping rig. Hauled us and the furry children and all our gear no sweat (until the way home I guess). Also did a small amount of mild fire road wheeling.

Please help guys. Any ideas appreciated.

 

[Fordum]

Don't know diesels all that well.
Check the air cleaner. Easy and fast. Actually had a friend suck a bird up in his one time.
Talk about a rough running diesel........

If its bad fuel, you my have another filter change in your immediate future.
On the off-hand chance that it uses a MAP sensor, you might try unhooking the power and letting it sit to clear out the memory.

It might have loaded the lower pressure in when at altitude and never replaced it. I know my truck reads the MAP at startup, but its not a diesel, plus its a Ford.....

 

[Smokinthehippies]

Don't know diesels all that well.
Check the air cleaner. Easy and fast. Actually had a friend suck a bird up in his one time.
Talk about a rough running diesel........

If its bad fuel, you my have another filter change in your immediate future.
On the off-hand chance that it uses a MAP sensor, you might try unhooking the power and letting it sit to clear out the memory.

It might have loaded the lower pressure in when at altitude and never replaced it. I know my truck reads the MAP at startup, but its not a diesel, plus its a Ford.....

7.4 is the big block gas
And I checked the intake nice and clean. Also disco'd the battery. Let it sit for a bout 10 mins and tried again. No dice. Same thing.

 

[4X4HIGH]

I would first run it at night and check for any wires/plugs arcing to ground. I would then replace the plugs with NGK V-power plugs (best plugs i've ever ran, and been running them for 20+ years now) and my next place would be MSD plug wires. Certainly wouldn't hurt to pull the dizzy cap and check the conditioon of the cap and rotor. If this is the year that used the plastic dizzy those are notorious problemsome dizzy's.

 

[b454rat]

When I had my 97 out in CO, I kept getting pressure in the tank. Taking the gas cap off would blow your hair back. It had to be the altitude, cause it didn't do anywhere else I had the truck....

 

[diesel4me]

If it came on suddenly it might be something simple...if you suspect bad gas I'd definately drain some out of the filter and look for any water or dirt in it..it could well be you got a tank of crappy contaminated gas along the way..


Other things to look for include a vacuum line cracked or fell off creating a lean mixture ,(PCV,etc) that the computer will try compensating for and possibly not set a code,maybe the charcoal canister purge valve let raw fuel get into the canister and now its overdosing on fuel (though that should set an EVAP code) ,or maybe your catalitic converter has started clogging up ,restricting the exhaust..

 

[Smokinthehippies]

Played with it for a few minutes this morning. Noticing a white smoke puffing out the exhaust now too.

http://i383.photobucket.com/albums/...E70BD41-4440-0000034981243194_zpscac2a17e.mp4

Does this make the picture Any clearer?

 

[Fordum]

7.4 is the big block gas

Well, theres your trouble right there......Stop putting diesel in it...........

Sorry about that, saw the 7 and jumped right to diesel.
When you say it won't go past 3K, what happens if you try? Does it just run out of power, or start misfiring so bad it can't go faster?
Or cut off completely?

The rough idle sounds like a missfire. Bad plug wires as mentioned, or dizzy problems.
But with the white smoke, it might be more serious. Does the smoke disappear a short distance from the pipe, or just dilute away.
In other words, I am trying tell if its moisture or oil smoke. Both can look white. If the engine is cold, and the weather is cool, it might be condensation, but if it smells like coolant, you have a leak.

Blown head gasket or a crack somewhere. Have you noticed a hesitation when cranking, like the starter wants to stall for a second? If so, its usually water in a cylinder.
Maybe the quickest check is to pull the plugs and look for moisture on one or more of them in a cold engine.

Hopefully its something else.

 

[Smokinthehippies]

So did the oil change and started pulling plugs afraid of finding head gasket leak. As of now I'm back to leaning towards sensor.
Oil was dirty but no sign of coolant.

Spark plugs I've only got left bank done so far.

#1

#3

#5

#7

Of those four so far. All of them came out looking moist/damp and smelling heavily of gas.
Number 1 wasn't damp at all but smelled a bit of gas.

Working on pulling other four now but I'm thinking now it's back to a running rich issue.
Wish it would throw a code to point me in the right direction.

 

[Smokinthehippies]

#2

#4

#6

#8

Again. All 4 smell of gas

 

[1BEATK5]

I bet the cat is plugged.

 

[Smokinthehippies]

I bet the cat is plugged.

But it has dual cats. Wouldn't they both have to be plugged to have the fuel issue on the plugs on both sides

 

[rockin kw]

check the cap and rotor. mine had similar problems. would not do it all the time and finally threw a misfire code. finally checked cap was corroded. new cap and rotor and it was good as new.

 

[Smokinthehippies]

Ok thanks. I have both those parts plus new wires to do tomoro. We will see how it goes after that.

 

[Fordum]

Yeah, def running rich. Are those gaps excessive? They look that way in the pics, but can't really tell.

Also, I assume that is deposits on the number 4 side electrode and not rust.

 

[4X4HIGH]

Plugs are shot and as Fordum said, those gaps looks huge (could just be the pics). Do yourself the biggest favor though and run NGK V-power plugs, you'll thank me for it later.

 

[Smokinthehippies]

Yeah, def running rich. Are those gaps excessive? They look that way in the pics, but can't really tell.

Also, I assume that is deposits on the number 4 side electrode and not rust.

Plugs are shot and as Fordum said, those gaps looks huge (could just be the pics). Do yourself the biggest favor though and run NGK V-power plugs, you'll thank me for it later.

The specs I found called out a .060 gap. I only actually checked one and it was at a .065-70 so while on the loose side it didn't seem drastically off.
And Scott those are the NGK V's. bought them based on your previous post.

Any body have any ideas as to where my problems could be coming from?

 

[4X4HIGH]

The specs I found called out a .060 gap. I only actually checked one and it was at a .065-70 so while on the loose side it didn't seem drastically off.
And Scott those are the NGK V's. bought them based on your previous post.

Any body have any ideas as to where my problems could be coming from?

Glad you took my advice, you'll love the NGK plugs.

Not every knows this but once a spark plug becomes fuel fouled they will NEVER fire correctly again even if you were to clean them up. Those plugs looks pretty nasty and once the engine starts running poorly and then become fuel saturated you have an issue like you're having. Start with the plugs ONLY then see how it runs.

 

[Smokinthehippies]

Glad you took my advice, you'll love the NGK plugs.

Not every knows this but once a spark plug becomes fuel fouled they will NEVER fire correctly again even if you were to clean them up. Those plugs looks pretty nasty and once the engine starts running poorly and then become fuel saturated you have an issue like you're having. Start with the plugs ONLY then see how it runs.

Roger that. Unfortunately I'm also going to need to do the wires and cap and rotor.
Only because popping off one of the original wires the boot ripped off the wire before popping off the plug. And if I'm gonna be up in there far enough to replace one ill replace them all. And if I'm up in there already ill do the cap and rotor as well. Hopefully ill get that all done and try to run it again tomoro.

 

[4X4HIGH]

Look to make sure it isn't the plastic distributor, if it is make DAMN SURE the shaft does not have ANY side play in it and if it does you'll need to replace the distributor. Somewhere right in those years GM used a plastic distributor which had issues with the housing wearing out and the shaft wobbling around. GM did not use bushings in those distributors they just ran the shaft in the plastic.