1997 v8 runs like garbage

[Explodemylifepls]

Ok, but what about the power drain, I don't think the voltage should be dropping so far down even with everything running.

 

[Turdle]

I use an non lighted, propane hand torch. To check for vacuum leaks. The nozzle gets into tight spaces, raw propane will definitely change idle, and, doesn't go everywhere.
Ad for the voltage drop, what is the condition of the alternator? Any high power stereo stuff? Smoothing capacitor?

 

[Explodemylifepls]

At some point there likely was some "high power" audio equipment but not now, I get it (the voltage drops) without the radio even on, just both AC blower motors (AC leaks but it's ice cold btw, hopefully can see the leak when it runs out again).

Alt spun fine but looks original with 200k on it, ik these trucks are sensitive to voltage.. I'll see if I can get the pcv valve to not leak, that's likely where the majority is coming from since I can't get to it with the intake on at all..

 

[C420sailor]

Somewhat normal for the voltage to take a dip with blower fan on, esp while burning headlights

Remember that pulling the ground resets all the adaptive tables, including the fuel trims. The truck may be running great with the trims reset…but after a while, the trims drift and the truck goes back to running like ass

 

[Explodemylifepls]

Yes that is why I thought it was the pcm. Stuck the pcv valve back in and looked everywhere for vacuum leaks, and can't find any, even though now it has a very loud vacuum leak type sound when warm that comes and goes and usually correlates with it running bad but not always.

 

[410Fortune]

Pcv valve out of its hole will cause some serious stumbling issues, can usually hear it when the 5.0 pushes that sucker (no pun) out of its grommet

If it keeps happening you need a new grommet or some silicon or both
That could be the noise you are hearing?
May consider a smoke test

I can access the pcv valve from the passenger side with my hand sliding behind the intake, might have to move the pcm wiring and egr wiring a bit but you can get in there. It can really help to remove the two nuts on the transmission mount and put a jack under your t case, jack the t case up until it touches the floor

 

[Explodemylifepls]

Well I managed to plug the pcv grommet and valve and hose back in n their hole with a generous amount of RTV. Doesn't seem to have made much difference in how it runs. The vacuum leak sound seems to be coming from the ac, if I unplug the iac with the ac on the noise directly correlates with compressor function. Edit: it does not always correlate but sometimes does. It's a loud whining beep type noise

Can't feel any leaks on the bottom on the drivers side manifold vacuum hoses. Nothing really seems to make any difference in how it runs. Still idles poorly and down on power, although it did upshift into 3rd a few times today, it would be much more fun to drive if it did that regularly.

 

[Explodemylifepls]

Pulled the upper last night to look things over and reinstall pcv with more rtv. Did not see anything obvious. Took it to town today and it was running even worse, one of the plug wires came off. Fixed that and it's still not right.

Still makes the whining noise when I unplug the IAC (or stick it in 2nd and punch it and let it settle back to idle), idles rough, fuel trims sit in the negative % at idle and go positive for a second when I punch it. But an entire can of ether or any amount of propane makes no difference in the rough idle, however if I unplug a main vac source while it's idling it will rev up and start to idle smooth..?

Still especially bad at low rpm high vacuum (ex cruising in OD), in fact on the way back from town it was so bad that it would bog down and backfire real loud out the exhaust if I kept it in OD.

New pcm no change, cleaned MAF and tested voltages no change. Don't think it's sucking through the intake manifold gaskets, lower install went good and everything is in place.

 

[CDW6212R]

How do the spark plugs look? With the engine running so badly with the many things done, I wonder how they are now. If any of the plugs look rough, wet or black etc, there may be something wrong with the gaps, coil packs, or the plug wires themselves. The plug wires are easy to damage when pulling them off, old or new.

If one or a few of the plugs look bad, you may have to replace them, or the wires, or all of them, depending on how they are. I'd pull the plugs and carefully inspect each one, and the wires, documenting the condition, don't mix them up, and consider why any would be fouled etc.

 

[Explodemylifepls]

I pulled the whole intake again to double check everything for leaks. Reinstalled and it ran great for the first 10 minutes then progressively worse to very bad, like its running on 4 but only sometimes.

No codes still, started it this morning cold and it idled perfectly..?

 

[410Fortune]

Coolant temp sensor is suspect?
Also I know I’ve said this before but progressively getting worse after a cold start you need to check fuel pressure to rule it out

 

[Explodemylifepls]

I think I've checked both of those a couple times. I pulled all the plugs and gapped them yesterday. 6 of them looked exactly like this, 2 on the passenger side looked different. One was more brownish like it's supposed to be and one them was black 1/3 of the way around looked partially oil fouled.

After messing with the plugs it now was a tick and misses really bad at idle so I'm gonna order a set of motor craft wires not these crappy densos. I have a new maf coming to rule that out although I already tested the voltage output on this one and it looked normal.

 

[410Fortune]

Messing with the plugs and wires the miss got worse!

One plug is black with oil, this points to possible valve seal problem which these engines are known for at higher
Miles

Get the motorcraft wires installed with the new gapped plugs, make sure you have correct firing order and then report back

 

[Turdle]

This is a late 97 , 98 right? Egr tube on tubular passenger side header?

I'm betting my last nutter butter you have a cracked passenger side exhaust manifold, ticking and sucking unmetered air thru the egr tube

 

[CDW6212R]

If that's it, you can test it by temporarily disabling the EGR, taking the vacuum line off and plugging it for the test drive.

 

[Explodemylifepls]

It's got new manifolds, dorman cast iron ones. I don't think the egr tube is cracked I tested it with my own lungs, not the best method I know but The tube was intact when I had it off messing with the intake. The ticking sounds like a plug wire it makes no sense that it would just appear after messing with plugs unless I damaged a wire.

The tick SOUNDS like it's coming from the drivers side, it was pretty faint till I messed with the wires and now it's not faint at all. Thought it was a lifter at first but now after messing with the plugs it sounds like a plug wire ticking.

I've plugged off all the vacuum accessories at the intake and none of them made any noticeable difference in how the engine ran.

 

[410Fortune]

Watch the engine run in the dark, any blue arching around the wires?

 

[CDW6212R]

Plug wires are very fragile and easy to break internally. They are fairly reliable for a long time, when they are not touched or pulled etc. It's a decent bet you have a wire or two that are not transferring the current to the plug well.

 

[410Fortune]

Just had a 98 in the shop yesterday, my stepdaughters truck started running rough..
Talking to the computer found cyl 3 misfire checked wire came apart in my hand. Was too close to manifold. These are motorcraft wires only 6 months old. Tossed in a new wire she’s back on the road

 

[Explodemylifepls]

New wires did not help. The rain came and I had a chance to look at it today. The 2nd spark plug back on the drivers side had a broken ceramic (the one that's kinda hard to reach behind the shock tower.). I replaced it with a similar plug I had on hand, added some fresh gas (tank was almost empty and I had put some howes diesel conditioner (??) in the gas thinking (and still do) that I might have a sticky or stick injector. (Both plugs I pulled looked way more oil fouled and the howes + low gas level is likely why).

It seems to run a bit better after chopping the throttle from WOT the issue comes back, I'm thinking I may have an injector issue. I might try some more sea foam but that stuff only seems to make stuff stop running ime.