'96 Tahoe 5.7 dead miss

[Jsdirt]

Here's one for ya. LONG story ...

 

Ok - this is my buddy's truck that died in his yard, was able to restart later on and drive it up into his barn, then would not restart - 5 years ago. Been parked in pieces ever since.

 

So begins the saga. Without any diagnosis, he dropped the tank and installed a brand new tank & fuel pump. Then he thought it jumped time (even though the engine is a replacement with about 40k miles on it) & tore into the timing cover without realizing it's now entangled with the oil pan. After sawing the Y pipe in half and busting off all 3 bolts on the passenger side manifold, he was still not able to get he pan out - so I get the phone call.

 

That was a year and a half ago. Long story short, I got that all fixed with new gaskets, welded the Y pipe back together, & buttoned everything back up. Still wouldn't start. Went to the local boneyard and grabbed a computer. At first I couldn't get the fuel pump to run (sat 5 years bone dry). After letting some gas sit in the tank a couple days, and flicking the key a few times, I got the pump to run. Now she runs and drives .... like crap, but at least it moves under it's own power now.

 

Immediately after firing it up and taking it for a short (2 mile) drive around the neighborhood, I got 4 codes : 0341, 0137, 0171, & 0327. I threw in the remaining parts he had in the back: cap/rotor, crank AND cam position sensors, plus 2 upstream o2 sensors. Did absolutely nothing for the way it ran, but it eliminated the lean code & the sensor code. Now I'm left with cam position and knock sensor codes. As mentioned in the title, it has a dead miss: #2 & #7 are ice cold after idling a few minutes, & # 8 is lukewarm (touching the exhaust manifold).Shakes like hell at idle, and misses all the way up to 4k where it seems to hit a rev limit - acts as if your stomping the throttle, letting up, stomping for as long as you keep your foot in it.

 

Fuel pressure: key on pump running is 64psi. As soon as the pump stops, immediately drops to 60 psi .. and it slowly loses 1psi about every 5 seconds. Running, it's 54psi - stab the throttle in neutral and it flashes to 62psi, let off and it drops to 52, then stays at 54 at idle. I'm guessing a new regulator is in order.

 

Live data on my Autoxray AX7000 is all screwy. For example, long term fuel trim 106, speed 106, misfire 106, engine temp 106 (wtf ??)... plus more jibberish in other parameters. The freeze data for the codes seems normal - about +10 fuel trim on the bank that was lean, 192° operating temp., closed loop.

 

This is precisely what I HATE OBD-II and would rather go through the trouble of slapping a carburetor on this thing. At least I know it would RUN! (not doing that though)

 

 

The next course of action I would take is replace aforementioned regulator, and probably just do the MFI conversion kit to eliminate the possibility of plugged injectors. Knowing OBD-II there's no guarantee this will do crap except drain my buddy's wallet even more.

 

What say you? Am I on the right track?

 

[Jsdirt]

Yeah I figured this one would be a can of worms .. and I was right. Tried talking him into cutting his losses now and dumping it ... but he's too deep into it now. Down the wormhole we go .....

 

 

 

Wires are next, but I doubt 2 can go bad just from sitting. I'll move them around and see what happens.

 

Replaced one plug on one of the dead cylinders just to see - no change. Also never seen a plug die from sitting .. but again, this is 2014. Timing light flashes when connected to dead cylinders.

 

Air filter is clean - blew it out during assembly. Also blew out the length of pipe from filter to throttle plate.

 

Fuel is fresh - as mentioned, tank was empty for 5 years. Threw 2 gallons in to start, then a few weeks later, another 3 when it died from running out after driving it around the neighborhood. Probably getting 6mpg with it running the way it is ...

 

Rest of the sensors are impossible to test with the scan tool parameters all haywire. MAF is showing like 600 gr/second at idle. None of the paramters are making sense. Says temp 103° when engine is fully warmed. I'll be throwing more money away replacing them. Will a MAP & MAF make 2 cylinders shut right down though?

 

Got the green light on the injectors. It's his money, and he wants it to run. Throwing parts at it seems to be how this one is gonna go. Praying for a miracle ...

 

I HATE OBD-II!!!

[Jsdirt]

$400 down the toilet! I knew it ... Got a new Delphi spider assembly with regulator.

 

I'm waiting for the green light to park it in my yard for a nice fire .... and/or AR-15 target. My buddy doesn't seem to like that idea as much as I do ...

 

I'll update once I gather the motivation for a comp/leakdown test ... or just the motivation to even look at the POS ...

[00Silverado4x4]

How are the plugs? wires? fuel condition? fuel tank condition? air filter? MAP sensor? MAF sensor? Intake leaks?

 

In other words go through the entire line up on the engine before spending any money. The truck's been sitting on it's tires for years, bound to have something messed up.