93 XJ 4.0 Check engine light, running rough, loss of power

Heya, so I have a '93 Laredo with the 4.0L and I need some help troubleshooting it. I replaced the CCV elbow up front, and immediately after I got a check engine light and she's not running right. The code says injector fault, but all my injectors are good, I replaced the distributor cap, rotor, plugs, and wires to no avail. The truck shakes while accelerating, and sounds like a lawn mower engine for lack of a better description.
Anyone know what's going on?
Thanks in advance!
-Vash

 

I checked all the vacuum lines, air filter is good. I'll double check the intake. It was running fine before I replaced that elbow, and it shattered in my hand when I went to pull it out. I put the new one in, and the light immediately popped on. I'm wondering if it's the crank positioning sensor, I don't think it's ever been replaced, but I'm not seeing a correlation.

 

There is a chance, and I didn't even think of that. I may have roughed up the seat for the rubber gasket piece getting the old one out. I'll slap some RTV on it and see if that doesn't do the trick.

 

Will do. It ain't pretty, but I ran a good bead on the rubber seal against the valve cover, and again between it and the elbow. I'll give it some time time to set up and see how it's doing.

 

Welcome! Since the problem(s) started after replacing the CCV then just focus there before venturing elsewhere. Make sure everything you replaced is installed correctly as RTV is usually not required.

 

My thought exactly, and the RTV only made my valve cover more colorful.
I'm starting to wonder if when the original elbow shattered if I lost a couple pieces in the valve cover, so tomorrow I'm gonna pop it off and look. I also have a buddy bringing his OBD scanner over so I can check the code again.
I've had this truck for 12 years, it has over 500k miles on it, and this is the first time I've been scratching my head over an issue.

Also, anyone know what the ohm value should be for the crankshaft positioning sensor? I figure it won't hurt to check.

 

"http://atlib.info/blog/133-how-do-i-check-a-crankshaft-position-sensor"

gobblygook!! you could never do it right!!
my pix is a scope pattern in good running 4.0 but you need to focus on just exactly what you did seconds b4 the trbl started! IF thats all you did,,,,or its a massive cooincidence that the cps went bad just then.

 

oops, better pix



2.5v peak pulse, spacing changes with rpm...

 

I'm working backwards from the issue at this point. About all that makes sense is that a piece of the old elbow fell into the valve cover, so I'm about to pop it off and take a look. Otherwise it's just the Jeep gods messing with me and it's completely unrelated. Let's have a look in the valve cover!

 

Just wanted to let y'all know I haven't forgotten about ya. I apparently passed a kidney stone and have been laid up for a few days, but I got a new valve cover gasket today and I'm opening her up in the morning. I'll let y'all know what I find.

On another note, can anyone advise a good place to get a new yoke for my driveshaft? The one in the back of the transmission is worn and I'm getting that "clunk" when I shift into gear. Thanks in advance!

 

Hope your feeling better! Local parts stores should stock replacement drive shaft pinion yoke, CV H yoke, axle yoke etc.

 

I FIXED IT!

Okay, so just under the elbow in the valve cover there is a metal plate that I'm assuming regulates the airflow into the elbow. When I was prying the old elbow off it looks like I bent it upwards on one side. I bent it back down, problem solved.

 

But, on our test drive the check engine light popped back on.....

 

Disconnect the battery to see if it clears the CEL. If the CEL returns identify the code and start from there.

 

I'm having the same problem. Is this what actually fixed it? Cause mine started after I replaced the transmission.