alright people, today I decided that I was going to work on the jeep a little bit more. I decided that I would work on the fuel injectors again and see if I noticed anything. I noticed that one injector was spraying very crappy compared to the others. So I went to town and picked one up, swapped it and also changed the pcv valve and a couple of old cracked vacuum hoses.

The jeep runs quite a bit smoother at idle, but when reving it up it still cracks and backfires, and it will only rev up too like 2000 rpm.

Tomorrow, I'm going to tow it too a local mechanic shop, and let him look at it, maybe he will know or see something that I don't.

 

hey guys, I took the truck into the shop and they diagnosed the problem as a bad EGR Valve. What do you all think, I personally don't believe them

 

Usually if its bad, it will throw a code. I still cant believe it would be running perfectly, then you change the transmission, and something goes wrong the first time you start it...[&:]

 

A badEGR can definitely make it run like crap if it is stuck open.
Disconnect the vacuum hose to it and take it for a ride.
Sometimes if it is stuck open and you tap it with a screwdriver handle or small hammer it will seal up for a bit.

 

Didn't see this post earlier, but when suspecting cam/crank sensors, it's usually best/easiest to throw a scope on them. 3-wire sensors are usually hall-effect, which need power, signal out, and ground. 1.2 volts from ground to....ground...possibly indicates a problem (depending on where your second ground is). Check the ground strap to the engine block. Scope the output of the sensor, sig to ground. You should get nice clean pulses, with no spikes....hall effect's give you a nice sharp consistent on/off output. 2-wire sensors are variable reluctance, just a coil with a core, and metal moving past it will induce a voltage...so you'll get a sine wave which will increasein amplitude with rpm. these MIGHT also be 3-wire if there's a shield around the 2 other wires, best off measuring between the 2 main wires. It won't be as pretty a signal, but it should be alright...if there's big spikes make sure the wire is clear of ignition HT wires, etc.

Scope can also be used to check injectors.

Hope that helps a bit if she's still not running right!

 

Good tip but few DIYers would have access to a lab scope.
Most techs don't even have them yet...

 

yea i appreciate the help, and i have alot of tools, but a scope is way out of my reach. I'm goingto change the EGR Valve this week and see if it works.

According to the mechanic with the EGR Valve not working correctly, excess CO2 and CO and going to the motor, and not enough oxygen, this is making the computer not give enough fuel(via the map sensor(I think)). Which is why the motor is not reving above 2000 rpm or so.

Also he said that the cat could be plugged, so since the truck doesn't have havea post CAT sensor, then a piece of pipe will work fine. (First I am going to just remove it and see if it runs better.

I actually think this could be the problem, because I am sure that when we removed the trans, that the cat got bumped and hit and all kinds of stuff.

 

I replaced the EGR valve, wasted 100 bucks

and I cut out the cat, and now I have to weld back in a piece of pipe.

It's still broke, and yes it happened the very crank after the new transmission.

 

Well, it's weird that it happened at the same time as your tranny swap...but at this point i'd start thinking skipped timing chain, something along those lines?