Topic: Jeep just shuts off. Need some help YJ

[Backroads]

I posted a while back that I was replacing the engine in my jeep YJ. Its a 90 Wrangler TBI 2.5L. I swapped in a 94 engine but just converted it to TBI. So its still Vbelt, and has all the original accessories etc from the 90 on it.

Now the problem. Aside from some exhaust leaks and a failing power steering pump  it starts and drives great.

So far its been a pretty random and intermittent problem but it just shuts off. As in the engine stops turning and stops running, accessories still work and steering enough for me to coast to the side of the road and restart.

There really hasnt been a pattern to it other than its usually after or during a turn. I was goofing around in the parking lot and if I would stomp on it hard and turn a little, it would die (did that twice intentionally)

Its quite possible I have vacuum lines messed up, but other than that I dont really know where to start! I'm hoping you guys can help me out some!

[sharpxmen]

check if you have fuel pressure when it stops. also see if the tacho indicates the rpm while in gear (so the engine is spinning) when dies, if is not showing the rpm (needle at zero) it means there's something with the spark or crank sensor or something electrical cutting off the spark, if it shows the rpm then most likely fuel related.

[Backroads]

Its at the point now where I can start it, it will run for a minute or so, but once the idle starts to drop down to where it should be (after cold start) it just keeps falling and sputters out.

I backed it up and down my driveway some to see how it acted and same thing, it will go but then instantly shut off.

As far as the needle showing rpm, I'd have to try it and see if i can get it to move enough to tell.



On a side note are there any good diagrams on this website or elsewhere of vacuum routing for a 2.5L from a 90 with TBI?

The haynes manual sucks, and all the diagrams i'm finding online are basically copies of that and it doesnt even really cross reference to whats on my engine.

[chardrc]

vacuum leak would generally make the idel higher, not make it die. unless you messed up the one to the map sensor or plugged the egr valve into the wrong line possible (wont run at normal idle)...
best vacuum diagrams i have been able to find are at http://jeepgarage.free.fr/ownersmanual.html.. don't have time to figure out which one actually has the vacuum diagrams atm... actually i think this is the one you want: http://jeepgarage.free.fr/OWN/2.5l%20cec%20system.pdf

[Jeffy]

TPS maybe?

[Backroads]

I've had a bad TPS in my XJ before and it would run, it just would act really strange with not shifting etc (its an auto) I guess its possible, just doesnt really seems not related to throttle position, it dies if I'm off the throttle, or mashing the throttle trying to get another 10 feet to swerve off the road!!!

Now EGR valve could very well be it. As I said the vacuum lines are a nightmare, I just wanna find a good diagram and know where everything is supposed to be so i can redo the lines. Gonna check the link above right now and see what i can find.

Thanks for the help so far guys.

edit: so I get the diagram in the second link above but why is the EGR valve T'd off into the MAP sensor line?? I dont think thats how mine is, but I'm wondering whats the purpose there?

[chardrc]

edit: so I get the diagram in the second link above but why is the EGR valve T'd off into the MAP sensor line?? I dont think thats how mine is, but I'm wondering whats the purpose there?

its not. it T-s into the EGR/Evap solenoid. look where the arrow points to for the MAP.. its a little misleading if you look at it to fast now that i think of it. maybe ill edit it in paint and color code it if you want.. lol  


i realize this diagram is misleading since in reality all the vacuum line go through those metal lines to the back of the motor then ever rap around or go out toward the air cleaner box... and it doesn't show the 2 (or is it 3) lines that go through the fire wall to work the heating and venting stuff (one comes form the drivers side of the motor and the other form the passenger line above the evap canister. they are kinda easy to spot because they are the only ones with check valves and they become hard plastic lines to go through the fire wall)

[Backroads]

  my friend... That is me buying you a beer!!! Thats exactly what i was looking for. And your right with all the lines going everywhere its hard to follow them on paper then retrace them through that hardline combo around the back of the engine. I will get on putting everything together right and report back! Thanks!

One more thing... On the rear of the plastic cover over the throttle body there are 2 ports and kind of a double plug of vacuum lines that goes into it... Where do those two lines go to? Is that the heater control vacuum lines?

[chardrc]

ya that thing on the elbow that attaches to the top of the tb is a valve for the vacuum that opens when the temperature is low enough (its for the hot air intake thing as you said) there is another one of those in the back of the airbox as well. as to where the lines specifically go. one goes to the back of the air box (on the smaller orifice (i think into the other thermo valve), not the big orifice that is for the positive pressure line for PCV system) the other one goes to a hard line near the back of the motor. i think its the hard line that is hidden under the big hard line that has the hose that goes to the airbox for the positive pressure PCV(it took me a while to get that one right last time i had the motor out). ill see if i have any pics of my jeep i can hack up to make it more clear.

edit: looked though my pics and realized i still don't have any good engine bay pics that show vacuum lines in a way i could make useful.

[Backroads]

Ok so one goes to the ports on the box the other goes to a hardline (is that hardline part of the group of 4 that are all connected?)
If it does, what does the other end of that hardline go to? Whats it pulling vacuum from?

heres a pic of said thing for future searches


I also have these 2 ports on the intake manifold itself that I'm unsure what goes there.
One is a pretty big opening, the other (might be bent?) is a small bent inlet (smaller than the one you can see)

heres a pic of those 2 holes (one has a hose going to it which is not going to the right spot im sure lol)


and lastly heres my EGR valve (after your diagram last night im positive I have everything hooked up right as far as EGR and MAP and the PCV lines etc) I just have 3 lines coming from the EGR and the diagram only shows 2 lines. pic here (the small plastic line is the one in questions)

[chardrc]

ok did allot of paint picture editing (lol) hope this helps. those hard lines get their vacuum form the lower part of the tb on the motor side (there is a rubber coupler to it (4 hard lines get vacuum form there) (1 of them gets vacuum form the 90 degree elbow you need per one of the fallowing pictures (your second picture).

some of the info i had to take from memory so not 100% sure (and put jeep in storage yesterday so can't check today) but i did find some pics form my jeep that may help.

i tried to stay with the same color coding as the original diagram made

[sharpxmen]

@chadrc - awesome job man 

@Backroads - hope you get your rig working ( if you do make use of that applaud button for chadrc  )

[Backroads]

Well its really starting to come clear how screwed up the whole thing is! no wonder it doesnt run right!!! I think I'm following ya there on all those traces. Gonna go back in and troubleshoot my mess tomorrow hopefully.

Again, I really thank you for taking the time to do that. Couldnt be a bigger help!

[Backroads]

All that is hooked up and good. Only issue is that line that you circled in purple, where those lines are supposed to be connected by an elbow...well I've got that BUT on the other end of the hardline (very bottom line on the joined 4 lines that cross the back of the head) what does that side (passenger) plug into?

There are also 2 vacuum lines coming from the transmission area in that loom of wires. One is a blue hardline the other is clear, although they may not be original color codes for that stuff.

[Backroads]

so now with everything hooked up right (I found another line on the pass side that SHOULD be the right spot for that bottom hardline hose thats going to the open port on the intake manifold.

but now it wont start. I'm guessing it was running before from all the open air vacuum it was sucking up~! so now I'm wondering TPS or the ICS (i think its called? the plunger the throttle hits when its closed?) are bad sensors.

gonna try and test the TPS now.