TBI Rebuilt, Hardly Idles

[mrmel2you]

'90 MJ, 2.5l w/ TBI (single injector) I rebuilt the TBI unit, new injector/regulator/fuel filter. Runs awesome, plenty of power, does not want to idle for crap (keeps loading up and dies whenever I stop at a light/sign). About at my wits end with this, it's worse now than it was before I did all this work :(

 

[HOrnbrod]

Sounds like a possible vacuum leak. How's the hoses going to the MAP sensor and EGR valve?

[mrmel2you]

I replaced all vacuum lines/pcv/EGR and MAP sensor.  When I replaced the vacuum lines, I replaced them one at a time so as not to get them crossed, so I know that much is right :)  The EGR valve was stuck (rusted) open and the gasket wasn't much better.  MAP sensor was toast.  After I did all this, truck ran great for 3 days, but had a slight stumble whenever I came to a stop---but leveled out within a few seconds.  Now whenever I come to a stop it stumbles and floods itself out (intake has fuel puddling badly in the bottom).  (2.5 with 4 speed manual trans)  I checked and re-tightened both the intake and exhaust manifold bolts, did not make any difference.

[mrmel2you]

What's up with this?  "Old" EGR-----vacuum line connected, idles like crap, floods out, unplug and cap the vacuum line---runs perfect.  Replaced the EGR valve, vacuum line connected, idles like crap, floods out, unplug and cap the vacuum line----runs perfect.  Can I do away with the EGR valve altogether (block-off plate) and just cap the vacuum line?  Starts up fine and runs great when warm (vacuum line disconnected) just don't know how well it will start up when cold (winter is coming up).  Any input out there?  Many many thanks to all for all the help on "The Beast's" issues so far :)  Could not have gotten this far without all help and info here in "ComancheClub"  Love this group :)

[buckwheat]

The EGR is part of the emissions control. So legally, no you cannot get rid of it and if your state does emissions testing you are not likely to pass without it working properly. 

 

Personally I say get rid of it. I have mine capped off on my truck and it runs just fine. This includes winter starts. However we do not have emissions testing. 

 

AFAIK the EGR works by shunting part of the exhaust back into the intake, forcing the engine to re-burn it. This lowers NOx levels in the final exhaust. Otherwise it doesn't do anything productive.

[mrmel2you]

I'm here in Kansas and haven't heard of any "pipe-sniffing" being done around here (on used vehicles) :)  Took her out for a spin out on Highway 70 East, heard just a bit of rattling (sounded like it was right under my butt) then I heard a loud clunk and then the exhaust got loud, looked in the rear view mirror and seen the muffler going end-over-end over a guard rail and down in a ditch, never did find it :(  Now I have a big gaping hole between 2 pipes that I need to fill in, LOL :)  I swear, if wasn't for bad luck----I wouldn't have any luck at all.  Just get one problem nipped in the bud----and something else goes to crap :(  The joys of owning a great MJ :)

[87Warrior]

Where about are located in this 400 mile long state?

 

You may want to replace the O2 sensor as well. The 2.5 relies heavily on the O2, MAP, CPS and Coolant temperature to run. Actually, my truck melted a plastic hose I ran to the MAP on the turnpike and idled just as you describe when I stopped to pay the toll.

 

At some point some of the EGR equipment fell off my truck... Runs great.

[mrmel2you]

"87Warrior"---I'm located in SE Topeka :)  Blocked off the EGR valve, shortened and capped the vacuum line-----starts and runs like a dream :)  The idle is so smooth, putting my hand on the side of the cab----can't feel no vibration or anything.  Not too shabby for a $200 beater that had a busted exhaust valve :)

[coathanger37]

Sounds like your egr is leaking or what ever opens it is defective.

 

You found an MJ for $200. Around here I've seen one that sold for $1000 and it had been rolled on it's side. Saw one that was pretty rusty go for either $1200 or $1500.

You got a deal there.

[mrmel2you]

"Coathanger",  if it wasn't for me investing so much $$$$$ into "The Beast" already----that $1,500 would have sounded sweet to me :)  But alas, the more I drive it----the better I like it, LOL :)  So far I have replaced f&r shocks, rebuilt the TBI (new injector and regulator also) complete new brake system on the front (rear setup is on order) new f&r tires, have new steering and front suspension arms/ball joints/center link/etc. on order and ordering new complete exhaust tomorrow.  Next on the agenda will be new doors, fenders, floor pans and carpet------then get started on body work and paint :)  Would love to put in buckets and console from an XJ in it----maybe later on down the road.  Sister's boyfriend came over and laid on some weld on the front sliders, took about an hour and a half to grind them down------brakes work like a charm now :)