monst3r

I'll do it after work but its a brand new line. What should happen?

cruiser54

I'm not telling you.

monst3r

Heh OK. Will do after work.

cruiser54

I'm subscribed.....

DFlintstone

Nothing will happen, the 2.6mm orifice is on the end of the line! (IIRC)

Just for giggles, you might try unplugging that new 02 sensor and see if the cycling changes.

monst3r

Well no change at all while unplugging the rear vaccum line on the valve cover, tons of vacuum though.

Unplugged the O2 sensor.. definitely worse without it but still cycles up and down. I did order a fuel pressure tester but wont be here for a bit.

I made a video of it, sorry about the loud exhaust.. I am going to change it out the previous owner loved the sound of a glass back I guess but its super loud, especially since I have no carpet right now.

noraayrrek

Subscribed

Eisenschwein

I know you've checked the vacuum stuff but damned if it doesn't feel like a vacuum issue. My 87 acted the same way when I had a small leak, even with doing the "tips". A tiny crimp or crack in one of the small tubes will cause a lot of trouble.

DFlintstone

I don't hear the idle speed fluctuate in your vid. Along the line of what Cruiser might have been getting at, (introducing a vacuum leak), try pulling the CCV line at the other end, by the TB. My idle goes up about 200 when I do that. If that helps you Idk, if it's not the IAC that might only leave the throttle plate.

monst3r

Well its not the fuel pump. Pressure tested it. 31 with regulator connected and 39 with regulator disconnected. Plus does not lose pressure.

Its possible its a very tiny vacuum leak, I suppose the only fix would be to replace the lines with new rubber ones.

The idle is definitly fluctuating the phone video just does a poor job of capturing it. I'm tempted to replace the IAC but I hate throwing more money at it, but I have went this far hah.

adamj

Subscribed to see what the issue is when you get it fixed.
Have you checked out the coolant temp sensor?

monst3r

The ecu temp sensor? The gauge works but I know that is a different sensor on the back of the motor. Where is the ecu temp sensor? Is there a way to test it? Not sure if it could cause this but anything is possible I suppose.

cruiser54

Here:

nicholas

Did we ever figure out the answer to this thread. my 88 XJ, 4.0, automatic, 4x4 AWD transfer case, limited with 3.55 rear gears and a tow package 129k miles garage kept by a little old man with no rust( he had it under coated YAY!). is having the exact same issue. I bought this jeep to learn how to work on vehicles (so I view it as an educational tool as well as an amazing vehicle that I have come to love, despite it being a constant pain in the butt) prior to this jeep my mechanical experience was changing the oil a few times. I have done all the work (with exception to checking the timing and installing some custom brake lines for the brake booster) by myself with help from these forums, and youtube (thanks!).

I have replaced/tested everything I can think of and found on the internet over the last 6 months and am still stuck, I have followed most of Cruisers list, including the
IAC, TPS replaced and adjusted.
cleaned the TB, set the butterfly valve adjustment,
replaced the o2 sensor, and relay,
new CPS sensor,
new distributor, cap, rotor, plug wires, plugs (autolite .35 gap),
fuel pump, fuel filter, fuel pressure regulator, fuel injectors remanufactured and cleaned (the upgraded 4 hole ones).
replaced the front and back of the vacuum harness, the ccv hose, and vacuum line from the rear of the valve cover to the intake manifold,
compression test 1-6, 140-132 front to back (dry).
vacuum off the manifold when idle is sort of normal (5-700rpm) is 18, it fluctuates down to around 15 when at 2-300rpm, I don't hear and vacuum leaks.
replaced valve cover seal that was leaking,
upgraded double diaphragm brake booster and master cylinder, replaced front brakes, (still need to adjust rear drums),
CAI through the cowl from spectre. and a bored out throttle body (60mm),
new battery, made my own 1awg cables and 4awg refreshed and and upgraded grounds and added with copper fittings and brass battery terminals, cleaned most of the plug connections,
c101 eliminated, and sensor grounds improved in wiring harness.
tightened the intake manifold,
replaced a leaking power steering pump, a bad alternator, new serpentine belt,
some of my cooling system had some issues, including the weird little plastic valve by the water bottle (it broke). as well as replacing the water bottle and cap,
timing confirmed TDC with a timing light by someone who's a professional mechanic and i alsoran a can of sea foam through the intake. of course several oil changes. all my gauges seem to be working, 13.5-14.5 volts, engine temp says around 200 depending on use 190-210 or so. oil pressure 20-40, gas gauge fluctuates a bit but works, speedo wiggles, i think its going to go at some point and its off about 3-4mph, RPM gauge does exactly what monst3rs does.

Additionally, but unrelated to the engine idle, I've replaced the track bar, drag link, tie rod, tie rod ends, 3" OME lift with nitro charged shocks, and stabilizer, replaced factory upper and lower control arms, front and rear diff fluid change, magna flow cat, borla cat back exhaust. and a sound system, with a new antenna. 30x9.5 BFG AT tires.

I have a different O2 sensor, distributor, ignition coil and engine temp sensor on the way, as well as a 1990 ECU. I'm running outa crap to replace. Its going to be a brand new 30 year old jeep soon.

Eisenschwein

Man, sounds like you've given it the royal treatment. You should post some pics.