Author Topic: New idle (A/C?) issues  (Read 2918 times)

0 Members and 4 Guests are viewing this topic.

Offline jfrabat

  • Gargantuan Mango Tree MechanicŪ
  • Member
  • *
  • Posts: 3676
  • Finally USING the Jeep!
New idle (A/C?) issues
« on: February 28, 2013, 02:56:12 PM »
Now that the YJ is again my daily driver, it has develped a new issue which I kind of put a bandaid on for the time being, but I would like to hear your opinions as to what it may be...

First, some prior issues (as it MAY be related).  When I first start the jeep, it starts just fine, but then the RPM's drop way below normal.  It also sputters, as if one cylinder is not working properly (kind of a brrrrrrrummm, brrrrrrummm, brrrrrrrrrrrruuuuum cycle).  I just use the hand throttle to keep the RPM's at about 1,500, and then, after 3 or 4 minutes, it idles just fine.

If I kill the engine, and try to restart, the engine will NOT restart unless I throttle up, and then it kind of starts one cylinder at a time...  Very odd.

But I kind of learned to live with the engine like that until, about a month ago, I started to see the throttle drop whenever I let off the gas.  It got to the point where the Jeep would just die on my, so I used the little screw that sets the closed position of the TB plate to open the throttle a little bit.  From then on, the Jeep will not die, but the RPM's would drop so low as to make the A/C compressor shut down whenever it detected the los RPM's (at least, now the Jeep would keep on running).

I started running the Jeep without the A/C, and noticed that the drop in RPM would not happen at all.  If I turned on the A/C, then the drop would immediatly happen.  I am guessing that the bearings in my AC comrpessor may be full of gunk, mud, or God knows what, and it is creating extra drag on an already small engine, and that this may be the cause of my problems, but what do you guys think?

Also, since I have not used the air filter oil on my Jeep, I am guessing that there may be some gunk in the conbustion chamber.  I have some new injectors laying around (the other half of the 8 I bought some 5 or 6 years ago when I went to the Ford ones) that I was gonna drop in along with a performance distributor ignition system (I ordered one when I relocated the coil high-up on the firewall; I was having problems killing coils in the stock location, and I guess my guess that the heat and water were killing them was right, as I have yet to burn up a coil since I relocated it).  I also want to throw in new plugs (gapped at .050") and see if that helps with my non-A/C related issues, but I also think I have issues relating to the A/C compressor.  Anyway, I figured the starting issues are either spark or fuel issues, and this should take care of both!

By the way, the issues on the engine are NOT caused by the ECU; I have 2 of those, and swapping them does not alter anything.  I am also changing out the fuel tank sending unit (finally got the 20 gal one, so I will be able to tell how much gas I have!  This means I am getting a new fuel pump...  I also got the new gaskets, roll-over valves and seals to try to eliminate that gas smell near the rear fenderwell...  When I install all that, I am also installing a new fuel filter, and will try to replace the fuel line from the tank to the filter).

So, what else should I be looking at?  Any ideas?  Is there a way to change the bearings on the A/C compressor, or does this mean a new unit?  I am even tempted to go back to the stock FPR (I have one of sharp's adjustable ones on) just to make sure that is not the issue (I will also check fuel pressure before I do to make sure it is stable and where it should be).

Anyway, feedback is greatly appreciated!
'94 YJ 2.5L with 4" RE lift, Superwinch EPi9.0, FoMoCo e-Fan, SD30 and SD35 w/ARB-5.13, 165A alt., 33" BFG KM2 on 15" AR wheels, Sony sound system, Pavement Ends Hardtop, Hydroboost

Offline neale_rs

  • Member
  • Posts: 3583
Re: New idle (A/C?) issues
« Reply #1 on: February 28, 2013, 03:02:47 PM »
Maybe you could get a non-AC serpentine belt and install it without the AC in the loop.  If the idle problems go away, then you know the AC drag was causing the problem.

'95 YJ, 33 x 12.5 mud tires, RE 4.5 ED lift, Atlas 4 speed, rear D44, ARBs front and rear, 4.56 gears, 8000# winch

Offline jfrabat

  • Gargantuan Mango Tree MechanicŪ
  • Member
  • *
  • Posts: 3676
  • Finally USING the Jeep!
Re: New idle (A/C?) issues
« Reply #2 on: February 28, 2013, 03:12:16 PM »
Maybe you could get a non-AC serpentine belt and install it without the AC in the loop.  If the idle problems go away, then you know the AC drag was causing the problem.



If I turn off the A/C (Compressor), then I have no problems when letting off the gas...  I still have the starting issues, though...
'94 YJ 2.5L with 4" RE lift, Superwinch EPi9.0, FoMoCo e-Fan, SD30 and SD35 w/ARB-5.13, 165A alt., 33" BFG KM2 on 15" AR wheels, Sony sound system, Pavement Ends Hardtop, Hydroboost

Offline neale_rs

  • Member
  • Posts: 3583
Re: New idle (A/C?) issues
« Reply #3 on: February 28, 2013, 03:15:32 PM »
I think the first thing to try would be to make sure the TB is clean, especially the IAC air bypass.
'95 YJ, 33 x 12.5 mud tires, RE 4.5 ED lift, Atlas 4 speed, rear D44, ARBs front and rear, 4.56 gears, 8000# winch

Offline Jeffy

  • Administrator
  • Member
  • Posts: 14934
Re: New idle (A/C?) issues
« Reply #4 on: February 28, 2013, 03:25:40 PM »
The idle issue sounds like an IAC issue.  Either bad IAC, or connector or wiring.  If the IAC isn't working the engine won't get enough air when starting cold.  You'll have to hold the throttle open till it warms up.

If you're AC is turning on, the RPM should drop because of the load on the engine.  That's normal.  The idle up is supposed to compensate but I find that it doesn't always catch it when idling.

Quote
A/C compressor shut down whenever it detected the los RPM's
How is it doing this?  The AC is a separate and independent circuit.  The only way the compressor turns off is when the pressure drops too low or when the thermostat turns it off.

I think you have an idle issue and the AC is only exacerbating it but is not the cause.
Youtube Channel: https://www.youtube.com/channel/UCZNlr60GXH5OlKIFrT7P6mg
My Jeep: http://4bangerjp.com/forums/index.php?topic=2783.0
"If the motor car were invented today, there is absolutely no way that any government in the world would let normal members of the public drive one."

Offline sharpxmen

  • Chief Squirrel BlowerŪ
  • Member
  • *
  • Posts: 7093
Re: New idle (A/C?) issues
« Reply #5 on: February 28, 2013, 05:29:26 PM »
leaky injector(s)?
'95 YJ, NSG370 6spd / Hurst shifter, Dana 300 + 4:1 Doubler / tri-stick, Custom skid, Super D35 / Auburn LSD / 4.88, 35x12.5x15 BFG KM2, 64mm t/b, 1.7 RollerRockers, MkVIII e-fan, Dual Diaph Booster
Latest: Corbeau BajaRS heated seats :dance: keeping warm the rear end

Offline jfrabat

  • Gargantuan Mango Tree MechanicŪ
  • Member
  • *
  • Posts: 3676
  • Finally USING the Jeep!
Re: New idle (A/C?) issues
« Reply #6 on: March 01, 2013, 07:54:16 AM »
leaky injector(s)?

That was my thought also; either that, or the spray pattern is shot and it is having a harder time igniting the mixture... 

I think the first thing to try would be to make sure the TB is clean, especially the IAC air bypass.

The idle issue sounds like an IAC issue.  Either bad IAC, or connector or wiring.  If the IAC isn't working the engine won't get enough air when starting cold.  You'll have to hold the throttle open till it warms up.

I will give it a thorough cleaning... Anyway, I will try to get a new IAC and see if that helps.  It could also be all gunked out because of the air filter not having any oil in it!

How is it doing this?  The AC is a separate and independent circuit.  The only way the compressor turns off is when the pressure drops too low or when the thermostat turns it off.

HOW it is doing it, I do not know...  But when the RPM's drop too much (it will go to the 400~500 range), the AC compressor shuts off.  The engine unloads, the RPM go back up, but the air starts coming out at ambient temperature.  Then you can feel the compressor come back on (I also see the engine efan come on; I have an indicator light, and it comes up whenever the compressor comes on), and the engine drops about 100 or 200 RPM's, and the cold air starts again...  After a while, the engine stops dropping the RPM's so much, so the AC stays on even when you come to a stop.

And, of course, as is always the case with the Jeep, today, a new hiccup...

I was on a traffic jam in the highway, and I see vapor coming from under the hood.  I immediatly switch to the e-fan override, and the temp starts dropping (it only went up to about 215*, so no biggie).  I get to the office, and check the DCC Controller; it was only getting about 1V.  Check the cable, and the cable cover (the plastic wrap to avoid vaving the cable cut) was a bit melted; guess it is time to swap it for a larger gauge cable!  After I moved it a bit, voltage went back to 12.4V (engine was off), but I still need to take out the battery and check how bad the damage really is...  And rewire it to avoid this issue in the future!
'94 YJ 2.5L with 4" RE lift, Superwinch EPi9.0, FoMoCo e-Fan, SD30 and SD35 w/ARB-5.13, 165A alt., 33" BFG KM2 on 15" AR wheels, Sony sound system, Pavement Ends Hardtop, Hydroboost

Offline sharpxmen

  • Chief Squirrel BlowerŪ
  • Member
  • *
  • Posts: 7093
Re: New idle (A/C?) issues
« Reply #7 on: March 01, 2013, 09:08:12 AM »
factory A/C install has a PCM cutoff - that's if the engine is overheating it will disengage the clutch, could be that it has the low rpm trigger as well, just guessing since i don't have one.
'95 YJ, NSG370 6spd / Hurst shifter, Dana 300 + 4:1 Doubler / tri-stick, Custom skid, Super D35 / Auburn LSD / 4.88, 35x12.5x15 BFG KM2, 64mm t/b, 1.7 RollerRockers, MkVIII e-fan, Dual Diaph Booster
Latest: Corbeau BajaRS heated seats :dance: keeping warm the rear end

Offline jfrabat

  • Gargantuan Mango Tree MechanicŪ
  • Member
  • *
  • Posts: 3676
  • Finally USING the Jeep!
Re: New idle (A/C?) issues
« Reply #8 on: March 01, 2013, 09:56:11 AM »
factory A/C install has a PCM cutoff - that's if the engine is overheating it will disengage the clutch, could be that it has the low rpm trigger as well, just guessing since i don't have one.

Could be...  As I said, I dont know WHY it does it; I just know it DOES!
'94 YJ 2.5L with 4" RE lift, Superwinch EPi9.0, FoMoCo e-Fan, SD30 and SD35 w/ARB-5.13, 165A alt., 33" BFG KM2 on 15" AR wheels, Sony sound system, Pavement Ends Hardtop, Hydroboost

Offline Jeffy

  • Administrator
  • Member
  • Posts: 14934
Re: New idle (A/C?) issues
« Reply #9 on: March 01, 2013, 12:13:37 PM »
Well, it sounds like there are a bunch of issues that are probably independent of each other happening.  Pick an area and start there...
Youtube Channel: https://www.youtube.com/channel/UCZNlr60GXH5OlKIFrT7P6mg
My Jeep: http://4bangerjp.com/forums/index.php?topic=2783.0
"If the motor car were invented today, there is absolutely no way that any government in the world would let normal members of the public drive one."

Offline sharpxmen

  • Chief Squirrel BlowerŪ
  • Member
  • *
  • Posts: 7093
Re: New idle (A/C?) issues
« Reply #10 on: March 01, 2013, 02:48:00 PM »
could it be something on the A/C request and sense wires going to the PCM? (as an alternative if your guess about the A/C compressor being almost seized doesn't turn out to be true)
'95 YJ, NSG370 6spd / Hurst shifter, Dana 300 + 4:1 Doubler / tri-stick, Custom skid, Super D35 / Auburn LSD / 4.88, 35x12.5x15 BFG KM2, 64mm t/b, 1.7 RollerRockers, MkVIII e-fan, Dual Diaph Booster
Latest: Corbeau BajaRS heated seats :dance: keeping warm the rear end

Offline Jeffy

  • Administrator
  • Member
  • Posts: 14934
Re: New idle (A/C?) issues
« Reply #11 on: March 01, 2013, 04:55:48 PM »
could it be something on the A/C request and sense wires going to the PCM? (as an alternative if your guess about the A/C compressor being almost seized doesn't turn out to be true)
Maybe if the engine senses it's going to stall, it might cut it off... maybe.
Youtube Channel: https://www.youtube.com/channel/UCZNlr60GXH5OlKIFrT7P6mg
My Jeep: http://4bangerjp.com/forums/index.php?topic=2783.0
"If the motor car were invented today, there is absolutely no way that any government in the world would let normal members of the public drive one."

Offline sharpxmen

  • Chief Squirrel BlowerŪ
  • Member
  • *
  • Posts: 7093
Re: New idle (A/C?) issues
« Reply #12 on: March 01, 2013, 05:44:06 PM »
Maybe if the engine senses it's going to stall, it might cut it off... maybe.
i meant as in the wiring going to the PCM for A/C sense to increase the idle going in and out (losing connection) - the vrrrrrruuum thing he was explaining :lol:
'95 YJ, NSG370 6spd / Hurst shifter, Dana 300 + 4:1 Doubler / tri-stick, Custom skid, Super D35 / Auburn LSD / 4.88, 35x12.5x15 BFG KM2, 64mm t/b, 1.7 RollerRockers, MkVIII e-fan, Dual Diaph Booster
Latest: Corbeau BajaRS heated seats :dance: keeping warm the rear end

Offline neale_rs

  • Member
  • Posts: 3583
Re: New idle (A/C?) issues
« Reply #13 on: March 01, 2013, 06:52:14 PM »
In other cars I've owned the AC air will come out warm on some long steep hills.  Maybe some (most) cars are set up to cut off the AC if the engine is under too much load.
'95 YJ, 33 x 12.5 mud tires, RE 4.5 ED lift, Atlas 4 speed, rear D44, ARBs front and rear, 4.56 gears, 8000# winch

Offline Jeffy

  • Administrator
  • Member
  • Posts: 14934
Re: New idle (A/C?) issues
« Reply #14 on: March 01, 2013, 08:18:23 PM »
In other cars I've owned the AC air will come out warm on some long steep hills.  Maybe some (most) cars are set up to cut off the AC if the engine is under too much load.
The AC should have a RPM cut-off.  This is so you don't over-rev the compressor.  Not sure if the Jeep has this though.
Youtube Channel: https://www.youtube.com/channel/UCZNlr60GXH5OlKIFrT7P6mg
My Jeep: http://4bangerjp.com/forums/index.php?topic=2783.0
"If the motor car were invented today, there is absolutely no way that any government in the world would let normal members of the public drive one."