'87 YJ Cold Start 2,000 RPM Idle / 300-500 (bogging) Going into Neutral. - JeepForum.com
 
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post #1 of 6 Old 09-21-2017, 07:55 PM Thread Starter
D_5644
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1987 YJ Wrangler 
 
Join Date: Sep 2017
Posts: 3
'87 YJ Cold Start 2,000 RPM Idle / 300-500 (bogging) Going into Neutral.

Before I get to into it, I want to say that each morning before work, I have to pop the hood, jiggle the throttle by hand THEN start the Jeep up so it DOESN'T start idling at 2,000 RPM...

I've had this problem for about a month. A couple months before that, I was having trouble with stalling every now and then (not often, maybe 2-3 times in the last couple months, coincidentally in, rainy, humid weather) but I have not had it in a few weeks *knocks wood*.

Today was the worst of both high and low idle occurrences, and was CLOSE to stalling. I did my morning routine of moving the throttle by hand, and when I started it up, it was up to 2,000 idle. How annoying! My routine, for once, did not work. Sometimes...sometimes, I'll crank it over and it'll start at around 2,000 then slooowly work itself down to a normal idle, but as soon as I put it in reverse then to first, it'll just start idling high again...

Anyway, this was in the morning. The drive to work was, eh, so-so. However, when I took it out in the afternoon, I noticed something that was a bit of a worry mid-drive. I shifted into fourth and there was some hesitation as soon as I pulled off the clutch, like it was going to stall. I had push down on the pedal a bit more to get it to giddyup again. Then when I got to a light, I put it in neutral and it was at almost bogging idle at around 300-400. I could barely hear the engine running almost, but as soon as I accelerated it seemed to run fine.

Other symptoms include the throttle sometimes hesitating, the throttle seeming like it's coughing (I'll be in third giving it some throttle and it feels like something is "not catching").

I've looked on these forums about this issue since late May. I've heard TPS, I've heard IAC, I'm heard vacuum leaks and in the rare cases, some mechanical problem in the motor. I've also heard it could as easy as blasting the throttle body with cleaner, or buying a new spring. I'm not too savvy when it comes to repairing, but with this problem, I'm willing to try anything at this point to get to know under the hood of my Wrangler better.

Before I buy a new TPS, or a new IAC, or a new carburetor, or a new throttle body (or, at this point, the less expensive purchase of a new Jeep!), I need some help with diagnosing and repairing.

Thank you for reading.

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post #2 of 6 Old 09-22-2017, 10:24 AM
mike134
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1989 YJ Wrangler 
 
Join Date: Aug 2014
Location: Cleveland
Posts: 5,955
Can you fill out your jeep profile? I assume this is a 2.5L engine?

Does your throttle still have the return spring intact?

Is your throttle cable binding up? Remove it from the throttle body end, and see if it slides in and out of the sleeve smoothly.
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post #3 of 6 Old 09-23-2017, 08:47 AM Thread Starter
D_5644
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1987 YJ Wrangler 
 
Join Date: Sep 2017
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I filled out as much as I know about my Jeep. It's a 4.2 6 Cyl.

The throttle spring is still intact. As for the throttle cable, it doesn't appear to be resisted by anything and can freely move.
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post #4 of 6 Old 09-23-2017, 10:06 AM
mike134
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1989 YJ Wrangler 
 
Join Date: Aug 2014
Location: Cleveland
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I know you said you hand jiggle the throttle, but do you push the pedal all the way to the floor, release, and then start the vehicle? This is the proper procedure to squirting some fuel into the intake and for setting the choke for start up. The choke should then slowly open as the engine warms up.

When was the last time you rebuilt the carburetor?

Have you done the "Nutter Bypass"? This can really help by removing some of the malfunctioning out dated emissions equipment.

Have you removed and tested your EGR valve?

I have some other basic maintenance advice below:
Also, if you haven't done a tune up in a while, you want to do that. Instead of getting replacement parts, you should purchase a HEI distributor from CRT Performance (~$100). It adds an enormous amount of reliability to the carbureted engines. They sometimes give you free spark plug wires during promotions. This replaces the ICM, Coil, Distributor, Distributor cap, Rotor, Wires. Add champion copper spark plugs on top of that to finish the tune up.

Change your fuel filter.

Carb rebuild: The more you drive, the less likely you are to need a carb rebuild. If you drive your jeep ocassionally, you might be rebuilding every couple years. If you drive it every day, then you might rebuild around 100,000 miles.
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post #5 of 6 Old 09-25-2017, 02:43 PM Thread Starter
D_5644
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1987 YJ Wrangler 
 
Join Date: Sep 2017
Posts: 3
Thanks for the response. Instead of holding the pedal down to the floor, I would pump it up a few times before starting, but the results have to be inconsistent to say if it helped on start up some days or not. I have not removed or tested my EGR valve because I'm not quite sure the procedure, and the same goes for the Nutter Bypass.

However, On Saturday afternoon, I cleaned up a portion of the throttle body. The valve was covered with black soot and the dirtiness went all the way up the right side of the inner wall. While I did this, I also discovered that oil was getting into the air filter and looked like it was collecting in the air duct hose that goes to the TB. The oil was dripping out of the hose when my bud and I held it upside down and the air filter on both sides was dirty with oil...

We also adjusted the idle screw to get it to idle just a bit higher than it was at rest. It seemed to help because it ran beautifully right after we were all finished all the way into this morning. It had a lot more giddy up then past months and the idle has been steady coming to a stop and shifting up and down.

NOW...I felt okay up until about an hour ago when I filled up my tank. The startup was fine, but as I was pulling out of the station in first, I threw it in neutral and the idle died down to a bogging 300 RPM again. When I pulled out and drove on the road, it felt sluggish, almost like something was holding it back, but it was still shifting fine and the idle didn't bog again for the rest of the trip. I'm aware it could be the added weight of a full tank of gas, but the bogging wouldn't be because of a little added weight...
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post #6 of 6 Old 09-25-2017, 06:27 PM
mike134
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1989 YJ Wrangler 
 
Join Date: Aug 2014
Location: Cleveland
Posts: 5,955
Replace your PCV valve, and make sure you have a vacuum hose connected to the top of your valve cover.

The crap you cleaned out of the throttle body was probably oil from the PCV/CCV system. It is usually fixed with proper vacuum hose diameter and new PCV elbow.
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