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Unread 07-09-2010, 04:54 PM   #1
vonericsen
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couple quick questions

first is this an unusually low idle temp?


its been like this a while but it seems rather low...not that that is necessarily a bad thing, better than overheating... i dont think the thermostat is a low temp one, and the hottest my v8 gets is right under the 210 mark. is this normal or is that a little low for idle?

also, my jeep seems to hesitate when i hit the gas from a stop. sometimes its not bad or noticeable, other times it seems like it hesitates a lot and i figured i'd ask how to fix this if it is something that can be fixed. hesitation does seem worse if i try and floor it versus just lightly pushing the gas. the engine was rebuilt about 14xxx miles ago. i searched and some people said its the tps, but i figured i'd ask since i was only able to find one thread on this

lastly, my AC hasn't worked in years. for all i know it only needs a recharge, but what would be a good way to test it myself? just recharge and use some dye to look for leaks?

i searched for these a little bit but couldn't find a whole lot. thanks in advance

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Unread 07-09-2010, 07:06 PM   #2
ZJPunk98
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Does your engine take a while to warm to normal operating temp? if so, your thermostate may be stuck open. That would cause it to run cool when idling. Not the end of the world.

the issue is similar to that of a failing O2 sensor, bank one. the first one downstream before the cat. This one helps the computer controll the fuel and air mixture. Bad mixture causes that hesitation at times.

get yourself a recharge kit. You could do the dye test, and it may be worth it to ensure you don't have a leak. do the recharge with dye and use a black light to look for leaks. You can do this for a lot less than paying someone to do it. If it holds the charge, great. if not, then start looking for that dye.
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Unread 07-09-2010, 07:27 PM   #3
vonericsen
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i wasn't really worried about the temp, just curious, but i'll keep an eye on it.

i guess i could have a bad o2 sensor since the old engine was burning oil for a while. is there a way to clean it rather than buy a new one?

i'm going to do the dye test tomorrow and see what happens. can't hurt any

thanks for your help so far
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Unread 07-10-2010, 02:37 PM   #4
vonericsen
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i charged the ac today and its working great so far. i plan to check the pressure again in a week or so, but i'm happy its working.

i did notice that my idle seems really low, would that be part of the hesitation while accelerating that i have sometimes?
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Unread 07-10-2010, 06:07 PM   #5
ZJPunk98
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some people have tried a wire brush on the 02 sensor to clean it, but i'm not sure if that works. If you buy a new one, only buy an OEM O2 sensor. Anything else will cause issues, these jeep engines are picky.

Remove your air intake from the valve body and clean the valve body. remove the IAC and clean it with a wire brush. Remove the map sensor and use a compressor to blow out any junk. While map sensor and IAC are out, clean the valve body thoroughly. This may help your idle issues.
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Unread 07-11-2010, 02:02 AM   #6
vonericsen
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i know where the IAC is, but where is the map sensor?
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Unread 07-11-2010, 11:58 AM   #7
sirgildus
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Quote:
Originally Posted by vonericsen View Post
first is this an unusually low idle temp?


its been like this a while but it seems rather low...not that that is necessarily a bad thing, better than overheating... i dont think the thermostat is a low temp one, and the hottest my v8 gets is right under the 210 mark. is this normal or is that a little low for idle?

also, my jeep seems to hesitate when i hit the gas from a stop. sometimes its not bad or noticeable, other times it seems like it hesitates a lot and i figured i'd ask how to fix this if it is something that can be fixed. hesitation does seem worse if i try and floor it versus just lightly pushing the gas. the engine was rebuilt about 14xxx miles ago. i searched and some people said its the tps, but i figured i'd ask since i was only able to find one thread on this

lastly, my AC hasn't worked in years. for all i know it only needs a recharge, but what would be a good way to test it myself? just recharge and use some dye to look for leaks?

i searched for these a little bit but couldn't find a whole lot. thanks in advance
I have a 94 ZJ Limited w/the 4.0 I6 and as soon as it reaches operating temp, that's where it stays. It rises just a tad when I'm stuck in city traffic but goes down as soon as I get moving; AC on or off. I think it's normal.

You might want to check your oil level though. The pressure is kinda low.
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Unread 07-11-2010, 12:01 PM   #8
nlynd1978
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Quote:
Originally Posted by sirgildus View Post
I have a 94 ZJ Limited w/the 4.0 I6 and as soon as it reaches operating temp, that's where it stays. It rises just a tad when I'm stuck in city traffic but goes down as soon as I get moving; AC on or off. I think it's normal.

You might want to check your oil level though. The pressure is kinda low.
you beat me to that.
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Unread 07-11-2010, 12:49 PM   #9
sirgildus
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Update

Quote:
Originally Posted by nlynd1978 View Post
you beat me to that.
Just a short update on the oil pressure... I just looked at my ZJ because my wife just got home and the oil pressure is at temperature and I was pinging at about the same. Just a tick higher than yours.

Still I would check the oil level.
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Unread 07-11-2010, 01:04 PM   #10
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Didn't mean to... ;o)
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Unread 07-11-2010, 01:28 PM   #11
nlynd1978
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Quote:
Originally Posted by sirgildus View Post
Didn't mean to... ;o)
all good

ten
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Unread 07-11-2010, 02:01 PM   #12
vonericsen
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i checked the oil level and its full. i did take a couple more pics (sorry if they are a little too big) of my idle when the engine is cold and when it has run for a bit to get to operating temperature...

cold:


warm:


these are cellphone pics so sorry about the quality. i'm going to check the IAC as soon as i find some tools. i dont have much with me in laramie right now
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Unread 07-11-2010, 08:45 PM   #13
ZJPunk98
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looks like someone just emptied their wallet into their gas tank! The temp looks good to me now, but the oil pressure does seem a little low at idle. does it increase when you are excelerating?
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Unread 07-11-2010, 09:21 PM   #14
vonericsen
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lol, yeah i did...when i accelerate the oil pressure does increase, its only that low at idle. i pulled the iac out earlier and it was a bit dirty so i cleaned it...idles really weird now. it was nearly at 0 for a bit, so i drove around and it went up, but it still seems low. sits at about 500rpm, maybe a little lower now. i'm also planning to go get it scanned for some codes tomorrow just to see if there are any

i just talked to my dad and he said about 5 years ago we took it into the mechanic we used to bring it to (not so much anymore) and they adjusted the idle to be lower at about 500 rpms, where its sitting now. i'm going to look for a shop somewhere near me that knows what they're doing and have them adjust it to where it should be. hopefully that will fix it.
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Last edited by vonericsen; 07-11-2010 at 10:05 PM.. Reason: add more info
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Unread 07-11-2010, 10:40 PM   #15
sirgildus
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Thanks for the pics. All your gauges are on the money when cold. Your oil pressure and temperature gauge worry me a bit. I've never seen mine go up that high before and I live in sunny Florida. Could it be you have air in the coolant? The oil pressure is still a tick too low but it shows that it does elevate past 40 psi when cold.

Your idle speed should be between 750-800 RPM. Could be slightly higher when it's cold. Where idle speed indicator is at when the engine is cold is where your idle should be when it's warm or just under that tick mark.

One thing that is definitely okay is your fuel gauge. Shows exactly where most Jeep owners' wallet capacity is at. EMPTY...
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