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General Forums => The Mess Hall => Topic started by: tallrugbyguy on December 01, 2008, 10:19:17 PM
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so my jeep idles really low. not sure if that is a bad thing about 700rpm.
but the problem is is when i start my jeep, the the engine will trun over then stop right away. if i give a bit of gas then she struggles through and after i rev it up its totally fine. seems to happen on cold starts.
i did just put a 62mm tb on. but i think this happened once before that conversion.
any ideas? i know my computer is shot and im still waiting for a new one. can that be it?
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so my jeep idles really low. not sure if that is a bad thing about 700rpm.
but the problem is is when i start my jeep, the the engine will trun over then stop right away. if i give a bit of gas then she struggles through and after i rev it up its totally fine. seems to happen on cold starts.
i did just put a 62mm tb on. but i think this happened once before that conversion.
any ideas? i know my computer is shot and im still waiting for a new one. can that be it?
700RPM is the normal RPM at idle. Actually I think it's 750RPM. If this is new, then I'd swap back to the stock TB and see if it is, just to be sure. The only other thing I can think if is the TPS might not be working right. Also make sure you have all of the vacuum lines connected.
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May be one of the TB sensors was not fully reconnected after the TB swap? :confused:
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Mine started doing that too right after I did the injectors, throttle body and PD kit, and I think its just the computer hasnt adjusted yet, cause if i keep the rpm's up for about 30 seconds and let the engine warm up some and the computer can start adjusting then its fine after that
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long did that happen to you for?
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Its still doing it, I just put them on this summer and have only put i think 125 miles on the jeep since I did all that. I can hear when it starts up that its sucking in a ton of air and it seems like once it gets the fuel mixture worked out then it quits running rough and drops down to about 6-700 i think maybe a lil higher I cant remember
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Its still doing it, I just put them on this summer and have only put i think 125 miles on the jeep since I did all that. I can hear when it starts up that its sucking in a ton of air and it seems like once it gets the fuel mixture worked out then it quits running rough and drops down to about 6-700 i think maybe a lil higher I cant remember
A vacuum leak will cause the idle to be high. Also, installing a 2.5L IAS sensor in a 4.0L IAS housing will cause a leak as well. Idle usually jumps to 1000RPM.
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Yeah but wouldn't the motor do that everytime it starts up Jeffy? Mine only does it the first time and then once its warmed up, if I stall it on the trail or something when I restart, it doesnt do that again.
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I did my 4.0TB swap this past summer and i have a weird idle as well. With the stock TB and TBS it idled smooth and steady at 700rpm. I took off the TBS and the 2.5l TB and as soon as the new 4.0l TB went on the RPMs jump up and down between 700 and 800 rpm at idle. I have replaced the TB gasket and even checked the 2.5l IAC housing and everything is sealed and tight. I would like to fix it without switching back but its starting to get annoying. I have a new TPS and IAC. The only thing i can think is that the engine is getting too much air if that even makes any sense since i am running the 4.0l intake tube with an arrait intake. Any suggestions? I would assume that the computer would have readjusted by now.
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don't they create a vacuum leak when the berring / shaft assembly for the tb "butterfly vavle" :confused:goes bad,
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Yeah but wouldn't the motor do that everytime it starts up Jeffy? Mine only does it the first time and then once its warmed up, if I stall it on the trail or something when I restart, it doesnt do that again.
Normally, yes. Although I'm wondering if it's the IAC. The IAC acts like a choke when cold, IIRC. I believe once the engine's up to temp, it no longer is used.
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I replaced mine with a brand new IAC and TPS when I did the swap, so unless it was bad to begin with...
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I replaced mine with a brand new IAC and TPS when I did the swap, so unless it was bad to begin with...
I did the same and still not a smooth idle. I might try and put the old setuo back on and see if that dose anything. Maybe adjust the screw on the throttle body, I dont know.
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Does yours do it constantly or just at startup then goes to just a normal idle
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At start up its around 900 it will settle down to 750 after warm up and then at idle fluxuates between 700 to 750 and 800. Its constant and only stops when the engine is inder an electrical load, ie elctric fan kicking on.
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hmm, would the screw do it? it seems like its somthing electrical since it only happens when its a cold start up. mine dosent vary too much at idle, my problem is more the starting. usually takes two tries...
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That more how mine is. If I don't give it gas right after if fires up it will die
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I have no problem at start up its just at idle after warm-up. like sitting at a traffic light in neutral.
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Any CEL Codes?
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I have not seen and check engine lights and the dash button trick dose nothing, I have a 97 by the way.
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ill let ya know as soon as i get my new computer in. in the cold weather right now il waiting for 6 minutes just for it to start.!
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I did my 4.0TB swap this past summer and i have a weird idle as well. With the stock TB and TBS it idled smooth and steady at 700rpm. I took off the TBS and the 2.5l TB and as soon as the new 4.0l TB went on the RPMs jump up and down between 700 and 800 rpm at idle. I have replaced the TB gasket and even checked the 2.5l IAC housing and everything is sealed and tight. I would like to fix it without switching back but its starting to get annoying. I have a new TPS and IAC. The only thing i can think is that the engine is getting too much air if that even makes any sense since i am running the 4.0l intake tube with an arrait intake. Any suggestions? I would assume that the computer would have readjusted by now.
I went back to the stock air intake with the 4.0tb and a TBS - after about 500 miles everything runs great. I was struggling through a lot of the same problems this is what the computer likes best. For the first 500 miles or so my Firewire plugs would work its way off the distributor, now that they are not moving everything seems to tie togther.
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I went back to the stock air intake with the 4.0tb and a TBS
That's exactly what I run...
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im lookin to upgrade to the 62mm TB and maybe a spacer on as well..i currently have an AEM intake that id like to keep-wonder if all that air would cause a problem. ideas anyone?
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I will throw the stock intake back on and see if that helps. I though that the Arraid might have been giving it too much air which is throwing off the sensors a bit.
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I have something along these lines and wonder what might be the cause.
Symptoms:
On most COLD days, it starts fine, but idle is horribly low...in the almost stalling range of probably 200-400RPM, and it runs rough. If I put it in gear and give it just a bit too much gas, it stalls right out. Sometimes, I'll sit and crank for anywhere from a second to 30+. As soon as the motor starts to warm, the idle/rough run goes away. If I don't stall and get moving, it's just fine until I let off the gas prior to warming up completely.
After reading through some of the 4banger yahoo threads, it could be either the CPS or the IAC. I've been running the 4.0L TB with a cold air can for a few years, and this just started when the weather began cooling off for the winter.
Now, with the 2.5L, I'll need to replace the IAC with the 4.0L due to the TB, correct?
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Just a little update. I put my stock TB back on afte rtrying the 4.0 TB with the stock intake and no change in my idle problem. After putting the stock TB back together and installing it the idle returned to normal and is smooth and consitent now. I wonder if there is something leaking causing a vacume leak somewhere. I am going to try cleaning up the mounting surfaces and see if that fixes it. pretty frusturating though.
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I could be wrong but don't you have to use the2.5l sensors with the 4.0l tb???...
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I could be wrong but don't you have to use the2.5l sensors with the 4.0l tb???...
Yes you do.
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New 2.5 TPS and IAC sensors and 2.5L IAC housing were also swapped over to the 4.0 throttle body when it was swapped.