4bangerjp.com
General Forums => The Mess Hall => Topic started by: bammerman on January 28, 2010, 05:09:42 PM
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I found this thread but there was no response
http://4bangerjp.com/forums/index.php?topic=4440.0
When I am sitting at a dead stop is it up to 2000 to 2500 RPM's and when I shift it goes back down to 1-1.5k
This doesn't seem right...
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You check your vacum hoses on the intake to see if one came loose?
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so this is a tbi 2.5l? if it is take a look at this http://jeepgarage.free.fr/OWN/fuel%20injection%20system%20tbi.pdf. isa motor sets the idle speed (from what the computer tells it). can you describe your situation a little more and what you have (whats happened in the last 2 years)... whats supposed to happen is when you shut off the jeep the asi motor fully extends (pushed throttle open a bit) to help with starting. then when you start up the jeep it lowers the idle to a regularly idle speed 900rpm-ish (which obviously isn't happening in your case) but since the idel rpm do change since you said it goes down to 1.5k when shifting... like previously said check the vacuum lines make sure you didn't miss any. there are some that are easy to miss (i did at least). there is one that connects under the line for the brake booster on the manifold side that is easy to miss. and they 2 from the hvac system coming out of the firewall like to fall off on my jeep. also make sure all wired connections are in good condition. hope this helps and we can be more helpful than in 2008
timing is controlled by the computer. only change you can do is move the cps a bit.
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You check your vacum hoses on the intake to see if one came loose?
I am not very savy, where would this be located?
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They will be on the intake near the throttle body, I think there are 3 or 4 of them I cant remember off the top of my head. What year jeep do you have?
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1990 YJ, I checked on the TB but nothing seemed unplugged. It just started happening recently, maybe within last month. Only thing I have done is add some KC lights, a new clutch and new oil pan and valve cover gaskets.
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they are the 2 that are more of a hard plastic, one comes from the firewall on the passenger side of the motor and connects into a check valve by the charcoal canister, and the other comes out of the firewall on the drivers side and also connects into a check valve and connects into the metal vacuum harness thing somewhere but i don't remember right now where exactly.. problem ive had with them is the hard plastic to rubber transition gets looser with time and if you have an oily engine bay like mine they get slippery and like to fall off when you hit rough terrain unless you secure them better (i used zip ties) im guessing that that isn't your issue though (or at least not all of it) since with those off mine still manages to idle down to 1.2kish it just takes a bit longer to idle down and runs rougher..
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I'm not sure on yours, I havent worked on one of the throttle body injection ones yet
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it is odd, sometimes I sit at 2k but then others it goes up to 2.5k and stays steady. I checked the lines and nothing is d/c'ed. Not sure if this matters but oil, and radiator fluid good. Not sure where to go next.
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it is odd, sometimes I sit at 2k but then others it goes up to 2.5k and stays steady. I checked the lines and nothing is d/c'ed. Not sure if this matters but oil, and radiator fluid good. Not sure where to go next.
i have no experience with the tbi setup and the guys before me covered most of the issues specific to that - so just going on a guess here and since it has not been mentioned: have you checked the throttle and try to move it back by hand? i'm just thinking that the return spring might be the issue, the accelerator cable has some problem and not letting the throttle return to minimum position or maybe the butterfly shaft/assembly get's stuck somehow - see if that brings the idle back down (try to also maybe unhook the cable). Check if the position of the butterfly lever is at the minimum where it should be for idle and like chadrc suggested also check and see if the idle control motor is keeping the throttle open.
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have you checked the throttle and try to move it back by hand? i'm just thinking that the return spring might be the issue, the accelerator cable has some problem and not letting the throttle return to minimum position or maybe the butterfly shaft/assembly get's stuck somehow - see if that brings the idle back down (try to also maybe unhook the cable). Check if the position of the butterfly lever is at the minimum where it should be for idle and like chardrc suggested also check and see if the idle control motor is keeping the throttle open.
x2 on that with the tbi there is a built in return spring in the tb (like the mpi guys have kinda)and an additional spring that looks like th one in the picture (not exactly the same as the stock one broke before i got it and this is some random one the po put on, which is why i am x2 what sharpaxmen said because the spring actually broke on mine and could possibly cause the problem in conjunction with a obstruction to the cable somewhere)
(http://i164.photobucket.com/albums/u25/chardrc/jeep/IMG_2612.jpg)
this is actually a pretty good picture of the asi motor for those wondering what it looks like.
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this is actually a pretty good picture of the asi motor for those wondering what it looks like.
he could also unbolt that ias motor once the engine is warm to see if it makes a difference (if all the other things check out ok).
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This is what I came up with... Is there a way to clean it? or is it the spring like you all said it could be? I tried adjusting the screw and nothing, but I push on that bar toward the thing with spring and it idels down to 1.0
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ok your return spring is in the stock setup(mine is wrong but works) so that should be good. when you push the throttle closed are you forcing the isa (what i was talking about before but i misspelled it) motor to retract or are you just pushing in the end cap of it (the end part should push in a little which is the closed throttle switch which tells the computer to take over idle control). if you are just pushing in the little end cap (closed throttle switch) then i would suspect binding in the linkage or a weak return spring.if you are having to physically force the isa motor plunger in then i would try adjusting it according to the top of page 6 in the link (don't know if you meant you fallowed that or you where just randomly trying to adjust the screw). other than that i don't know of any special way to clean it.. good luck
http://jeepgarage.free.fr/OWN/fuel%20injection%20system%20tbi.pdf
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ok your return spring is in the stock setup(mine is wrong but works) so that should be good. when you push the throttle closed are you forcing the isa (what i was talking about before but i misspelled it) motor to retract or are you just pushing in the end cap of it (the end part should push in a little which is the closed throttle switch which tells the computer to take over idle control). if you are just pushing in the little end cap (closed throttle switch) then i would suspect binding in the linkage or a weak return spring.if you are having to physically force the isa motor plunger in then i would try adjusting it according to the top of page 6 in the link (don't know if you meant you fallowed that or you where just randomly trying to adjust the screw). other than that i don't know of any special way to clean it.. good luck
http://jeepgarage.free.fr/OWN/fuel%20injection%20system%20tbi.pdf
is it possible that the throttle position switch is in the wrong position? so the control is sent to PCM before his throttle is all the way back? i have no idea how the tbi is setup but just going on some guess work here based on what you 2 are saying.
i still think would be a good test to unbolt the isa motor and see if the idle goes down (to rule out the binding or cable problems) and he should maybe also check when that microswitch is closing (i assume if it's hit before the idle position that the isa would take over and hold the idle high, but again this is guessing so maybe you can clarify how it works)
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basically the tip of the isa motor has the closed throttle switch on it so for the isa motor to effect the throttle position the closed throttle switch has the be pushed in (unless it somehow got stuck open). step 4 for adjusting effectively does what you suggested except without removing it. but removing it would also be a good way to test.
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4) Fully retract ISA motor by holding closed throttle (idle)
switch plunger inward as throttle is opened. Closed throttle switch
plunger should not touch throttle lever in closed position. If
contact is made, check linkage and/or cable for binding or damage.
Repair as necessary.
When mine closed it touched the throttle lever. I can just give it a little push to idle it down. Wonder if that means it is a bad ISA motor?
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Replaced the ISA with NAPA part, Chrysler no longer makes it and it idle's around 1.2 now
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Replaced the ISA with NAPA part, Chrysler no longer makes it and it idle's around 1.2 now
so you need to adjust that a little bit, should be able to drop it down to 8-900
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I have the screw turned all the way in, so do i just unscrew it a few times?
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I have the screw turned all the way in, so do i just unscrew it a few times?
i think "in" is where you need to go to lower the idle. you should see if loosening the support bolts you can move that bracket back a bit or maybe shim the isa motor on the back of the bracket - you have to move "away" from the throttle lever
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How much? I did that by at least 3-4 full turns and it still about the same 1k to 1.2k (haven't taken it on highway yet to see how it reacts).
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Also when I stop at a stop light I a sitting at 2k again. Is this norma? Figured it would go back down to 1k rpms.
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Also when I stop at a stop light I a sitting at 2k again. Is this norma? Figured it would go back down to 1k rpms.
no, it's not normal - have you figured out if anything binds in there and the butterfly does not return fully or it's the ias motor that keeps it open - you need to figure that out first. unbolt the isa and see if that would let the rpm come back or still stays up at 2k. if it stays there then you need to look for something else.
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Took the motor off at you were right it went right down, at first it started to climb to 2k and i went and pushed on the throttle lever and it went back down and stayed there. I dont see any kinks or anything on the cable. I put the motor back on at original factory position (screws all the way back) same thing. When I unscrew the plate the plastic on one side is coming off. Don't think that is right. (the corner piece in the picture without a screw mount.
The screw looks to be WAY out but that is as far as it will go. Picture below
I am going to go get a new spring later today and see if that helps. I talked to two mechanics yesterday and they said that it was my ISA and to replace. Let's hope I didn't waste 70.00 on it.
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if you are talking about plastic coming off on the new Isa motor i would return it and get another new one. after looking at your picture and then mine some more (other pics on my pc). if you think its the spring and you don't want to have to buy a new one you could try routing yours like mine is (from the pcv tube (metal part that goes to vacuum line) and to the upper part of the throttle linkage so that it is still pulling it closed) never knew it but my spring is the stock one but the inner spring broke so only the outer spring is doing the work now. but with the routing mine has its more stretched out at closed throttle.
if you have a accurate way to measure, you could measure the distance from the isa motor bracket to the throttle linkage with the motor on (and fully pushed in) and then without it on (and at 900rpm idle) to makesure that set screw/bolt isn't too long) although the falling apart plastic would be my main concern
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I think I fixed it this time. I have the screws all the way back and took the old bolt that touched the throttle lever and replaced the gold one. It is about a 1/2 inch shorter and running at 900-1k steady now. letting it run till it gets up to temperature though to see if that changes anything
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I was wrong, when it heats up and I start driving it stay between 1.5-2k even though on startup it is at 900-1k rpm. I think I am just going to have to take it to a shop sicne i cannot fix. I am not sure what to do next.
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Latest and last update i guess before I take to a shop.
I took off the motor again and backed out the mounting screws as far as they can go, good 1/2 in. Start it up sitting at 900-1k again. go for a drive, put in neutral and poof 1.5-2k again. what can go wrong with such a high idle and is there a way to reset it? like the computer in the jeep. I had a problem with it awhile ago. the plug came loose and my jeep would randomly stall and when it started up rpms would shoot to 4k. found out just loose wire and fixed it. could that be the cause and maybe just resetting it would fix it?
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it's not the isa motor - you said it doest the same thing with it unbolted. so next take the thing off once the engine is warm and get in the driver's seat and accelerate - if it stays at 2k then stop the engine and unhook the cable at the t/b. start the engine again and rev it by hand - if it goes down to 900 then it's the cable or the pedal, if it stays up to 1.5-2k then it's something at the t/b.
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Hey Sharp, I never drive tested it with it unbolted so I am not sure if it does it while being under a load. I did play with the throttle lever and it went back down to normal both with it bolted and unbolted, but like I said I never drove around with it unbolted.
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I think its the time for you to try and drive it unbolted like what sharp said...
This might help you figure the problem...
TO be honest I didn't know I was to drive around with my electrical unit just flopping around with no mounts.
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you can totally uninstall / unplug it so it isn't flapping around. only other thing i can think of is that the computer will use the isa motor to control the motors deceleration when you totally let off the throttle when moving. so maybe a sensor that inputs for that is going bad. tps maybe? although it sounds like its running fin other than the idle issue its easy enough to test though with a multimeter (see pdf)). although a sticky linkage still seems possibly so totaly removing the isa and driving around should be next step.
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I remove the ISA and mounted it on the valve cover. Drove around awhile and low and behold still up in the 1.5k - 2k RPMs. I check the wire going from the throttle to the inside of the jeep and at least in the engine compartment there isn't a bind by the looks of it, almost straight into the cab. I could not see it in the cab though.
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did u try my suggestions: push the throttle lever back by hand and unhook the cable and see if it still up in the 1500 to 2000)?
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did u try my suggestions: push the throttle lever back by hand and unhook the cable and see if it still up in the 1500 to 2000)?
Do you mean the spring?
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Do you mean the spring?
i mean the accelerator cable that goes from the butterfly lever (throttle lever on the throttle body) to your accelerator pedal. Unhook it at the lever and see if that releases the throttle back to idle at low rpm. leave the spring connected
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I looked at it, do i just force it off by pushing towards the ISA motor? I didn't see any clips it looks like it just snaps on. I don't see any diagrams on that earlier pdf on how to remove.
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I looked at it, do i just force it off by pushing towards the ISA motor? I didn't see any clips it looks like it just snaps on. I don't see any diagrams on that earlier pdf on how to remove.
slide off that clip or snap it off with a flat screwdriver between the end of the cable and bracket. there is a clip that wraps around the metal part at the end of the cable which you can slide off i think
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i use a flat screw driver and pry it away from the tb sound pop right off..
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I will give it a try today. Now here is another question my jeep doesn't rev high until after I start driving 70% of the time. I will drive it around the block to get it to do it and then I will pop it off.
*To any of you who have help me if you computer or website questions send me a PM. I would like to repay your help somehow.
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Yeah I think I am an idiot, figured this out while driving. I put my foot and pull on on pedal and it idles down... it sticks to push back on the pedal but it idles down so motor was fine... did have a vac hose off too. now just have to figure out why pedal is doing that. thanks for all ideas
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at least you know where the prob is now, glad you found the cause.
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Ya the top of my gas pedal is getting hung up on the air box. I have to bend the pedal since I cannot more the air box any farther. Bending it shouldn't affect anything right?
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Ya the top of my gas pedal is getting hung up on the air box. I have to bend the pedal since I cannot more the air box any farther. Bending it shouldn't affect anything right?
depends on which direction you will bend it - might take some of the "travel" away - make sure that once you're done bending you check to see if the throttle is fully open when the pedal is to the floor.
I do think that it could be something else though - did you try losening the mount and see if you can move it so it won't get stuck - that should be better than bending the pedal.
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Sounds like the ISA sensor on the throttle body. At a U pull it in Alabama you can get the TB and both sensors for $19. If you get a 4.0 TB be sure to put a 2.5 ISA in the 4.0 TB, or your idel will be screwed again!!!
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Sorry, forget what I said, TBI!!!