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General Forums => The Mess Hall => Topic started by: Backroads on January 09, 2011, 02:22:22 PM
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Its been in the garage more than on the road so I dont know how long its been going on...
When I'm decelerating in gear I get a popping/backfiring at the throttle body (at least thats where it sounds like its coming from) If I was to take a guess its the idle control (the box the throttle plate lays on when the throttle is closed) I tried adjusting it out for more idle but didn't make a difference. My idle right now is right around 1K rpms when warmed up. When cold its a bit lower, but I dont have the hot air tube going to the airbox.
Is theres something I need to be adjusting here? Or is something bad? Thanks!
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only thing I can think of off the top of my head would be to check the throttle position sensor it may not be going back far enough to cut the fuel on decelerate. aka thinks that your holding the fuel slightly open so keeps the fueling.
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I thought that backfiring thru the TB was a timing issue? :puzzled: Not that I know much about engines. :confused:
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the reason the idle position didn't change is probably because the idle control box will adjust in and out to get the idle rpm it wants. Ive found that when my jeep isn't used a lot it tends to idle close to 1000 rpm where if i use it steadily for a while i get an idle near 800 rpm. i don't run the hot air tube either (mine deteriorated to pieces and got sucked into the air cleaner) but haven't had any ill effects form its removal. I would probably start by testing the tps like Torch_Ind suggested. but could also be a timing issue...
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Come to think of it, when I first swapped this motor in, I dont remember it doing that....Then had all the vacuum and gas (if you guys remember me) issues and I did change out the TPS while trouble shooting. I actually tossed the original muddy colored TPS in my YJ spare parts box! Maybe I'll try swapping it out, heck it might just need adjusted if I remember right the bolt holes on the sides are slotted right? I'll have to find the correct way to set it.
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I thought that backfiring thru the TB was a timing issue? :puzzled: Not that I know much about engines. :confused:
I know what your referring to, and maybe I'm mistakingly describing it becuase I did exactly that when I first set the timing. It was way off and it would backfire through the TB, but it wouldnt even start, just snap crackle and pop...
This is runs fine, it just has a popping sound when decelerating in gear...but doesnt do it if I let off throttle and put it in neutral and coast.
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Come to think of it, when I first swapped this motor in, I dont remember it doing that....Then had all the vacuum and gas (if you guys remember me) issues and I did change out the TPS while trouble shooting. I actually tossed the original muddy colored TPS in my YJ spare parts box! Maybe I'll try swapping it out, heck it might just need adjusted if I remember right the bolt holes on the sides are slotted right? I'll have to find the correct way to set it.
+1 on the adjust the tps as starter point. there should be a spec as to what the feed back should be at when throttle closed.
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So Ive been messing with this on and off and I can not get this thing to run right.
It seems like its got a dead spot when accellerating where it kind of sputters. Especially if I hold the throttle constant at that spot, but above and below that in speed and on the throttle it will accelerate fine.
Also still pops and backfires when decelerating. If I decelerate in gear enough to really slow down it will give a good backfire through the exhaust.
what am I doing wrong here?! it didnt always run like this and everything I changed aside from the entire gas tank, I've tried putting back to stock and its still the same issues
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considering you have a dead spot in your throttle did you try a tps sensor?
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Not a new one no.
after I posted that I went back out and swapped to another TPS I have, and now that dead spot on acceleration has stopped...but still pops and backfires when decelerating. It only really does it if the RPMS get up pretty high, if I gradually slow down using the brakes before I downshift its not as bad, but still does it.
So I'm pretty sure the dead spot was because of the other TPS.
But how do I probe the TPS to test it? I popped the little cover on the back of the sensor plug but there is no way to get the multimeter probes in there to contact anything.
My manual says to put the positive on the center wire and negative on the black (ground) but neither of my other 2 wires are black lol.
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Check for an exhaust leak.
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i might as well take a shot at it too
1 - too much fuel (injector leaking could be one of the reasons, but that would make it run rich at idle also)
2 - some ignition problem (if fuel does not burn completely would cause backfiring)
3 - a bad valve or maybe cam related (incomplete fuel burn as before).
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i might as well take a shot at it too
1 - too much fuel (injector leaking could be one of the reasons, but that would make it run rich at idle also)
2 - some ignition problem (if fuel does not burn completely would cause backfiring)
3 - a bad valve or maybe cam related (incomplete fuel burn as before).
+1 on #3 that was also beginning symptoms of my jeep when my cam lob worn off on the exhaust side wasn't letting exhaust gasses out causing it to rumble throw the intake
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Well that #3 option would fit the rest of the new year so far!!
SO I think im just gonna drive it til it goes kaboom then look for something else haha
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This thing is driving me freaking crazy.
SO I changed out to a different TPS (spare I had) also the IAS or whatever it is that controls your idle speed, right at the throttle lever on the TB. After that it actually ran pretty descent. It would still get a little pop and backfire if I downshifted at a high rpm and let the engine whine down....But all the sputtering and crap stopped.
Fast forward to yesterday. Took it to the carwash to spray off all the salt and accumulation because for the first time in a long time I drove it a week or so with no problems!!!
Washed it off, tried to avoid the engine area as much as possible. Finished up drove home fine, woohoo everything is good!
So I poked around, checked my belts and oil yada yada, didnt really mess with anything electrical. Fired it up to park it back in the driveway and its sputtering and popping and wont idle.
had no choice but to drive to work today and it was backfiring loudly now, popping under deceleration, runs ok if I'm heavy into the throttle, but doesnt like easing up to speed. Is it the damn TPS? But how nothing got wet! As hidden as that freakin this is under the TB I cant imagine water got to it.
What do you guys think? I cant afford to go out and buy a bunch of new sensors for trial and error.
also, seemed like I burned up most all of a tank of gas on my way to work. I cant verify because my gauge sucks...but I ran 100 miles or so on the last partial fill, this time I went about 45-50 and it was back at my predicted 'empty' spot lol? hat gives?!?!?!?!?!!!!!
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Is it triggering the CEL? have any stored codes?
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I didnt think the older yjs had the CEL? Its a 1990. If it does how do I check that? I dont have any engine lights or service lights on. It just randomly went back to running like crap.
It would be more explainable if it did it right after the wash, and something got wet. But I literally took the long way home and played around and it was running the same as it was before the wash. I added about 1/2qt of oil, but i dont see how that would change a thing!
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Doh, my mistake! You're right, it's pre-OBDI.
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So unless my TPS somehow got ruined what else could it be? CPS? Or 02 sensor?
I read in the manual about checking these things for voltage, but how do I get to the wires without shaving some of the coating off to expose the wire to tap into?
It just really doesnt make any sense anymore! Its does it immediately after starting it, so I almost think its not a sensor. I thought I also read that if a sensor was bad it wouldnt really cause any problem until it was warmed up.
So could it be something with the fuel tank? or pressure?
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So unless my TPS somehow got ruined what else could it be? CPS? Or 02 sensor?
I read in the manual about checking these things for voltage, but how do I get to the wires without shaving some of the coating off to expose the wire to tap into?
It just really doesnt make any sense anymore! Its does it immediately after starting it, so I almost think its not a sensor. I thought I also read that if a sensor was bad it wouldnt really cause any problem until it was warmed up.
So could it be something with the fuel tank? or pressure?
The computer?
To tap into wires you can use a VOM with a probe at the backside of the connectors. Or you could push a pin through the wires although I don't really like doing that.
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id triple check the tps and then move onto trying to check the cps. and if all else fails make sure you have good connections to the battery and the big collection of wires at the firewall between the motor and the battery. weird things can happen if your not getting good connections. although that would be less likely than tps or cps id think. but easy to check anyways. i would digg into the books abit for you but school is killing me right now. :brick:
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I appreciate the input. So I messed with the TPS (2) I have, they both result in the same thing, BUT if I manually push the little lever it does make it idle up and down slightly. I'm thinking its not that...
But I did pull the cover off the throttle body and compared to when I looked at it before it looks like its REALLY getting a lot of fuel dumped in it. I can literally see it all but pooling up on top of the butterfly at warmed up idle. Would the CPS cause that? That would have been the only thing that really could have gotten soaked when washing the thing the other day.
I'm just thinking if its fuel related, it doesnt seem likely that its gonna run great one day, and then flooded and like crap the next. I guess I could have a clogged return line, but I just put in the tank and new lines and filter etc.
So should I try a cps? Is that even something that causes these kind of symptoms?
also my whole exhaust sucks, could it be an exhaust issue? From when it was doing this a week or so ago, I havent touched the exhaust and it went from not running good, to running good, back to not. crappy exhaust stayed the same.
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I appreciate the input. So I messed with the TPS (2) I have, they both result in the same thing, BUT if I manually push the little lever it does make it idle up and down slightly. I'm thinking its not that...
But I did pull the cover off the throttle body and compared to when I looked at it before it looks like its REALLY getting a lot of fuel dumped in it. I can literally see it all but pooling up on top of the butterfly at warmed up idle. Would the CPS cause that? That would have been the only thing that really could have gotten soaked when washing the thing the other day.
I'm just thinking if its fuel related, it doesnt seem likely that its gonna run great one day, and then flooded and like crap the next. I guess I could have a clogged return line, but I just put in the tank and new lines and filter etc.
So should I try a cps? Is that even something that causes these kind of symptoms?
also my whole exhaust sucks, could it be an exhaust issue? From when it was doing this a week or so ago, I havent touched the exhaust and it went from not running good, to running good, back to not. crappy exhaust stayed the same.
cps would have nothing to do with the extra fuel (if that's the problem) - for that check the MAP sensor that is actually hooked up properly and that the output is correct (something like 0.6v at idle, 4.6v at wot, not exactly that but somewhere around those values, if you have >1v at idle that could be your problem for example). also, what's your fuel pressure and is your injector leaking any fuel when the engine is not running?
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Ill have to check and see if its leaking. not taht I was aware of.
I guess its possible the MAP got wet when I opened the hood and had some drippage, its right there ready to get dripped on...
I dont have any kind of gauge to test fuel pressure. Whats a cheap something to buy for that? I went and asked about it before at a local store and it was astronomical!
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injector is not leaking. The top of the butterfly is dry now thats its been sitting for an hour or so. I did pull the vacuum hose for the MAP sensor earlier and it actually wanted to stall when I did that. I duno if that means its working properly or not. Going to attempt to test it later.
jeffy; the problem with my voltmeter is the prongs are too big and there are rubber grommets at the back of all the sensor plugs, theres no real way to get in there to contact any metal without breaking it apart...Thats what I was looking for tricks on how to do..
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injector is not leaking. The top of the butterfly is dry now thats its been sitting for an hour or so. I did pull the vacuum hose for the MAP sensor earlier and it actually wanted to stall when I did that. I duno if that means its working properly or not. Going to attempt to test it later.
jeffy; the problem with my voltmeter is the prongs are too big and there are rubber grommets at the back of all the sensor plugs, theres no real way to get in there to contact any metal without breaking it apart...Thats what I was looking for tricks on how to do..
if it was about to stall when you pulled the vac line off the MAP would indicate that it works so start with the fuel pressure. I had my return plugged and my pressure was going nuts.
how's your O2 sensor?
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o2 is old and ugly. just like the rest of my exhaust haha
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o2 is old and ugly. just like the rest of my exhaust haha
just something to consider though
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just something to consider though
you got it!!!!!
Well sorta...I did however figure it out. After trying EVERYTHING I could short of replacing the whole damn engine.
So last friday I checked my belts, which included reaching under the intake/exhaust mani to loose up the pivot bolt for the power steering. WELL I must have tweaked the manifolds enough to cause a leak. Here I found the bolts to the firewall side of the engine that hold the intake/exhaust mani on were just a bit loose. So it was 1 leaking exhaust causing all the popping and backfiring. 2 it was leaning itself out with a vacuum leak on the intake mani, causing it to overfuel which explains it eating up a tank of gas as well as all the backfiring!
So I snugged those bolts up and its purrs like a kitten.
Damn simple crap gets me every time!
Thanks a million for all the help guys! :bow:
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you got it!!!!!
Well sorta...I did however figure it out. After trying EVERYTHING I could short of replacing the whole damn engine.
So last friday I checked my belts, which included reaching under the intake/exhaust mani to loose up the pivot bolt for the power steering. WELL I must have tweaked the manifolds enough to cause a leak. Here I found the bolts to the firewall side of the engine that hold the intake/exhaust mani on were just a bit loose. So it was 1 leaking exhaust causing all the popping and backfiring. 2 it was leaning itself out with a vacuum leak on the intake mani, causing it to overfuel which explains it eating up a tank of gas as well as all the backfiring!
So I snugged those bolts up and its purrs like a kitten.
Damn simple crap gets me every time!
Thanks a million for all the help guys! :bow:
:beers: awesome these small things really put egg on your face but there cheep fix to!!! lol just glad you found your problem thats all that matters in the end!!