Never heard anything like this before but recently when my car is at idle there is this popping noise coming out of the exhaust. Its not very loud but you can hear it if your standing right next to it. It will pop and a second or two will go by and it will pop again. Any body experienced this before.
Popping exhaust
Sm0key23
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Never heard anything like this before but recently when my car is at idle there is this popping noise coming out of the exhaust. Its not very loud but you can hear it if your standing right next to it. It will pop and a second or two will go by and it will pop again. Any body experienced this before.
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281 Posts
Maybe you are experiancing detonation???
My engine makes this sound too if I dont pour a few gallons of Xylene in there.
My engine makes this sound too if I dont pour a few gallons of Xylene in there.
My car does the same thing and I don't know what's causing it either. Some help here would definitely be nice! I'm wondering if it's related to my idle problem though. My idle has a CONSTANT surging problem (usually between 1200-1500 rpm). I can't seem to make it go away. I was told that more than likely it's due to the fact that I'm running a Walbro 255HP pump with 660cc injectors on an otherwise stock fuel system and my stock FPR is being overrun. I've been told that I need an Adj. FPR. So I'm thinking that "maybe" the surging and the popping are related?! Anyone, anyone??
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871 Posts
Are you running rich? Does your engine miss?
Usually popping is caused by excess unburnt fuel being exhaust-expelled and spontaneously combusting on the catalytic converter... But it may not always be the cause.
Is your O2S good?
Usually popping is caused by excess unburnt fuel being exhaust-expelled and spontaneously combusting on the catalytic converter... But it may not always be the cause.
Is your O2S good?
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DsmTrance
I have the same problem as you with the popping exhaust and constant surge between 1200 and 1500rpm. I have no cat, walbro 255HP and stock injectors. Anyone with the insight please inform.
I have the same problem as you with the popping exhaust and constant surge between 1200 and 1500rpm. I have no cat, walbro 255HP and stock injectors. Anyone with the insight please inform.
I do not think that I am running rich and I have the problem that around 4-5 grand under WOT my car jerks in every gear just for a split second, people seem to think that its fuel cut but I have the walboro 255 pump and I too do not have a cat
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207 Posts
the idle surge usually caused by a faulty base idle set screw. usually it has backed itself out to far.....
the slight popping in the mid range of your rpm sounds like you might have old or improperly gapped plugs. the car will still pull to redline but will have slight minor pops through the pull. fuel cut is much more violent and will STOP the car from excellerating.
the idle "popping" usually happens when you remove the lower honeycombs, and have a full exhaust system. this causes the car to be slightly lean, and can be solved by richening the idle with an afc or something similar.
the slight popping in the mid range of your rpm sounds like you might have old or improperly gapped plugs. the car will still pull to redline but will have slight minor pops through the pull. fuel cut is much more violent and will STOP the car from excellerating.
the idle "popping" usually happens when you remove the lower honeycombs, and have a full exhaust system. this causes the car to be slightly lean, and can be solved by richening the idle with an afc or something similar.
I've already put in a new biss screw and it did'nt help the popping or the surging. And just to get anywhere near livable I had to put it in FULL tight! It still surges and pops like crazy at idle. I do have a 2G mas (I have a 91 AWD) though with the side HC's removed and I also have a S-AFC. But tuning up or down on the AFC does'nt get rid of the problems either. It's starting to get really frustrating. I'm wondering if what some people have said is right...I need an Adj. FPR because I'm running the Walbro 255HP and 660cc injectors. I just want to make sure I'm not missing something before I go and buy a $325 FPR kit from Buschur (from what I've seen I like theirs the best). Anyone think of anything else?
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you should just get the B&M Command flow and fuel pressure guage set for 100$.Or you can just get the SX regulator for 135 plus 35 for the guage and that does not require cutting the stock fpr like the B&M. I don't know what you were buying for 325$.just trying to save ya some money.
Late
Late
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207 Posts
as far as i can acertain. you should never have to tighten the biss all the way in. if you do its probably covering some other problem. and you run the risk ofscarring the inside ofthe throttle body, which can affect airflow through the biss.
one thing came to mind..... if you let the car idle for a while does it start to stutter and possibly die? this could indicate your cam timing is incorrect. and if your cam gears are offthey will cause a "lumpy" idle.
just some suggestions. thats all
one thing came to mind..... if you let the car idle for a while does it start to stutter and possibly die? this could indicate your cam timing is incorrect. and if your cam gears are offthey will cause a "lumpy" idle.
just some suggestions. thats all
Hey if your going with a FPR get the Buschur racing instead of the B&M. Its a great looking kit and is a bolt on for 1gs. The B&M for your case is not the way to go cause your running rich. B&M can only be adjusted for more psi pressure only and can't be set at a lower psi than stock. With the SX it can be adjusted either way which is great for larger injectors and pumps.
Well thought i'd shed some light on the FPR thing.
Well thought i'd shed some light on the FPR thing.
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i have a 1G talon and i also had the surge on idle. mine went from about 1200-1500 also. i took it to the dealer and had a diagnostic check run. the dealership said it was my idle speed control motor. i changed it and the problem was gone. the iscm is down and right below the throttle elbow about 2 inches. it's expensive though about $260. hopefully that is it. good luck!
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I had the same throttle problema nd I fixed it tonight.. . . I don't know if maybe my mechan ic was just an ass and forgot some stuff or if it may be the same for you. . . two things, (I have a 1g, so forgive me if some things are different), but pull the black sensor out of the throtle body that has (I think) a green wire. . I think it is the throttle position sensor, but forgive me if I am wrong, I am used to domestic. . . clean the contacts with some electrical parts cleaner and re-install it. . . them also, on the back of the engine, there is a gang of vacuum lines that all come together on a metal fitting (it is under the intake manifold, but U can reach it without removign anything). . . anyway, make sure all the lines are plugged in, becuase once I plugged one in that was just hanging the idle came back under contol. . good luck
Check the vacuum lines going to your throttle body. Mine were a little hard and ripped on the ends that attached to the nipples on the throttle body. I took them off an cut the ends off and reattached them for a better seal. Also make sure the little vacuum hose clamps are on them good too. I also took the BISS screw out and cleaned the threads and put a little 3-in-1 oil on the O-Ring. This cured my idle surge problem.dsmtrance said:
Well, I did the fuel pump rewire this weekend and it only made my idle problem worse. Which is not all that surprising IF the FPR is actually the problem since doing the rewire mod only INCREASES the fuel to the injectors. Which may be my problem anyways (too much fuel). One weird thing I did notice though. While idling my EGT's are usually right around 500c. While cruising at 80-85mph they are usally around 760c-820c. BUT, after I did the rewire I noticed that while cruising at about 85mph they would climb to about 820c and the o2's would be cycling like normal and then all of a sudden the o2's would slowly start reading richer and richer and my EGT's would start to fall to damn near 680c-700c...with no change in speed or throttle position! So maybe my whole problem IS pressure related? I just don't know. 
My car is going wacky on me!!!
My car is going wacky on me!!!try cleaning your throttle body
I thought i fixed my idle surge by re-doing the vacuum lines to the throttle body, but it's back. Idle surge is usually caused by a vacuum leak, unmetered air getting into the intake from everything I read online. Take a look at the VFAQ. Even though i dropped a jap-spec engine into my car, the shop used my original intake with 144k miles instead of the "cyclone" intake (I still have it if anyone wants to buy it). I decided it probably needed a good cleaning (the TB), so i went down to the local mitsu dealer and picked up new TB gaskets. I just got done taking it off and cleaning it real well with carb cleaner. I used the haynes manual, it also said to clean out the ISC motor/housing, which I also do. Hopefully this solves my idle surge, usually takes a day for it to come back after i think I fixed it. I'll let you know my results.
dsmtrance, sounds like u need an AFC (do you already have one?) to lean it out a bit at cruising speed. I think if you make any mods to the fuel system (bigger injectors or bigger fuelpump/rewire) the car's ecu really can't handle it, because it's expecting a certain pressure, etc. I'm still pretty new at this, so if someone would like to correct me or back me up, please do.
[Edited by flluke on 09-10-2001 at 07:16 PM]
I thought i fixed my idle surge by re-doing the vacuum lines to the throttle body, but it's back. Idle surge is usually caused by a vacuum leak, unmetered air getting into the intake from everything I read online. Take a look at the VFAQ. Even though i dropped a jap-spec engine into my car, the shop used my original intake with 144k miles instead of the "cyclone" intake (I still have it if anyone wants to buy it). I decided it probably needed a good cleaning (the TB), so i went down to the local mitsu dealer and picked up new TB gaskets. I just got done taking it off and cleaning it real well with carb cleaner. I used the haynes manual, it also said to clean out the ISC motor/housing, which I also do. Hopefully this solves my idle surge, usually takes a day for it to come back after i think I fixed it. I'll let you know my results.
dsmtrance, sounds like u need an AFC (do you already have one?) to lean it out a bit at cruising speed. I think if you make any mods to the fuel system (bigger injectors or bigger fuelpump/rewire) the car's ecu really can't handle it, because it's expecting a certain pressure, etc. I'm still pretty new at this, so if someone would like to correct me or back me up, please do.
[Edited by flluke on 09-10-2001 at 07:16 PM]
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