My car's making coffee or popcorn or something!
05-02-2005, 03:50 PM
#1
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Join Date: Aug 2004
Location: Bay Area, CA
Posts: 1,075
My car's making coffee or popcorn or something!
Lately, I've been noticing something different when I drive my NA '82 280ZX. I could swear it's slightly louder, but more important is this noise I've been hearing. When I let off the throttle but am still in gear (coasting), I hear this burbling noise, almost like coffee percolating or popcorn popping. Any idea what this is or how much I should be worried? Is this some kind of misfiring or fuel issue? (my gas mileage still seems ok)
The engine was rebuilt by the previous owner and I have had no mechanical difficulties in the 6 months I've had the car. Supposedly it's had some internal work done and its got some bolt ons like, intake, exhaust, MSD ignition, and a high flow cat.
The engine was rebuilt by the previous owner and I have had no mechanical difficulties in the 6 months I've had the car. Supposedly it's had some internal work done and its got some bolt ons like, intake, exhaust, MSD ignition, and a high flow cat.
05-02-2005, 03:53 PM
#2
Externally Wastegated
Join Date: Oct 2001
Location: San Diego
Posts: 1,220
It's probably normal combustion processes. My bro's Spec V made backfiring noises out the exhaust once we added a header on it, and so does my friend's RSX-S. I think the decrease in backpressure is what causes it. My Z does the same thing under deceleration.
05-02-2005, 05:15 PM
#3
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Join Date: Dec 2004
Location: squwamton
Posts: 1,046
if your getting back fire then try tighting your header bolts i have to do this all the time lately for awhile they are all good but awhile after that there not .so tighten that **** up 
cold air sepping in with the hot air coming out of the head makes a nice little poping sound when i let off of it after its been reved up..its like it sucks up a little air right in between the head and header.... it seem to do this more when my timeing was off. it was BAD so maybe check your timeing .. try to turn your cap and see if it moves at all if it does then mabe your nut that locks it in place came lose.put it on the timeing light and addvance it 
pop pop pop means more power 
. hope this helps after some messing with mine my pop pop seemed to gone but i still hear it after i decelerate hard from 95 mpg to 65 mpg thats the only time i hear it any more
cold air sepping in with the hot air coming out of the head makes a nice little poping sound when i let off of it after its been reved up..its like it sucks up a little air right in between the head and header.... it seem to do this more when my timeing was off. it was BAD so maybe check your timeing .. try to turn your cap and see if it moves at all if it does then mabe your nut that locks it in place came lose.put it on the timeing light and addvance it pop pop pop means more power . hope this helps after some messing with mine my pop pop seemed to gone but i still hear it after i decelerate hard from 95 mpg to 65 mpg thats the only time i hear it any more
Last edited by 81 Black L28E; 05-02-2005 at 05:22 PM.
05-03-2005, 09:25 AM
#5
Doesn't post much...
Join Date: Dec 2004
Location: Escondido (San Diego) California
Posts: 3,617
Man, I hate it when my gas mileage drops from 95 mpg to 65 mpg... wait a minute... my mileage really sucks compared to yours, I'm getting like 22-25 mpg! that sucks! How'd you get such awsome mileage?!
Rod.
Rod.
05-03-2005, 12:17 PM
#7
The Evil Twin
Join Date: Mar 2001
Location: Seattle, WA
Posts: 9,294
I've been getting 21-24 for a long time. That's pretty good for the L28. That's overall milage. I have taken some long road trips and average 27-28mpg for the trip wich means I'm probably getting close to 30mpg while on the highway.
Guys with the L24 with dual SU's are getting 16-19 mpg on well tuned engines. We have it easy.
Guys with the L24 with dual SU's are getting 16-19 mpg on well tuned engines. We have it easy.
05-03-2005, 06:05 PM
#9
Registered User
Join Date: Apr 2005
Location: Temecula, CA
Posts: 5,485
Damn, I get 17 mpg averaging city and highway. Missing 5th gear though, that could contribute to my S@#$y highway mileage. I heard these things don't get great mpg anyways though. I try to keep it off of the highway for long trips.
05-03-2005, 07:06 PM
#10
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Join Date: Aug 2004
Location: Bay Area, CA
Posts: 1,075
On my recent trip to Los Angeles, mostly highway miles, with some stop-and-go rush hour traffic, I got 26mpg.
So anyways, the concensus here is that I should not be too concerned about the noise? I could swear the car does smell a little gassier when the window's down. ^^ No one thinks something's up with my fuel system?
So anyways, the concensus here is that I should not be too concerned about the noise? I could swear the car does smell a little gassier when the window's down. ^^ No one thinks something's up with my fuel system?
05-04-2005, 10:12 AM
#12
Registered User
Join Date: Jan 2004
Location: Mesa, AZ.
Posts: 1,055
Originally Posted by Heat Rave R
Lately, I've been noticing something different when I drive my NA '82 280ZX. I could swear it's slightly louder, but more important is this noise I've been hearing. When I let off the throttle but am still in gear (coasting), I hear this burbling noise, almost like coffee percolating or popcorn popping. Any idea what this is or how much I should be worried? Is this some kind of misfiring or fuel issue? (my gas mileage still seems ok)
The engine was rebuilt by the previous owner and I have had no mechanical difficulties in the 6 months I've had the car. Supposedly it's had some internal work done and its got some bolt ons like, intake, exhaust, MSD ignition, and a high flow cat.
The engine was rebuilt by the previous owner and I have had no mechanical difficulties in the 6 months I've had the car. Supposedly it's had some internal work done and its got some bolt ons like, intake, exhaust, MSD ignition, and a high flow cat.
If the BCCD (or something like that) valve is capped off, it will do that. Basically, what that valve does is make the car's idle evenly decelerate on a shift down. If the valve goes bad, you can cap it off to avoid "chatter" in the valve, and the car will "burble" while coming to a stop (shifting down). Normal....
05-04-2005, 04:28 PM
#15
Pro Pumpkin Carver
Join Date: May 2004
Location: Oakland Cali-****en-fornia
Posts: 2,160
Originally Posted by Carl's Z
If the BCCD (or something like that) valve is capped off, it will do that. Basically, what that valve does is make the car's idle evenly decelerate on a shift down. If the valve goes bad, you can cap it off to avoid "chatter" in the valve, and the car will "burble" while coming to a stop (shifting down). Normal....
That was the case with my BCDD. Friggin thing drove me NUTS!!! just disconnected it and now the car "burbles" when coming to a stop. dosent bother me tho, just sounds like normal back fire when using the tranny to slow down. check out the post asking about it, i point it out
https://www.zdriver.com/forum/showthread.php?t=11654
05-09-2005, 05:53 PM
#20
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Join Date: Aug 2004
Location: Bay Area, CA
Posts: 1,075
Regarding the "popping" my car's doing, I do notice that it's pretty consistent at only happening when it drops below 2000rpms. I wonder if it's just the MSD multi-sparking at low rpms. If so, I wonder why I never noticed it months ago.
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