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popping noises

S

sanman

Guest
maybe someone can help here,i own a 93 vette lt-1,i added a
k&n filter with a open box lid,air foil to tb/and tb bypass. the
car is a 6-speed,Ive noticed in the last month that when i accelerate kinda hard and let off the gas the car starts popping,
almost like backfiring.it does this mainley in 1st and 2nd gear when the motor is winding down,and its always about 3or4 pops in a row ......thanks
:(
 

c4c5specialist

Technical Advisor
Joined
May 29, 2001
Messages
3,682
Location
New Haven, Ct. USA
Corvette
Nope, but someday.
Hi there,
I would say that you are having extra air induced into exhaust, from the air injection.
This is usually more pronounced when you have an aftermarket exhaust, but it does happen from time to time.
I would check to see if your air injection check valves are working correctly.
If you would like further information, please let us know, c4c5:hb
And no, there is no problem with what is happening.
 
C

Chick

Guest
possibly but

Hi Paul...(wink)

sanman....I'd scan it. I think it needs a "snap shot".

The air injection pump should not be running (it should be timed out by roughly 3 minutes after the car is started) though it can still pull air in through the check valves.

Have some one listen to it and look at the data, that would be the smartest thing to do.

Paul wheres the info I asked for??????huh!
 

Hib Halverson

Technical Writer for Internet & Print Media
Joined
Jan 10, 2001
Messages
13,453
Location
CenCoast CA
Corvette
71 04 12 19
Re: possibly but

Chick said:
Hi Paul...(wink)

sanman....I'd scan it. I think it needs a "snap shot".

The air injection pump should not be running (it should be timed out by roughly 3 minutes after the car is started) though it can still pull air in through the check valves.

Have some one listen to it and look at the data, that would be the smartest thing to do.

Paul wheres the info I asked for??????huh!

I need to be enlightened
A scan test would detect an AIR pump running when it's not supposed to do so--in fact, I'll bet that would set a code.

But, does the ECM moniter the check valves, too? That'd be the only way they'd show up as values in a scan test, correct?
 
C

Chick

Guest
It would detect an air pump thats running when it shouldn't be but my point is I'd want to hook it up to my TECHII and see the data and see if I personally see what might be slightly unusual (I am keen with reading this data)

It should set a code technically but that's not always the case. I've seen many screwed up cars not set codes that should.

No the ECM does not monitor the check valves.

The parameters of other values can change if the check valves aren't working properly this is where the trained eye comes in.

I'd want to look at the fuel pressure and condition of the ignition system also.

I really think rather playing guessing games that a qualified tech at a chevy dealer should be evaluating your car.
 

c4c5specialist

Technical Advisor
Joined
May 29, 2001
Messages
3,682
Location
New Haven, Ct. USA
Corvette
Nope, but someday.
Hi Chick,
Glad you are feeling better.
Infos in the mail. :)
As for the scan data you are refering to, I concur as well, as I think that you are looking for 02 sensor drop out, to full lean, as if the air pump was running?????
That was not something I thought of, thanks, Goddess of all Vettedom.
You still rock, thanks again for a refresher, c4c5:hb
 
T

TomsToy

Guest
Poping

Very interesting analysis. I've have the samr problem, but it goes away(almost) when the engine warms. I was told when the chip was reprogrammed, it causes the same effect(gurgle & pop). However, I havent seen any code sets? I'm interested in the results too!:(
 
C

Chick

Guest
wow

c4c5 you must be the sweetest wrench in CT. Cape Coral becons 2 experts for their own retail corvette shop? It's after warranty heaven not to mention sun and palm trees.
 

vms4evr

Well-known member
Joined
Jul 18, 2001
Messages
466
Location
Durham, NC
Corvette
2002 Flat Black Z06
I'll be curious about the result too. I have a 92. The car never did this. I added an SLP claw (3 K&Ns), air foil, and did the TB bypass. From time to time the car will do that little popping. Not often.
Not sure if this helps, but..
My car is an auto trans with 3.54 gears. It is more noticeable now than with the 2.59 gears.
It does it after it is warmed up, and only if I've been goosing the accelerator with the car in Drive and hitting say 60 or so and then just letting off the accelerator and letting the car coast down. My exhaust is factory but since I made the changes on the intake end it flows more air and the exhaust is louder.
It almost sounds like a toned down version of what the Borlas do when they're sucking air and pop like in freinds car.

Chick,
That air pump. Maybe that is the sound I hear everytime I start it. After about 3 minutes it does go away. Then I never hear it again.
I take it that this is not an AIR pump like on the late 70's Chevies?

The car runs great so I never gave it much thought. It does not set any codes at all.

Graham
 
S

sanman

Guest
thanks for the info, I will have it checked and let you all know

what i find out.
 

69MyWay

Well-known member
Joined
Jul 3, 2001
Messages
4,364
Location
Auburndale, Florida
Corvette
1969 Killer Shark
You know, when we opened up the exhaust on Nikki's 90 and trimmed out the air box etc. it picked up a wicked cool sounding pop, pop, pop, out the tail pipes during down shifts. It was there all along, but you could not hear it so well before.

I love the way it sounds, and it is not any sort of a problem, it is just what happens when the engine is being reved down by the down shift action, and the free flow interchange at the gear shifting pulling the exaust pressure back and forth in the exhaust system with unburned fuel ect. exscaping.

Then again, it is hard to tell via the electronic forum through a written description what something really sounds like and whether or not is it a problem or a side effect. I have been reading this thread with interest in what would "pop" up :L and have learned a little bit more about the A.I.R. system than I knew before. Thank you!
 

69MyWay

Well-known member
Joined
Jul 3, 2001
Messages
4,364
Location
Auburndale, Florida
Corvette
1969 Killer Shark
Re: wow

Chick said:
c4c5 you must be the sweetest wrench in CT. Cape Coral becons 2 experts for their own retail corvette shop? It's after warranty heaven not to mention sun and palm trees.

Hey Chick,

Don't know exactly what this is all about, but I sure can tell you that yes, the palm trees are nice, and I was out in the shop after work last night building my passenger door assembly in shorts.

The cold front finally started pushing through last night, and they are thinking we could have some frost on the lawn Christmas morning.

I can't think of anywhere else I would rather live, work, and play.

Sounds like a great opportunity.
 

Trance_LT4

Well-known member
Joined
Dec 11, 2001
Messages
140
Location
Suffolk, VA
Corvette
Red 96 LT4 coupe
You're complaining about the pop and gurgle? I've always thought it sounded meaner when you are downshifting and hear a nice gurgle and a few pops. Loud=Good (thats why no cats are better than any cat system, no matter how much flow they claim)
 
C

Chick

Guest
69myway...are you in cape coral? I'm jealous.
 

69MyWay

Well-known member
Joined
Jul 3, 2001
Messages
4,364
Location
Auburndale, Florida
Corvette
1969 Killer Shark
No Chick, I am North of there quite a bit, but still enjoy very mild Florida weather. It is a little chilly today however, I have to put on a light jacket to go out.
 

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