Date: Thu, 17 Oct 2002 14:11:40 -0000
From: "Jeff Lucius" <jlucius@stealth316.com>
Subject: Re: Team3S: Causes for Backfire on deceleration

You're right. I did not consider that a person might gap the plugs down so far
that they are ineffectual in their car. I assumed a person was using a proper
gap. But yes, if a gap is too small the spark voltage will be too small and
the combustion could be incomplete. And if the gap is too large, there can be
many misfires and incomplete combustion cycles (that is, unburnt fuel going
into the exhaust track).

Now, 0.028 usually is not too small a gap unless a person is using the
precious metal spark plugs (platinum, iridium, etc.) or there is some problem
with the car (weak coils, for example). Precious metal plugs always produce
(actually "require" is a better term) less voltage at a particular gap
than "copper" plugs at the same gap (*only* because of the electrode tip
size).

My personal experience has been that there has been no change in backfire
frequency now that I use 0.028"-gap "copper" plugs than when I used 0.034"-gap
copper plugs or 0.034"-gap platinum plugs.

- ----- Original Message -----
From: "Gross, Erik" <erik.gross@intel.com>
Sent: Wednesday, October 16, 2002 4:42 PM
Subject: RE: Team3S: Causes for Backfire on deceleration

smaller gap -> physically smaller spark -> smaller initial flamefront -> less complete combustion -> more leftover fuel in exhaust gas

If you have an exhaust leak, then the more fuel in the exhaust gases, the more likely you are to have rice crispies in your exhaust...

Date: Thu, 17 Oct 2002 14:11:40 -0000
From: "Jeff Lucius" <jlucius@stealth316.com>
Subject: Re: Team3S: Causes for Backfire on deceleration

My personal experience has been that there has been no change in backfire
frequency now that I use 0.028"-gap "copper" plugs than when I used 0.034"-gap
copper plugs or 0.034"-gap platinum plugs.

I've been following this thread for a couple days now. Early on, a couple
of listers replied that the cause of the backfire was probably an exhaust
leak. Is there some reason why this suggestion is being ignored, or did I
miss something?

My car has had backfiring issues in the past, too. It occurs in the form of
several consecutive pops during hard deceleration, but doesn't happen
every time. I've always assumed that this was a symptom of leaking exhaust
because after I replaced the gaskets, the popping would go away. In fact,
in recent weeks I started getting the backfiring again. I removed my
downpipe this weekend to install a new clutch, and noticed a bad-looking
gasket at the rear pre-cat that showed obvious evidence of leaking badly.
Not having a new gasket on hand, I put some silicon on the old one,
re-installed it and the backfiring seldom occurs now. Eventually I will
replace the gaskets.

I'm not guaranteeing this is your problem, but it's worth looking in to
before you start replacing spark plugs, wires, timing belt, etc.

Date: Thu, 17 Oct 2002 11:00:04 -0400
From: "Starkey, Jr., Joseph" <starkeyje@bipc.com>
Subject: RE: Team3S: Re: Causes for Backfire on deceleration

I've never heard that a leaking exhaust can CAUSE backfiring, although a
leaking exhaust can SOUND like backfiring on deceleration, and
backfiring can CAUSE a leaking exhaust. Of course, I'm a self-taught
mechanic who just refuses to take his cars anywhere to get serviced
because I've had nothing but bad experiences taking my cars anywhere, so
I might be missing something. It's my understanding that backfiring is
caused by excess unburnt fuel. I don't know how a leaking exhaust can
cause excess unburnt fuel. Maybe your gaskets are going bad because of
the extra heat generated by your backfiring condition.

Date: Thu, 17 Oct 2002 10:03:03 -0500
From: "Brandon Wieschhaus" <bwish@umr.edu>
Subject: Re: Team3S: Re: Causes for Backfire on deceleration

I'll have to agree to that. When I first got my car, I had backfire. At the
time, I thought it was just the aftermarket muffler making all the noise,
but upon further inspection, found that my flex tube was completely shot.
What I would do, is if your car is starting to sound like it has
glass-packs, take a really close inspection of the exhaust system. I would
think the problems that Jeff and others have alluded to about gas entering
into the exhaust system would create MUCH louder pops, more like bangs
really... Just my 2 cents...
-Brandon

A leaking exhaust will let air into the exhaust stream while it is still hot
enough to ignite with out the aid of a spark. Witness the flames from a
Racing car exhaust when the exhaust stream meets the air at the pipe exit.
The inertia of the flow will pull in air between pulses of the cylinders
dumping.

Date: Thu, 17 Oct 2002 09:44:46 -0700
From: "Geddes, Brian J" <brian.j.geddes@intel.com>
Subject: RE: Team3S: Is A/F ratio my problem?

Nope - stoich for gasoline is 14.7:1. That's the point where there are
exactly enough oxygen molecules to combust all the gasoline molecules. In
reality they don't actually all combust though, so the optimal power comes
at about 13.0:1, or so I've heard.

> -----Original Message-----
> From: Dennis Ninneman [mailto:dninneman@comcast.net]
> Sent: Wednesday, October 16, 2002 4:17 PM
> Subject: Re: Team3S: Is A/F ratio my problem?
>
> Great point about lowering ratio to reduce detonation.
> Always thought
> stoichiometric ratio was around 17:1 though?

Date: Thu, 17 Oct 2002 16:49:58 -0000
From: "Jeff Lucius" <jlucius@stealth316.com>
Subject: Re: Team3S: Causes for Backfire on deceleration

>> Early on, a couple of listers replied that the cause of the
>> backfire was probably an exhaust leak. Is there some reason
>> why this suggestion is being ignored ...

To summarize what I and several others have pointed out, three items are
required for a backfire to occur.
- unburnt fuel
- oxygen
- ignition source

A leaky (or extremely short) exhaust can supply the oxygen (fresh air).
However, a leaky exhaust does not cause backfire unless fuel and an ignition
source are also present.

Unburnt fuel is the main reason backfire occurs. However, oxygen and ignition
are required to make a backfire happen. Fuel can often go through the cylinder
unburnt during deceleration (especially if the throttle plate closes too
fast). Strangely, this can be because the mixture is too *lean* to burn, that
is, the A/F is less than 18-22:1. The rich burn limit is ~6:1 A/F.

The ignition source can be readily available. With the wasted spark ignition
system our engines use, the spark plug always fires on the exhaust stroke. In
addition, the exhaust gases themselves or some part in the cylinder (plug tip,
carbon on piston crown, etc.) could be hot enough to cause ignition (~1000ºC
or thereabouts).

The fresh air source can be readily available because of valve overlap. Look
at the summary figure I drew to illustrate this on the bottom of my web page
below.

However, significant fresh air/fuel mixture should not be flowing into the
cylinder until well after the wasted spark has occurred. During decel, advance
is usually up near 50º BTDC. Even during shifting advance is still fairly
high, like 30-50º BTDC. The intake valve (NA or turbo DOHC) begins to open at
16º BTDC.

My exhaust has two leaks that I know about. One is at the exhaust flange where
the front turbo connects. The EGT pyrometer that the engine builder
installed there leaks around the threads. See the bottom pic on my web page
below.

The other leak is between the ATR downpipe and the front precat housing. That
one is my fault for not making a good contact of the gasket and both parts. It
is minor (and after the turbo) and I will fix it when I take the ATR exhaust
off to have flanged welded onto the pipes (getting rid of the slip-fit
connections).

I drafted a figure to show where best torque (~11.5-13.1), best power (about
12.6 according to all the books I have read), best economy (~16.2), and
stoichiometry (~14.7) occur with respect to usable A/F range. Also shown are
typical HC, NOx, and CO production across the A/F range.

yeah. I never have gotten to replacing the rear bleeders. I believe they
are smaller, and NA cars are smaller all around. At the time I tried
replacing the rear bleed screws, they were rusted in so darn tight I just
said "it aint broke" and called it good. They remain there today.

I know that torch heating is a trick for getting rusted nuts off studs.
The nut expands more than the stud. But what about getting bolts (or
bleed screws) out of holes? You'd have to put a ton of heat in there. I
would like to replace the rear bleeder screws at some point, but I don't
want to shear something off and end up with a much bigger job.

> Thanks Dave. That looks like what they sent me. Checked the rears and they
> appear to be the same as the fronts, i.e a lot thinner than these. I guess
> the NAs have smaller bleeders all round then?
>
> -----Original Message-----
> From: David Margrave [mailto:davidma@eskimo.com]
> Sent: Thursday, October 17, 2002 2:34 AM
> Subject: Re: Team3S: Speed bleeders
>
> Andre, All,
>
> stock front bleeder screw from my '91 R/T TT is M10x1.0x25 (10 mm dia.,
> 1.0 mm/thread, 25 mm from 'nut' part to tip of bleed screw)

According to the information posted at
http://www.pocketlogger.com/?page=faq&faq=dsm, there are "plans to
support 94-95 3/S cars in the future but no ETA is known at this
time." Does anyone have additional information? I'm interested in
logging the ECU and correlating it with GPS readings next time I visit
the track. Thanks!

*** 3000GT-Stealth International (3Si) Member #0030 ***
http://www.the-matthews.com/stealth.html
Jet Black '94 Dodge Stealth R/T Twin-Turbo AWD AWS 6-spd
Adjustable Active Suspension, Adjustable Exhaust System
K&N FIPK, A'PEXi Super AVC-R v.1 (1.0 bar @ 64% BADC)
A'PEXi Turbo Timer (30 sec), Blitz Super Blow-Off Valve
Magnecore spark plug wires, Optima Red Top 830 Battery
Redline synth fluids (trans= MT-90, xfer & diff= SPHvy)
Cryoed rotors, R4S pads, braided lines, red calipers
Michelin Pilot XGT-Z4 245/45ZR17, Top Speed: 171 mph
G-Tech Pro: 0-60 4.79 sec, 1/4 13.16 sec @ 113.9 mph
1 Feb 99 Dyno Session: 367 SAE HP, 354 lb-ft torque

Date: Thu, 17 Oct 2002 11:35:38 -0700
From: "Geddes, Brian J" <brian.j.geddes@intel.com>
Subject: RE: Team3S: PocketLogger for hybrid ECUs

Don't hold your breath. :( I talked to the Pocketlogger guy about a year
and a half ago about support for the hybrid ECU's, and he was "interested"
then as well.

> -----Original Message-----
> From: Jim Matthews [mailto:jim@the-matthews.com]
> Sent: Thursday, October 17, 2002 11:20 AM
> Subject: Team3S: PocketLogger for hybrid ECUs
>
> According to the information posted at
> http://www.pocketlogger.com/?page=faq&faq=dsm, there are "plans to
> support 94-95 3/S cars in the future but no ETA is known at this
> time." Does anyone have additional information? I'm interested in
> logging the ECU and correlating it with GPS readings next time I visit
> the track. Thanks!

Date: Thu, 17 Oct 2002 13:47:37 -0700 (PDT)
From: Geoff Mohler <gemohler@www.speedtoys.com>
Subject: RE: Team3S: PocketLogger for hybrid ECUs

> Don't hold your breath. :( I talked to the Pocketlogger guy about a year
> and a half ago about support for the hybrid ECU's, and he was "interested"
> then as well.
>
> - Brian

***
NEW Supra Product!
6/6 Nylon suspension bushings are available for MK3 supras NOW!
Check out http://www.speedtoys.com/bushings.html for details.
This is the only planned purchase -ever- of these, until October 5th.
***

Date: Thu, 17 Oct 2002 15:03:00 -0400
From: "Zobel, Kurt" <Kurt.Zobel@ca.com>
Subject: RE: Team3S: NA MAS on TT car for large injector accommodation

You had better be very careful in checking this out.
This assumes the same variation in flow restrictions in the intake
tubes, and the same flow variations in the injectors at various flow
values.
The SAFC can tune at the different ranges to account for these, you're
going to have a static system.

The flow should be closely dependent on the area, so proportional to r^2
as PI drops out in both.
If diameter is 2.75 in , r=1.375, r^2=1.89 That's the 2/3 flow.
The add-on tube will be 50% of that, 1.89 / 2 = .945 to get the 1/3 flow.
.945 sq root= .972 which is r, and diameter= 1.94 inch.

- -----Original Message-----
From: Riyan Mynuddin [mailto:riyan@hotpop.com]
Sent: Wednesday, October 16, 2002 7:17 PM
Subject: RE: Team3S: NA MAS on TT car for large injector accommodation

How about if I bought a good quality BOV that vents to the atmosphere
(though I prefer intake). Then, use the opening that is created for
another small cone air filter. That is a pretty small opening. About
1" ? But with the stock MAS and no fuel control, this amount of air
bypass may still be right for 450cc injectors (they're being mailed
to me right now). I have the A/F gauge as well as some cheap copper
plugs that I can foul up while I'm playing around. I'll put the
platinums back in when I get a decent mixture.

Date: Thu, 17 Oct 2002 17:51:33 -0400
From: "Steve Sullivan" <Sully@carolina.rr.com>
Subject: Team3S: IS Anyone looking for a 7th Injector setup?

Has anyone been looking or made any inquiries about wanting a 7th Injector
setup? Basically it is a 7th injector that is boost activated. They have
been using them on Grand Nationals for years. Anyway this company talked to
me today about using my car to prototype a kit for our Cars and I was just
curious if people were looking for them. They used my car to prototype for
their stainless downpipe and exhaust a few years ago.

Date: Fri, 18 Oct 2002 01:44:23 +0200
From: "Roger Gerl" <roger.gerl@bluewin.ch>
Subject: Re: Team3S: IS Anyone looking for a 7th Injector setup?

3 additional injectors in the rear of the plenum or water/alcohol injection
will do the job. I see no chance other than this to get a good travel for
the fuel evenly into the runners !

- ----- Original Message -----
From: "Steve Sullivan" <Sully@carolina.rr.com>
Sent: Thursday, October 17, 2002 11:51 PM
Subject: Team3S: IS Anyone looking for a 7th Injector setup?

> Has anyone been looking or made any inquiries about wanting a 7th Injector
> setup? Basically it is a 7th injector that is boost activated. They have
> been using them on Grand Nationals for years. Anyway this company talked
> to me today about using my car to prototype a kit for our Cars and I was
> just curious if people were looking for them. They used my car to
> prototype for their stainless downpipe and exhaust a few years ago.
>
> Sully

Date: Thu, 17 Oct 2002 19:47:41 -0400
From: "Steve Sullivan" <Sully@carolina.rr.com>
Subject: re: Team3S: IS Anyone looking for a 7th Injector setup?

yes.. it is generally used to add fuel only at higher boost when it is
needed instead of running bigger injectors all the time. You can adjust how
much fuel it adds by changing 7th injector size and adjust at what boost
level it kicks in via a hobbs switch.

- -----Original Message-----
From: Jim Fay [mailto:jfay@tssu.com]
Sent: Thursday, October 17, 2002 6:13 PM
Subject: RE: Team3S: IS Anyone looking for a 7th Injector setup?

Date: Thu, 17 Oct 2002 17:00:49 -0700
From: "Tigran Varosyan" <tigran@tigran.com>
Subject: RE: Team3S: IS Anyone looking for a 7th Injector setup?

Correct me if Im wrong, but isnt the reason that cars went to Injection VS
carb setups because Carb (imitated by the 7th injector in this case) is
inefficient/un-even/unpredictable etc?
Tyson

- -----Original Message-----
From: Steve Sullivan
Sent: Thursday, October 17, 2002 4:48 PM
Subject: re: Team3S: IS Anyone looking for a 7th Injector setup?

Date: Thu, 17 Oct 2002 19:06:01 -0700 (PDT)
From: Geoff Mohler <gemohler@www.speedtoys.com>
Subject: RE: Team3S: IS Anyone looking for a 7th Injector setup?

IMHO, not sure how many people could USE it, because the additional
injector hardware & electronics surely would cost more than a large
injector upgrade & electronics.

On Thu, 17 Oct 2002, Tigran Varosyan wrote:
>
> Correct me if Im wrong, but isnt the reason that cars went to Injection VS
> carb setups because Carb (imitated by the 7th injector in this case) is
> inefficient/un-even/unpredictable etc?

- -----Original Message-----
From: Riyan Mynuddin
Sent: Thursday, October 17, 2002 4:32 PM
Subject: RE: Team3S: (was NA MAS on TT...) fooling the MAS

I actually got 6 450cc injectors. I'm going to use a K&N jumbo size
crankcase breather filter as the second intake and pipe it to the hole that
is created when an open atmosphere BOV is used. I'll use the A/F gauge and
go from there. If there's no luck then I'll buy the AFC or ARC-1... or maybe
just put the stock 360s back in. Either way, it's probably going to be at
least two weeks from now, since I don't have my timing belt on quite yet and
I have lots of reassembly to do.

Date: Thu, 17 Oct 2002 20:33:28 -0500
From: "Matt Jannusch" <mjannusch@attbi.com>
Subject: Re: Team3S: IS Anyone looking for a 7th Injector setup?

> Has anyone been looking or made any inquiries about wanting a 7th Injector
> setup? Basically it is a 7th injector that is boost activated. They have
> been using them on Grand Nationals for years.

The problem is that the ECU is still going to see tons of airflow and then
fuel cut on you, so you won't be able to use this on an upgraded turbo setup
(or at least not to its full potential).

HKS and others have been selling AIC's for a while, but not many people buy
those setups for that reason (among others - like the intake manifold not
being designed to flow fluids, as Roger mentioned).

Thanks for the welcome, and thanks for the offer. Be careful though, I might
take you up on the offer. Hopefully I won't have many problems though.

Ooops, I already have a question. Do you ever hear a quiet ticking noise
when you are sitting at a stop? It doesn't sound like a metallic tick (ie:
lifters) but more like a leaf in the blower motor. However, it doesn't
change with fan speed, doesn't go away when the HVAC is turned off, and
doesn't change in amplitude with the windows up or down. In fact, if the
radio is on, it is barely audible. It doesn't happen often enough for me to
figure out if it changes with engine speed or not.

> i have the exact same car as you, so let me know if you need any help or
> have any questions. welcome aboard.
>
> Riyan
> 93 stealth rt tt

Date: Thu, 17 Oct 2002 22:46:26 -0400
From: "anthonymelillo" <anthonymelillo@sprintmail.com>
Subject: Team3S: speaker-ectomy successfully completed

Well, thanks to all the invaluable help, I have successfully completed replacing all the speakers on my 1997 VR-4 with aftermarket
JBL's. They fit in the stock locations, with a little help, and sound incredible.

The speakers I bought were as follows:
Dash Tweeters (JBL GTO15T-1" tweeter kit)
Door Speakers (JBL GTO635-three way 6-1/2")
Rear Speakers (JBL GTO935-6x9" three way)

I used the spray paint cap adapter thing, that a fellow list member, of course now I can't locate the web page anywhere, it was the
222hp stereo if anyone can shed light on that one.

The stock tweeters in my car were a little different. It did not have the little bracket under the speakers, the only bracket went
around it with nothing underneath. But I still used the same idea, with the spray cap, and mounted the tweeter inside. All I had
to do is put a couple of screws on each side, and I was set.

One strange thing was the wires on the speakers did not match the colors in the factory wiring diagram. So, again with the help of
a list member, and his battery trick, I was able to determine the correct wires. Red was positive, and yellow negative.

With the tweeters out of the way, I then tackled the door speakers. They were pretty straightforward and bolted right into the
stock holes. All I had to do is drill new holes because the mounting holes were a little off.

Since I bought 3-way speakers, I had a little problem with the inside element sticking out and not allowing the door panel to fit
flush. But all I had to do is remove the spider web like bracing inside the door grill, and it fit perfectly.

As for the rears, they fit perfectly. All I had to do is cut a little piece off of the vent tube that is on the factory housing for
bass, and whala. Fit like a glove.

If you looked at my car, you would never know I had replaced the speakers. But as I said, the sound now is absolutely incredible.
Much better than stock, even before the front speaker blew out.

Hope this is helpful. If anyone ever needs help, now that I have done it once, Just drop me a note and I will be happy to help
Happy motoring
Anthony Melillo
1997 VR-4, Firestorm Red
http://home.sprintmail.com/~anthonymelillo/3000gt.htm

Date: Fri, 18 Oct 2002 01:02:40 -0700
From: "Riyan Mynuddin" <riyan@hotpop.com>
Subject: RE: Team3S: (was NA MAS on TT...) fooling the MAS

I don't take offense to that at all (it's not like I don't know it). The
truth is...I can probably afford the AFC too. I'd just hate to have another
thing in my dash that's all. Anyway, the biggest reason that I'm not worried
is that I'm just making the car run rich. And if it's really gonna be too
rich, then I'll give it up. Do you think that playing around and trying to
lean out a rich fuel mixture could be deadly as well? I thought it was more
of a concern the other way around. Correct me if I'm wrong.

Be sure to use the entire address if it does not all appear on one line in
your email reader. I have purchased manuals from the sellers "lorieandjeff"
before. They are reliable.