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Timing, backfiring and low idle.

Hi.
Yes, Drew is right, my '81 comes from Florida (Ft Lauderdale).
It did have an O2 sensor (long since removed by previous owner) and I'm not sure
if I have a frequency valve, or where it exactly is and looks like.
Ed

>>> "Dan Bubb" <jdbubb@verizon.net> 2006-05-24 3:49 PM >>>

If the car has an O2 sensor then it has the frequency valve. Early cars ( I have no clue what dates) that had an O2 sensor and frequency valve did not have the WOT switch. I think that came with the GTI and the 1.8 engine in the Scirocco.
With my late 84 setup with the correct dwell, triggering the WOT switch made the engine rev just a little bit higher and the idle would smooth out mostly cause the system wasn't oscillating the AFR around stoichiometric.
Dan

From: "Scourge" <scourge@cogeco.ca>
Sent: Wednesday, May 24, 2006 3:31 PM
Subject: Re: Timing, backfiring and low idle.


> Maybe I'm wrong but I thought the 1.7's had no frequency Valve??  I know my 
> 82 with a 1.7 have no WOT switch.
> 
> My advice would be to set the timing to stock, like Mr. Bubb suggests, and 
> asjust your CO. You need the ol' long 3mm allen for that. Without the aid of 
> a sniffer and/or dwell meter I personally wouldn't turn the screw more then 
> a half turn or so. Righty richey, lefty leaney!  lol
> 
> On my car, when roughly setting it, I make use of the WOT switch and freq 
> valve. I try to have it so when the car idles smooth(~900rpm is what I like) 
> and you manualy hit the WOT switch it'll bog down to a near stall but stay 
> running and come back up once the freq. valve turns off.
> 
> **Disclaimer: That's just what I've found to work well with my car. Like 
> many others I'm sure, I plan on making use of Timbo's offer at Cincy to 
> tweak out my car with a dwell meter.
> 
> HTH
> -George
> 
> 
> ----- Original Message ----- 
> From: "Dan Bubb" <jdbubb@verizon.net>
> To: "Edward Effinger" <Eeffinger@conestogac.on.ca>
> Cc: <scirocco-l@scirocco.org>
> Sent: Wednesday, May 24, 2006 2:10 PM
> Subject: Re: Timing, backfiring and low idle.
> 
> 
> First off, timing does not make your car run lean. So, start by setting the 
> timing back to factory spec.
> Second, as Jim suggests, make sure your frequency valve is humming then set 
> the idle mixture. Good to have a dwell meter to set this, but if not set it 
> so the engine has the highest idle speed.
> Is WD-40 flammable? I don't think it is, so how would that help to find 
> vacuum leaks? I know carb cleaner sprayed at a vacuum leak will make the 
> engine rev, but don't understand how non-flammable will help?
> 
> 
> From: "Edward Effinger" <Eeffinger@conestogac.on.ca>
> Sent: Wednesday, May 24, 2006 1:37 PM
> Subject: Re: Timing, backfiring and low idle.
> 
> 
> I'm fighting with my car doing a lot of that at this very moment.
> Have played with the timing a bit as a noticed the plugs were all very white
> rather than the usual light tan color.
> 
> I retarded the timing a fair bit and the car runs better, but the idle speed 
> is too low.
> I could get the idle speed up by advancing the timing, but I'm concerned 
> about running too lean.
> 
> Played with the idle adjustment valve last night, it didn't see to respond 
> properly, although now
> the car has absolutely no power at low idle, takes a bit before the revs 
> begin to build in order
> to drive off.
> 
> I've checked for intake leaks by spraying WD40 around all the hoses and 
> didn't find any leaks
> other than a very slight one on the air hose to the throttle body which I 
> snugged up.
> 
> The car also seems to miss/hunt at any speed and the exhaust pipe is quite 
> sooty looking.
> 
> Lots of mixed signals here.
> 
> I welcome any tips/tricks to sort this baby out.
> Cheers
> Ed '81S  1.7 with no cat and aftermarket exhaust and headers.
> 
> 
>>>> "Brian Spinney" <vw_85roccoZ400@hotmail.com> 2006-05-24 8:05:51 AM >>>
> 
> My first 85 Scirocco use to do it alot on both downshifting & hard
> acceleration up until 2500 rpm.  My exhaust wasn't anything special, just an
> Autotech 2.25 CatBack system and a header.
> 
> It definitely turned heads when I was in high school.  I would roll into the
> parking lot and downshift into second with waaaaaaam pop, pop, pop, pop,
> ummm   pop, pop, pop, pop.
> 
> The car was running alittle richer than stock but I didn't think much about
> it at the time, or for that matter much about CIS or cars.  I did my own oil
> changes and brakes and that was about all.  It wasn't until my Senior Year
> that I started learning more.
> 
> Brian
> 
> 85 Scirocco 8vT                    01 Jetta 20vT                        84
> Rabbit GTI
> 
> 
> 
> 
> 
> ----- Original Message ----- 
> From: "C Boyko" <roccit_53@scirocco.cs.uoguelph.ca>
> To: "Scourge" <scourge@cogeco.ca>
> Cc: <scirocco-l@scirocco.org>
> Sent: Wednesday, May 24, 2006 6:35 AM
> Subject: Re: Tech'ish question. Inquiring minds want to know.
> 
> 
>> Klaus did it a lot before this functional fuel distributor, so that means
>> three holes were likely rich, one likely lean, nobody burning all the
>> gazzzzz....pop pop pop... (so perhaps Blackie's just not misfiring like
>> previous incarnations?)
>>
>>
>> The popping's not so bad now (he's lean) So I'll report back when I start
>> turning that screw righty richy....the exhaust is free flowing I'd say
>> (2",
>> no cat), and is obviously capable of sounding like it'd been into the bean
>> burritos...
>>
>> Cathy
>>
>> On 11:27:05 pm 05/23/06 "Scourge" <scourge@cogeco.ca> wrote:
>>> Hmm..... odd. Blacky doesn't do it at all ..... at least not that I
>>> can hear. I think I'm even running a touch on the rich side right now
>>> too.
>>> About the low backpressure response. I'm currently running the Dual
>>> Out mani, TT long DP, and TT 2" w/ no cat ..... where as my old golf
>>> that went nuts with it was stock save the muffler(N/A diesel muffler,
>>> haha, sounded like a dirtbike) it was definately not free flowing,
>>> lol.
>>> I agree that rich during low vacuum would be a fair assesment ....
>>> but i'm not sure why some cars do it and others don't.
>>>
>>> -George -Oh, and my car didn't even do it much with an open DP(the
>>> whole "exhaust giving me the finger" fiasco on the dragstrip last
>>> year)
>>>
>>> ----- Original Message -----
>>> From: "Ron Pieper" <rapieper@yahoo.com>
>>> To: "Scourge" <scourge@cogeco.ca>; "Scirocco List"
>>> <scirocco-l@scirocco.org> Sent: Tuesday, May 23, 2006 9:45 PM
>>> Subject: Re: Tech'ish question. Inquiring minds want to know.
>>>
>>>
>>> > I can only answer by telling you my experiences with this via
>>> > Megasquirt, where I learned from
>>> >  someone on their forums that you can eliminate the backfiring you
>>> >  are desiring by leaning out the
>>> >  mixture at VERY low vacuum levels - seen only with the situation
>>> >  of zero or negative load with the
>>> >  engine typically decelerating.  With MS, that's really easy to do.
>>> >  I leaned out that range, and
>>> >  presto, no more pop-pop-pop.
>>> >
>>> >  This was only evident with my free-flowing exhaust (straight
>>> >  through) because a normal exhaust
>>> >  muffles it greatly.
>>> >
>>> >  Sooo...we can extract from that that your engine is getting more
>>> >  fuel in those conditions than it
>>> >  needs, and some 'explosion' is likely happening in the exhaust
>>> >  system. With CIS, I reckon you're
>>> >  stuck with it.
>>> >
>>> >  I guess the little holes you write of could cause or amplify this,
>>> >  but it happens anyway under the
>>> >  right conditions.
>>> >
>>> >  Dan Bubb, please shed your light here.
>>> >
>>> >  HTH
>>> >
>>> >  Ron
>>> >
>>> >  --- Scourge <scourge@cogeco.ca> wrote:
>>> >
>>> >>  So I've been wondering.
>>> >>
>>> >>  What makes a car backfire? Not regular loud single shot
>>> >>  backfires, but the awsome little pop pop
>>> >>  pop some cars have on heavy downshifting.
>>> >>   My golf used to do it like mad, I loved it. Made it sound so raw
>>> >>  and hardcore, lol. Non of my
>>> >>  rocco's have ever done it.
>>> >>
>>> >>  One guy I know once told me it was cause by small holes farther
>>> >>  up the exhaust(I guess he meant
>>> >>  near the DP) that while leaking a bit would also create a sort of
>>> >>  scavenging effect and pull
>>> >>  some air back into the exhaust system. That air had oxygen in it
>>> >>  and could then act as an
>>> >>  accelerant with the bit of unburnt fuel and it would ignite in
>>> >>  the exhaust, thus creating the
>>> >>  "pop pop pop" when downshifting. I have no idea how accurate this
>>> >> is.
>>> >>  Any thoughts/input??
>>> >>
>>> >>  -George -missing crazy things my golf could do(like shoot flames
>>> >>  out the tailpipe!)
>>> >>  _______________________________________________
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>>> >>
>>> >
>>> >
>>> >
>>> >
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>>>
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