| Author |
Message |
Bill Sebestyen (Bill308)
Member
Username: Bill308
Post Number: 400
Registered: 5-2001
| | Posted on Sunday, October 27, 2002 - 4:11 pm: | |
Lawrence,
Both systems are present on many of the cars. You were thinking of the air injection system which discharges air into the exhaust port of the cylinder head to burn residual gas in the exhaust. Steve got it right for Bill V's question where the gas sampling ports are for sampling the exhaust gas with an exhaust gas analyzer, for diagnostic purposes. I'm pretty sure your 328 has these gas sampling ports also. They are normally located on the exhaust manifold, perhaps 8-inches or so, down stream of the cylinder head.
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JohnR. (Rivee)
Junior Member
Username: Rivee
Post Number: 115
Registered: 1-2002
| | Posted on Sunday, October 27, 2002 - 2:45 pm: | |
J. H. Christ Lawrence. Get it right!
lol |
Lawrence Coppari (Lawrence)
Member
Username: Lawrence
Post Number: 342
Registered: 4-2002
| | Posted on Sunday, October 27, 2002 - 11:04 am: | |
Whoops, it must be different from a 328! Sorry, just trying to help.
I get into this same sort of trouble on a Porsche list with Porsches that are similar to mine but, to my chagrin, different. |
Steve Magnusson (91tr)
Intermediate Member
Username: 91tr
Post Number: 1154
Registered: 1-2001
| | Posted on Sunday, October 27, 2002 - 10:27 am: | |
Bill V. -- Those "sampling ports" on the exhaust manifold tubes are for measuring the CO content of the exhaust gas (from which you can deduce the Air/Fuel ratio). Having a separate one for each cylinder is more important on the carbed Fs, but even the injected cars have them. On my TR there are even "multiple" sets of ports -- each cylinder has a sampling port near the cylinder head which is plugged by the short hex bolt/plug 110860 (and is not usually accessed by the technician) and then where 3 tubes merge into 1 there are four more sampling ports that have the external tubes attached (and is where the technician usually hooks up the CO analyzer for A/F adjustment). My experience is that the external tubes really can't take the heat long-term and they become horribly embrittled with time if left in place so I remove the external tubes and replace them with the 110860 plug for normal operation (and only reinstall the external tubes when needed for servicing/adjusting the A/F ratio). Here's a thread with a shot of the 110860 plug installed on my TR (in place of one of the external tubes):
http://server.ferrarichat.com/~ferrari/ferrarichat.com/discus/messages/112/73413.html
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Lawrence Coppari (Lawrence)
Member
Username: Lawrence
Post Number: 341
Registered: 4-2002
| | Posted on Sunday, October 27, 2002 - 8:45 am: | |
The 328 has a fresh air intake system that leads to the tubes at the exhaust manifold. There is a scavenging effect with the exhaust. There are check valves in the complete system that allow additional air to enter the exhaust during warmup. They get the cat up to temperature faster. When the entire system is present, it has the same purpose as an air pump. There is a vacuum controled valve that shuts the system off based on engine or exhaust temperature. |
Bill V. (Doc)
Junior Member
Username: Doc
Post Number: 173
Registered: 9-2001
| | Posted on Sunday, October 27, 2002 - 8:23 am: | |
What in the world are those 4 brass tubes on each exhaust manifold on an '85QV ? I think I've heard them referred to as CO2 tubes? They all are capped off with bolts--what are they there for--what do they do? I noticed that a couple of the retaining nuts on the manifold are broken, but the tubes are still solidly imbedded and I don't notice any leaks. What would be the consequences of a leak and are these tubes really necessary for anything? |