Probably a few AIV's being stored in various garages around the country just for the day when CAM-OEM needs to put back some tech that we all know was really just taken off to cut manufacturing costs like the vvt (not). My AIV is blocked off like most, so...
Basically, every add-on such as EGR, AIV and so-on are aimed purely at the exhaust emissions area. None of these systems actually increases power. What happens then is the ECU/engine tuning is bent, and can adapt around these gadgets which basically, route air in and around the engine. EGR is one example and when removed from an engine, can result in some additional leanness which has actually been accounted for in the ECU tuning to begin with. Older carb engines struggled hard to cope with all the emissions bollocks and power gains were significant when blocking off all those systems was done back in the day. VVT on a VG is a pretty agricultural 2 step affair that simply advances the inlet cam timing up *blah*degrees up off idle and then pulls that cam advance at circa 5000 rpm. just makes the engine "think" it has a slightly longer duration inlet cam is all. there is no progression at all, advanced or not is what you get. The gains in the midrange area are pretty limited to begin with. With a forced induction engine, a carefully matched turbo setup could easily overcome the small loss to be had by deleting the setup. This against the cost savings of pulling the technology out altogether might make a lot of sense in the very big picture. it just another form of "collateral damage". Like take one for the team for the greater good!!!! This kind of thing happens regularly. Even to the point of actually adding in a possible problem and finding it is far cheaper to fix the usually isolated problem at dealer level than it is to actually PREVENT it in the first place at manufacturing level. As technology progresses, VVT has become a pretty important part of engine tuning but its fully ECU (intelligently) controlled and continuously variable rather based purely on rpm as the old system. Hence its a very common addition in later high performance engines As technology has progressed, the number of these pollution systems has reduced. look under the bonnet of very late model cars and there simply isnt such a rats nest of rubber hoses and crap running off to mysterious looking valves and so-on. its not needed anymore!! E
What about the AIVs Tas? If the 90's EPROM has allowances for the AIV's. what would be the negative effects (if any) to my 93' system w/out AIV's?
Lol dude, I dont know what the AIV's actual purpose/outcome is!!!!!! Never bothered to find out!!!!!! Anybody? E
Really?? Learn something new each day!!!!!! Mebbe Nissan just used cheapshit cats and so spent a gazillion setting the aiv's up to compensate.........gah! E
Yes it is to cool the cats. A solenoid controls an actuator to inject fresh air before the cats to keep them running optimum and cool. Many people delete the solenoid and this causes no error codes at all.
When the exhaust is rich they let secondary air into the pipes to burn off the excess fuel. The cats don't like a rich exhaust - they need oxygen to work properly. So the AIV's open when the engine is mapped to run rich, which is during warm-up with the throttles closed.
Yes, from all I have read its this - gets the cats to operating temps faster thus minimizing exhaust emissions at start up.
