AIV Crap

[Madcat]

This is rant for the AIV, piece of crap rust factory.

 

http://www.nissanpathfinders.net/forum/index.php?showtopic=19382

 

Ive dealt with that rotted AIV box. About a week ago I took it and the AIV case out of the damn engine bay. The AIV box was rotted completely, just mushy rust that reeked of exhaust odors. The AIV case was calcified, but I might try to salvage it. The rust is bad, its a shame I have no camera, youd be surprised at the gap over the wheel. MY1PATH is lucky he doesnt have my rust damage, hehe.

 

I take it for a spin and notice the car makes a lot of more noise. I come back and play with the throttle under the cleaner, all that noise comes from that pipe. I also noticed moisture, so I freaked out and grabbed some WD40. I used up half of a full can, drenched the area it sprayed. It wasnt bad, but cmon, exhaust gasses had eaten the AIV box. I couldnt take any chances with rust. I stuffed a rag into the pipe and wrapped it a piece of cloth, then secured it all with a zip tie. The pipe coming from the intake to the aiv case I also plugged. Whats the point? Id be losing air?

 

Now Im wondering about the vacuum line that was connected to the aiv solenoid. I forgot when it was was open or capped, but the engine would take noticably longer to decelerate back to idle before I would shift to another gear. This is after i removed the box, case, and solenoid.

 

I noticed the car runs better, a bit stronger. Gas mileage took a drop, a bit too much. Engine sounds different too. Instead of having two alternating sounds from the exhaust, there would be one larger sound. After reading the service manual, Ive come the conclusion that the ECU is running the engine in "heavy load or high speed mode" or some such. Normally the injectors should be runing alternating, instead its both at the same time. No codes displayed from ECU in Mode 3 or 5, btw. Ill have to learn how to read Mode 1 and 2.

 

All this time I thought the AIV crap brought exhaust into the engine to reburn it. Now I dont have a clue. Im going to check all sensors, clean the TBI, MAF, and hell knows what else. Im gonna mess with the wiring for the aiv solenoid plug. Gonna solder a 35 ohm reisitor to it, maybe it will fool the ECU? Theres a diode in the plug that mustve blown, so I dunno about that.

 

Yeah I know long rant.

[MY1PATH]

All this time I thought the AIV crap brought exhaust into the engine to reburn it

In doing so the sysetem reduces combustion temperatures which helps MPG's. mine sitll drips rust and leaves pretty stains inside my engine bay so I don't think its functioning 100% after I replace it I hope to see .5 more MPG's @ the least.

[TerranoNZ]

You mean yours looks like this one Madcat?

 

 

Came out of my 88

[Madcat]

In doing so the sysetem reduces combustion temperatures which helps MPG's. mine sitll drips rust and leaves pretty stains inside my engine bay so I don't think its functioning 100% after I replace it I hope to see .5 more MPG's @ the least.

 

Honestly I dont get it how combustion temperature could affect the gas mileage. I can understand lower temps to prevent exhaust pipes and brackets from getting worn due to heat. Makes sense to me now that the AIV system blows air into the car that causes emissions to be reburned again, but thats all I gather.

 

 

You mean yours looks like this one Madcat?

 

 

Came out of my 88

 

Haha very close Teranno. Mine was in worse shape, yours looks like it has a few more miles to go on it. I was a moron and tossed out the whole thing, even the reed valve for the box. I didnt even want to disassemble the reed cover. The whole thing was collapsing from rust. Ironically the aiv box bracket was clean as a whistle, not a spec of rust. I only kept some tubing and the AIV case. I should attempt a salvage at it.

 

 

You know what folks? Madcat here is gonna try to make his own AIV box. To hell with the hot and the cold aiv. Get a coffee can with a small air filter in there and a one way valve on the catalyst line (to prevent emissions backfeed). I bet you this would be better than blowing 150$ on a aiv box. Whatdya say?

[MY1PATH]

Honestly I dont get it how combustion temperature could affect the gas mileage. I can understand lower temps to prevent exhaust pipes and brackets from getting worn due to heat. Makes sense to me now that the AIV system blows air into the car that causes emissions to be reburned again, but thats all I gather.

I belive it works something like this;

Higher combustion temps means more energy is used creating heat, energy used to create heat is not being mechanically used by the engine to propel the veicle therefore it is wasted energy and wasted fuel. even if you pickup power from having a cleaner air/fuel mixture it comes @ the cost of a less efficent engine.

[Madcat]

I belive it works something like this;

Higher combustion temps means more energy is used creating heat, energy used to create heat is not being mechanically used by the engine to propel the veicle therefore it is wasted energy and wasted fuel. even if you pickup power from having a cleaner air/fuel mixture it comes @ the cost of a less efficent engine.

 

I think I get what youre saying. Well on the bright side this AIV system doesnt recirculate exhaust gas all the time thru the engine, just the EGR system at certain times. What bugs me is the sound of the engine. I swear it sounds like both injectors are firing at the same time rather than seperate. Im gonna have to check it.