Yeah, I understand that for a carb (non-CCC), but we're dealing with EFI. How can an oxygen sensor do anything useful when there's an extra stream of oxygen pumped in between the combustion chamber and the sensor?
CK5
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A.I.R system?? -have loss of power… code 43 for knock, and 44 for lean condition????
- Thread starter scouthead
- Start date
Most likely calculated, using Act, ect, and map/maf/baro sensors and diverter valve position
I don't think it can do that. First of all, the TBI ECU is pretty primitive. I also don't think the airflow calculation can be very accurate over RPM, air temp, etc. Then, you're basing the engine tuning on the exact operation of that convoluted system of vacuum valves, check valves, etc., which must vary over time and from vehicle to vehicle. The biggest problem is that you want to control AFR inside the engine and you want it to be near 14.7:1. With the air pump, your exhaust is way leaner than 14:7 and the O2 doesn't detect anything else. So when the air is pumped into the exhaust manifolds you have no idea what AFR is. You could revert to open loop whenever the diverter valve swings, but that doesn't sound like an emissions improvement.
That's why I was hypothesizing that on TBI engines, the pump is only for warmup- to get the cat hot faster. It seems like a competing goal with getting the O2 sensor hot, though, and I would think that getting to closed loop is more important than having the catalyst active.
That's why I was hypothesizing that on TBI engines, the pump is only for warmup- to get the cat hot faster. It seems like a competing goal with getting the O2 sensor hot, though, and I would think that getting to closed loop is more important than having the catalyst active.
I'll see if I can find the TBI AIR Stratagy in my manuals. It has been a long while since I needed to diagnose and TBII AIR systems
Throw it in the dumpster. That is where it does its best work
that where mine is 
Unfortunately you know he can't do thatthat where mine is
Probably yes.
You just can't remove it.
So yeah check this out… I disconnected the AIR bypass valve from the throttle body and capped the port. From cold engine to fully warmed up- I was not able to suck or blow air through the discharge hose that attaches to the manifolds- it was effectively capped in this state, and all air directed to the air cleaner. Not sure if the ECM thought it was doing something through the electrical connection, but without being connected to a vacuum source, the flow into the exhaust seems to be stopped. So the vacuum diaphragm inside it must be seperated from the air passages the pump air runs through…
Anyway- I’m not saying a #10 screw cut its head off and wrapped its body in Teflon tape… and then jumped into the vacuum supply line before I reconnected to the throttle body???? I’m not saying that… but IF it it DID happen…
All my rich smelling exhaust was instantly fixed??
Aaaaaaand that definitely didn’t happen because yesterday morning tue truck passed its visual inspection, passed the gas tank pressurization BS, and then ran through 1st and 2nd gear on the dyno like a champ with the government’s sniffer shoved up its butt… one of the cleanest measured smog tests the truck has ever done
Well this is certainly good news, and it seems to all track together. The sucky part is that someone knew that it was only a matter of time before part of this system fails and makes the truck run super rich. This is way worse emissions than you get from a slowly warming cat.
It took a while to figure out because you had 2 real failures at the same time.
At least it was easy to fix the heater. (I noticed the hose went from hot to cold right at a junction...)
It took a while to figure out because you had 2 real failures at the same time.
These things do happen. We found a bolt in my son's heater hose.
At least it was easy to fix the heater. (I noticed the hose went from hot to cold right at a junction...)BOOST!
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