injected vacum, air fuel, and egt

[ABUSEDDOG]

I'm reading a little on:

a. vacum bieng re-introduced into the system and affecting the air fuel gauge readings, and how it tends leans it out.

Question. anybody have any experience with this on turbo's at higher rpm's? can an aftermarket ecu compensate for false readings?


b: exhaust tempature gas sensors not being the most accurate sensor because of timing issues, advance - cooler,retarded - hotter, and how it can produce skewed numbers, not necessarily related to the air fuel mixture, ie lean - hot, rich - cold.

Question. Does an egt sensor have any place as an input in a aftermarket ecu operation?

Just trying to figure out how it all relates together, any help would be appreciated

[Junkie]

Don't quite understand the vaccum question,never heard anything like that .....Link to readings please ???

Now,as for AF/EGT readings.Yes,timing will change both of these.But,what most people still don't get ....... these gauges are just that ..... a gauge.They are by no means perfect.You MUST still read your spark plugs,to get an actual idea,of what is really going on in the comustion chamber.
I can set a car up to read rich as hell on the AF,and cool as hell on the EGT,and burn the pistons out of it 10 minutes later,because the comustion chamber is actualy burning lean.How ???? set the cam gears,and timing to scavenge more fuel from the comustion chamber "advance the intake,retard the exhaust".
HTH,don't know how to expalin any better at the moment ...... need more coffee ;)

[ABUSEDDOG]

Junkie,

I was indeed wrong with the question about vacum, it was actually the air pump putting air into the exhaust stream to reduce emissions, that can result in the ecu into reading leaner condtions (didn't get enough coffee either!) No links, it's an actual book, anyway it suggests disabling any such device while tunning.

Question:
Would the aftermarket ecu need this input sensor? or could you just remove pump/ sensor?

The comment about scavenging the combustion chamber makes sense, it would indeed increase volumetric efficency.

Question:
If the average car is between 80 and 90 percent VE, what would be the VE of a well tuned car?

Back to the leaner/ rich question.

Question:
What would the aftermarket ecu try to compensate as it 's primary function, to resolve conflict.
A.regulate air /fuel
b. regulate ignition
c. combination of both

oops it's kinda like school and multiple choice

Once again, thank you for your time.

[Junkie]

Supras don't have air injection pumps,at least mkii's on up "would have to ask prof.eng about mk1".And,no an aftermarket ecu would not get a signal from one.There is no signal.Air injection pump is,just that,ity injects air into the exhaust mani. It was a cheap copout "IMHO" to lie to the "sniffer" because the manufaturers weren't ready to spend the real money to make engines run efficiently.

VE.... have to talk to one of the true geeks on here.I hate doing math formulas anymore,and even worse,hate looking for those formulas.

Lastly.... Aftermarket ecu does not try to compensate as much as a factory unit.It does what you tell it to do.It regulates fuel,ignition,timing,etc. But,only does what you set in whatever style map it has.Look at the SDS site in the SDS thread,and check out AEM's site,to get an idea of what a couple different styles of ECU are.
I will say,tuning is very time comsuming,too really do correctly.Making full throttle pulls on a dyno,and dialing in the AF there,as most guys seem to do,will cost you money,in fuel or parts,or both.