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The mkiv Supra Owners Club

AFR's on a single


GeordieSteve

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Now I know sod all about AFR's hence the question. Does this sound normal as I'm a tad worried:

 

Idle: normally about 14-15.5

Neg boost: WAY lean! Around 16's and even 17's

Boost: 14's

WOT: 10's

 

I've been idling anything between 10's and 18's on cold lately but I think the plugs are in a right state but I have IK24's sitting spare to replace them

 

Should I be worried??? :search:

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The MAP ECU 2 can do ignition timing but I think it's only one way? You can add or remove but not both?
That can't be right, surely?

The mapecu web site says

Timing adjustments are easier because the table provides Advance and Retard control over the OEM settings.

 

 

The PHR guys are pushing the MAP2 right? Perhaps one of them could confirm.

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Guest MikeSupra

about 15.5 is safe for off boost, if your about 2000-3000 revs, just crusing or 16-17 for really light to no throttle.

It's usually mapped like that to give good economy when driving round town etc. If you have anything lower the 14.7 when just crusing, you may foul up your plugs real quick!

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MAP2 can indeed do ignition timing both ways, negative for retard and positive for advance, 0 for no alteration to OEM signal. All in a table of pressure vs. rpm, for example:

 

image

 

Cheers,

 

Brian.

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It had to be pulled due to an error with the ECU (ECU was brand new with no diagrams for the J spec). Sure it can be set up now :)

 

Sounds like Thor maybe haven't got to grips with the MAP2 yet?

 

I'm learning the hard way myself.

 

Cheers,

 

Brian.

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about 15.5 is safe for off boost, if your about 2000-3000 revs, just crusing or 16-17 for really light to no throttle.

It's usually mapped like that to give good economy when driving round town etc. If you have anything lower the 14.7 when just crusing, you may foul up your plugs real quick!

 

No that's not right at all!!

 

The MOST economical/cleanest burn is at 14.7:1.

IDLE and cruise-0.3bar should be looking for 14.7:1...some find the engine works well in the low 15's at idle which is fine...

16's whilst cruising is just asking for trouble.

 

As the boost climbs the AFR's should get richer...by 0.7bar you should be in the 11.7:1 ballpark....and hold that from there on...richening slightly with higher rpm'....I'd say 10.8-11:1 at full throttle & 7000 rpm

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Yes i must agree with alex, you don't want to be seeing 16 or 17s unless your letting off. Cruising should be no less than mid 15s and on WOT no richier than mid 11's.

 

11's dead at very high rpm's give just a smidge extra protection....after all we're not driving race cars ;)

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