Bizarre SAI Behaviour

BraveSirRobin

Member
Mar 19, 2015
10
0
State of denial
04 NAS DII: SAI no longer engages when rover is cold started.

Hawkeye confirms all relevant live feed data related to SAI to be "off" - (pump, solenoid, etc.) when they should be on.

No SAI DTCs are present...?

The only recent work was a wire and plug change but if it is related to that DTCs should be present and hawkeye should not have been able to read SAI live feed condition if a wire was broken etc.

Has anyone encountered this?
 
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discostew

Well-known member
Sep 14, 2010
7,706
1,015
Northern Illinois
Have you looked at other readiness tests ? Sounds like its not running the test for secondary air . If it ran it and failed the light would be on . Strange stuff causes readiness tests not to run . Not really directly related to your issue . The BMW range rover won't run tests when they have a vac leak at a small port at the rear of the intake . Not bad enough to store a fault , but tests won't run if it doesn't like fuel trim . See what tests have ran and passed .
 

KyleT

Well-known member
Mar 28, 2007
6,059
8
39
Fort Worth, TEXAS
The sai does not run every start. It takes certain conditions for it to run including coolant temp, outside air temp, and iirc O2 readings.
 

BraveSirRobin

Member
Mar 19, 2015
10
0
State of denial
Have you looked at other readiness tests ? Sounds like its not running the test for secondary air . If it ran it and failed the light would be on . Strange stuff causes readiness tests not to run . Not really directly related to your issue . The BMW range rover won't run tests when they have a vac leak at a small port at the rear of the intake . Not bad enough to store a fault , but tests won't run if it doesn't like fuel trim . See what tests have ran and passed .

Not getting any other symptoms of unmetered air. All available readiness tests done and passed. fuel trims appear to be behaving normally. purring like a kitten closed loop. no symptoms relatable to vacc leak. there only about 5 or 6 places it could really be leaking and all are sound. the only place I can't directly see is if something got between the intake manifold and its gasket but the odds on that are long and that would be a pretty sizeable leak - sufficiently so to cause symptoms. Besides and more importantly the engine cold starts up in Open loop so it shouldn't be looking at fuel trim to decide on whether or not to run SAI testing....

I am not aware of a port at the rear of the intake manifold. The only ports I am aware of are on the intake casting that holds the throttle body and attaches to the intake runner manifold at the front of the engine. Where is this port at the rear of the manifold; or were you referring to the cluster of three ports on the right side of this front casting (PCV/Brake Servo/SAI)?

Thanks for your help!

BTW - edited my OP to reflect that this is happening on cold/first start of day when SAI should run to warm the cats.
 

discostew

Well-known member
Sep 14, 2010
7,706
1,015
Northern Illinois
That's cool . Hope your not sorry its running again . I call that a hard reset , I hold both terminals together and discharge the capacitors fast .
 
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Maximumwarp

Well-known member
Mar 22, 2015
836
26
Fairburn GA
That's cool . Hope your not sorry its running again . I call that a hard rest , I hold both terminals together and discharge the capacitors fast .

We do this on a lot of brand new vehicles, esp ones with complicated infotainment units that freak out periodically. It solves a surprising percentage of problems.
 

discostew

Well-known member
Sep 14, 2010
7,706
1,015
Northern Illinois
How do you like that hawkeye scan tool ? It looks a lot like the handheld unit Land Rover gave us when the T4 first came out in like 2001 . I think about getting one but never had a chance to use one .
 

FB111

Well-known member
Jun 7, 2004
475
0
My 04's SAI works when the ambient temperature is above 55 degrees or so but doesn't operate when colder on initial cold start. It has not thrown any SAI related codes.
 

BraveSirRobin

Member
Mar 19, 2015
10
0
State of denial
How do you like that hawkeye scan tool ? It looks a lot like the handheld unit Land Rover gave us when the T4 first came out in like 2001 . I think about getting one but never had a chance to use one .

I'd give it a solid "B". there are things one can do with other rover scan tools that can not be undone with the hawkeye but it does all the important things well - live feeds, actuators, keyfobs, SLS disable, brake flush, etc... it loses ground on BC/"security" settings and some adaptions where other units seem to go a bit deeper. The interface is very.... British.... and not on par with the state of the art laptop software and USB connected interfaces. It probably is the unit you remember.

Wish I had shopped used before paying too much for a new unit. there are plenty of bargains on ebay.

Anyone who thinks this is the VDCS/VAGCOM for a LandRover (as I did) needs to recalibrate their expectations a little bit.
 

BraveSirRobin

Member
Mar 19, 2015
10
0
State of denial
That's cool . Hope your not sorry its running again . I call that a hard reset , I hold both terminals together and discharge the capacitors fast .

I'm half German... If I know something is supposed to happen a certain way I get twitchy when it doesn't.

I discharge caps through a resistive load instead of a short - a practice probably more borne of superstition than science.
 

discostew

Well-known member
Sep 14, 2010
7,706
1,015
Northern Illinois
Really . You will see the bulb light up when your discharging the capacitors like you do it ? I'm not sure how a capacitor could get hurt from just shorting the cables together , but I'm interested . My test light draws 256 ma , will I see that light ?
 

BraveSirRobin

Member
Mar 19, 2015
10
0
State of denial
i use a 12v test light. sometimes i get a glimmer sometimes not. it makes me feel good to use it... as per earlier post it's probably more superstition than science for automotive applications but I used to work at a place where we serviced CRT displays and computer gear - some of those caps pack a punch!