upstate bob

That engine looks and sounds to be operating perfectly. Be happy. Damage? lean mixtures DO NOT BURN VALVES or whiskers or any other old wives tale. -Take it from an old aircraft mechanic, airplanes run constantly at 75% power, much more than a normal car. We lean them out at altitude for gas mileage. -No damage.

123quattro

I don't think that is what's going on, bit it's possible. There is a fair amount of reversion in the exhaust under low load. Same type of issue when you have a wideband near the exhaust outlet. It needs to be a more than a foot up the tailpipe to not get erroneous readings.

KenRudd

Sorry, I had not checked the case closely, and I thought I had seen an A/C adapter in the case. So, yes, I would the like to be able to connect to the jump post. Can I drop by this afternoon after work?

KenRudd

I'm not too worried about being a little lean in itself, based on earlier comments and the fact that I have not destroyed the engine yet. But I do think it is set wrong, and want to get is set back to specs.

KenRudd

When I am adjusting the AFR at idle using the variable resistor and the Bink'r, am I adjusting only the "Closed Loop" context , or does it also somehow affect the "Open Loop" context/map as well?

And the related questions just to make sure my fundamentals are sound:
1. The Open Loop uses a preset map to set AFR, right?
2. Porken's chips optimizes ( or completely replaces) this map in a read only fashion?

neilh

Sure, i have the adapter on my bench.

dprantl

Is this on your '86? IIRC the LH 2.2 928's idle in open loop, hence the ability to adjust the idle CO. '87+ with LH 2.3 idle in closed loop. There is no adjustability for closed loop operation, a properly working system will always strive to swing around 14.7:1.

Dan
'91 928GT S/C 475hp/460lb.ft

Imo000

I think you are trying to fix a problem that doesn't exist.

KenRudd

Maybe. But I do know it dies when giving it gas when it is very hot ( see link in first post), and I know it gets horrible gas mileage, even for a 928. So,it makes sense to make sure the fueling system is running to spec before following up other possibilities. And its fun.

KenRudd

Dan-

Based on Porkens notes here:
"IIRC, it's most effective at idle, but it does affect the cruise map, but less and less as the load increases, and that it doesn't affect the WOT map, much, if at all. "
And follow up by FlyingDog Here:
"I would think the effect would increase again at WOT because the LH switches to open loop. On Euro/ROW cars which are always open loop, the MAF adjustment effects mixture at all loads and rpms. "

I think you are correct.

KenRudd

Before making changes, I wanted to document current settings. The MAF CO resistance is at 349 ohms, based on Pins 14 (MAF CO) and 25 (ground) on the LH plug. Porken indicates default is ~380 ohms
While I had the LH plug off and the meter out, I checked the TempII resistance. It looked good.
WOT and Idle switch also worked while testing gas pedal travel.

KenRudd

Data point: From the picture above, you may have noticed that the Brown Wire/Plugs were connected. I noticed it and I disconnected them. The WO2 readings are now MUCH less spastic, and they appear to be lower (richer). I can't tell you accurately how much because the meter was so erratic before, but I would guess by ~1 point on average during cruise and about the same at idle. Still seems a little lean and I will move forward with diagnostics/testing, but I may not make any more changes until I go through a whole tank of gas.

neilh

Low octane loop? When i picked up the black 86 that was plugged in as well - made a big difference when i unplugged it. Do you still need the power cable adapter for the Innovate ? . I'm home now - 3:30 EDT.

KenRudd

Update: I have intentionally done nothing since disconnecting the brown wire, so I could get a feel for things. As noted, with brown wire open, AFR seemed smoother, idle bettter and maybe a little better MPG ( 1 to 2 MPG is within margin of error.), BUT, and this is a huge BUT- I had not really wound out the motor since the disconnect. Fast forward to the first session at VIR on Friday. I hit ~4,600 RPM and BAP-BAP-BAP. Just like hitting the rev limiter but almost 3K RPM too low. Back off the gas, go for it again and BAP-BAP-BAP. I am hitting some type of rev limit. Other than that, running perfectly. Every time I hit ~4,600 BAP-BAP-BAP. I'm a little panicky, but pull into the pits, and on a hunch, connect back up the brown wire. VROOM! RPM's go back up where they belong and I am shifting at ~6K.
So, why did the brown wire connection cause the drop in the Rev Limiter, and other than a slightly different map, can somebody tell me exactly what the Brown wire actually does?
Sidenote: Even limited to 4.6K, still faster than early Boxsters.

KenRudd

Update:
I made the following changes:
1. New 02 sensor. May not be needed based on Stan's service records, but I wanted a clean sheet;
2. Newer Injectors: Bosch 0280150947 Ford Racing 24lb/hr Fuel Injectors
;
2a. Replaced Pintle Covers and O-Rings with kits from Roger:
;

Then using a borrowed a Blink'r kit from Neil Harman, I went about testing and setting the AFR.

Porkens instructions are pretty good, but here are my notes:
1. Let your motor get good and warm. When you think it has warmed up enough, it hasn't. Keep waiting. A motor that is not up to temp will give Blink'r readings that will make you question your sanity.
2. An air leak will make decent idle impossible to set. Get your air leaks sealed!
3. Porkens instruction say this:He means turn the IDLE screw 1 or 2 turns, NOT the CO screw on the MAF.
4. You need to be patient, very patient. The lights can take a while to change, and any changes you make on the MAF CO screw may take a bit to really settle in, and may require a little goosing of the throttle. It will take you multiple iterations of going too far each directions and slowly finding the center to get it.
I think mine is fairly close to dead on. It looks like this: