Lizard928

You're right, I had it backwards 2 white one black......

Imo000

The stock injectors are 19lb and not 24lb in the S4s. The early 32Vs had the 24lb units as stock.

Lizard928

True, but the LH can adapt enough to run 24# through the adaptation.

Tom M has 24# in his GT without any problems....

jcorenman

With a worn-out MAF, yes-- compensates nicely. Adaptation doesn't have enough range, otherwise. But Brian is running PK's chips, which are tuned for 24# injectors and apparently have a greater adaptation range, once they've had a chance to adapt. But of course if the O2 sensor (or wiring) is toast then all bets are off.

If the voltage is sitting near-zero as BC reports, then that is signalling lean and the LH will be adding fuel, once the engine warms up.

A stinky-rich mixture and a lean-signal from the O2 sensor means either the O2-sensor signal is bogus, or there are cylinders with no fuel or spark sending excess-O2 down the exhaust.

BC

I didn't see these posts until now. Rennlist seems to be a bit spotty on emailing me on subscribed threads.

Seeing that the car is running better now with no o2 input at all, I will put on the wide band sensor into the stock location and dial it in with the CO pot.

An intake refresh that was not needed. Oh well. I mean, both knock sensors were completely submersed in oil and not shielded, broken wires, etc. And the intake was flaking, the flappy had a weird line on it.... So there is justification....

To be clear, it a bit foggy now from months ago, but unplugging the o2 never made a positive difference before.

siscogts

O2 sensor or cats heavily clogged, imo...

Imo000

Disconect the catalytics and see if it makes a difference when the engine warms up.

BC

The cats have been off for months. The first time they glowed, I took them off so as to not hurt them/

siscogts

So... Get a new lambda... After that I am actually short ofopinions.... If oit was my car the last chance is... an exorcism.

BC

Yes, I will get a new lamda after I research with the Wide Band what the car is doing on the current setup, and with turning of the CO pot.

BC

Hooked up the innovate but the sensor that I simply didn't use very much last time it was installed on a different car, is dead. 20.8 at all times.

So... ordered another one from amazon. Should be here monday....

I will be interested to see how its looking. Car is running fine/good - though I'm hesitant to say "Perfect"

jcorenman

Why is it running well?

BC

Unfortunately I am not sure. If this was not the last straw before something more drastic, I would surely want to find out. But I don't care.
I just need it for transportation for right now, and it runs and drives evenly.

The CO pot that Ken supplies with his chips was lost and then found, so I put it in and started leaning it out, which did nothing (I explained this above). I then unplugged the o2 sensor like I had done dozens of times before WITH NO RESPONSE - *but this time the engine thrummed into a proper idle and started to accelerate and run properly*

ECUs and MAFs have been swapped for KNOWN good ones previously with no positive effect, so it was not the chips. That's why I replaced all the vac and breather lines.

If it was the o2 all along then fine - but it was removed from the system previously with no effect.

I have the innovate replacement sensor on order, and when that gets here I will figure out what the afr numbers are throughout the driving cycle and will post here.

If they seem "normal" - then I will assume it was the o2 sensor. Also, if I was properly measuring the voltage on the o2 sensor (like I have 100s of times over 23 years), then the o2 sensor was not supplying the proper voltage at idle or rev - it was telling the ecu it was SUPER lean.

BC

OKay.

The car did run better, but then when it got warm after a longer run, it continued to lose power until you have to plant your foot to accelerate.

Remember - it still idles JUST FINE.

That last part is different now that the o2 sensor was unplugged, and a somewhat unrelated issue where the computer was attempting to solve a lean condition that did not exist because the o2 sensor was OUT of the exhaust path.

Anyway -

1) Unplugging and replugging the o2 sensor, connected to the ECU, with no change is now a NON-symptom, as it is not the reality of what was going on.

2) The car STILL acts essentially in the same way it always has, which is running well until it heats up enough to operating temps - then loses power and the ability to rev normally - though it is BETTER with all the ancillary parts changing going on.

3) The ECU and MAF swapping from before cannot count, now, as a "test" - because this was when the o2 sensor was reading air instead of exhaust - (although I did disconnect the sensor during tests with no change... )

4) This essentially leads me back to plugging in a stock set of ECUs and MAFs again.

5) The MAF I had rebuilt for this car DOES have a POT. The pins to test are at 385ohms.

Hilton

When you say the car idles fine, do you mean it idles fine at first startup, or continues to idle fine once the car has warmed up, or continues to idle fine even after the car has been driven a couple of miles?

The O2 sensor being unplugged does make a difference on a properly wired and properly running S4. Disconnecting the O2 sensor does not make the LH go open loop - it will make the car run progressively richer until it hunts badly, loses power, then stalls (at least with a manual - I've not owned an auto so not sure what effect the torque converter and auto timing map has on the behaviour).

If you're still seeing no change with the O2 sensor disconnected, then there is still a problem with the O2 sensor signal reaching the LH ecu or with the ECU itself. As you state, the previous tests were invalidated by the O2 sensor being in air, so you need to repeat those tests first to determine whether the problem is the ECU.

Also worth noting that even if there's no change with a swapped ECU, that doesn't mean the original ECU is fine, it just means there is a problem elsewhere which needs to be resolved before the ECU can be tested adequately. You could be facing multiple issues here.

The pot on the MAF is irrelevant in an S4 as there are no wires on the car side of the MAF connector for it. The wires for the LH ECU potentiometer input on an s4 are on the (unused on a US car) 3-pin harness connector loose behind the CE panel.

Given you had the car running well (albeit briefly) recently, my gut says its intermittent and likely a wiring issue - I'd be very carefully testing and wiggling the O2 sensor harness all the way to the LH ECU, looking for anomalous resistance/shorts/voltage between the signal pin and the sensor heater ground/supply pins.

Are you using a separate narrow band sensor for the ECU input, or a simulated one from the innovate?