Still running lean under partial throttle.

[The Shaolin]

2000 SC1. '98 DOHC head. Cams, SAFC II...all the bolt-ons. Full list in garage.

I've got it tuned for mid 13's. Under partial throttle, such as, right after I shift to second, the AFR jumps to 17, 18, 19 or ---, which is higher than 19, and there's massive amounts of power loss. More throttle fixes the problem.

This happens mostly when it's cold and on the tune. It happens less when it's warm or on the factory tune, but it still does it.

The most confusing part...the SAFC isn't pulling any fuel when this happens. I can map CORR % and it stays at 0%.

Swapped trannies in the last month, so the PCM was most definitely reset, and it still does it.

ECTS is original, but wasn't cracked a couple months ago when I put the DOHC in. Coolant temp gauge seems to be accurate. Could the ECTS be at fault? I'll change it out anyways (lol saturnfans)...but any other ideas as to what is wrong?

DTC light is on, but the last two times I've had it checked it was just EGR FLOW OMG, and I have no reason to think I've got any new codes.

[Anonymous]

what do you mean by 'cold', cold enough to be in open loop mode? if so, the safc aint gonna do shit.

[The Shaolin]

When does open loop happen?

[Tatusmi]

When does open loop happen?

correct me if I'm wrong... but it's during WOT and when the car is warming up (until temp sensor hits something like 600*C).

- Tatusmi

[SupraCharged007]

(until temp sensor hits something like 600*C)

I'm pretty sure that part isn't even close to correct,

[Tatusmi]

ya... I defiantly typo'd there. It's 600*F (I'm Canadian, used to putting C).

Whenever the vehicle is first started, the PCM operates in "Open Loop" fuel control. When the Powertrain Control Module (PCM) determines that the engine coolant temperature (ECT) sensor has reached at least 20 degrees C (68 F), and the oxygen sensor has reached operating temperature of 318 degrees C (600 F), it will then go into Closed Loop fuel control operation.
Closed Loop fuel control operation will be maintained as long as certain parameters are met.
In "Closed Loop" fuel control, the PCM varies the fuel to the engine according to signals received from the oxygen sensor, located in the exhaust manifold. The oxygen sensor varies a voltage signal to the PCM, indicating the oxygen content of the exhaust gases. If the oxygen sensor signals that the air/fuel mixture is lean, the PCM will increase the amount of fuel to the engine. If the oxygen sensor signals that the air/fuel mixture is rich, the PCM will decrease the amount of fuel to the engine.
During "Closed Loop" fuel control operation, the PCM is constantly adjusting the amount of fuel to the engine, according to signals received from the oxygen sensor, to try and obtain a 14.7:1 air fuel ratio.
If there are any oxygen sensor related PCM/EC diagnostic trouble codes, or if the oxygen sensor does not switch between rich and lean, or if the ECT does not obtain 20 degrees (68 F), the PCM will not go into "Closed Loop" Fuel control operation.

From the service manual (page 23)

- Tatusmi

[The Shaolin]

hmmm....probably still in open loop then. I knew about WOT, but not the cold engine thing.

[dream36realms]

I'm having these issues as well nathan. Even after warming it does it too. I was always curious about a dead spot in the pulls, like it will be 13.8----------------------------------until about 3400rpm's then spikes at 14.5 just for a second then back to the 13.8. do you have this issue as well? The problem you described makes me want to adjust the Low THR, but that is a scary thought

[punkboySL2]

I'm having these issues as well nathan. Even after warming it does it too. I was always curious about a dead spot in the pulls, like it will be 13.8----------------------------------until about 3400rpm's then spikes at 14.5 just for a second then back to the 13.8. do you have this issue as well? The problem you described makes me want to adjust the Low THR, but that is a scary thought

i have this same problem, but i only have intake/exhaust, that's pretty much it. i'll be cruising and hit like 3000rpm's and it'll die, then if i let off and punch it again it'll pick up somewhat. and it doesn't happen all the time either.

[Tatusmi]

any solution to this?

I had the car out for a run with no tune (0% across the board) and it was doing the same thing.

- Tatusmi

[getz999]

I also have the same problem, except mine will go as fair down as 11.xx and my car will start bogging down. I can only remedy the problem by goin WOT for a second

[The Shaolin]

uhhh..that's the opposite problem I'm having.

Did it a lot last night...when engine was at full operating temp, I could recreate it on command. Leans out to 16 or 17 with no adjustment from the SAFC.

[S.Bretz]

Is the PCM receving a stock NB o2 sensor siganl or one generated by a WB sensor?

Have you tryed replacing the NB sensor, if you are still using it?

[getz999]

uhhh..that's the opposite problem I'm having.

Did it a lot last night...when engine was at full operating temp, I could recreate it on command. Leans out to 16 or 17 with no adjustment from the SAFC.

I meant to say around the area of 17ish, I was thinkin of the nitrous problem I was having [img]{SMILIES_PATH}/rolleyes.gif[/img]

[The Shaolin]

Is the PCM receving a stock NB o2 sensor siganl or one generated by a WB sensor?

Have you tryed replacing the NB sensor, if you are still using it?

Brand new o2 sensor when I did the headswap this summer. Wideband is tapped in behind the flexpipe.