There quite a few things that are required for the car to go into Closed loop... .

Coolant temp >= 190F, Intake air temp < 123F, Baro >= 22.9 inHg, Baro <= 31.6 inHg

Also any of these will make the car get stuck in Open loop

Throttle position too high (varies by RPM), Airflow too low (units are tricky, but it's very low),Coolant temp < 87F, The O2 sensor did not switch around 0.5v for over 20 seconds while running in closed loop mode. In that case, the ECU locks itself in open loop mode.

Well, the temp reads 192 steady through the logger, checked the intake temp and it was no where near 123 was a double digit, baro pressure I don't remember it exactly but believe it was like 28.

As for the TPS from what I've found in my searches it is high at 14% at idle and lower then desired at WOT, 96%. Air flow at idle in hertz was fluttering around 128 and 148 depending on rpms. But my o2 volts were constant at 4.95 under the o2-r on the mmcd.

Going out now to adjust TPS. Maybe it is to high:-(

The Tps threashold is a lot higher then that around 35% at Idle going up to about 50% in higher Revs till it drops to 0% at 4k IIRC

Your Airflow sounds a bit high should be about around 30-60hz

My guess with out seeing a log is that the o2 is dead or you have a high/low Baro because of a bad connection from the Matt...

Sorry, my mistake.

Just adjusted my TPS and throttle cable idle its at 10.5 now and now max's out at 99.6. Airflow I was mistaken at an idle is 37-45 hz. Bara pressure was moving between 14.2 and 14.5 psi.

Just did a lap around block to warm up car then did a 3rd gear pull at WOT from 2k to 5.5k. Pulled alot better. Had 1 hit of knock after when I let out of 2nd gear to coast to a stop to review log. But not a single knock in whole pull. Going to go try another with the other o2 reading selected to see if that registers at all. But when I started car earlier looked at it and it was fixed at 2.5.

Did another lap. This time with o2-f selected. No change stayed a flat 2.5v. Think my sensor is dead. But car is running unbelievably smooth and nice. Previous owner did emission delete and undid the egr valve but never installed a block off plate. I made one at work using a new gasket as a template out of titanum. Not sure if it was the plate or the tps adjustment but those were the only 2 things i did and its an amazing difference.

And the load whoosing noise is gone now too. Egr plate probally something to do with that.

Now I just cant wait for the new O2 sensor to arrive tomorrow in mail. Then can reset ECU and be done trouble shooting the Fuel Trim and o2 reading. And start tuning MafT.

I will update this tomorrow when or if I find out the o2 sensor is shot. The current one appears pretty old. Rusted exterior...... May be original. Haha.

But thanks LOADS my1gdsm for your info. Exactly the info I was looking for.

Just hope its as easy as a worn and old sensor.

Assuming the default 100% is rich because exhaust is a bit gassy and during pulls experience almost no knock.

I realized you had it right when you said your o2-f is 2.5v. As its based of the trim. It will go up and down along with the high trim IIRC...

I Must not have had enough coffee and was posting from my phone, Sorry edited my post so there is no confusion.

Your logging the right o2, But if it's reading above 1 volt you probably have a short an getting the power from the sensor Heater... .

You Baro and AIT should be "locked" as the MAF-t put's out 3.9 volts on both and not move at all With a MAFT if they are you have a a bad connection or bad grounds ect. AIT should be around 77 degrees and the baro right in between what it is.

Haha, you guessed the IaT exactly haha, yep 77. Bara is just slight less then half of that. 14.5psi x 2.4 = 34.8 in Hg. Found conversion multiplier online so unsure or that accuracy.

So tomorrow afternoon is when the new o2 sensor will be here. I will post an update after thats installed and I do a run.

Thank you so very much my1gdsm.

No problem hope the info helps

It does help. I have 450's as well. Aux=0, Base=2, Idle=0, Mid=E (2 clicks left), Wot=E (2 clicks left).

Been logging with my palm and still not getting any knock at those settings but don't feel comfortable going and leaner. May move my base to 3 to lean out whole trim. When I got car settings were set up for a 3.5 maf and was a 0,2,E,D,D. I reset everything and put the settings to 3" and started fixing leaks and such and figured I'd tune it when I was comfortable but try to keep it richer until I could monitor my trims.

With the previous owners settings car ran like ass. Had vacuum and boost leaks every where. 2 of the spark plug wires were corroded horribly in coil, #1 injector pintel was melted and all the gaskets brittle as glass. After replacing all those ran a heck alot better just tune and adjustments was out of whack.

MY1GDSM said:

There quite a few things that are required for the car to go into Closed loop...

The O2 sensor did not switch around 0.5v for over 20 seconds while running in closed loop mode. In that case, the ECU locks itself in open loop mode.

Click to expand...

And_44 said:

But my o2 volts were constant at 4.95 under the o2-r on the mmcd.

Click to expand...

Assuming MMCd O2-R is the correct O2 sensor on a DSM. Reading 4.95v usually is a sign that the ECU has leakage between pins due to a bad EMI filter or the input buffer on IC101 for the O2 sensor is bad. The narrowband O2 sensor shouldn't be able to make 4.5v by itself.

Disconnect the O2 sensor and see what it reads. If you can release the pin at the ECU connector you'll avoid any question if a wiring short to the sensor.

Well, thats interesting. I looked at the ECU was a refurbished EPROM from motoguys, caps were newer style and couldn't see any leakage. BUT the board had some repairs done to it. I haven't had any running issues besides this fuel trim one.

I will try unplugging it at plug. But will still replace sensor anyway. And will hunt down the pin diagram for it and undo it from there to eiminate the wire harness.

If it doesn't work I will most likely pick up a non-eprom or let car sit for a week or so and send it into Ecmlink. I like their work alot and trust them.

I'll update tomorrow after installing the new sensor.

And_44 said:

Well, thats interesting. I looked at the ECU was a refurbished EPROM from motoguys, caps were newer style and couldn't see any leakage. BUT the board had some repairs done to it. I haven't had any running issues besides this fuel trim one.

Click to expand...

I saw this sort of problem a couple dozen times in the years that I was repairing ECU's and it's something that Motoguys might not test for. I never showed it to them when they tricked me into teaching them how to repair ECUs.

Tom and Dave at ECMLink know about the problem with the EMI filters, we discussed it several times and put together a bulk purchase of new ones since reusing originals that had been contaminated by the electrolyte often caused this sort of problem at a later date once back in the customer's hands.

Once you have disconnected the O2 sensor from the ECU harness if you still see something more than maybe a tenth of a volt on O2-R you'll need the ECU fixed.

Thank you very much Steve. Your guys input has been very valuable. Haha, been searching for days and trying to find this information.

Yeah, I've never really felt to good about motoguys. But wasn't able to make it home today. Been spending time with my partner today.

So Thursday or Friday will install the new sensor and do the wire thing. Already started looking for a replacement ecu. Car is a 92 wired for the 90 eprom ecu.

And_44 said:

Car is a 92 wired for the 90 eprom ecu.

Click to expand...

That's a 30 second change if you with up looking for a 91+ ECU.
I'd just sent this one to ECMTuning since fixing it will be cheaper than replacing it.

True, but would be nice to have a back up ecu. Haha, with previous dsm's I've found its always nice to have a back up part for some problems.

Well finally got around to putting new o2 sensor in today.

Before changing it I unplugged it like Steve mentioned and voltage on o2-f on mmcd dropped to .01 from the 4.5v. Put in the new o2 sensor and now it all works. My fuel trims are adjusting them selfs now.

Old o2 sensor was rusty, and the tip was broken.

Typo it was o2-r on mmcd not o2-f. Now fluctuated between .01 and .9

Cool, I'll make a note. I've never seen the sensor do that on it's own but then that's what we have diagnostic processes for...

Haha, yea. Now just tuning the maft to get the settings right. Got the Base and now woking on the mid and Wot settings.

I will mark this as solved when I get home to use my laptop. Kinda hard to do it on my Android.