OL vs CL with the MAF and LT's
 

Hey

I have tuned my car with a AEM WB and am keeping the MAF and now trying to run CL with STFT only and due to the collectors on the LT's the trims bounce around some. not real bad and after the O2's get warm, the trims usually settle down to ~ -6 or so to +6 or so...not real bad I think, but until they get good and hot I have seen the trims as far as -15 or more and have wondered if this is dangerous or wasteful.

Some people have said the AEM is not a real accurate WB, but after the stock NB's are good and hot they basically agree with the AEM....my question is with this situation would it be better to stay with the NB's and CL or run OL based upon the AEM tune...BTW I am not planning to keep the AEM installed because I can't see a good place to mount it, I don't want a gauge pod on my a-piller or want to remove a a/c vent and mount it there, and if I go OL, won't I have to monitor the tune myself or will the MAF help? I was hopeing to just turn it back over to the computer in CL and be done with the engine tune.

All advice and opinions will be appreciated!

You are tuning in open loop with all fuel modifiers disabled, right?

Correct, I believe I did the tune correctly and have it pretty close.

You need to play with your o2 swith points and proportionally fueling. When you move the o2s further from the heads it takes longer for them to heat up. You may need to make you car go into open loop slightly later related to ect to allow them to heat up to make sure they are hot. Send me your tune bl885365@hotmail.com or in a pm and ill take a look. Also send me a log if you can.

You can always set it up to run OL at idle.

I tried that and it has not worked, it stays in OL when driving, every now and then it goes in to CL for a little bit then right back to OL...doesn't make sense.

If it is doing that then you need to make some changes. Follow the thread on the Hptuners forum and you will be able to sort it out.

I did, word for word and I have looked at the tune and don't see anything wrong, but I guess there must be?

I will attach my latest tune, and all advice will be appreciated.

The issue is the relocation of the O2s to a further point away from the exhaust port and the loss heat at the sensor; the latter is harder to get around. You can begin to address this in the Closed Loop Integrator Delay tables in the OL/CL area of HPT. You have a delay value vs. airflow mode that can be lengthened in the right place to help. Log airflow to figure out your consumption during the slow sensor transition times. The Mode vs. Airflow table is where you look up (or change) airflow modes based on the airflow that I just mentioned logging. You have several approaches here. The tables can be made to point in different places and/or the end values can be modified. You will likely be in the 6-9g area at idle (this is just in general). The integrator delay table shows the greatest OEM delay (1.00) in airflow mode 0. In the mode vs. airflow table, for example, you can point the lazy airflow area at mode 0 instead of 1 or 3 that it is at now.

Thanks for the info Frost...I don't think I have read about doing this, thanks again!