Running olsd with Maf

[2000Phoenix]

Follow up on ltft/stft not showing in scanner. Changing 02 sensors switched it to closed loop. Thanks @5fdp for clarification. Now Im getting p0101 which is what I gather is a vacuum leak, check exhaust and maf and all looks ok. I read increasing the delta by 1.5-4 on the maf delta fixes the issue but I have never had to mess with that table. Also my oxygen sensors are all over the place. Any ideas would be great. I think its another mechanical issue and not in the tune. Going to get af cleaner and check the again to see if it helps. Any feedback is appreciated.

[2xLS1]

That's what narrow band O2s are supposed to do in closed loop. Oscillate like a sine wave from 100mv to 900mv. You need to study up on how closed loop with O2 feedback on EFI systems works. If you don't understand the theory you will never grasp the tuning process.

[Fast4.7]

Follow up on ltft/stft not showing in scanner. Changing 02 sensors switched it to closed loop. Thanks @5fdp for clarification. Now Im getting p0101 which is what I gather is a vacuum leak, check exhaust and maf and all looks ok. I read increasing the delta by 1.5-4 on the maf delta fixes the issue but I have never had to mess with that table. Also my oxygen sensors are all over the place. Any ideas would be great. I think its another mechanical issue and not in the tune. Going to get af cleaner and check the again to see if it helps. Any feedback is appreciated.

You need to tune both your VE and MAF to get the P0101 code to go away. If they are both tuned correctly you will not see a P0101 code. The VE and MAF are compared against each other and too much of a difference sets the code.

[2000Phoenix]

That's what narrow band O2s are supposed to do in closed loop. Oscillate like a sine wave from 100mv to 900mv. You need to study up on how closed loop with O2 feedback on EFI systems works. If you don't understand the theory you will never grasp the tuning process.

I understand it. They normally would be between .4-.8v never seen it at .1 before so I thought something was off. Also my maf errror correct is staying in one cell which is weird. I?m guessing it?s because the ve and the maf are so far apart so would raising the maf p0101 help settle it down? Also would ltft be better to use on the ve table versus stft or a blend of both? Thanks again on your feedback.

[2000Phoenix]

I am use to seeing the sensors between .4v-.8v. It through me off to think something was wrong but no hanging idle so I guess that would rule out out a vacuum leak. Using narrow band blended between LT and ST trims are working and the ve table is smoothing out nicely I’m guessing due to the iat sensor being put in front of the tb. After getting close to zero I will raise the rpm disable back to 4K to tune the maf then go back into OL for wot with the wb. Is this the correct train of action? Thanks again for your feedback.

[Fast4.7]

I am use to seeing the sensors between .4v-.8v. It through me off to think something was wrong but no hanging idle so I guess that would rule out out a vacuum leak. Using narrow band blended between LT and ST trims are working and the ve table is smoothing out nicely I’m guessing due to the iat sensor being put in front of the tb. After getting close to zero I will raise the rpm disable back to 4K to tune the maf then go back into OL for wot with the wb. Is this the correct train of action? Thanks again for your feedback.

I do VE tables first, then MAF. To do the MAF only set the blend at like 400 rpm. Then re-enable the blend when the MAF is tuned. Once both are tuned I have found that I still have to slightly tweak the MAF to make things perfect. I tweak the MAF because the fueling is heavily tied to it and slight changes to the MAF seem more effective then VE changes. When I am tuning, I disable CCP with the scanner to make sure fuel vapors from the canister are not throwing off the fueling. I had some bank to bank fuel trim variance at low rpm and idle that was getting pretty wide. Like 10-12% trim difference. I found a pin hole leak in a weld and had a header collector that was slightly loose and had signs of exhaust soot coming out of the donut. Fixed both and now my trims sit at a more negative value and are only 3-4% different bank to bank. Even the smallest exhaust leak will throw your fueling off.

[2000Phoenix]

Thanks for clarifying. I am currently tuning the ve table. The maf only shows at 1500hz area. Rpm disable is at 400rpm. Bank 1 and 2 o2 sensors are within -5 and slowly coming down as i adjust the ve table Could you advise where the blend is to set for 400rpm and where the ccp is for the vapers/canister are located?

[Fast4.7]

Thanks for clarifying. I am currently tuning the ve table. The maf only shows at 1500hz area. Rpm disable is at 400rpm. Bank 1 and 2 o2 sensors are within -5 and slowly coming down as i adjust the ve table Could you advise where the blend is to set for 400rpm and where the ccp is for the vapers/canister are located?

CCP diable, either physically unplug the purge valve or disable it in the fuel system tab on the diagnostic tools window on the scanner by selecting OFF option, prior to logging.

Blend is set to 400 rpm in the dynamic air settings. IIRC it is Engine, Airflow, Dynamic, then Maximum RPM for Dynamic Blend value. Should be around 4,000 as a stock value.

[2000Phoenix]

Thanks for clarifying. I couldn’t find anything on the forum about this or in the hptuners books. It definitely sounds like something that should be mentioned with a few other things I’m sure are not mentioned to help with not chasing your tell while tuning. I have a few math filters i throw in to remove bad cell data as well. Will see how this works tomorrow. My fuel trims on each bank are around -7 so hope fully this will bring them all the down. Thank you again.

[Fast4.7]

Thanks for clarifying. I couldn’t find anything on the forum about this or in the hptuners books. It definitely sounds like something that should be mentioned with a few other things I’m sure are not mentioned to help with not chasing your tell while tuning. I have a few math filters i throw in to remove bad cell data as well. Will see how this works tomorrow. My fuel trims on each bank are around -7 so hope fully this will bring them all the down. Thank you again.

While this was a little of an unusual thing, I connected the CCP stuff to my L31 based 383 after it had not run for close to a year. Soon after the engine went into closed loop, still during warmup, the purge solenoid opened, the engine stuttered hard and the short-term fuel trims went to -25% at idle almost immediately. The canister can become heavily loaded with fuel vapors and drive the fuel trims around a fair amount.

[Fast4.7]

Currently getting closer on my tune. Revised shift points and an earlier lockup on the torque converter as well as higher average speeds on a longer trip brought out errors at both over-run coasting and higher KPA load readings. Previously non data logged areas of the fuel map are now being used.

80 MPH Cruise.jpg

[2000Phoenix]

Wow! Your fuel trims are looking really good. My fuel trims are coming close to zero after turning off the purge system but a few cells went lean as it was a hot day, and temps in the intake bello where the iat sits right in front of the tb hit 130degrees and it was only 88degrees out. Surprisingly the narrow band are keeping them in check and they are not swinging super lean or rich like it was when i was in open loop and they are moving not even a full point it looks like. I'm wondering if i move the iat back outside in the front bumper would be a good idea as the temp was only going up around 10 degrees max and with the narrow bands running to 4krpm will keep them in check. im thinking shouldn't have the lean rich issue like i was before or should i just keep it right in front of the tb and just keep chipping away at the ve table? Thanks for all your feedback.

[Fast4.7]

Wow! Your fuel trims are looking really good. My fuel trims are coming close to zero after turning off they purge system but a few cells went lean as it was a hot day and temps in the intake bello where the iat sits in right in front of the tb hit 130degrees and it was only 88degrees out. Surprisingly the narrow band are keeping them in check and they are not swinging super lean like it was when i was in open loop and they are moving not even a full point it looks like. I'm wondering if i move the iat back outside in the front bumper would be a good idea as the temp was only going up around 10 degrees max and with the narrow bands running the show under 4krpm i shouldn't have the lean rich issue like i was before? Or should i just keep it right in front of the tb and just keep chipping away at the ve table? Thanks for all your feedback.

If the sensor is showing 133F, your IATs are ~133F. I would not relocate the sensor personally. PCM needs to be able to pull timing when the intake tract is heat soaked to avoid detonation/engine knock as well as adjust for air density. Does not matter if it is only 88F outside, the temperature under the hood in the air intake is what matters. My IATs get as high as 170-180F in the middle of summer. I cut the IAT spark retard values in half thinking it would help years ago and all it did was cause pinging and tip-in knock retard. I leave the IAT and CTS tables alone on everything I tune now.

[2000Phoenix]

��! Yes it’s heat soaking now up to 130 degrees but after I hit 40mph it’s only about 5degrees off and above 40mph it’s dead on. Maybe adjusting the iat more would help since it’s such a drastic increase of heat soak? What do you think?

[eXo3901]

There is no adjusting the IAT unless we are talking sensor placement. It needs to be right before the TB. Fix the heatsoak with a fender-well intake or something.

[2000Phoenix]

There is no adjusting the IAT unless we are talking sensor placement. It needs to be right before the TB. Fix the heatsoak with a fender-well intake or something.

Sorry for the confusion. I meant the iat table. Everywhere under the car is heat soaking and it seems to be worse closer to the engine under the hood. I had it in the Bumper when i was in open loop but the fuel trims were swinging lean rich really bad. Now I?m using a blending mix with the narrow bands they are not swinging but the iat is right before the tb. I was wondering if I put in back in the bumper or adjust the table would be the best option?

[eXo3901]

Neither is correct. The IAT sensor has a specific electrical calibration. The same goes for MAP sensors and injectors. The data for these parts is what it is. It gets entered into the tune file and never changes unless the physical sensor/injector changes. The IAT sensor needs to be as close to the intake valve as possible.

Something that helps heat escape the engine bay. An intake that sucks air from a non-engine bay source or at-least has a somewhat sealed direct fresh air source. Sensor placement could help like moving it to the top of the intake pipe further away from the radiator and motor heat. Shielding the sensor from outside heat sources. Changing intake pipe material. Changing the physical sensor might also work(not shilling, but RIFE makes IAT sensors that come with real data).


The solution is to fix the heatsoak problem and neither plopping the sensor in the fender nor changing the sensor calibration data accomplishes that.

[2000Phoenix]

I guess I’m confused my iat sensor was not matching the outside temp when I got it so I had to adjust that table so it matches but your saying not to touch it and leave it stock and close to the intake. Also fbody’s have a known to heat soaking which is why I moved it in the bumper, and a lot of people have done this. I have seen shops move them as well.

[Fast4.7]

I guess I?m confused my iat sensor was not matching the outside temp when I got it so I had to adjust that table so it matches but your saying not to touch it and leave it stock and close to the intake. Also fbody?s have the radiator in a bad spot from factor and are known to have heat soaking issues which is why I moved it before in the bumper and a lot of people have done this. I have seen shops move them as well.

It makes zero sense to move the sensor. If the intake heat soaks it heat soaks and moving the sensor still does not change that fact.

After an overnight sit, before the sun heats up the hood is when I check my sensor accuracy. IAT, CTS and in my case the 4L85E trans fluid all read practically the same.

[2000Phoenix]

Sensor in the early morning is spot on for the outside air temp so I will leave it to heat soak my question is since the heat soak is a definite being inside the engine bay on these cars should I adjust the iat more or revert it back to factory settings is it was off?