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  • Question on cold start and gauge readings

    So, first, I have read the manual, something that I hadn't done in detail and see that it's time for me to start looking at short FT. I applaud the old heads and moderator's patience with those numbers because many of the questions I see are answered in the manual

    In an old post, I had an intermittent O2 sensor, that is fixed and other than following the advanced tuning instructions the truck seems to be OK. However, it has an odd new thing at start and I am trying to figure out if it is an issue with the new O2 sensor or a characteristic of the programming

    (FYI, because I was concerned that the LAST problem was a harness issue and I was throwing money away, I bought a cheapo Ebay knock off O2 sensor, so that's why the concern with a new part)

    When I fire the truck, O2 sensor is always in the green now and runs fine, just maybe a little smelly, but runs well. However, AFR reads 10, no wiggle. Doesn't matter if I change cold start values, always 10, and just about the time I am going to shut it down, it goes perfectly normal after it runs a minute, maybe 2, it starts working correctly.. The truck is a little smelly, but not pegged at 10:1 smelly

    First, is this normal? I didn't think the last one did this, but it was real wonky so hard to trust. I was wondering if maybe the cheap O2 sensor didn't have a good heating element or some other Chinese shortcut, but if that is normal cold start behavior, the truck runs pretty darn good and is ready for advanced tuning.

    Thoughts? Also anyone know of a brand name O2 sensor part number with a shorter lead? The one that comes with it I have to loop the heck out of it and tuck it in a frame rail.

  • #2
    From page 26 of the instructions.

    AFR: The Air Fuel Ratio is measured by the wideband oxygen sensor and is displayed as AFR gasoline (Stoich 14.7). Higher values are leaner and lower values are richer. The lowest possible value that can be sensed is 11.0. A value of 10.0 will be displayed any time the sensor is warming up or not ready to report accurate AFR readings. Note that when Decel Fuel Cut Off is active, AFR will report full lean – this is normal and expected

    Mine displays 10.0 for 15-20 seconds at key on then goes fully lean if engine is not running.

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    • #3
      if you bought a cheap 0-2 sensor stop and buy a Bosch replacement you spent to much to cheap out now . there is a list of parts hear in a post . N A P A should have it in stock

      Comment


      • #4
        Here is a link a Premium Sensor that we know works as expected.

        https://www.summitracing.com/parts/bch-17025

        Beware of " Knock-off " or el cheapo sensors: Your engine is worth more than a few $'s you are trying to save or being lazy/ trying to rush things.

        Comment


        • #5
          First, thank you for backing me up, especially when I told you I read the directions and then I missed it clearly. LOL

          JM73340, thanks for the cut and paste as well as what you see, I will order the right one, but will likely time mine and see, certainly is way longer than 15-30 seconds. So it sure seems like the hunch that the HEGO was warming up slow was accurate.

          However, I didn't cheap out in the way you'd think, given the intermittent performance and a new in the box Edel sensor that didn't read right at install, I was expecting that a wire broke or something else in the harness and I was going to have the same repeat problem and have to start shooting wires. The 22 dollar sensor is really a 22 dollar troubleshooter, and in this case, it was wasted as anything but a spare, but if I bought a 90 dollar Bosch and it was still intermittent I'd be whining.

          That being said, don't get me wrong, I would likely give me the same advice, I do build some very high dollar engines and as such, you can work the margins on your own as long as you know the limits. In this case it told me exactly what I wanted to see. Would have been cool if "el cheapo" worked perfect, but the fact that it works, unlike the supplied one is a bonus on the cheap. If there was a better way to test the HEGO than the Bic lighter (which the intermittent one passed) I wouldn't have bought the cheapo, but I really never expected a replacement to work given my intermittent problem.

          Thanks again, and I am pretty excited to start doing some real tuning, needless to say, after I get the O2 sensor that speaks English (or German) first LOL



          Comment


          • #6
            427,

            I also have a spare O2 sensor Just in case I have an issue. I have tested it and it works exactly like I described above. Hopefully other than for testing I’ll never have to use it.

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            • #7
              2700 Cast, is the original a Bosch? It has no marking on it. Surprised that replacement is relatively common on this board compared to other systems I have installed.

              Comment


              • #8
                Originally posted by 2700 Cast View Post
                Here is a link a Premium Sensor that we know works as expected.

                https://www.summitracing.com/parts/bch-17025



                Is this Bosch 17025 also the correct 02 sensor for the XT intake systems (mine is the 35790 kit)?

                DC

                Comment


                • #9
                  Update, the wife and I took the old F100 for about a 75 mile run yesterday and it just got better and better as it learned. So far so good. I will replace the O2 sensor with a name brand, but it's quite amazing, toward the end of the drive, I would get to a stoplight and almost felt like it stalled it was idling so smoothly (500 HP 461 inch FE), very pleasant to drive (except for the fuel pump, watch for another post, would be interested in your experiences)

                  So far pretty happy with how it's coming together

                  Comment


                  • #10
                    I'm pleased as well 427stang. Mine is a 468 BBC in an el camino but was it not for the lumpy cam and 3" exhaust and axel dumps id swear it was stalling at idle. I went to great lengths and expense to install this thing correctly from the get go incuding a new tanks inc tank and return fuel system and it paid off with a zero issue install, immediate fire up and learn cycle. I have my SFT within single digits either way and the LFT are settling in to within single digits as well. Now I'm going to start working on feeding it timing.

                    Using the app Its currently at 22* initial(was 15), 5* vacuum advance and 36* all in by 2900(was 3000) RPM. With newest update I'm told you can now feed it up to 15* advance max instead of 10*.

                    My plan is to take it out on an open road and take note of vacuum at a steady speed(Like 60-65 mph). Stop and feed it a bit more timing for initial then 10 and then 15 for the vacuum advance. Then cycle off wait 15 sec reboot blue tooth connection and verify settings on tablet , Then Ill start bringing in the total timing in sooner and sooner since I have 4.10 gears and TKO600. Ill keep doing t his fine tuning until vacuum stops rising and/or starts surging at the same speed and load i was using at the beginning.

                    That's my plan anyway. feel free to critique.
                    Last edited by marc s; 09-21-2020, 07:24 AM.

                    Comment


                    • #11
                      Originally posted by DC3 View Post


                      Is this Bosch 17025 also the correct 02 sensor for the XT intake systems (mine is the 35790 kit)?

                      DC
                      Yes, all PF4 use the same O2 sensor.

                      Comment


                      • #12
                        Originally posted by 2700 Cast View Post

                        Yes, all PF4 use the same O2 sensor.

                        Perfect. Thank you.

                        DC

                        Comment


                        • #13
                          Originally posted by marc s View Post
                          I'm pleased as well 427stang. Mine is a 468 BBC in an el camino but was it not for the lumpy cam and 3" exhaust and axel dumps id swear it was stalling at idle. I went to great lengths and expense to install this thing correctly from the get go incuding a new tanks inc tank and return fuel system and it paid off with a zero issue install, immediate fire up and learn cycle. I have my SFT within single digits either way and the LFT are settling in to within single digits as well. Now I'm going to start working on feeding it timing.

                          Using the app Its currently at 22* initial(was 15), 5* vacuum advance and 36* all in by 2900(was 3000) RPM. With newest update I'm told you can now feed it up to 15* advance max instead of 10*.

                          My plan is to take it out on an open road and take note of vacuum at a steady speed(Like 60-65 mph). Stop and feed it a bit more timing for initial then 10 and then 15 for the vacuum advance. Then cycle off wait 15 sec reboot blue tooth connection and verify settings on tablet , Then Ill start bringing in the total timing in sooner and sooner since I have 4.10 gears and TKO600. Ill keep doing t his fine tuning until vacuum stops rising and/or starts surging at the same speed and load i was using at the beginning.

                          That's my plan anyway. feel free to critique.
                          I think you have a good test plan, the only difficulty I see is that by the time you hear a ping, you went too far., come back enough that you know you aren't hurting anything. I think you could likely go for a curve all in by 2750 or so and call it good enough, and total timing is likely known out there, for your combo just look around for dyno tests with your head, quench, compression piston combo, or at least your chamber design. 36-38 is generally pretty close for a big bore big block, it usually gets better (lower) with more modern parts, tighter quench and small chambers. Additionally, if you are racing, you'll never be below that so coming in earlier may not help all that much.

                          I am not familiar with how the vac advance works on an Edelbrock, however, if it's a low load addition, I think the only reason you'd need to go a large number is if you were leaning it out quite a bit for cruise. Lean likes advance, even though it can't tolerate it as much. However, I would defer to tuning the Edelbrock specific vacuum advance to someone with more experience, which I'll be watching too

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