I was curious to know if anyone has encountered long cranking times after upgrading to 750cc injectors (from the TRDs), not only just long cranks, but needing multiple attempts before the vehicle starts. When it finally starts, there's a plume of rich black smoke from the tailpipe. I have the correct injector constant and offsets. The LTFTs are +/-3%. This TRD S/C'd 2011 has a Walbro 450 fuel pump and the stock fuel pressure regulator, not boost referenced. It transitions to Closed Loop in about 90 seconds. It runs fabulous in every other respect. All that I changed were the injectors, the inj. constant/offsets and adjusted the fuel trims. The only unusual aspect is my elevation of 8000ft. I thought that I was getting somewhere by bumping up the Startup Airflow tables, but as it turns out that really doesn't solve it. Thanks for any feedback/ideas.
You mention the issue of hard cranking when using large injectors. I maxed out my TRD 535cc injectors so I installed some 750cc ones. I updated HPTuners with the relevant data relating to them, but now have a pretty consistent hard starting issue. I was wondering if you would be willing to share some guidance as to how this might be dealt with. Any time you can spare to this is greatly appreciated.
2008 Land Cruiser (stock)
Looking for Harrop Stage 1 and Stage 2 tune
Last edited by Romulo; 05-27-2023 at 12:51 AM.
@SlowNStock, @JustDSM, et al.
I've uploaded my tune and these logs in an effort to try to solve my warm/hot starting conundrum. One log is a cold (overnight) start. One is an immediate hot restart. The two remaining are warm/hot restarts.
TRD blower
750cc injectors
Walbro 450lph pump
Black soot from tailpipe on warm/hot restarts, not on cold (overnight) starts.
Just prior to the 750 injectors, I had the TRD green injectors and zero starting issues, with the same pump. Fuel pressure has been checked out at a rock steady 50psi. Truck runs great otherwise...
Thoughts, feedback and questions craved. Thanks for your time.
23-06-06 10-25-18.hpl
23-06-05 18-06-27.hpl
23-06-05 18-15-30.hpl
23-06-06 09-51-33.hpl
Wynnded 2011 Tundra SC'd.hpt
The problem generally stems from cranking injector pulsewidth, exasperated by a few factors (altitude, higher fuel pressure, etc.). Unfortunately, that isn't defined in the calibration for your truck (it would be under Engine -> Fuel -> General -> Cranking Fuel). Here's what that table looks like for a non-SC truck, for reference:
Cranking Injector.PNG
As a bandaid, we can come in and add to the base startup airflow table (Engine -> Idle -> Airflow -> Startup -> Startup Airflow ECT) to bring in some more air and offset the excess cranking fuel. Startup Airflow IAT can be worked as well, as the greater of the ECT and IAT tables will determine the cranking target.
You'd referenced trying Startup Airflow with mixed success - what values and which table(s) were you using?
Other feedback
From your logs, you're getting quite a few Cylinder 7 misfires - have you done any troubleshooting to see what's going on there?
While you didn't ask for it, just a word of caution: you have component protection disabled, but haven't added fuel in PE.
Thank you for your time and insight, I really appreciate it.
I have seen this table in other calibrations, usually in 2018 and newer versions, but never for what appears to be a FFV version like in the screenshot. I have wished that it was available in my calibration as it seems to me that's where the issue would be best improved.
Yes, I have dabbled with both Startup Airflow ECT and IAT tables focusing on the columns where temperatures are above 100?F as this is where the starting difficulty resides. This is one of the first things that I tried. I began with adding small amounts to the stock values, then I increased them in greater increments. I can't recall at present how high I went with the values (utilizing both tables) as it was some time ago, but it could be that I blew right past a workable value or got frustrated when the initial attempts were nonproductive. I will go back again with a more systematic methodology. I see that the values have a possible range from 0 to 20 L/s, I'll break that down and respond with feedback/results. Maybe I wasn't diligent enough with that trial and I've been chasing around in the wrong areas of the tune.
The posted version of the calibration is my Base version that I make individual alterations to so that I don't get too many changes mixed up and lose track of them. The misfires were from an experimental variation that I abandon upon getting them. The same applies to PE/component protection as I'm trying to keep my focus on the starting aspect; I'm not that far into my tune yet. Your assessment was more thorough than I was expecting, many thanks for that. I should have feedback some time tomorrow.
Additional: For reference, I see in the Airflow ECT table that the lowest value for Barometric Pressure is 86.7 kPa. Where I live it's 75.3 kPa. Would there be any benefit to scaling that axis to reflect that?
Last edited by Wynnded; 06-06-2023 at 08:12 PM.
The "easy" way to work Startup Airflow ECT is to take an airflow value from a temperature you know works - say 50F - then carry that forward into higher temps at the same baro. Knowing that we shouldn't need more air than that at higher ECT, you can then simply iterate downwards (say, 10-20% at a time) for the higher temps until you get a satisfactory start - too much airflow and it will struggle to start, a little high and it will have some excessive startup flare.
Startup Airflow IAT is a little trickier, and sorta requires a reasonable Startup Airflow ECT to be tuned well, so better to save that for later, if it ultimately needs much attention at all.
Yes, you can try scaling the axis some to get more range in the table, since you'll regularly see low baro.
Here's an example revision, showing how that the ECT table may look with a scaled axis and increased airflow at low baro (this is just notional, so you'll have to make adjustments): Wynnded 2011 Tundra SC'd EDITS Example.hpt
This file uses a later TRD startup airflow table as the base, with some of the drop in the 14F - 50F range smoothed, the 50F airflow carried forward at 75 kPa, and the 87.5 kPa set roughly in between. Keep in mind your current base has the older TRD startup table, which has a big shot of airflow (>7 L/s) at 50F - 86F and 86.7 kPa, so if you have startup issues with the attached file, you may try something similar to your current file. The basic idea for the ECT table remains the same, though: find a startup temperature that works well, carry that airflow value forward to higher temps, then iterate the airflow value downwards.
I had a little time to earlier to try some of what you just suggested, of sorts. I looked at the value in the 50?F/86.7kPa cell (a temperature where the vehicle starts perfectly, in essence, a cold start) and somewhat arbitrarily input 5 L/s. I am certain that this is a value quite a bit greater than what I tried in previous experiments. As you mentioned, this may be a little bit too high as there is a startup flare. The thrilling thing is that there isn't the sooty puff at the tailpipe. Excited to finally be on the right path! Tomorrow I'll experiment with incrementally reducing that to minimize the flare.
I have noticed that 2008-2011 and 2012+ have different Airflow ECT table values and will be altering the one originally associated with my calibration, that's what prompted me to start with such a large value. I will also rescale the barometric pressure axis. If tuning the Airflow ECT table if found to be too coarse, maybe that would be an indication to have a go at the Airflow IAT table for a finer adjustment.
This is great, when I get this sorted I can look at PE and Component Protection which I know you've discussed with Snivilous and written about in great detail. ZPhilip, he and I have been scratching our heads on this starting issue to no avail and I know this will make them happy as well. I'll report on how this goes tomorrow.
Thanks again!
For the IAT table, the basic procedure is:
1) Drive until the ECT reaches operating temp, then shut it off immediately after stopping (to keep IAT low).
2) Restart the truck and note any issues (flare, excessive cranking). Add/remove to address long crank/flare if IAT airflow is greater than ECT, otherwise make the corrections to the ECT table.
3) Let the truck idle until maximum IAT is reached, and shut it off.
4) Repeat (2); restart the truck, note any issues (flare, excessive cranking), and adjust the appropriate IAT cell as needed.
Getting the ECT table working well should be done first, just be mindful of where the IAT table may command more airflow. You can zero out the IAT table while working on the ECT to prevent it from affecting startups, then use a similar approach to start tuning the IAT table (start with a high value, and decrease until excessive flare disappears) once the ECT table is done.
Keep us posted on any questions, issues, or successes you have.
Your timing is impeccable, I just returned from trying out some basic Airflow ECT values and a drive. While doing so, I was trying to imagine a scenario where IATs might ever be greater than ECTs. I was unable to. ECT operating temps are in the neighborhood of 185+ degrees, and I've never seen an IAT of greater than 130?F and that was after shutting off the engine and heat soaking the engine compartment. In such a case, when restarting the engine, the AITs drop 15-20 degrees. Even after letting the engine sit for a couple of hours, I can't say that I've noticed IATs > ECTs. Maybe this is just a regional phenomenon with the really thin air. Maybe this will lessen the time necessary for this procedure, possibly even eliminating it. I suppose time will tell. I tend to get ahead of myself.
Are you familiar with what stored information HPT is "erasing" when it flashes as it relates to this? I noticed that after a flash (tweaking LTFTs, no Airflow ECT change) when I restarted, there was a puff of black from the tailpipe even with the higher values in the Airflow ECT cells from last evening. I'm wondering if I should discount those observations and only take into account warm/hot starts when there have been no changes as that's more in line with a typical restart scenario.
Speaking of getting ahead of myself, it's tricky for me to not consider what might be recommended if I happen to reach values in the 86?F ECT and greater columns that are equal to the presently greatest value in the table, in this case, the 50?F column. I'd be inclined to go with even greater values until I experience startup flare/lean hard start but thought I should inquire as a safety measure. There's still a lot of airflow to go up to as suggested by the 0-20L/s range indicated in the software for that table. Thoughts....
Meanwhile, so far every starting event has been brief and successful on the first attempt. This is a great improvement!
To clarify, the IAT table value is referenced if the airflow value is greater than in the ECT table, not the temperature.
Referencing the base values per your earlier file:
IAT-ECT Comparison.PNG
If we had a startup where IAT was at 120F and ECT was at 185F, the IAT airflow would be 1.25 L/s (via linear interpolation) and the ECT airflow would be 0.0781 L/s, so the greater airflow value of the two (IAT) would be referenced and startup airflow would be 1.25 L/s, even though the IAT temp is less than ECT.
In practice, this means that, for the base calibration, cold starts are dominated by the ECT table (ECT airflow is greater than IAT airflow for the majority of cases where ECT temp = IAT temp), hot starts by the IAT (minimum IAT airflow is greater than ECT airflow for ECT of 158F+), and warm starts can be either one (because of the interpolation in airflow values between ECT of 86F and 158F relative to the floor of 0.47 in the IAT table).
The first start and drive after a flash can be a bit funny, particularly if it's warm, so it's usually something you can disregard. Just keep an eye on it for subsequent starts not immediately after writing and address as needed.Are you familiar with what stored information HPT is "erasing" when it flashes as it relates to this? I noticed that after a flash (tweaking LTFTs, no Airflow ECT change) when I restarted, there was a puff of black from the tailpipe even with the higher values in the Airflow ECT cells from last evening. I'm wondering if I should discount those observations and only take into account warm/hot starts when there have been no changes as that's more in line with a typical restart scenario.
Other than the issues you mentioned (hard start, excessive flare), not really any risk. Just be sure to make reasonable increments and keep testing so you don't accidentally step far outside of a useful value.Speaking of getting ahead of myself, it's tricky for me to not consider what might be recommended if I happen to reach values in the 86?F ECT and greater columns that are equal to the presently greatest value in the table, in this case, the 50?F column. I'd be inclined to go with even greater values until I experience startup flare/lean hard start but thought I should inquire as a safety measure. There's still a lot of airflow to go up to as suggested by the 0-20L/s range indicated in the software for that table. Thoughts....
Meanwhile, so far every starting event has been brief and successful on the first attempt. This is a great improvement!
Last edited by SlowNStock; 06-07-2023 at 03:55 PM.
Copy, thanks for the clarification. ECU looks at ECT and IAT tables and utilizes the greater airflow value and applies it for startup.
Understood.The first start and drive after a flash can be a bit funny, particularly if it's warm, so it's usually something you can disregard. Just keep an eye on it for subsequent starts not immediately after writing and address as needed.
10L/s appears to fit that bill. Hard warm start and misfires. BoundariesOther than the issues you mentioned (hard start, excessive flare), not really any risk. Just be sure to make reasonable increments and keep testing so you don't accidentally step far outside of a useful value.
This morning I went out and trialed values for Startup Airflow ECT at the listed temperatures in the table. I zeroed out the IAT table to avoid confusion. In the attached tune are what seemed to work for no startup flare and minimal sooty puff from the tailpipe upon post-flash restart.
Here's the bugger; when I return to the vehicle later in the day, say after 90 minutes pass, two attempts are required to get it to start again and there's notable soot upon firing. That log is included.
Wynnded 2011 Tundra SC'd ECT IAT Testing.hpt
23-06-08 11-37-31.hpl
Quick thoughts from the log and cal:
1) You'll want to blend the ECT airflow across baro, otherwise small changes in baro above 75 kPa result in fairly significant changes in airflow.
2) The MAF transfer function has been changed quite a bit with some irregularities - are you running the TRD/Magnuson intake?
3) We're still seeing quite a few Cyl 7 misfires after startup, so it would be worth checking the plug, and swapping the coil and injector each to a different cylinder to see if the misfire follows.
Overall, the logged startup being more challenging without a tuned IAT airflow table isn't entirely untoward, as it has a warm ECT, but fairly high IAT.
Got it. I went into it thinking that it would be better to change as few cells as possible.
I don't know what MAF transfer function is. I have a Hewitt SAIS bypass kit installed that makes some changes to the signal to the ECU from the ECT and IAT sensors. I've had it connected and disconnected at various times and I don't notice that it makes any difference relating to the starting issue that I'm experiencing other than that the SAIS pumps don't run when it's connected and they do when it isn't according to however Toyota has the system set to run. I disconnected it this morning before experimenting and will leave it so for the duration of this process.2) The MAF transfer function has been changed quite a bit with some irregularities - are you running the TRD/Magnuson intake?
Yes, the intake I have installed is the TRD/Magnuson system that it came with originally; the air filter is an AFE dry filter element. There are no modifications to the airbox.
Ya wow, hadn't been looking at that. I went back and looked at logs that I made while making adjustments and they were happening then as well. Something else that I noticed on logs where I made changes, flashed and started the engine, there were more misfires on that first post-flash restart and far fewer to none on subsequent restarts. I moved the Cyl 7 plug to Cyl 6 (logs indicated no misfires for that cylinder) and the coil to Cyl 4.3) We're still seeing quite a few Cyl 7 misfires after startup, so it would be worth checking the plug, and swapping the coil and injector each to a different cylinder to see if the misfire follows.
Overall, the logged startup being more challenging without a tuned IAT airflow table isn't entirely untoward, as it has a warm ECT, but fairly high IAT.
I watched misfires more closely today. On cold start (50F) there were 3 misfires, Cyl 2 had 1, and Cyl 4 had 2. On 95F start there were misfires for Cyls 1,3,4, and 5. I don't know if this is typical or not. As the engine warmed, the misfires became less in number and frequency. They never seemed to be dominated by one specific cylinder, they were just all over the place. The only exception that I might note was that after everything was warmed up and on the first start after a flash, Cyl 1 had the most misfires (up to 13) with infrequent others in random cylinders. As things settled, they decreased to zero. Subsequent restarts without a flash had minimal or zero misfires, as the engine continued to run, there were zero additional misfires. I logged while on an errand and there are now pending codes for P0300, P0301, and P0307. I hadn't realized this was occurring.
Tomorrow I think I'm going to try the example ECT table that you posted and see if I can make any progress.
Usually a good approach to limit the changes, but have to also be careful about making an "island" where there's a large difference from adjacent cells. Don't have to be overly scientific about it, just smoothing vertically between 75 and 100 kPa a couple times will get it in the ballpark.
My mistake, should have been clearer - that's the Engine -> Airflow -> General -> MAF Calibration -> Airflow vs. Voltage table. "Transfer function" is the generic name for these tables - it's any function (in this case, a lookup table) that converts (transfers) an input (sensor voltage) to an output (mass airflow).I don't know what MAF transfer function is. I have a Hewitt SAIS bypass kit installed that makes some changes to the signal to the ECU from the ECT and IAT sensors. I've had it connected and disconnected at various times and I don't notice that it makes any difference relating to the starting issue that I'm experiencing other than that the SAIS pumps don't run when it's connected and they do when it isn't according to however Toyota has the system set to run. I disconnected it this morning before experimenting and will leave it so for the duration of this process.
Yes, the intake I have installed is the TRD/Magnuson system that it came with originally; the air filter is an AFE dry filter element. There are no modifications to the airbox.
Since you are running the TRD/Magnuson airbox unmodified, your transfer function should be unchanged, and any changes should result in a smooth, approximately polynomial function - the only real exception being due to intake design issues (MAF too close to a transition, bend, TB, etc.). The table in your most recent file has some fairly significant changes in a few places and some irregularity overall.
Misfires immediately after startup and writing are pretty common and nothing to worry much about, but the regular misfires on 7 jumped out as a possible injector leak given your starting issue.Ya wow, hadn't been looking at that. I went back and looked at logs that I made while making adjustments and they were happening then as well. Something else that I noticed on logs where I made changes, flashed and started the engine, there were more misfires on that first post-flash restart and far fewer to none on subsequent restarts. I moved the Cyl 7 plug to Cyl 6 (logs indicated no misfires for that cylinder) and the coil to Cyl 4.
I watched misfires more closely today. On cold start (50F) there were 3 misfires, Cyl 2 had 1, and Cyl 4 had 2. On 95F start there were misfires for Cyls 1,3,4, and 5. I don't know if this is typical or not. As the engine warmed, the misfires became less in number and frequency. They never seemed to be dominated by one specific cylinder, they were just all over the place. The only exception that I might note was that after everything was warmed up and on the first start after a flash, Cyl 1 had the most misfires (up to 13) with infrequent others in random cylinders. As things settled, they decreased to zero. Subsequent restarts without a flash had minimal or zero misfires, as the engine continued to run, there were zero additional misfires. I logged while on an errand and there are now pending codes for P0300, P0301, and P0307. I hadn't realized this was occurring.
You may need to increase the values based on your recent testing, just be sure to blend that increase per the above.Tomorrow I think I'm going to try the example ECT table that you posted and see if I can make any progress.
Speaking of "island", how about that one in the 50-86F cells of the 2007-2011 models. The newer Startup Airflow ECT table didn't work out, so I reverted to the older one and hopefully made some improvements.
I think that I've made some improvements to this table in terms of smoothness. This would bring us to the matter of Fuel Trims though. That table was a result of trying to get LTFTs that were near zero. Is that not the goal that it seems to be made out to be? I've never seen fuel trims from a stock engine, so I don't know what kind of percentage swings are typical. How much correction is normally left to the ECU? I know that it has limitations. I understood that the intent was to minimize that swing.My mistake, should have been clearer - that's the Engine -> Airflow -> General -> MAF Calibration -> Airflow vs. Voltage table. "Transfer function" is the generic name for these tables - it's any function (in this case, a lookup table) that converts (transfers) an input (sensor voltage) to an output (mass airflow).
Since you are running the TRD/Magnuson airbox unmodified, your transfer function should be unchanged, and any changes should result in a smooth, approximately polynomial function - the only real exception being due to intake design issues (MAF too close to a transition, bend, TB, etc.). The table in your most recent file has some fairly significant changes in a few places and some irregularity overall.
I'm beginning to recognize this pattern after startup and writing. Cyl 1 looks to misfire the most after writing but then stops. Other seemingly random cylinders misfire too, but less so and then stop. Cyl 7 will sometimes miss post-write, other times it won't. After start and things settling, Cyl 7 might occasionally see a miss, other times nothing. We did do a pressure test a month or so ago and found nothing suggesting a leaking injector.Misfires immediately after startup and writing are pretty common and nothing to worry much about, but the regular misfires on 7 jumped out as a possible injector leak given your starting issue.
This morning it seems that I was motivated enough to swap around some fuel injectors. 1 <---> 3, and 5 <---> 7.
I drove it around some with this tune: Wynnded 2011 Tundra SC'd ECT IAT LTFT Testing.hpt
And the first log: 23-06-11 09-50-03.hpl
The occasional misfires that were seen at Cyl 7 now appear to be at Cyl 5, and a single miss at Cyl 6. What is considered acceptable and what warrants replacing the injector? It has occurred to me that considering that there weren't misses at other cylinders, that that would be enough to warrant replacement, but I'm just speculating.
The vehicle sat for 90 minutes, and here's that log on the same tune: 23-06-11 11-27-02.hpl
This one was still a really sooty start, but much smoother than in the past. I attribute this to no misses immediately after starting. There are again occasional misses at Cyl 5. Subsequent restarts on this tune were also quite sooty.
I changed this tune by bumping up the Startup Airflow ECT considerably: Wynnded 2011 Tundra SC'd ECT IAT LTFT Testing2.hpt
And the log: 23-06-11 11-31-38.hpl
Here, as has been mentioned, there are post writing misses upon start. Then there are the now familiar spotty misses at Cyl 5. The restarts were much less sooty.
Then there's a log after just sitting for a few minutes, no tune changes: 23-06-11 11-36-19.hpl
Note that there are misses at other cylinders, but none at Cyl 5. This observation is the basis for my "acceptable amount" question.