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on a side note, unless you are running ethanol free gasonline, your stoich value should be 14.108 not 14.67. most pump gas around the country is mixed 10% ethanol content.
on a side note, unless you are running ethanol free gasonline, your stoich value should be 14.108 not 14.67. most pump gas around the country is mixed 10% ethanol content.
Dang I didn't realize it was that low, thanks for the tip!
There is a table known as charge temp blending that by default gives too much weight to the IAT instead of ECT. I found much more stable tuning/data when I scaled the weight over to the ECT side since its more stable typically than IAT is.
I played with the charge temp bias table some after reading a lot of threads about it, iirc you were in some of them. Got it to where the iat doesn't change the afr as much, 30* over what it should be and afr is high 15s. But the cold start is stupid rich now until the ect gets up over 155 or so. Olfa is at 1.0 and it doesn't seem to be afterstart enrichment, it is 90* in the mornings so I don't figure it needs to be that rich. May explore it some more when I get some free time.
Dang I didn't realize it was that low, thanks for the tip!
That is correct. But if you are OL and using a wideband I thought it didn't really matter? Since lambda is same for any fuel and the WB hits the lambda value with an equation that makes it 14.7. It's like guys running E85 but still have the WB on the gas scale.
Could be way off on this but that is what I thought to be true
I played with the charge temp bias table some after reading a lot of threads about it, iirc you were in some of them. Got it to where the iat doesn't change the afr as much, 30* over what it should be and afr is high 15s. But the cold start is stupid rich now until the ect gets up over 155 or so. Olfa is at 1.0 and it doesn't seem to be afterstart enrichment, it is 90* in the mornings so I don't figure it needs to be that rich. May explore it some more when I get some free time.
If it's stupid rich on cold start it's either the OL commanded fuel tables, or a adder. The afterstart enrichment has always been key for me to stop an overly rich condition at startup. This of course assumes the MAF and VE is dialed in.
If it's stupid rich on cold start it's either the OL commanded fuel tables, or a adder. The afterstart enrichment has always been key for me to stop an overly rich condition at startup. This of course assumes the MAF and VE is dialed in.
I may could have left the stupid off and just said rich lol. It is low 13s at startup and once the ect gets over 150- 160 it comes up to 14.7ish. I am SD so no maf, I put it back closed loop and it's a lot better obviously. But my stft cold start are like -12 then they come up to -2 or so. I'm pretty sure its ect based but haven't found the right table. I took the afterstart to 1.0 or whatever no change is and it made no difference. Been a month or so since I was playing with it tho
I may could have left the stupid off and just said rich lol. It is low 13s at startup and once the ect gets over 150- 160 it comes up to 14.7ish. I am SD so no maf, I put it back closed loop and it's a lot better obviously. But my stft cold start are like -12 then they come up to -2 or so. I'm pretty sure its ect based but haven't found the right table. I took the afterstart to 1.0 or whatever no change is and it made no difference. Been a month or so since I was playing with it tho
That sounds correct. Your OL commanded fuel tables likely shoots for 13s around 120 or 130. You shouldn't shoot for stoich on startup unless it's a hot start.
Interesting. You run full open loop no narrowbands at all? Where is your IAT located? I believe mine and the OPs are in the same place, the intake manifold. Where in the charge pipe pre TB may not be as bad. And it's not terrible, if I let it idle or just sitting after driving for 10- 15 mins the IAT temps will climb. My research found a lot a guys with similar issue even in fbodies with the ist in the stock location. It is a non issue now that I've got stfts adjusting it.
no narrowbands on my truck at all.
iat sensor is in the charge pipe a few inches from the throttlebody.
Just to re-post, my friend moved his air intake to behind the headlight. He also installed a heat shield - and installed the IAT in the same location.
I'm not sure if that is what fixed the problem or not, but this go around of tuning I used the "real time tuning" to where we never stopped the car and WOW, we got all AFR errors down to 0% just within an hour!! It was amazing seeing the tuning process actually work. I wasn't aware that you can stop logging/restart logging without screwing up the RAM VE table, once I saw that you can change the VE table and reset the scanner, that made everything super easy
His IAT stayed consistently at 96-99 degrees the whole drive
So I have my friends car tuned now, but mine is still giving me hell
Would an increase of 10 degree IAT and a 10 degree coolant temp make the AFR go from 13.1 to a 14.9 ????????????
I was getting consistent fueling, but once my IAT went from 100 to 110 degrees and my coolant went from 190 to 200, the AFR went lean without making any adjustments.. I disabled cylinder charge temperature also, this didn't do anything either - same result of going lean after the car increases in temp
Would an increase of 10 degree IAT and a 10 degree coolant temp make the AFR go from 13.1 to a 14.9 ????????????
I was getting consistent fueling, but once my IAT went from 100 to 110 degrees and my coolant went from 190 to 200, the AFR went lean without making any adjustments.. I disabled cylinder charge temperature also, this didn't do anything either - same result of going lean after the car increases in temp
I think to see if this is the issue, I'm going to install a resistor in in the IAT plug that will make the IAT stay constant (using resistor that gives close to ambient temp). If that fixes the issue, I'm going to be moving my IAT to the outlet of the intercooler. Right now my sensor is right before the throttle body in an aluminum pipe. The fans from the radiator flow directly onto this pipe. Wondering if this is my issue.
Would an increase of 10 degree IAT and a 10 degree coolant temp make the AFR go from 13.1 to a 14.9 ????????????
I was getting consistent fueling, but once my IAT went from 100 to 110 degrees and my coolant went from 190 to 200, the AFR went lean without making any adjustments.. I disabled cylinder charge temperature also, this didn't do anything either - same result of going lean after the car increases in temp
I think to see if this is the issue, I'm going to install a resistor in in the IAT plug that will make the IAT stay constant (using resistor that gives close to ambient temp). If that fixes the issue, I'm going to be moving my IAT to the outlet of the intercooler. Right now my sensor is right before the throttle body in an aluminum pipe. The fans from the radiator flow directly onto this pipe. Wondering if this is my issue.
If you're sure youre in open loop, that charge temp blending is the only thing that will do it assuming you dont have some other scalar/adder going on. Is the timing the same between the 2 AFR's/temps?
I've been chasing cooling issue for a while, so today I decided to make sure all the air was out the system.
I had the scanner running on HPTuners, logging coolant temp, IAT, and spark. For some reason the wideband wasn't logging, but I could see the AFR via my guage.
I Had the radiator fans forced OFF to get the engine up to a higher temp around 210.
The temp got up to 212, so the radiator started boiling over (I had one of those radiator refill funnels on the cap, so no big deal). I turned the fans ON to cool the temp back down. The AFR was 14.6 for the duration of the fans being OFF. Right when I turned the fans on, the AFR started climbing and you can see the IAT temp start climbing. The idle spark stayed constant during this whole time, so that didn't end up being the issue.
So the radiator fans blow on my intake pipe (which has the IAT sensor in it) is causing this lean condition..
Here is the chart. You can see the coolant temp start dropping right when I turn the fans on, and the IAT start to climb. When the red line (ECT) bottoms out, I turn the fans back OFF - and you can see the IAT (white line) start to decline (going back to the correct IAT value).
Have you verified fuel pressure? I had the same issue you did and it turned out to be inconsistent fuel pressure @ the rails. Once I fixed that, everything was finally stable.
Hook up a fuel pressure gauge and verify.
Originally Posted by TXjeepTJ
I Had the radiator fans forced OFF to get the engine up to a higher temp around 210.
I'm confused as to why you did this. What was your reasoning behind this? Why not just tune it to the true temperature, aka the temperature with real world conditions such as having radiator fans on? Genuine question, not condescending.
Also, the higher the IAT temps, the richer it would be running. Someone correct me if I'm wrong. Higher IAT = less air mass?
Unless, you have vapor lock at the rails, causing you to run lean. Which would indeed happen if you turned your rad. fans off..
Have you verified fuel pressure? I had the same issue you did and it turned out to be inconsistent fuel pressure @ the rails. Once I fixed that, everything was finally stable.
Hook up a fuel pressure gauge and verify.
I'm confused as to why you did this. What was your reasoning behind this? Why not just tune it to the true temperature, aka the temperature with real world conditions such as having radiator fans on? Genuine question, not condescending.
Also, the higher the IAT temps, the richer it would be running. Someone correct me if I'm wrong. Higher IAT = less air mass?
Unless, you have vapor lock at the rails, causing you to run lean. Which would indeed happen if you turned your rad. fans off..
I have a fuel pressure gauge on the rails, dead flat on 55 or so psi the entire time (I run a boost reference regulator)
I forced the fans off, not to tune, but to get the engine up to a high temp because I was messing with a different issue (coolant system related). That's when I noticed this issue showing itself really bad. Before I would notice it, but only while driving or after shutting the car off and turning it back on, but figured it was due to something else.
Hotter air = engine pulls fuel (hot air is less dense, requires less fuel)
My IAT would spike due to the radiator fans pushing very hot air on it, this false spike would make the PCM pull fuel.
Another major issue that caused this that I just found out the the other day - I had my "cylinder charge temperature" disabled, meaning it relied 100% on the IAT temps for it's fueling calculations.. I moved the IAT sensor away from the hot radiator fan air, and also ENABLED cylinder charge temp and set the BIAS to 1.00 so it doesn't pay much attention to the IAT for fueling calcs. This solved my issue 100%.
Back when I started this thread, it was brought up about the cylinder charge temperature table. The stock table, when enabled, favors the IAT 85% and engine temp 15% (it had a value 0.3ish, so my % is based of of 1.00 being 50/50) - which was also not helping the issue. Switching to a 1.00 value, means it's supposed to look at IAT 50% and ETC 50%, but after doing some testing it looks like it favors ETC more, which is fine by me.
I did some testing yesterday after making those changes, I let the car idle for 20 minutes, had the fans come on at 210 to blow hot air into the engine bay. AFR stayed the same the entire time, where as before it would spike.
I've seen this pretty often with SD fueling. IAT in a hot aluminum pipe at low airflow conditions.... the radiant heat from the surrounding hot metal becomes a significant factor and causes the IAT to read higher than actual. And with IAT actual < IAT indicated, it pulls significant fuel, thus lean condition. Once you have significant airflow, the radiant heat xfer becomes negligible. So, IAT placement is very important with speed density. My Focus ST is SD fueling from the factory and they put the IAT on the intercooler end tank, which makes sense, it being "outside" the engine bay and all.
I have EFI Live but it says that a value of 1.0 in the bias table ignores IAT completely? But it allows a max value of 2.0, so maybe that's a typo. But either way, surely coolant temp is way higher than IAT generally.. .I'm not sure how biasing it towards coolant temp more is helping the lean situation here. Unless I'm missing something here. I am glad you got it sorted, but the solution doesn't quite make sense to me.
I have EFI Live but it says that a value of 1.0 in the bias table ignores IAT completely? But it allows a max value of 2.0, so maybe that's a typo. But either way, surely coolant temp is way higher than IAT generally.. .I'm not sure how biasing it towards coolant temp more is helping the lean situation here. Unless I'm missing something here. I am glad you got it sorted, but the solution doesn't quite make sense to me.
I have this problem too but am slowly fixing it. I moved my iat sensor to the intercooler outlet, and it still wanders around some. I believe it gathering heat from the radiator 2 inches away now. But slowly raising the low air of the bias table is bringing it in.
to your question, the coolant temp is not as likely to wonder or be affected my heat soak. And the computer isnt saying the air temp is 195 degrees. The bias temp or mat temp is a calculation it does using the iat and ect, have no idea what formula is used tho. Should be floating around some where.
07-30-2018, 06:39 PM
