When hot, it goes lean
Jul 15, 2017, 11:57 AM
#1
Evolving Member
Thread Starter
When hot, it goes lean
Gentlemen,
To give you an idea on the conditions in my country in the summer, we have 45c = 113 F ambient temperature at night. On the Cobb screen i see 125 F intake air temps as soon as oil is in operating temps. After some city stop and go traffic i see 161 F IATs.
The intercooler performance is good and as soon i go WOT manifold air temps matches exactly IAT and in some cases drops 1-2 degrees below it.
When IAT temps are around 140 F and i go WOT no issues whatsoever and my AFR is solid around 11.8. Once IAT temps go beyond 150F, at WOT my AFR goes to 15s quickly. Also in slow driving and off boost, AFR goes lean and i can feel the engine struggling to get going in the low RPM below 2000.
I already changed the fuel rely to the latest one and it helped for a while, but problem is back again. Once car is off and cooled off, i can get few WOT runs with no issue.
As you can see in my build, i have Asnu fuel pump and im starting to suspect that it cant operate under these temps.
Anyone here have another theory on what could cause such lean conditions in hot operating temps?
To give you an idea on the conditions in my country in the summer, we have 45c = 113 F ambient temperature at night. On the Cobb screen i see 125 F intake air temps as soon as oil is in operating temps. After some city stop and go traffic i see 161 F IATs.
The intercooler performance is good and as soon i go WOT manifold air temps matches exactly IAT and in some cases drops 1-2 degrees below it.
When IAT temps are around 140 F and i go WOT no issues whatsoever and my AFR is solid around 11.8. Once IAT temps go beyond 150F, at WOT my AFR goes to 15s quickly. Also in slow driving and off boost, AFR goes lean and i can feel the engine struggling to get going in the low RPM below 2000.
I already changed the fuel rely to the latest one and it helped for a while, but problem is back again. Once car is off and cooled off, i can get few WOT runs with no issue.
As you can see in my build, i have Asnu fuel pump and im starting to suspect that it cant operate under these temps.
Anyone here have another theory on what could cause such lean conditions in hot operating temps?
Jul 15, 2017, 09:39 PM
#3
Evolving Member
Thread Starter
Last summer with stock fuel pump i didnt have this issue so not sure about fuel temps causing such issues. Also my other cars using the same fuel doesn't act like this.
What do you mean by MAT temps?
Jul 16, 2017, 11:04 AM
#5
Evolving Member
Thread Starter
Yes the Asnu fuel pump is wired to OEM connection and in the same location of the stock pump.
Not sure if the stock fuel pump can handle the 18k turbo fuel needs, but im thinking to switch it to see if thats the issue. Unless there is something else i can check before doing the fuel pump swap again.
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