Ka24det Idle/Tuning

[r3b]

So I picked up my car this weekend and before I got it I new there was a weird idle going on and wasn't sure why. Everything else checked out fine when driving, just the idle was pretty rough and could smell very rich fuel in the air. Ive been looking mainly at sr20 engines and information to that since I was originally going to get a s13 with a blacktop swap but they guy was a **** and asking way to much money. I found a fairly clean, newly painted, 1992 s13 with the original ka and a turbo.

So here is the dilemma, right now I got the car to idle perfect at 950-1000 rpms by cleaning out the spark plugs which were very very very black on the tips and hardly worn out and by increasing the safc lo setting across the board by 10%. The car didnt bog at all and the smell of rich fuel wasnt in the air but a more burnt lean smell was around. What I noticed was that my air/fuel ratio was around 13.7-13.5 which was so strange since thats pretty lean. If I tried to decrease the lo setting or set all the ne's to 0% in the safc my air/fuel ratio would increase but my car would idle more and more like s***. I tried messing with the deccair setting but that didn't do much.

Thats what I have done right now to the car and it sounds strong but whats concerning is the lean air/fuel ratio and if I try to make it even the slightest bit richer the car would bog and idle like s***.

Before I did all of that ^ I initalized the safc which basically the engine reads normal off the ecu. When I did this the rpm would jump down to low as 700 and go high as 1300. It would settle down after 5 minutes but you could smell very dark and rich fuel around the car. My air/fuel gauge would also jump around with the rpm as well and would go low as high 14s and even touch sometimes 20...

I think there is also something wrong with how the previous owner has the turbo setup since if I try to give the car some foot I could hear the turbo spool but I could never get anything past 0psi of boost, the gauge only shows the vacuum pressure and when I put foot the gauge stops at 0psi. IIRC the guy told me his wastegate is set to 6psi and hasn't touched his manual boost controller to add more boost to the car.

His set up goes air into turbo with no filter, air goes into hot pipe where the BOV sits, then the air goes through the FMIC, then exits to the cold pipe where the MAF is and then goes to the engine intake. Normally I would see in setups that the MAF would be before the filter and then to the turbo. Then the BOV was on the cold air pipe on the other side of the car.

Another strange thing about the previous owners setup was that he had 720cc injectors.... Ive seen similar ka-t builds and the highest ive seen for injectors was 550. Do you think that having such big injectors is dumping way to much fuel into the engine and is running way to rich and causing to idle like s***? I think that could be an issue and also might be a vacuum leak somewhere. I dont know exactly what he asked for when he shipped his ecu to be tuned but I could give a list of all the parts he put on. Any sticky threads on tuning I should read or turbo building on a ka would help tons. Ive only found a couple basically saying setups but no details the process of installing and tuning the car for the turbo.

rs-enthalpy tune
aem wideband
s14 intake manifold
3in downpipe
thich gauge turbo manifold
720cc injectors
z32maf
new water pump
new radiator
emmisions deleted
battery relocated
no egr or cat
ac was lost due to downpipe rubbing on ac line
new break master cylinder
new alternator
new starter
2 new rear calipers, pads
raceland coiulovers
full isi adjustable arms
solid subframe bushings
j30 diff
Energy suspension rack
Safc
All electronics working and not rust.

[65ShelbyClone]

Although I'm not well-versed in the realm of KA-T setups, yours is questionable even in a general sense. Why is an SAFC involved when the ECU has been chipped already? The MAF and injector parameters should have been put on the chip....or was chipped at all? The blow-through MAF is also a big can of worms all by itself; it's usually done to overcome atmospheric flow limitations of an undersize MAF. You're also stuck taking the PO's word on what your injector size actually is.

Before I did all of that ^ I initalized the safc which basically the engine reads normal off the ecu. When I did this the rpm would jump down to low as 700 and go high as 1300. It would settle down after 5 minutes but you could smell very dark and rich fuel around the car. My air/fuel gauge would also jump around with the rpm as well and would go low as high 14s and even touch sometimes 20...

That suggests to me that the ECU is still set up for smaller injectors. The 20:1 AFR is indicative of a misfire, not what the AFR actually was. Lean misfires and rich misfires both show up as a lean condition on a wideband.

I think there is also something wrong with how the previous owner has the turbo setup since if I try to give the car some foot I could hear the turbo spool but I could never get anything past 0psi of boost, the gauge only shows the vacuum pressure and when I put foot the gauge stops at 0psi. IIRC the guy told me his wastegate is set to 6psi and hasn't touched his manual boost controller to add more boost to the car.

Where is the boost gauge tapping a signal from?

His set up goes air into turbo with no filter, air goes into hot pipe where the BOV sits, then the air goes through the FMIC, then exits to the cold pipe where the MAF is and then goes to the engine intake. Normally I would see in setups that the MAF would be before the filter and then to the turbo. Then the BOV was on the cold air pipe on the other side of the car.

One benefit of running the MAF downstream of the BOV is that metered air isn't venting to atmosphere and won't screw with the mixture...

Another strange thing about the previous owners setup was that he had 720cc injectors.... Ive seen similar ka-t builds and the highest ive seen for injectors was 550. Do you think that having such big injectors is dumping way to much fuel into the engine and is running way to rich and causing to idle like s***? I think that could be an issue and also might be a vacuum leak somewhere. I dont know exactly what he asked for when he shipped his ecu to be tuned but I could give a list of all the parts he put on. Any sticky threads on tuning I should read or turbo building on a ka would help tons. Ive only found a couple basically saying setups but no details the process of installing and tuning the car for the turbo.

Large injectors alone are not a problem, but the tune for them is. Unfortunately I think you need to do a lot of backtracking in order to verify what the PO told you vs. what was really done.

[r3b]

So I basically figured out the idling issue and was a mixture of everything but about a week ago after I got the idle fine it ran super rich and even with trying to lean out the afr with the safc which I basically initialized my afr would not go higer than 10. I switched off the car and herd a loud slap/noise and it wouldn't start.

Im thinking my injectors were finished and leaked way to much fuel into the car now and caused a hydrolock. Literally five minutes ago I looked at the start and it was broken to pieces... Good thing is, nothing internally is broken and now all I got to do is basically get a new tune on the right injectors, get ride of the blow through maf setup and get new vacuum lines and piping. Here is a picture of the broken starter lol