AFR wierd issue.
Aug 15, 2014, 07:37 AM
#1
Evolving Member
Thread Starter
AFR wierd issue.
Hi mates. I am experiencing a wierd AFR-related issue and really need some help and new ideas to sort it out.
The car is Evo8 2004 with evo9 turbo and different bolt ons - deatchwerks fuel pump, 3" exhaust, kelford264, tubular ex manifold, ets intake, piping and IC, ID1000 injectors (812 scaling, 0.936@14v 1.2@11.76v), Innovate LC1 for AFR monitoring. Tephra7 9653 MAF rom. It uses full time open loop for now. No boost leaks, no exhaust leaks, timing is dead on.
The problem is that the car is going super lean (18-21) on idle and super rich (10-9) on partial loads. The car behaves accordingly to super rich and super lean AFR.
At first it starts fine holding 13.3 at 1000rpm idle, but then in a few minutes (8-10) it drops to ~21ish at 500-700rpm almost dying. Logs sometimes show that at this moment it starts using AFRMAP 17.1, thats very strange as I dont have any numbers leaner than 14.7 in Fuel maps in that rom. But most of time it follows fuel map, giving wierd real afr. As for super rich condition it shows correct AFRMAP numbers.
Any ideas what can cause such issue?
The car is Evo8 2004 with evo9 turbo and different bolt ons - deatchwerks fuel pump, 3" exhaust, kelford264, tubular ex manifold, ets intake, piping and IC, ID1000 injectors (812 scaling, 0.936@14v 1.2@11.76v), Innovate LC1 for AFR monitoring. Tephra7 9653 MAF rom. It uses full time open loop for now. No boost leaks, no exhaust leaks, timing is dead on.
The problem is that the car is going super lean (18-21) on idle and super rich (10-9) on partial loads. The car behaves accordingly to super rich and super lean AFR.
At first it starts fine holding 13.3 at 1000rpm idle, but then in a few minutes (8-10) it drops to ~21ish at 500-700rpm almost dying. Logs sometimes show that at this moment it starts using AFRMAP 17.1, thats very strange as I dont have any numbers leaner than 14.7 in Fuel maps in that rom. But most of time it follows fuel map, giving wierd real afr. As for super rich condition it shows correct AFRMAP numbers.
Any ideas what can cause such issue?
Last edited by Biggy VIII; Aug 15, 2014 at 01:49 PM.
Aug 15, 2014, 05:35 PM
#6
Evolving Member
Thread Starter
The car is in open loop, so no fuel trims. Anyway you can compare AFRMAP to LC1 afr in idle and cruise areas of the map...
Aug 15, 2014, 05:37 PM
#7
Evolving Member
Thread Starter
Trending Topics
Aug 16, 2014, 08:20 PM
#8
When you retuned for the larger injectors did you remember to also change your idle, start up, and accel tables? You have to decrease the amount of fuel added by the ratio of the increase in your injector scaling increase...
Read the sticky "Advanced fuel tuning" by Mr Fred
Read the sticky "Advanced fuel tuning" by Mr Fred
Aug 17, 2014, 06:51 AM
#10
Seems like there are compensations being added to increase the effective ipw on the rich side ( some don't adjust the afr map value as I recall) and a similar thing on the lean side except it occasionally does effect the afr map value ..
How is lean spool set ? On or off and with periphery bit or adjustment to start and stop? Absolutely positive about no exhaust leaks? There must be a compensation table for fuel based on something like iat and perhaps the iat sensor is fluctuating in the maf?
How is lean spool set ? On or off and with periphery bit or adjustment to start and stop? Absolutely positive about no exhaust leaks? There must be a compensation table for fuel based on something like iat and perhaps the iat sensor is fluctuating in the maf?
Aug 17, 2014, 10:49 AM
#11
Biggy VIII,
Start by checking the fuel pressure at the injector rail on idle. Check it when the AFR is good at 13.3, and also when it goes very lean. You will need a pressure gage and adaptor. Also probe the voltage at the pump. If the pressure remains constant at 3 bar (42 - 45 psi), this test will quickly eliminate the fuel pump, the pump low voltage circuit, and the FPR as the source of your problem. If the pressure drops, the FPR valve may not be seating correctly, the fuel filter or line may be blocked, or the fuel pump may be bad. Check the fuel pump low voltage for any variation, the inlet sock, filter and feed pipes for blockages.
Next use the fuel pump actuator button in Evoscan to measure the fuel pressure at full pump voltage. Monitor the voltage at the pump. Again pressure should remain at 3 bar and voltage constant. If voltage is not constant, check all three fuel pump relays and the resistor pack.
Grab a friend, and get them to monitor pressure and fuel pump voltage during a WOT run. If pressure is too high the FPR could be sticking closed, or there could be a blockage in your return line.
If everything looks good with the fuel supply, the next thing to test are your injectors and FPR for leaks. Start then stop your engine and watch the fuel pressure gauge. It should not drop much over two minutes. If it does, watch the rate of drop and troubleshoot as follows:
Start, then stop the engine and squeeze the fuel return line closed. If the pressure no longer drops this means a leak from a bad FPR - valve not seating or weak spring.
Next, squeeze the supply line closed and check the pressure drop. If it stops the drop, you have a bad fuel pump check valve.
Finally, if it continues to drop with fuel supply and return lines squeezed closed, your injectors are leaking. Pull them out and get them inspected and cleaned.
When everything is good with the fuel system, move on to the MAF air temp thermistor. Log it with Evoscan (MAF air temp scaled on MUT 11), to see if it is reading too high during idle, or too low during WOT. The ECU compensates for air temp and this could be the cause for your symptoms. Pull the plug and measure the resistance between terminals 5 and 6. Standard values:
13 − 17 kΩ [at −20°C (−4°F)]
5.3 − 6.7 kΩ [at 0°C (32°F)]
2.3 − 3.0 kΩ [at 20°C (68°F)]
1.0 − 1.5 kΩ [at 40°C (104°F)]
0.56 − 0.76 kΩ [at 60°C (140°F)]
0.30 − 0.42 kΩ [at 80°C (176°F)]
If you still don't find anything wrong test the engine coolant temp sensor. This would have a much smaller effect on open loop AFR. Drain the coolant and pull the sensor from the thermostat housing. Put it in a water bath, heat it slowly, and use a thermometer to measure temp while you check resistance. Standard values:
14 − 17 kΩ [at −20°C (−4°F)]
5.1 − 6.5 kΩ [at 0°C (32°F)]
2.1 − 2.7 kΩ [at 20°C (68°F)]
0.9 − 1.3 kΩ [at 40°C (104°F)]
0.48 − 0.68 kΩ [at 60°C (140°F)]
0.26 − 0.36 kΩ [at 80°C (176°F)]
The only other thing that I can think of that could cause the symptoms you describe is the rheostat track in the TPS (throttle position sensor). Pull the plug and probe pins 1 (left) and 4 (right). Resistance should be 3.5 - 6.5 kΩ. Probe pins 1 and 2 as you open the valve. The resistance should change smoothly in proportion to the angle of opening with no jumps in the reading.
Good luck! Post up how you go.
Start by checking the fuel pressure at the injector rail on idle. Check it when the AFR is good at 13.3, and also when it goes very lean. You will need a pressure gage and adaptor. Also probe the voltage at the pump. If the pressure remains constant at 3 bar (42 - 45 psi), this test will quickly eliminate the fuel pump, the pump low voltage circuit, and the FPR as the source of your problem. If the pressure drops, the FPR valve may not be seating correctly, the fuel filter or line may be blocked, or the fuel pump may be bad. Check the fuel pump low voltage for any variation, the inlet sock, filter and feed pipes for blockages.
Next use the fuel pump actuator button in Evoscan to measure the fuel pressure at full pump voltage. Monitor the voltage at the pump. Again pressure should remain at 3 bar and voltage constant. If voltage is not constant, check all three fuel pump relays and the resistor pack.
Grab a friend, and get them to monitor pressure and fuel pump voltage during a WOT run. If pressure is too high the FPR could be sticking closed, or there could be a blockage in your return line.
If everything looks good with the fuel supply, the next thing to test are your injectors and FPR for leaks. Start then stop your engine and watch the fuel pressure gauge. It should not drop much over two minutes. If it does, watch the rate of drop and troubleshoot as follows:
Start, then stop the engine and squeeze the fuel return line closed. If the pressure no longer drops this means a leak from a bad FPR - valve not seating or weak spring.
Next, squeeze the supply line closed and check the pressure drop. If it stops the drop, you have a bad fuel pump check valve.
Finally, if it continues to drop with fuel supply and return lines squeezed closed, your injectors are leaking. Pull them out and get them inspected and cleaned.
When everything is good with the fuel system, move on to the MAF air temp thermistor. Log it with Evoscan (MAF air temp scaled on MUT 11), to see if it is reading too high during idle, or too low during WOT. The ECU compensates for air temp and this could be the cause for your symptoms. Pull the plug and measure the resistance between terminals 5 and 6. Standard values:
13 − 17 kΩ [at −20°C (−4°F)]
5.3 − 6.7 kΩ [at 0°C (32°F)]
2.3 − 3.0 kΩ [at 20°C (68°F)]
1.0 − 1.5 kΩ [at 40°C (104°F)]
0.56 − 0.76 kΩ [at 60°C (140°F)]
0.30 − 0.42 kΩ [at 80°C (176°F)]
If you still don't find anything wrong test the engine coolant temp sensor. This would have a much smaller effect on open loop AFR. Drain the coolant and pull the sensor from the thermostat housing. Put it in a water bath, heat it slowly, and use a thermometer to measure temp while you check resistance. Standard values:
14 − 17 kΩ [at −20°C (−4°F)]
5.1 − 6.5 kΩ [at 0°C (32°F)]
2.1 − 2.7 kΩ [at 20°C (68°F)]
0.9 − 1.3 kΩ [at 40°C (104°F)]
0.48 − 0.68 kΩ [at 60°C (140°F)]
0.26 − 0.36 kΩ [at 80°C (176°F)]
The only other thing that I can think of that could cause the symptoms you describe is the rheostat track in the TPS (throttle position sensor). Pull the plug and probe pins 1 (left) and 4 (right). Resistance should be 3.5 - 6.5 kΩ. Probe pins 1 and 2 as you open the valve. The resistance should change smoothly in proportion to the angle of opening with no jumps in the reading.
Good luck! Post up how you go.
Aug 18, 2014, 08:31 AM
#13
It's definitely these jumps in AFRMAP. They are making the injector duty cycle go crazy.
Try to find what affects it. I know that lean spool affect it, coolant temp affect it.
-Lean spool on and off are set a the same RPM value?
-Do you read coolant temp at the right place (MUT10, Formula: 1.8x-40)
Maybe something in this ROM is corrupted. You could start with a downloaded V7 ROM and XML and copy over the tables.
Try logging 2byte compensated load
Try to find what affects it. I know that lean spool affect it, coolant temp affect it.
-Lean spool on and off are set a the same RPM value?
-Do you read coolant temp at the right place (MUT10, Formula: 1.8x-40)
Maybe something in this ROM is corrupted. You could start with a downloaded V7 ROM and XML and copy over the tables.
Try logging 2byte compensated load
Last edited by domyz; Aug 18, 2014 at 08:35 AM.
Aug 18, 2014, 09:07 AM
#14
Evolving Member
Thread Starter
Most of time it happens following correct AFRMAP from the fuel map, but sometimes it follows wierd 17.1 number.
As an example - I know that turning off closed loop in periphery bits, makes ECU follow wierd AFRMAP that is not actual Fuel map value, and also makes it hunting at idle.
Any more opinion on injector scaling and latencies used? I've used them a lot of times, +\- varying them a bit depending on setup. I could make the car drivable by using 960 scaling(which seems to be too high in my opinion) and adding some more latency at 12 and 14 volts. But that just doesnt seem right.
Ok some more facts:
- lean spool is off in periphery bits and by settin start and stop points at the same rpm
- I've tried using several different ROMs as a staring point, including fresh downloaded rom from Tephra V7 dedicated thread.
- Injectors are brand new ID1000
- Coolant temperature and Air temperature readings are adequate. Both are using correct requests and formulas in evoscan.
- It behaves about the same way, but milder with stock maf-turbo intake pipe.
- the car rand just fine and responded to ROM tuning adequately before Cams, IC, piping,
intake and injectors installation.
- Timing set correct. Checked twice.
As an example - I know that turning off closed loop in periphery bits, makes ECU follow wierd AFRMAP that is not actual Fuel map value, and also makes it hunting at idle.
Any more opinion on injector scaling and latencies used? I've used them a lot of times, +\- varying them a bit depending on setup. I could make the car drivable by using 960 scaling(which seems to be too high in my opinion) and adding some more latency at 12 and 14 volts. But that just doesnt seem right.
Ok some more facts:
- lean spool is off in periphery bits and by settin start and stop points at the same rpm
- I've tried using several different ROMs as a staring point, including fresh downloaded rom from Tephra V7 dedicated thread.
- Injectors are brand new ID1000
- Coolant temperature and Air temperature readings are adequate. Both are using correct requests and formulas in evoscan.
- It behaves about the same way, but milder with stock maf-turbo intake pipe.
- the car rand just fine and responded to ROM tuning adequately before Cams, IC, piping,
intake and injectors installation.
- Timing set correct. Checked twice.
Last edited by Biggy VIII; Aug 18, 2014 at 09:09 AM.
Aug 18, 2014, 09:11 AM
#15
Most of time it happens following correct AFRMAP from the fuel map, but sometimes it follows wierd 17.1 number.
As an example - I know that turning off closed loop in periphery bits, makes ECU follow wierd AFRMAP that is not actual Fuel map value, and also makes it hunting at idle.
Any more opinion on injector scaling and latencies used? I've used them a lot of times, +\- varying them a bit depending on setup. I could make the car drivable by using 960 scaling(which seems to be too high in my opinion) and adding some more latency at 12 and 14 volts. But that just doesnt seem right.
Ok some more facts:
- lean spool is off in periphery bits and by settin start and stop points at the same rpm
- I've tried using several different ROMs as a staring point, including fresh downloaded rom from Tephra V7 dedicated thread.
- Injectors are brand new ID1000
- Coolant temperature and Air temperature readings are adequate. Both are using correct requests and formulas in evoscan.
- It behaves about the same way, but milder with stock maf-turbo intake pipe.
- the car rand just fine and responded to ROM tuning adequately before Cams, IC, piping,
intake and injectors installation.
- Timing set correct. Checked twice.
As an example - I know that turning off closed loop in periphery bits, makes ECU follow wierd AFRMAP that is not actual Fuel map value, and also makes it hunting at idle.
Any more opinion on injector scaling and latencies used? I've used them a lot of times, +\- varying them a bit depending on setup. I could make the car drivable by using 960 scaling(which seems to be too high in my opinion) and adding some more latency at 12 and 14 volts. But that just doesnt seem right.
Ok some more facts:
- lean spool is off in periphery bits and by settin start and stop points at the same rpm
- I've tried using several different ROMs as a staring point, including fresh downloaded rom from Tephra V7 dedicated thread.
- Injectors are brand new ID1000
- Coolant temperature and Air temperature readings are adequate. Both are using correct requests and formulas in evoscan.
- It behaves about the same way, but milder with stock maf-turbo intake pipe.
- the car rand just fine and responded to ROM tuning adequately before Cams, IC, piping,
intake and injectors installation.
- Timing set correct. Checked twice.
1byte load is not compensated.
At least log 2byte compensated Load
Last edited by domyz; Aug 18, 2014 at 09:15 AM.