745volver
Member
- Joined
- Oct 3, 2010
- Location
- Modesto CA
Volvo 940 running rich
1991 940 SE Turbo. 295k miles. Car is all stock
Family member was driving the car prior to the issue so I cannot comment on what lead up to this condition. All I was told was it was getting terrible gas mileage.
Symptoms:
1. Poor performance. Sluggish acceleration. Got 12.4 mpg on a 150 mile all highway trip. Black smoke out of the exhaust. Low and lumpy idle.
2. Throws five codes
3-1-2: Signal missing for knock-related fuel enrichment
2-1-3: Throttle switch full load setting faulty or grounding short
2-2-2: Signal missing to/from idle air control valve
1-1-3: Fuel trim (Lambda Control) too lean or rich
2-3-2: Fuel trim too lean or rich at idle.
3. The car also does not start with the spiked idle speed and then settle to the 750 rpm range?.it starts as if running really rich at around 450 rpm and struggles to climb to about 600 rpm where it settles. This is especially worse at operating temperature.
What I have done:
1. Cleaned the throttle body
2. Tested TPS switch when I had the throttle body off. Also, distinctive click is heard on cracking the throttle.
3. Inspected for vacuum leaks with a smoke machine. Also inspected for boost leaks with a homemade pressure tester. Found none
4. Tested and inspected the wiring for the engine coolant temperature sensor at the ECU with the ECU connector cover removed. (Pins 13 and ground). Within spec for hot and cold engine according to the FAQ page.
5. Inspected plugs. All four are equally sooty.
6. Swapped the o2 sensor. No change. I am getting about .85 volts at idle and .6 volts is as low as I can get the signal feed to go with throttle manipulation on either o2 sensor. From what I read, it sounds like it should be fluctuating back and forth around .45 volts as the ECU adjusts the mixture.
7. Car has a new catalytic converter
8. FPR tested. Pressure sits at 43 psi. Also swapped with a known good unit with no change.
9. Swapped the ECU. No change. Throws the same codes with either ECU.
10. Inspected and tightened ground straps. Nothing loose or out of place.
11. New plugs/wire/cap and rotor.
12. Timing is within spec.
13. Inspected all underhood wiring. Nothing out of place found.
14. Not sure on LH 2.4 ability to ?learn? or not, but the car sat with the battery off overnight in an attempt to reset it.
15. Swapped the AMM and IAC valve from a donor car. No change.
16. I unplugged the cold start injector and the car runs worse. Was curious if it was stuck open.
I know these Volvo codes are to be taken with a grain of salt, but due to it throwing 5 codes, I am leaning towards a wiring issue?which should be a joy to track down IF that is the problem.
I also have a 1990 740 turbo that I have been using as a donor car to swap parts but I am now at a loss for which direction to go to search for a solution.
Any ideas are greatly appreciated! This one has me stumped. Any major players in the mixture control that I haven?t mentioned or should be aware of?
1991 940 SE Turbo. 295k miles. Car is all stock
Family member was driving the car prior to the issue so I cannot comment on what lead up to this condition. All I was told was it was getting terrible gas mileage.
Symptoms:
1. Poor performance. Sluggish acceleration. Got 12.4 mpg on a 150 mile all highway trip. Black smoke out of the exhaust. Low and lumpy idle.
2. Throws five codes
3-1-2: Signal missing for knock-related fuel enrichment
2-1-3: Throttle switch full load setting faulty or grounding short
2-2-2: Signal missing to/from idle air control valve
1-1-3: Fuel trim (Lambda Control) too lean or rich
2-3-2: Fuel trim too lean or rich at idle.
3. The car also does not start with the spiked idle speed and then settle to the 750 rpm range?.it starts as if running really rich at around 450 rpm and struggles to climb to about 600 rpm where it settles. This is especially worse at operating temperature.
What I have done:
1. Cleaned the throttle body
2. Tested TPS switch when I had the throttle body off. Also, distinctive click is heard on cracking the throttle.
3. Inspected for vacuum leaks with a smoke machine. Also inspected for boost leaks with a homemade pressure tester. Found none
4. Tested and inspected the wiring for the engine coolant temperature sensor at the ECU with the ECU connector cover removed. (Pins 13 and ground). Within spec for hot and cold engine according to the FAQ page.
5. Inspected plugs. All four are equally sooty.
6. Swapped the o2 sensor. No change. I am getting about .85 volts at idle and .6 volts is as low as I can get the signal feed to go with throttle manipulation on either o2 sensor. From what I read, it sounds like it should be fluctuating back and forth around .45 volts as the ECU adjusts the mixture.
7. Car has a new catalytic converter
8. FPR tested. Pressure sits at 43 psi. Also swapped with a known good unit with no change.
9. Swapped the ECU. No change. Throws the same codes with either ECU.
10. Inspected and tightened ground straps. Nothing loose or out of place.
11. New plugs/wire/cap and rotor.
12. Timing is within spec.
13. Inspected all underhood wiring. Nothing out of place found.
14. Not sure on LH 2.4 ability to ?learn? or not, but the car sat with the battery off overnight in an attempt to reset it.
15. Swapped the AMM and IAC valve from a donor car. No change.
16. I unplugged the cold start injector and the car runs worse. Was curious if it was stuck open.
I know these Volvo codes are to be taken with a grain of salt, but due to it throwing 5 codes, I am leaning towards a wiring issue?which should be a joy to track down IF that is the problem.
I also have a 1990 740 turbo that I have been using as a donor car to swap parts but I am now at a loss for which direction to go to search for a solution.
Any ideas are greatly appreciated! This one has me stumped. Any major players in the mixture control that I haven?t mentioned or should be aware of?