The proverbial light at the end of the tunnel for the S4:
After months of whittling down symptom after symptom, I've finally narrowed it down to two final problems. Here is the long list of symptom and cures...mind you, ALL the symptoms existed concurrently. The evolution has been a process of uncovering and curing one symptom at a time:
1. Throttle Cut: Caused by a faulty/old Mass Air Flow (MAF) sensor. Cured by swapping out a new one...picked one up for free from a trade of parts I had on hand.
2. Throttle Bucking: Caused by faulty/old Exhaust Gas Temp (EGT) sensor. Cured by swapping out both banks...PITA to R&R and expensive to boot...got a great deal through Audizine classifieds.
3. Poor gas mileage and part throttle hesitation: Caused by faulty/old primary Oxygen (O2) sensors. Cured by swapping out both primary banks...another PITA DIY and also quite expensive...another bargain found on Audiworld classified.
4. Boost surging: After several pressure test discovered it was caused by a rupture in the bank 2 Up-pipe to the throttle body. Cured with new up-pipe...easy DIY, picked up a nearly new one for free from an Audiworld brother.
5. Total engine power cut: Caused by lower intercooler hose slippage. Cured by double clamping both inlet and outlet with Zebra Hi-Torques...only an act of god will pop it off now.
6. Boost Spike beyond normal parameters, 27 psi!: Discovered with the use of the Uber AWE Tuning vent boost gauge. Cured by downloading GIAC Manual Boost Controller (MBC) program, re-flashing the ECU to accept MBC control, and lowering boost spike via lap-top to 24 psi spike to 21 psi taper.
7. 16805 and 16815 efficiency error codes: Caused by inefficient hi-flow catalytic converters. Cure...nope, I'm leaving this one for the new owner. More an inconvenience than anything else.
8. Oil Leak: Caused by cracked oil pan and old gasket and sealant. Cured by replacing oil pan, gasket, and sealant.
9. Premature Waste-gate actuation: Caused by faulty/old N75 wastegate valve. Cured by swapping out N75 valve...easy DIY and pretty cheap part, even new.
And the FINAL symptoms to square away to get the engine in tip-top shape:
- Boost fluttering at part-throttle and near WOT conditions. Don't know the cause, could by a torn wastegate line...very difficult fix, can't do this one myself, could be costly so I'm crossing my fingers.
- Leaking raw coolant: Don't know the cause, not too problematic given the coolant is RAW meaning it has not flowed through the engine. Could be due to splashing coolant in the resevoir spilling out into and through the resevoir hose.
When these final issues are resolved, the car will be put up for sale...after a couple of weeks of enjoying the motor at full bore...hehe.
1. Throttle Cut: Caused by a faulty/old Mass Air Flow (MAF) sensor. Cured by swapping out a new one...picked one up for free from a trade of parts I had on hand.
2. Throttle Bucking: Caused by faulty/old Exhaust Gas Temp (EGT) sensor. Cured by swapping out both banks...PITA to R&R and expensive to boot...got a great deal through Audizine classifieds.
3. Poor gas mileage and part throttle hesitation: Caused by faulty/old primary Oxygen (O2) sensors. Cured by swapping out both primary banks...another PITA DIY and also quite expensive...another bargain found on Audiworld classified.
4. Boost surging: After several pressure test discovered it was caused by a rupture in the bank 2 Up-pipe to the throttle body. Cured with new up-pipe...easy DIY, picked up a nearly new one for free from an Audiworld brother.
5. Total engine power cut: Caused by lower intercooler hose slippage. Cured by double clamping both inlet and outlet with Zebra Hi-Torques...only an act of god will pop it off now.
6. Boost Spike beyond normal parameters, 27 psi!: Discovered with the use of the Uber AWE Tuning vent boost gauge. Cured by downloading GIAC Manual Boost Controller (MBC) program, re-flashing the ECU to accept MBC control, and lowering boost spike via lap-top to 24 psi spike to 21 psi taper.
7. 16805 and 16815 efficiency error codes: Caused by inefficient hi-flow catalytic converters. Cure...nope, I'm leaving this one for the new owner. More an inconvenience than anything else.
8. Oil Leak: Caused by cracked oil pan and old gasket and sealant. Cured by replacing oil pan, gasket, and sealant.
9. Premature Waste-gate actuation: Caused by faulty/old N75 wastegate valve. Cured by swapping out N75 valve...easy DIY and pretty cheap part, even new.
And the FINAL symptoms to square away to get the engine in tip-top shape:
- Boost fluttering at part-throttle and near WOT conditions. Don't know the cause, could by a torn wastegate line...very difficult fix, can't do this one myself, could be costly so I'm crossing my fingers.
- Leaking raw coolant: Don't know the cause, not too problematic given the coolant is RAW meaning it has not flowed through the engine. Could be due to splashing coolant in the resevoir spilling out into and through the resevoir hose.
When these final issues are resolved, the car will be put up for sale...after a couple of weeks of enjoying the motor at full bore...hehe.
posted by supergoober at
11:48 AM
1 Comments:
Hell no!...though my wife would love the idea. I've narrowed it down to 3 cars:
1. E46 M3, used. If I can find a bone stock car with sub 25K miles within my price range, I'm takin it.
2. Subaru Imprezza WRX STI, 05 or 06 model, super-low miles with Spec-C comparable mods.
3. EVO 9, no 8's or lower. Low miles with preferably a WORKS stage 2 package or comparable.
Regardless, and needless to say, I ain't modding the motor to my next car. The suspension will be completely dismantled, replaced, and upgraded, and perhaps some sub-frame strengthening bits but that's about it.
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