Boosting with Faulty Knock sensor
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Joined: Mar 2001
Posts: 470
Boosting with Faulty Knock sensor
Ok. I have a previous post concerning hesitation under boost. I checked for vacuum leaks and everything seems fine. I do get full boost at 4psi, egt's are normal and fuel is good. However, I do have a faulty knock sensor... The ohm reading is below norm and the ECU reports code 0304...
Now the knock sensor can either advance or retard timing under engine loads. But if the knock sensor is bad, a safe table is used by the ECU. This safe table will allow the car to drive under minimal conditions... But when boosting, how would this affect performance??
I did a test run in 3rd under boost and the rpm’s will not go above 4200. Not in boost it will climb past that threshold and rev smoothly... Even at idle it revs out smoothly.
Do you think the knock sensor will cause this problem??? Or is it a MAF issue?
Now the knock sensor can either advance or retard timing under engine loads. But if the knock sensor is bad, a safe table is used by the ECU. This safe table will allow the car to drive under minimal conditions... But when boosting, how would this affect performance??
I did a test run in 3rd under boost and the rpm’s will not go above 4200. Not in boost it will climb past that threshold and rev smoothly... Even at idle it revs out smoothly.
Do you think the knock sensor will cause this problem??? Or is it a MAF issue?
Do you hear the engine pinging, I don't know if the ECU can compesate and try to save the engine from cracking a piston? You might be detonating really bad in one or more cylinders but I have no idea what I am talking about.
Thread Starter
Senior Member
Joined: Mar 2001
Posts: 470
No the engine is not pinging. But in vacumm everything runs good.. I guess under-boost the safe-tables in the ECU can not handle boosted pressure without the knock sensor functioning correctly... I'm going to replace the kS and subharness... This should fix things, otherwise Im **** out of luck...
Originally Posted by spanishrice
Do you hear the engine pinging, I don't know if the ECU can compesate and try to save the engine from cracking a piston? You might be detonating really bad in one or more cylinders but I have no idea what I am talking about.
I'm throwing the 0304 code now too. Threw it a few days after the turbo went in, and I keep resetting it, but it keeps coming back, so I think it's time for a new one. But my car is running totally fine. It goes up to redline in any gear, I just dynod it at 256 whp which seems ballpark where it should be.
I had a MAF problem too, but when that was happening, the car just wouldn't run. It kept stalling at idle.
I had a MAF problem too, but when that was happening, the car just wouldn't run. It kept stalling at idle.
Originally Posted by Morfeus17
Ok. I have a previous post concerning hesitation under boost. I checked for vacuum leaks and everything seems fine. I do get full boost at 4psi, egt's are normal and fuel is good. However, I do have a faulty knock sensor... The ohm reading is below norm and the ECU reports code 0304...
Now the knock sensor can either advance or retard timing under engine loads. But if the knock sensor is bad, a safe table is used by the ECU. This safe table will allow the car to drive under minimal conditions... But when boosting, how would this affect performance??
I did a test run in 3rd under boost and the rpm’s will not go above 4200. Not in boost it will climb past that threshold and rev smoothly... Even at idle it revs out smoothly.
Do you think the knock sensor will cause this problem??? Or is it a MAF issue?
Now the knock sensor can either advance or retard timing under engine loads. But if the knock sensor is bad, a safe table is used by the ECU. This safe table will allow the car to drive under minimal conditions... But when boosting, how would this affect performance??
I did a test run in 3rd under boost and the rpm’s will not go above 4200. Not in boost it will climb past that threshold and rev smoothly... Even at idle it revs out smoothly.
Do you think the knock sensor will cause this problem??? Or is it a MAF issue?
Thread Starter
Senior Member
Joined: Mar 2001
Posts: 470
OK.. I see.. Well I just changed both my KS and Sub-harness today... My 0304 code is totally gone... But I'm still getting a bit of hesitation under-boost at 4200rmp. And at times it would hesitate for a second then clear up, then the rpms will go straight to redline... At this point there are no trouble codes.. My next test would be to change the fuel filter, it may be clogged??? Then probabaly my fuel pump and MAF... This problem is a bit strange...
Thanks for the feedback.
Thanks for the feedback.
Originally Posted by Shadow
I'm throwing the 0304 code now too. Threw it a few days after the turbo went in, and I keep resetting it, but it keeps coming back, so I think it's time for a new one. But my car is running totally fine. It goes up to redline in any gear, I just dynod it at 256 whp which seems ballpark where it should be.
I had a MAF problem too, but when that was happening, the car just wouldn't run. It kept stalling at idle.
I had a MAF problem too, but when that was happening, the car just wouldn't run. It kept stalling at idle.
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