Code 52.... WTF, Replace Everything

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supraguy31

New Member
May 10, 2005
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Pembroke, NC
Im having a Problem with a Code 52, It only comes on when I either rev the engine above 2800 rpms or I Accelorate it to that Level at Normal Driving.

Ive Replaced both Sensors even though Both of them checked out fine VIA TSRM
New 87-88 Supra Manual tranny Wiring Harness Straight from Toyota and I have replaced the ECU with 3 good ones and Im still gettting this dam Code 52.

Can someone please tell me what Ive forgotten. I think im having Problems with the AFM as if I start the car up, It will run great at High Idle, Once it warms up and Drops below 1000 rpms, The A/F drops off the earth and it stumbles badly. If I tap to top of the sensor it Idle Jumps back up and runs fine for a minute then starts it again, Tap once more and same thing Occurs.

Please someone help me here. Im out of Options and this certain car is being sold once I resolve these Issues. Buyer is patiently waiting for this to be resolved.

Thanks for all of your time and I love this Community. Alot of great People and alot of good Advice.

Robert
 
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suprahooked

Built 7M
Jun 20, 2006
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supraguy31 said:
Im having a Problem with a Code 52, It only comes on when I either rev the engine above 2800 rpms or I Accelorate it to that Level at Normal Driving.

Ive Replaced both Sensors even though Both of them checked out fine VIA TSRM
New 87-88 Supra Manual tranny Wiring Harness Straight from Toyota and I have replaced the ECU with 3 good ones and Im still gettting this dam Code 52.

Can someone please tell me what Ive forgotten. I think im having Problems with the AFM as if I start the car up, It will run great at High Idle, Once it warms up and Drops below 1000 rpms, The A/F drops off the earth and it stumbles badly. If I tap to top of the sensor it Idle Jumps back up and runs fine for a minute then starts it again, Tap once more and same thing Occurs.

Please someone help me here. Im out of Options and this certain car is being sold once I resolve these Issues. Buyer is patiently waiting for this to be resolved.

Thanks for all of your time and I love this Community. Alot of great People and alot of good Advice.

Robert
Click to expand...
The stumbling make me think igniter or in the spark system. But pm Jetjock he will help you.
 
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supraguy31

New Member
May 10, 2005
626
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Pembroke, NC
I did, He said do a Re-Wire on the Knock Sensors but this was before I got the New Harness. So Im still Stumped at this. I need this car gone and for $4,000 Dollar Its my Motivation to get it fixed. Just need someone Elses thinking cap on this with me.

Also, If I dont tap on the AFM, It starts to smoke out the Exhaust and smell like Raw fuel, Tap the AFM and it goes away.

Robert
 
bigaaron

bigaaron

Supramania Contributor
Apr 12, 2005
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www.driftmotion.com
I had a similar problem on my car, it had a knock sensor code at random even after installing a new engine harness and several different knock sensors. I went standalone before I had a chance to figure out what the problem was. JetJock would be the best guy to ask about this. I'll send him a link to the thread.
 
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supraguy31

New Member
May 10, 2005
626
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Pembroke, NC
Thanks I appreciate the Help on this matter. Im just at a loss here and Ive never ran into a Situation with a motor that I havent been able to figure out.

Robert
 
jetjock

jetjock

creepy-ass cracka
Jul 11, 2005
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Redacted per Title 18 USC Section 798
Throwing parts at a problem is never good technique and having new (if they are new) sensors and a harness means nothing to the ECU. Clean and correct signals are what matter. You need to verify the sensors are working and the sginals are arriving at the ECU. The easiest way to do that is with a meter (a scope would be better) right at the ECU connector either while driving or rapping near (never on) the sensor. Try whacking the intake manifold with a wrench; that usually excites the piezo element. The shielding of the the wiring also needs to be verified. If everything checks out then it has to be the ECU. Same with the AFM. It's all about measuring signal quality although it sounds as if the AFM does have a problem. Could be a bad connector though. The only way to know for sure is to measure it.
 
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supraguy31

New Member
May 10, 2005
626
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Pembroke, NC
I will recheck the Sensors tomorrow and Give ya a Update. I really really want this Solved.

Its just funny that when the Idle drops to the point that the car is Sputtering really bad and I lightly tap the top of the AFM Sensor the Idle jumps back up or slowly moves back up to normal Idle and all the Raw fumes go away from the Exhaust. Im goingto go over toa Friends and Borrow his AFM and see what the Outcome there is.

Robert
 
jetjock

jetjock

creepy-ass cracka
Jul 11, 2005
9,439
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Redacted per Title 18 USC Section 798
That's actually not strange at all. The AFM is one of the two main inputs the engine uses to calculate the basic fuel injection duration, the duration used before all the other corrections are applied. I can tell you from running my engine off a frequency generator instead of the AFM that the ECU is very fussy about the signal it receives that represents airflow. It takes very little error to completely drive the loop out of fuel control.

Btw, I tell you to measure and what are you going to do? Swap out more parts....
 
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supraguy31

New Member
May 10, 2005
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Pembroke, NC
Im sure that would have nothing what so ever to do with the code Popping up would it. Im just throwing stuff out there. Its only at 2800+rpms that it pops on. I can rev it up t0 2400rpms all day and not get the code.
 
jetjock

jetjock

creepy-ass cracka
Jul 11, 2005
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Redacted per Title 18 USC Section 798
What code, the knock code of 52? No, the AFM has little to do with that. However, we need to define what you mean by "code". A code being set in memory is not the same as an MIL that illuminates. Several conditions have to be met for the MIL to come on and code 52 is handled in an even more special way. In other words the MIL won't come on as soon as a knock sensor fault is detected. Other things have to happen first. Exceeding a certain rpm is just one of them. You have to be careful...the diagnostic system in this engine is both stupid and sophisticated at the same time.
 
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supraguy31

New Member
May 10, 2005
626
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Pembroke, NC
That is correct. Everything right now is geared around the Code 52.

Again, I can reset the ECU and check for any Codes I get Blinking light as no codes are found. If I rev the motor up to 2400rpms and check to see if anything comes on or if I have any codes.... Nothing but as soon as It hits 2800rpms then the CEL comes on and I get a Code 52
 
jetjock

jetjock

creepy-ass cracka
Jul 11, 2005
9,439
0
0
Redacted per Title 18 USC Section 798
He claims to have a new harness and sensors Nick. Then again he also claims the knock sensors "checked out" according to the TRSM. Since I'm unaware of any procedure in the book for doing that I don't know what to think at this point. All I know is this should be a simple problem to resolve by using a bit of signal tracing.
 
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supraguy31

New Member
May 10, 2005
626
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0
Pembroke, NC
I just have a New Harness. I have Multiple Knock Sensors here here that Basically Im installing, Running the car and Pulling out once I get the Code 52. I was told that the Best way to ensure Knock Sensors were good is to tap on them the way you recommended not too... Im going to redo the Signals today the way you recommended and see how it comes out. Again, Sorry for the Misunderstanding. I was told that the way I did check them was in the Manual but I never looked myself. Basically taking work of mouth.

Robert
 
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supraguy31

New Member
May 10, 2005
626
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0
Pembroke, NC
I dont

Crazy Question for you. If you look at the block from the Side that the Knock Sensors screw in. you Definitely know where the rear Knock Sensor hole is. and you see where the Front Knock Sensor hole is also. Question is what is that other Hole a little farther Forward but a Little Higher on the Block. Ive seen Knock Sensors Screwed into it before. Just wondering what that hole is for and infact it serves a Prurpose.
 
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suprahooked

Built 7M
Jun 20, 2006
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supraguy31 said:
I dont

Crazy Question for you. If you look at the block from the Side that the Knock Sensors screw in. you Definitely know where the rear Knock Sensor hole is. and you see where the Front Knock Sensor hole is also. Question is what is that other Hole a little farther Forward but a Little Higher on the Block. Ive seen Knock Sensors Screwed into it before. Just wondering what that hole is for and infact it serves a Prurpose.
Click to expand...

The knock sensors are inline with #2 cyl and # 5 cyl and the front sensors is slighty higher on the block than the back sensor.
Are you sure you have the front sensors in the correct spot?
 
S

suprahooked

Built 7M
Jun 20, 2006
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pa
suprahooked said:
The knock sensors are inline with #2 cyl and # 5 cyl and the front sensors is slighty higher on the block than the back sensor.
Are you sure you have the front sensors in the correct spot?
Click to expand...

p699172_1.jpg
 
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