Performance Issue

[Backlash2032]

Well, my car was seeming slower than usual, and it started burning oil on deceleration and after boosting. Typical blown turbo symptoms. So I purchased a 57 trim CT off a member on here. Expecting to rip the tires off the first time I hit boost in first gear after the turbo swap, instead, it felt nearly the same as before the 57 trim.

By the way, this is a BPU 7M. Full 3 inch turbo back exhaust, 2.5 inch intercooler piping, with fmic, and the CT26 57 trim.

Ive checked for boost leaks and couldn't find any. This was capping both ends of the intercooler piping, and putting 15-20 psi in it. I couldnt find a leak, although there could be one I didn't find.

One of the things i thought of was this. I redid the knock sensor wiring when I had the engine out, and I ohmed out the wiring. I had 1 ohm. When I checked the wiring on my n/a harness, I had like 7 ohms or so. Is that going to be a problem? I never got a code 52 with the n/a wiring. I have, though, occasionally got a code 52 with the new wiring, but after clearing it takes a couple months for it to show up again. Is the wiring not resistive enough for the knock sensor circuit?

Also, I found this kind of odd. Instead of the usual turbo whistle, its more of a woosh. I really noticed it the first time out, but then I tightened up two hose clamps that I forgot to tighten and it lessened slightly. It takes a ridiculous amount of throttle to spool the turbo. Like.. it would create a couple psi at a quarter throttle before.. now it takes half throttle to do the same couple of psi. I originally attributed this to the fact that its a bigger compressor wheel with a clipped exhaust wheel, but I feel it should be a little more.. alive than that.

So basically, I'm asking if its a boost leak, or a problem with my knock sensor wiring. Or a combination of both.

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[Nick M]

it started burning oil on deceleration and after boosting. Typical blown turbo symptoms.

That doesn't mean it is your problem. Vacuum problems from the short block will do the same thing. And your turbo will not respond as fast with lower cylinder pressure.

Ive checked for boost leaks and couldn't find any. This was capping both ends of the intercooler piping, and putting 15-20 psi in it. I couldnt find a leak, although there could be one I didn't find.

If you have an intake leak, you will have a code 34.

One of the things i thought of was this. I redid the knock sensor wiring when I had the engine out, and I ohmed out the wiring. I had 1 ohm. When I checked the wiring on my n/a harness, I had like 7 ohms or so. Is that going to be a problem? I never got a code 52 with the n/a wiring. I have, though, occasionally got a code 52 with the new wiring, but after clearing it takes a couple months for it to show up again. Is the wiring not resistive enough for the knock sensor circuit?

Running rich and retarding the timing circuit will also cause your turbo to not respond and smoke.

It takes a ridiculous amount of throttle to spool the turbo. Like.. it would create a couple psi at a quarter throttle before..

Your problems are either the 52 or the short block. That is my best over the internet, I can't quite see your car from here answer.

 

[IndigoMKII]

I wouldn't say that every boost leak will show a code 34. Code 34 is only abnormal boost pressure. If you have a big enough boost leak, it can cause a code 34 but I wouldn't say that the small leaks cause a 34.

I've had leaks before that didn't have a code 34.

 

[Backlash2032]

The 52 only shows itself every once in awhile and it definitely sucks for performance. Obviously. And its not the shortblock. I just rebuilt that. There's maybe 10k miles on the engine. And the turbo doesn't smoke anymore. That was only the old turbo, because the oil "seals" were shot.

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[Nick M]

I wouldn't say that every boost leak will show a code 34.

I would. Code 34 is abnormal boost pressure. And since it seems you don't know what that means, I will explain it to you. It means the Hz reading from the airflow meter indicates the turbo is pushing more air than expected. With an intake leak, a normal turbocharger will move more air than expected.

 

[Nick M]

And its not the shortblock. I just rebuilt that.

Famous last words of the internet. You can rebuild a short block, but can not diagnose its failure.

And the turbo doesn't smoke anymore.

You didn't feel the need to mention it no longer smokes? Small details. :nono:

I originally attributed this to the fact that its a bigger compressor wheel with a clipped exhaust wheel, but I feel it should be a little more.. alive than that.

Bigger compressor wheel than what? The 57 you took off? Good luck to you.

 

[Backlash2032]

Code 34 is fuel cut. So the turbo is pulling in more than the ecu says is okay. In order for the boost leak to result in a code 34, the boost leak would have to be bad enough that the turbo has to exceed that limitation set in the ecu to reach wastegate pressure.

Since I suck ass at explaining things... Say fuel cut is 12 psi. And the wastegate opens at 8 psi. There's a boost leak resulting in a 2 psi drop. Now the turbo has to push 10 psi to make 8 psi. Not enough for a code 34. If the leak is big enough to make a 4 psi drop, then the turbo has to put out 12 psi to make 8 psi. Now it hits fuel cut and sets a code 34.

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[Backlash2032]

Famous last words of the internet. You can rebuild a short block, but can not diagnose its failure.

Because it's not the shortblock. Any sort of compression leak that leaks enough for these issues would definitely also leak oil.

You didn't feel the need to mention it no longer smokes? Small details. :nono:

That's because it was typical blown turbo symptoms. I replaced the turbo, and I assumed one could put two and two together. Sorry, I will keep that in mind next time.

Bigger compressor wheel than what? The 57 you took off? Good luck to you.

I'm sorry, but you need to read a little closer before you start the bashing.

Well, my car was seeming slower than usual, and it started burning oil on deceleration and after boosting. Typical blown turbo symptoms. So I purchased a 57 trim CT off a member on here. Expecting to rip the tires off the first time I hit boost in first gear after the turbo swap, instead, it felt nearly the same as before the 57 trim.

 

[Nick M]

Since I suck ass at explaining things... Say fuel cut is 12 psi.

Here is the disconnect. Fuel cut is not controlled by PSI. It is controlled by the Hz reading from the KV airflow meter. A CT26 with the stock wastegate and 5 psi can set 34. That is why the code exists. Running a T04E compressor or electronic wastegate controller is not what Toyota had in mind with the code.

If you want free help. the least you can do is provide correct and full information on what you have done. Your post indicates your car smokes and the turbo does not respond as fast, including after turbo replacement. That is not a turbo problem. The fact that nothing changed is your clue. As I said, good luck.

 

[Backlash2032]

Okay. I was using psi as an example. I realise that fuel cut is from air flow rather than psi. The argument is still true that not all boost leaks result in 34.

Alright. Here's the deal. The car seemed slow with the factory ct. Turbo spooled fine. Car burned oil. Replaced the turbo with a rebuilt 57 trim, no more smoke, car still seems slow, and it responds a lot slower.

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[IndigoMKII]

Okay. I was using psi as an example. I realise that fuel cut is from air flow rather than psi. The argument is still true that not all boost leaks result in 34.

Alright. Here's the deal. The car seemed slow with the factory ct. Turbo spooled fine. Car burned oil. Replaced the turbo with a rebuilt 57 trim, no more smoke, car still seems slow, and it responds a lot slower.

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How's your base timing? I know when my base timing was near 2 degrees instead of 10, it was slow as hell.

 

[jake8790]

Check for exhaust manifold leaks

 

[Maple191]

Check for exhaust manifold leaks

+1 on this I just fixed my exhaust manifold leak last month = night and day difference in performance.
Found all cylinders except number 1 was leaking. allot of stripped studs and previous owners repairs had backed out.

 

[Backlash2032]

I half hope, and half don't want it to be an exhaust manifold leak. Not looking forward to pulling the turbo... Again. Haha.

But I checked base timing yesterday, and its at 10*. I also ohmed out the pickups in the CPS. Two are at 190 and the other is at 180. The high side of the spec, per tsrm, is 180. Could this be causing my issues?

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[jetjock]

No

 

[Backlash2032]

No

Okay then.. Am I on the right track with the knock sensor wiring? No matter where I look in the TSRM, I cannot find a spec for the impedance of the wiring.

 

[jetjock]

Impedance is irrelevant. Either fix the problem with your previous rewire or do it again.

 

[Backlash2032]

[video]http://s707.photobucket.com/user/Totenhosen/media/VIDEO0005.mp4.html[/video]

Impedance is irrelevant. Either fix the problem with your previous rewire or do it again.

How is impedance irrelevant? I'm trying to get a grasp on this here, so bear with me. I googled TCCS and knock sensors and it led me to this site. http://www.autoshop101.com/forms/h24.pdf. Searching through there led me to the knock sensors, their signals, and how TCCS deals with them. From my understanding, there are two different kinds of knock sensors used in Toyotas. One which outputs a voltage on a broad range of frequencies, with its peak voltage at 7Khz, which is also the frequency at which knock occurs most often. There is also a knock sensor which outputs voltage on a very narrow range of frequencies, again, with its peak voltage at 7Khz.

Also, the same site mentions that "In the event that the ECU continues to sense detonation, timing retard is limited based on a clamp value stored in memory. If the ECU determines that the knock retard is not functional, it will enter a fail-safe mode and fix the retard angle to prevent engine damage." To me, that sounds a lot like code 52. Am I correct?

If the previous statement is true, then wouldn't that mean that if the wire is less resistive, it lets more current through, and therefore has a higher voltage, making the ECU think that there is detonation, and the ECU retards timing appropriately? And then in the chance that there IS knock, the ECU judges that the timing retarding is not working, and sets a code 52, to keep the engine safe?

Again, I'm just talking here with a very basic understanding of electrics, so please bear with me.

ALSO I checked for exhaust leaks in a very basic (and according to the internet, effective) way. I put some seafoam into a vac line, not for its "cleaning abilities", but for its smoke. I did not hear, see, or feel any exhaust leaks with the engine (and manifold) cold. It was quite the smoke show though!

Here's the video that I posted on the last page, but failed to notice that it didn't work. So heres me trying again!

[video]http://s707.photobucket.com/user/Totenhosen/media/VIDEO0005.mp4.html[/video]

Edit: That's the best I got. If I knew how to imbed it, I would.

 

[jetjock]

Well, you're right about one thing: you have a very basic understanding of this stuff. I thought you just wanted to fix the car. My bad.

 

[Nick M]

Also, the same site mentions that "In the event that the ECU continues to sense detonation, timing retard is limited based on a clamp value stored in memory. If the ECU determines that the knock retard is not functional, it will enter a fail-safe mode and fix the retard angle to prevent engine damage." To me, that sounds a lot like code 52. Am I correct?

Running rich and retarding the timing circuit will also cause your turbo to not respond and smoke. Your problems are either the 52 or the short block. That is my best over the internet, I can't quite see your car from here answer.