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THE WITZL
Forums Junkie

Toymods Social Secretary

Location:
Sydney
Registered:
July 2002

Re: Boost issues with 4AGZE

Mon, 04 July 2005 12:11

i am not trying to be condescending.... this is a discussion, and i have a different viewpoint based on my experiences and results from dyno testing/tuning, street driving etc.. along with the experience of a rather knowledgeable and electronically wise 4ag* guru. Most people call him Ant.

Quote:

Karl, I do not see how you can effect the knock sensor by taking it off the block. If it is insulated (resilient mounted)and left connected it should not effect the operation, and it will be detecting 0 noise.

Say what you will about Ant's (and my) knock sensor theory, but until you get a scan tool and test it out you cannot eliminate it. Actually you wont need a scan tool... just pull the knock sensor out tonight and go for a drive!!! *NB: dont plan on going too far in a hurry :P*

theory based on multiple cases of 4age 20v's with unexplainable flat spots. Use of scan tools shows knock control, without an audible knock

Quote:

As for the resistor bridge option, if TRUST make a knock sensor signal adjuster then it is obvious that there is a way around the knock sensor using electronics. It may not be as simple as using a single resistor but it would not be much more. I am very dubious about it being the knock sensor anyway.

Yes, electronics theoretically can solve the problem. THis is what Ant was going to work on in his spare time, but that's still in the future. The idea was to "attenuate" the frequencies upon which the ECU detected knock, and attempt to maintain the regular engine noise frequencies.... because the use of a simple resistor resulted in either no resultant change, or complete retarding of ignition timing. Not that simple, and a lot of effort. Toyota were just too smart for their own good.

FWIW - Ant took jasonp1977's old AE92 blacktop 20V for a spin with the scan tool plugged in. WIth normal driving on an engine that was otherwise considered "VERY healthy"... there was a fair bit of knock being detected by the ECU! But the timing wasnt retarded very much when it was detected.

Quote:

As for detonation, it is VERY easy to hear det with any 4ag and it is not happening with my car.

i said the same about mine.... yet there was knock control alright Smile

... every so often you would hear a teeeeeeny weeeeny bit of knock, but hardly anything for the ECU to go as spastic as it used to!

Quote:

The fact that my car still runs after 3 months is a great indication that it is not.

So did mine Smile

WIth some HARSH driving.
And for 12 months prior to that as an N/A 100kW 4A-GE.
Funny thing was, in both guises the engine showed very similar signs of knock control. **see dyno graphs below**

Quote:

Why clowns still compare turbo outlet (compressed air) temps with roots type supercharger outlet temps is beyond me. There is no comparison and the supercharger air will always be hotter. As for my outlet temps, I will soon data log it and confirm my suspicions. Toyota quote temps up to 250deg are possible.

I am well aware of the outlet temps possible from roots style chargers! Once you get them to the higher extremeties of their efficency and operating range, the outlet temps go WAAAAY up there. I quoted this as being a more prevelant problem for you than what i would have experienced, since my intake temps would have been much lower than that....

Quote:

The fact that it does it in one gear and not in the next is a good indication that your hypothesis is completely incorrect.

hmmm... true in a sense, but it does emphasise my knock control/ignition timing retard theory. WHen mine started retarding it would do it erratically, all over the place... and eventually all the time. Only solution was turn off car for a little bit, and start it again.... the ecu was then usually alright for a while.

My thoughts are that with the uber-retardo timing

Quote:

I have no intention to "give up" on my project and I have not had a failure yet.

good!! dont give up!! that would be giving up!! Razz

But i do suggest that an aftermarket ECU might be able to help with your problems. Get the car on a dyno or on the road with a scan tool reading serial data (btw - EXACTLY which ecu are you using?) and see what the ECu says it's doing... i'd be VERY interested to know Smile

BTW - here are the dyno graphs for both non-turbo and turbo, of the same engine in the same car. Note the severe dips in power from around 5000-6000rpm on both?

non turbo setup was using 100kW ecu, turbo setup was using AE92 map gze ecu + greddy emanage (tuned by SAS who identified the problem, and tuned around it as best as possible)

http://www.rollamods.com/witzl/sml-ae71-dyno.jpg

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