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E-throttle close at high Rpm


VtrSp1

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Last week i have do a few track test with the E-throttle setup, downshift blip and the Ewp!

All work good but i have an issue with the E-throttle, a few time when the engine is at 8000 rpm , the Throttle close a few % so the TP error accumulator go high. In another time the Throttle closed a very high amount and the Upshift isn't good

The setup is with a Honda K20Z4 E-throttle

Take a look at log fram 2:00

 

@Adamw

 

 

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Yeah I have seen this before on a Honda K and a R35 GTR - there is some very strong resonant vibration at high RPM that causes the brushes in the DBW motor to "bounce" off the armature and lose contact.  If the motor can come apart then you may be able to put stronger springs in it.  Otherwise you need to reduce the engine vibration or try a different throttle body and hope it is better.  One Honda I diagnosed was cured by re-fitting a damper on the crank nose (had been built with a light weight pulley).

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@Adamw i have done a similar setup Honda K20 with K20Z4 E-throttle on a Aem Infinity and i have the similar issue..so i have changed the Throttle body with a Bosch Unit and the problem was solved. This setup was on a Lotus Elise with Kswap engine and 75A Engine mounts, Oem engine and Oem Crank pulley.

My car is a race car with 95A engine mounts , stock Honda Oem crank pulley (with damper).

Honda use a very tought intake manifold support and normally this is removed due to the weight ( 0.7Kg each). One of this support is bolted near the Throttle body flange, possible to reduce manifold vibration?

This question is because i'm a Honda Tuner, and i do some Honda Fn2 Car with 75A engine mount Hondata Flashpro and i haven't this issue..but in this car i have the manifold stand support

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3 hours ago, VtrSp1 said:

One of this support is bolted near the Throttle body flange, possible to reduce manifold vibration?

I dont know sorry, it is something you will have to investigate yourself.  The car that I discovered this on it would happen at exactly 8300RPM everytime, there were some other strange issues that made me suspect vibration such as the crank sensor had failed several times.    I put a scope on the E-throttle motor and found the ECU was sending max voltage but the current was fading away to zero indicating there was no connection through the brushes.  So it seemed there was some very serious resonance going on around that RPM.  It was a fairly serious race car with sequential etc so I dont know what it had for a flywheel etc and how or if it had been balanced - but on this car the re-fitting the factory damper was enough.

It maybe possible that a good quality aftermarket damper will be tuned for a different resonant frequency to shift it outside of normal operation. 

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@Adamw , Yes a damper tuned for a different resonant frequency can figure out the issue but it's easy and less expensive change the E-throttle.

I have  change the E-throttle to a Bosch Unit 0280750151.

Do you have a Pid setting and Frequency as starting point for this E-throttle?

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5 hours ago, VtrSp1 said:

Do you have a Pid setting and Frequency as starting point for this E-throttle?

I havent used exactly that throttle, but for the similar 74mm I have P=7.0, I=0.137, D=30.  Frequency 500Hz.

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No, I think it needs to be improved a little further, I dont like that oscilation you have on opening (one oscilation is normal but you have 2 or 3).  Generally I dont like to see the error accumulator go above 10% with heavy throttle use.

Im not sure which factor is causing it so you will have to experiment adjusting one at a time. 

rmmXB94.png  

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That last one again looks pretty similar to the P=8 but it is closer to values that I would normally run.  If you ECU log at 100Hz instead of PC log you will see a bit more detail of the response difference but you will never notice any difference in real life and both of these look quite acceptable.  

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  • 2 weeks later...

@Adamw , yesterday i go the track for test the new Bosch DBW . The new Bosch don't solve the issue, at high rpm (about 7900-8100 rpm) the throttle close :-(

Before install them ,i have check and the throttle plate is flat at 92 % so i have se the e-throttle target at 100% Apmain to 92% of throttle plate.

This time the throttle is a brand new Bosch, same as i use on another customer car (same engine)  without issue to 9400 rpm with Aem infinity.

This is a link for download the log

https://wetransfer.com/downloads/362b9b6f679f9914dcc8fcef3293919020200724231110/52ee085967770622040861db2aa6fedf20200724231130/bfa095

 

 

 

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It sounds like you are going to have to solve the vibration issue then.  If the brushes arent touching the commutator then ECU can do nothing - you could connect the throttle motor directly to the battery and it will still close.

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  • 10 months later...
On 7/25/2020 at 4:51 AM, VtrSp1 said:

@Adamw ok i try with ATI Damper for try to remove the Vibration Harmonic ..hope it can help me

Hello, could you tell me if you were able to solve your issue? I am also having this exact problem on two different engines K20 and K24, Factory ECU however, and both are CSS and I fear this is somehow related. I have just ordered the ATI damper before seeing this thread but curious if you had any success?

I appreciate your time!

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Ive had this on two K engines now.  The first one I discussed above was in a civic circuit car, refitting the factory balancer fixed that one.   The second one was a Juno sports car so no almost no flywheel and no room for a damper on the front, on that one the owner had to mess around trying a few different ideas to isolate the throttle.  The final solution was a bracket to support the manifold (it was underneath and connected to the block with a rubber mount at one end), and he also made some sort of soft plastic/urethane or similar spacer between the throttle and manifold. From memory it also had some soft "washers" under the nuts a bit like a cam cover has.   

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I appreciate the feedback man, thank you. This is my personal street vehicle with a K24A1 running a fairly aggressive all-motor setup with 13:1 pistons, Flat Valves, Drag Cartel 3.2 cams (using a stock TB lol) in an 8th Gen Civic Si Chassis... and it's just noisy as all hell.

It looks like however I was thinking similarly as yourself, as those are basically the solutions I am attempting. I have ordered ATI Damper and poly/thermal gaskets for Intake Manifold and Throttle to attempt to isolate the throttle also. The USDM Civic Si does come with a brace from the manifold to the block from factory, but just a solid chunk of metal and I have axed that a while ago.

I am on my third OEM throttle at this point, and I hope success finds me soon. :(

Thanks again!

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