Throttle plate closing @ high rpm

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VitViper
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Throttle plate closing @ high rpm

Post by VitViper » Tue Sep 02, 2014 6:50 pm

Do we have a fix for this yet? It's been an intermittent problem on various TB's, kind of annoying. I'm prepping for a track day next week and just had the TB slam shut on me @ my 9200 rpm rev limit. This is my built motor 2008 Si. The TB is an OEM Honda TSX throttle body, been on the car for several years, first year I'm running it past 9k rpm tho. Would hate to look stupid at the track because my TB won't open due to the P2101 code. Seems the problem only happens once you get the motor revving high enough... went 2 years with an 8800 limiter and never had an issue.

FPM 1.9.1. Log emailed to Derek & Doug.

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Hondata
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Re: Throttle plate closing @ high rpm

Post by Hondata » Thu Sep 04, 2014 11:39 am

The code is generated when the throttle plate does not match the commanded throttle position (the difference needs to be about 6 degrees for half a second). In the past we have seen this error generated from low voltage conditions, which presumably reduce the output power of the throttle body motor.

If you want a specific fix for a vehicle then tell me what model / ECU and I'll see if I can find the error conditions.
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VitViper
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Re: Throttle plate closing @ high rpm

Post by VitViper » Thu Sep 04, 2014 6:25 pm

The ECU part # is RRB-A13, this is my personal 2008 67mm turbo Civic Si. I'm getting more interested in running the car as a dedicated drag vehicle, and the TB issue is surprising/annoying (I reset the code, took off and was able to powershift all the way through 4th no problem... so it's definitely intermittent). I'd hate to look stupid at the track coasting to the 330ft cause my TB slammed shut...

Voltage drop is the first thing I looked at, and the log doesn't show any issues, the car is always a rock solid ~14v. Failing TB? Maybe... I don't know... seems like maybe the ECU is just giving up trying to control it for some reason... spent too much time at the rev limiter maybe which caused the TB angle to vary a bit?

Gernby
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Re: Throttle plate closing @ high rpm

Post by Gernby » Mon Sep 08, 2014 3:43 pm

Does it do it when you use the stock equivalent settings for everything related to throttle?

While working out the kinks in an ITB setup using the OEM actuator in my S2000, I've been blown away by the ECU's level of pickiness. It wouldn't surprise me if the issue you are having is due to a resonant vibration in the TB. The TPS inside the OEM actuator uses 2 curved magnets that rotate around a coil to determine the position. If there is some weird vibration that causes "the force" to look funny, the ECU might interpret it as a mechanical problem.
'06 NFR S2000

Gernby
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Re: Throttle plate closing @ high rpm

Post by Gernby » Mon Sep 08, 2014 3:48 pm

If your TB "body" is electrically isolated from the motor / chassis by a composite spacer, then it might also help to add a ground wire.
'06 NFR S2000

VitViper
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Re: Throttle plate closing @ high rpm

Post by VitViper » Mon Sep 08, 2014 8:40 pm

The TB is never electrically isolated as it's got 4 bolts going through it into the IM... if that was a problem simply running an IMG on the intake manifold could cause something like this.

MOre than likely the ECU is seeing some kind of vibration and giving up... which is stupid.

I had it slam shut on me again today, of course at the top of 1st gear, TPlate was perfectly matching TPedal until the ecu gave up and let go control of the actuator. Fail.

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Re: Throttle plate closing @ high rpm

Post by Gernby » Mon Sep 08, 2014 9:56 pm

You'd be surprised what kind of things happen to circuits when they don't have a good ground.
'06 NFR S2000

VitViper
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Re: Throttle plate closing @ high rpm

Post by VitViper » Mon Sep 08, 2014 11:49 pm

Gernby wrote:You'd be surprised what kind of things happen to circuits when they don't have a good ground.
I'd expect the problem to show up before now... electrical problems don't wait 3 years and for me to rev past 9200 to pop up :p Not to mention this has happened in the past on our other cars, with no thermal gaskets, just revving very high. It's not an electrical problem lol

Gernby
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Re: Throttle plate closing @ high rpm

Post by Gernby » Tue Sep 09, 2014 8:50 am

Maybe it isn't an electrical problem.

Another suggestion is to adjust your target throttle map a little lower, so that it isn't trying to open the plate any further than it needs to. I had an issue with the ITB's that was causing the max plate opening to be about 98.4%. With the default throttle map, it was trying to reach 101 or 102%. In 1st or 2nd gear, the ECU didn't have a problem with it, but in 3rd, it would throw a code for the actuator malfunction after I had been at WOT for a few seconds (reaching the upper RPMs). When I inspected the throttle plates visually, I could see that they looked 100% open when the TPS showed 96%, so I just altered the throttle map so that it would only try to open it to 96%. That worked perfectly.

However, I don't know if the Civic has this same behavior, but the S2000 target throttle map is weird. Anything above about 66% is multiplied by about 1.5 by the ECU, so 66.7-100 translates to about 99-102% on the throttle plate. Since I wanted the max plate to be 96%, I had to set the max target to 65.5. Now my datalogs show that whenever TPedal is at 100%, TPlate is at 96%.
'06 NFR S2000

VitViper
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Re: Throttle plate closing @ high rpm

Post by VitViper » Tue Sep 09, 2014 1:12 pm

The throttle map that's exposed in the software isn't the final throttle target... this isn't news, the various DBW platforms have other modifiers to the throttle map you see that changes the final target.

Gernby
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Re: Throttle plate closing @ high rpm

Post by Gernby » Tue Sep 09, 2014 2:33 pm

It wasn't intended to be "news". It was a suggestion to fix your problem.
'06 NFR S2000

New Guy
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Re: Throttle plate closing @ high rpm

Post by New Guy » Tue Oct 28, 2014 8:00 am

I'm having the same issue
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Alex_FN2
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Re: Throttle plate closing @ high rpm

Post by Alex_FN2 » Fri Dec 19, 2014 3:19 am

Same problem on euro fn2 civic with US SI ecu and a J37 DBW TB with Rotrex.

It was occasionally at the beginning but today on the dyno persists every time engine revs more than 8400rpm.

If it's not electrical then we need a fix please.

J37 replaced with a brand new one with no success.

Alex_FN2
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Re: Throttle plate closing @ high rpm

Post by Alex_FN2 » Wed Dec 31, 2014 5:13 am

Anyone came with a solution yet?

VitViper
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Re: Throttle plate closing @ high rpm

Post by VitViper » Mon Feb 09, 2015 2:06 pm

Can we get some attention to this problem? I have a customer's car with a K20/K24 build that we simply cannot rev over 8000 rpm as the ECU gives up controlling the TB -- the vehicle has a J37 TB, and the problem persists with the stock TB. Repeatable on *every* single pull. The TB control after 7400 rpm becomes very "jittery" (2-3% variance or so) until the ECU finally gives up controlling it and lets it slam shut. I have tried reducing the throttle plate target, to no avail, problem continues to persist. ECU is 37820-RRB-A14, Using FPM 2.0.6.

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