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Supra gone- Cobra here!
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Greetings from the Great White North..... Where Hockey and good Canadian Beer are king..... eh!

This is my first post I have not seen the exact same question in any other seaches. I have not turned up the boost in the car yet. I do have a 3 inch exhaust and downpipe with a cat in place and I am planning on installing a Boost Controller

I purchased a BCC from Supra Store

1)Followed the instructions on MKIV.com on installation( as their were no instuctions in the box) this included testing the voltage It was at 3.8 volts. I turned it up to 4.3

2)We installed it, with no problems, no check engine light no codes

3)Two weeks after installation. Check engine light has gone on, two codes show, code 35 and 55

4)Check the BCC and the voltage is up to 5.8 volts, we turn it down all the way but the farthest it will go down is 4.48 volts.

5)I drove the car for 30 minutes. No codes

6)Drive it home that night and the the check engine light goes on again. Codes start again

Supra Store said the have never heard of a problem with a BCC and Greddy will not cover it. Has anyone here had this same problem? Or have any suggestions?

Bishop03
 

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Nope, never heard of anything like that, and I wrote the mkiv.com bcc tech article.

The BCC is an extremely simple circuit, so defective units are virtually unheard of. Years ago when I took a lot of mail on this, people thinking they had a defective unit had always just spliced it to the wrong wire. But your symptoms are very different than the usual story.

Just be 100% sure you are measuring it as described in the article, and that your voltmeter is working right (also at least try a different voltmeter). If that is check, and check, you are probably about the 1st or 2nd person I've ever heard of with a truly defective unit.

So Suprastore says Greddy doesn't warranty their new parts to even work....that's hard to believe. And Suprastore won't stand behind new product they sell? That's B.S. How about you ask them to let you buy a second one, but if it works fine, proving that the first one is defective, they refund you?
 

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Since you aren't running high boost yet, it shouldn't even matter if the BCC fails to cap the voltage at 4.3v, because you're not sending any higher voltage than whats coming off the turbo pressure sensor. At near-stock boost levels, the only way the BCC could cause a problem would be if it isn't even allowing low voltage signal to pass through.

So you could test for this by hooking it to a 3 volt source, and seeing if you get 3 volts out. I would also double check the quality of your BCC's ground lead. It won't pass signal correctly if you have a shaky ground connection.
 

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Supra gone- Cobra here!
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Discussion Starter #4
Thanks for the advice, we are going to go through the connections one more time.

One thing that you had said that was interesting is; that even if there was 5.8 volts going into the ECU from the BCC that it should not trip the check engine and through codes, is that correct?

In terms of the Supra Store quite an experience. I was able to hook up with a Canadian Distribuor that was good enough to call Greddy for me. Greddy said that if if their was voltage problems they would warranty.

I have learned one important lesson from this whole experience. Buy your parts from MVP. Lesson learned
 

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One thing that you had said that was interesting is; that even if there was 5.8 volts going into the ECU from the BCC that it should not trip the check engine and through codes, is that correct?
If there was 5.8v going into the ECU, I'd expect that to trip codes and lights.

But what I mean is, that if you have no mods except exhaust, your max boost won't be more than about 13-14 psi, and the turbo pressure sensor unit won't send any voltages downstream high enough to need the BCC to do anything. So even if the BCC wasn't doing its job to cap the voltage at no more than 4.3v, as long as it just let the voltage pass on through, there shouldn't be any voltages high enough to matter.

make sense?
 

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Supra gone- Cobra here!
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Discussion Starter #6
Makes sense. I think. You are correct it boosts to around 13psi or .95 Bar.

So we got back in there again, I am getting really good at pulling up the carpet and taking off the plastic molding that covers the ECU. We checked each connection with a volt meter and they were fine. We even changed the ground and ran it right to one of the bolts on the floor.

The interesting part was when we checked the voltage this time on the BCC it was at 2.66 volts. In addition to that, it would not go any higher and it would bottom out at 1.6 volts. Really weird, when I first got it, the voltage was fine.It was set at 3.8 and we slowly tuned it to 4.3,no problem. It ran fine for two weeks and then thats when the problems started.

We unhooked it on Friday and I have put at least 500 miles on it since. No codes and the car runs awesome. As improbable as it may seem we are about 95% sure the BCC is bad. The voltage is all over the place, hooked into the car or ortherwise.

I am sending it back to Supra Store on Monday, getting this taken care of properly will be my next challenge.

Thanks for your information and encouragement. I will let you know how it works out.

Question is there any other way of dealing with the fuel cut off parameters outside the bcc, that does not cost $1000?

Take Care
 

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Supra gone- Cobra here!
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Discussion Starter #8
Nope I will definitely try again with a new BCC. Just ordered one in fact. I will put in next week and post my results.
 

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Nope I will definitely try again with a new BCC. Just ordered one in fact. I will put in next week and post my results.
Hang in there! With the care you've taken it was THE boost control and you'll be fine once the new one is on. Thanks for the heads up on SStore.
 

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beezupra or Bishop03 or anyone that has a BCC....I just purchased a used BCC from a supraforums member and I just opened it up. I checked out the installation guide on mkiv.com and looked at the picture of the BCC circuit board and noticed that the BCC that I purchased has a resistor saudered on one of the chips. Here are some pictures to show what I am trying to describe.

This picture is on mkiv.com of the BCC circuit board:


This is a picture of the BCC that I just purchased:


Can anyone open up their BCC and check if they have a resistor saudered on their chip? Does anyone know why a resistor would be there? Any info would be greatly appreciated.

thanks
 

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William - that is an interesting question, but I can't give you a certain answer. I don't even currently own a BCC to look at. I do know that were slight changes to the BCC over the years, so I would guess that probably they both came from Greddy as you see them, and are just from different design runs.

I believe the pics on mkiv.com are about 6-7 years old, so maybe yours is the newer type. It would be good to see someone else with a newer one post up a pic.
 

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Supra gone- Cobra here!
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Discussion Starter #12
William, I do not remember mine looking like that. I am getting a new one next week and I will need to open it up to properly tune the voltage. I will let you know if there is resistor placed across the chip.

Cheers
 

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Supra gone- Cobra here!
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Discussion Starter #13
Just to let you know the BCC I had was faulty and Greddy is going to warranty.

If anyone else has their check engine light go on and or Code 35/55 after BCC install its probably a voltage problem with the BCC, meaning the BCC is probably faulty.

Bottle and Titian did a pretty good job at dealing with it.

Look forward to full BPU on Saturday. What are auto's dynoing at BPU ?( full exhaust,intake, BOV, boost turned to 18psi on 94 octane)

Cheers

Bishop03
 

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I got a question on somewhat the same subject. I totally forgot to tune it before I hooked it up to the feilds harness replica so my Q is, if I have already wired up(soldered the ground and 12v) to the bcc and the harness, when I go to tune it should I just connect the harness to the ecu, turn the ignition to on, then proceed to tune it?IDK
And Since I am using the white bcc wire to any automotive voltage source of 5-12V and the green to the voltmeter probe, is it important that I re-connect the tps green wires on the harness back together????
btw Im using brad D's instructions.
 

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I got a question on somewhat the same subject. I totally forgot to tune it before I hooked it up to the feilds harness replica so my Q is, if I have already wired up(soldered the ground and 12v) to the bcc and the harness, when I go to tune it should I just connect the harness to the ecu, turn the ignition to on, then proceed to tune it?IDK
And Since I am using the white bcc wire to any automotive voltage source of 5-12V and the green to the voltmeter probe, is it important that I re-connect the tps green wires on the harness back together????
btw Im using brad D's instructions.
why don't you use my article since it describes what to do with it already hooked up:

http://www.mkiv.com/techarticles/bcc/bcc_install/bcc_intro.htm

but basically you just can leave BCC's red/black hooked up, yes turn car's ignition on so power is going to the BCC through the red wire, doesn't matter to re-connect the harnesses TPS wires for purposes of adjusting the BCC. Just run a wire from your battery, or a batttery charge to the BCC white wire (disconnected from the harness) and the positive voltmeter probe to the green BCC wire (disconnected from the harness, negative of volt meter to any ground or black wire, measure/adjust.
 

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Just to let you know the BCC I had was faulty and Greddy is going to warranty.

If anyone else has their check engine light go on and or Code 35/55 after BCC install its probably a voltage problem with the BCC, meaning the BCC is probably faulty.

Bottle and Titian did a pretty good job at dealing with it.

Look forward to full BPU on Saturday. What are auto's dynoing at BPU ?( full exhaust,intake, BOV, boost turned to 18psi on 94 octane)

Cheers

Bishop03
Thanks for the follow-up. Does it feel special to be about the only person ever to truly have a defective BCC?:)

I'm about ready to get one myself - will be fun to get back to BPU
 
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