Cobra stuttering under boost

[JayJay]

Hi guys

I have done an installation of a ported eaton with an 2.8 upper pulley.
Supporting Mods:
- Kenne Bell BAP
- NGK TR6 Plugs (gapped at .028)
- 90mm MAF

- Also wanted to change the injectors, just that everything is not running anywhere near the limits. But the tuner said he couldn't adjust those siemens deka 60lb which i've bought. So, still stock injectors.

I took her from the shop, drove home and soon I noticed, that the car is running smooth (healthy idle). Driving perfect, but as soon as I hit boost in low rpm / high gears, it starts stuttering. It feels like the injection is timing out for a split second. I have made a video so you can see it.

High rpm pulls to the limit she feels good. Low driving, cruising also. Just when it gets to boost with low rpm there comes the problem.
Also made an Picture of the sparks, with about 400 miles on them.

Wrote him a Mail, but I would like to hear what you guys saying.

Thanks for your help!

 

[01yellercobra]

Sounds like a tune issue. I'd find another tuner. The fact that he said he can't tune 60lb injectors is a huge red flag. They are very common and easy to tune. And .028" is a little tight IMO. I have a 2.8 pulley and run a .032" gap.

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[Bdubbs]

Lol. Am I reading and seeing this right? Making 692 rwhp on a ported eaton?

 

[01yellercobra]

I thought it was Newton Meters. I know that's a metric torque measurement. I think he's over seas.

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[MastaAce03]

How much boost? Might be too hot of a plug. I run Tr7IX in my gt500 and were recommended by vmp. Car loves them.


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[Bdubbs]

Sounds like a tune issue. I'd find another tuner. The fact that he said he can't tune 60lb injectors is a huge red flag. They are very common and easy to tune. And .028" is a little tight IMO. I have a 2.8 pulley and run a .032" gap.

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Maybe that's it. If so I missed it.

 

[JayJay]

Yes, sorry I live in switzerland, so it's newton meters. thats about 510lb

I think he was just to lazy to tune the injectors properly...
What do you guys think about the spark? Is it save to drive there, about 100miles?
A friend of mine said he never saw a Spark plug like this, and it would be running waaay to lean.

I wrote the shop a message. I want him to recheck my car... I'll see what he replies.
He told me, that this is an issue with the BAP, because its boost controlled, so when the boost instantly goes away, the voltage drop does that to the car?
Never heard of anything like that with the BAP.

Don't know... feeling sad my car isn't running as it should.

 

[Bdubbs]

Op do you know how the bap is wired? A bap shouldn't do anything but help apply voltage to the fuel pumps. When I had one I wired it "pre" fpdm. Only thing it did was lowered the fpdc like its suppose to do.

 

[MastaAce03]

Yes, sorry I live in switzerland, so it's newton meters. thats about 510lb

I think he was just to lazy to tune the injectors properly...
What do you guys think about the spark? Is it save to drive there, about 100miles?
A friend of mine said he never saw a Spark plug like this, and it would be running waaay to lean.

I wrote the shop a message. I want him to recheck my car... I'll see what he replies.
He told me, that this is an issue with the BAP, because its boost controlled, so when the boost instantly goes away, the voltage drop does that to the car?
Never heard of anything like that with the BAP.

Don't know... feeling sad my car isn't running as it should.

Looks like it's too hot of a plug my man. Try the NGK TR7IX gapped between .028-.032. And I wouldn't put the car into boost at all until you try the new plugs. Also, you need to data log your car and make sure your tune is on point.


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[Bdubbs]

Looks like it's too hot of a plug my man. Try the NGK TR7IX gapped between .028-.032. And I wouldn't put the car into boost at all until you try the new plugs. Also, you need to data log your car and make sure your tune is on point.


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Crazy if that's the case. Plenty of guys running tr6's making 700+rwhp.

 

[JayJay]

Don't exactly know how the BAP is wired. Will check that.
I've read that it's better to wire it pre fpdm. But I can't imagine that if it's not, there would be such a big issue in drivability? There would be much more bad feedback i guess.

I have bought the tr6 because i've only heard good about it? the first time anybody is saying I should change them.
Hope I'll get that fixed soon.

 

[Inj3cti0n]

Mine just did the same thing, after 30ish min it would sputter under boost, i found the valve cover leaking a small amount of oil onto the cyl 6 plug, only happened after it ran for about 30 min though

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[Rich'sTRsvt]

That plug looks a little more lean than usual but plugs looking lean is pretty normal because the car always runs on the lean side at idle or well cruising. The correct way to check a/f with a plug is to do a pull and immediately shut it down and pull the plug to see how it was during wot, but most people don't check a/r that way anymore. As far as the bap voltage going up and down with boost that is if they are using the hobbs switch that turns the bap off and on with boost. Most people don't use the hobbs switch anymore because of the driveblitiy issues that it introduces and just connect the two wires that go to the hobbs switch together to remove it. If your tuner did use the hobbs swtich you will need a new tune if you remove it.

 

[whitedevil95]

Do you have the Hobbs witch hooked up? If you do I would wire it to be on full time rather than off and on with the hobbs switch.

 

[JayJay]

They have done it with the Hobbs Switch connected somewhere in the front.

Can you wire every BAP without it? Im going to search an electric drawing to send them, so they can wire it the right way.
I really think this is the problem.

But, yesterday i did a test tun with the car and datalogged everything. There were about 15min without any stuttering? I have no idea why...

 

[whitedevil95]

From what I udnerstand the reason having it wired up with the Hobbs on a PD blower is that sometimes a quick push of the throttle gives boost, where as a turbo or centri wouldnt. This leads to the BAP sending a bunch of voltage to the pumps when it isnt needed. This is why my tuner told me to cut the hobs switch off and wire the two wires in the cord together so that the BAP is activated all the time.

 

[Bdubbs]

Right. I also didn't use the hobb switch. Turned the bap dial to max and put electrical tape over the knob so it couldn't move.