De-cat no mapping question

[DC5Adam]

Evening everyone.

This has more than likely been asked plenty of times but I couldn't seem too find a topic on it.

My question is would running a de-cat manifold without any mapping cause any issues at all?

Cheers in advance.

 

[spooke]

Evening everyone.

This has more than likely been asked plenty of times but I couldn't seem too find a topic on it.

My question is would running a de-cat manifold without any mapping cause any issues at all?

Cheers in advance.

From what I've read or been told, you'd only require a map when changing the inlet manifold or internal engine work. Of course it's still worth mapping, even on a stock car.

 

[SamDC5]

Everyone I've spoken to says remapping these is the best thing you can do. Transforms the car, so it's a worth a thought. Don't forget the car can only change it's original map so much, I think there was a guy on here selling a K-pro V3 for £350.

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[Kenz]

It will be okay but your eml will likely be on. The dc5 runs a wide band therefore the ecu can make minor adjustments to the air/fuel ratio.

I believe Huw (Fez) has been running a 421 for over a year now with no issues, when he had it dyno'd his a/f ratio's were okay too.

However, if you do have it mapped, you know that your car will be mapped to suit the mods you have fitted. For me a map on the car has made quite a good difference, not in straight line speeds, but out of corners the car pulls better due to improved mid range.

In a straight line, 20/30bhp isn't really going to make a noticeable difference in speed.

Just my input, others may disagree.


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[DC5Adam]

Thanks for the input guys.

I will be getting the car mapped in the future, I wanted to make sure it was safe 1st before I get my manifold bolted on, hate having parts sitting around not being used.

 

[BigCarlo]

I never knew this myself I'll be getting an exhaust manifold now as well before remapping the car sweet haha

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[MilanoChris]

There have been stories floating about of people melting pistons running a decat when combined with exhaust and aftermarket intake. Whether true or not I don't know, it could be an internet fallacy. Getting it run and datalogging knock and/or A/F ratios would tell you all you need to know and with the DC5 having wideband this helps.

What would stop me from doing it however is that the power gains would be negligible without a map. So personally I would save and have it all done at once.

 

[DC5Adam]

There have been stories floating about of people melting pistons running a decat when combined with exhaust and aftermarket intake. Whether true or not I don't know, it could be an internet fallacy. Getting it run and datalogging knock and/or A/F ratios would tell you all you need to know and with the DC5 having wideband this helps.

What would stop me from doing it however is that the power gains would be negligible without a map. So personally I would save and have it all done at once.

I'm not looking at power gains as such just yet Chris, yes that is my end goal but for the short term it would be getting it on the car so it's not sat around and getting a little bit more noise out of the exhaust, plus then it's already on the car when the time comes for a k100 or kpro.

 

[C2AXG]

I'm running injen 3" intake with solid fab race header and 3" cat back.
No problems or EML light here 👌🏼

 

[MilanoChris]

Without it being mapped? You're brave.

 

[Rom]

I ran an rbc, buddyclub header and spec 3 system, mugen intake, and later a J's intake. Without a map.

Not hard, and wasn't used that much tbh. Before it was mapped. No track days in that time. I'd checked afr, but couldn't do it under load, only on mot machine.

It was lean top end when it was mapped, but not dangerously so. And again, it wasn't used a whole lot. Maybe 1k miles if that.

The map is what makes the difference though. All that bolted on wasn't getting me any benefit really. As until the car is tuned for the extra air, quicker release of gas etc. It can't use it. Map is definitely worth it.
And certainly don't give it too much beans until you're confident it's not lean top end.

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[DC5Adam]

Nice one Rom cheers for the info