Quickvr4

I currently have the Eurocharged tune to accommodate and air filter and secondarr cat removed upgrade. If i upgrade my headers and eliminate the main cats do I need a re-tune? I am sure a re-tune would optimize the power however will my car drive like crap until then?

Thanks,
Derek Eshleman

ghiaguy

Yeah, you are opening the exhaust quite a bit and will need a re-tune. I wouldn't hit WOT until you get the fresh tune, but that re-tune will give you serious gains!

91RS

It's completely find to drive it before a retune. The car will adjust itself as needed.

Quickvr4

91 RS, if that is the case then do I need a re-tune at all even if I have the stage 1 tune?

91RS

You will need the retune or your check engine light will come on because it doesn't have catalytic converters any more. However, it won't do any harm to the car driving it like that. When I got my exhaust done, I left spinning tires so they could hear it!

Lenin

Be aware that with the tune turning off the CEL when you remove the cats, the tune will only remove the CEL. But next time you go for an inspection, your car will be in the "not ready" state and you will fail the inspection. At least that's what happened to me and others in the past. Look into the J-pipes that needswings sells or the O2 sensor simulators (not sure who sells these).

C3Duece

a retune after a big exhaust upgrade like headers/cats (most restrictive parts) is well advised but not absolutely necessary. The car will compensate to a degree to the extra exhaust flow and not go lean to the point of detonation...especially due to not being forced induction. But what the hell...you're doing the upgrades to get the most power/best running car possible so why cheap out?


GL and keep us posted on the gains!

vsix

Yep, the danger of running lean...due to increased airflow, I mean exhaustflow is really existent.
You would be definately better of retuning the car, just dont do a mistake and JUST chip the car, instead get the car on a proper dyno and tune it there.
It might cost a few bucks more, IMHO it would be worth for me instead of blowing a motor up...
Been there done that...enough said.

91RS

It shouldn't do that. My car is always ready on the catalytic converter test.

Lenin

Just to confirm. You removed primary and secondary cats. You O2 sensors are in the pipe and no CEL. And the car is always ready on the catalytic converter test. That's unusual.

91RS

I have high flow converters to pass a visual inspection, but there isn't room for the oxygen sensors after the converters so all 4 sensors are in the pipe in front of the converters. The check engine light was on for converter codes before Kleemann retuned me.

Lenin

That's great that Kleemann figured out how to get the car into the "ready" mode and not just turn off the CEL. I just use little the J-pipes.

vaiste001

Basic principle with petrol cars:

1. Check your fuel pressure
2. Check your AFR with wide-band

Monitor these two variables and you know if you need a retune. If your fuel pressure is ok but AFR is a little bit lean, then you need a retune (to put it simple).

Quickvr4

Thanks for all of the info guys. I will get her tuned on the dyno. Can you elaborate on the J-pipes?

Lenin

Here is a picture of my headers from this thread. https://mbworld.org/forums/5711768-post14.html