It seems every time I get my car tuned I get another problem....

So I put in my catless downpipe a little while ago and finally got around to tuning my car Stage 2 today. But now if I put in more than about 2/3-3/4 throttle in 3rd or 4th or go flat out in 5th the engine backfires like it's on launch control and I don't accelerate. Plugs are basically new, coil packs are all good.

I also had a bit of this problem once I put the downpipe in but before the tune. It would only happen if I loaded up in 3rd or 4th (cruised at like 3-4k RPM) then floored it.

I'm thinking either carbon buildup on the valves taking it's toll (57k miles, never done to my knowledge) or I need a high pressure fuel pump, as I've been having the car go in limp mode for a second right after start, and the code is low fuel rail pressure. I assumed it was just a cold start issue because it would go away once I started driving. Any other thoughts?

 

If I'm not mistaken Manic Tunes increase the demand for more fuel (making more boost sooner) and if your HPFP is already on its way out the tune will only amplify your problem. I think your issue is obvious, low fuel pressure.

 

I have 2 issues with the HPFP theory though. 1) I had this issue (sort of) before the Stage 2 Tune and 2) I was under the impression backfiring (especially with flames) if anything is an indication of too much fuel. Plus my friend who has a sense of smell (I don't) tells me it smells like it's running rich.

 

There's a problem with that theory, if your are backfiring that means your ignition is firing way late which means your not burning the air/fuel charge and it could be igniting on its way out the exhaust. You said you had an issue after first starting your car when cold and you had a CEL triggered indicating "low fuel pressure". It's not uncommon to have misfiring or backfires when running lean.

Also understand why you are having issue when attempting to punch it from a cruisi speed, when you increase load you naturally require more fuel rail pressure and if that can't be met your engine with cough because it's starving for fuel. You have air and spark, only one other thing is require to launch a car = fuel.

 

My friend had this same issue and it feels like the car hits a rev limiter. We worked on his car for weeks and then decided to change the HPFP. Once that was fixed it was flawless. Also check to make sure your DV and wastegate are adjust correctly

mQubed Motorsport, Manic Tuning Dealer

 

That's exactly what it's like. Like I have a two step system on my car that engages when I floor it. I guess I'll go for the HPFP then. Easy enough to do myself and not as expensive as a carbon cleaning, though I should still probably get that done soon.

EDIT: Wait, an S fuel pump is like a grand and a JCW one is $2-300... wtf, what's the difference?

 

The N18 has two different HPFP, one is a Continental on early 2012 and older. The later mid 2012 and newer N18 have the Bosch HPFP (these don't fail often). Make sure you buy the correct one and yes, the prices of HPFP doubled in the last couple months. Ouch!! Also, you can't upgrade to new Bosch pump with out changing, about 5K-6k worth of other parts.

mQubed Motorsport, Manic Tuning Dealer

 

I'm kicking myself for not buying one before the price increase, I hate Mini that much more now! It's evil to charge that much for such a **** poor quality HPFP, sure it might not be that bad if one would last most of the cars lifespan and not need another one down the road.

I don't understand why the newer Bosch HPFP wasn't made backwards compatible with all 2nd Gen engines as that would have solved to problem for everyone, guess Mini isnt as intelligent as everyone thought. The dealers used to charge $850 long before they dropped down to $300. I'm still on my original HPFP at just under 70,000 miles. I still can use the HPFP warranty 120,000 miles or 10 years.

 

Welp, not like I have a choice....

EDIT: Found a good price on ebay from a BMW dealer. $845 stings a little less than $1200.

 

Curious... I have a 2008 MCS at about 40,000 miles now. Does mine fall under that warranty?

Thanks, James

 

Mini should cover it, if you believe the HPFP to be bad ask dealer to perform pressure tests on both fuel pumps. Also if you manage to actually get a Fuel Rail Pressure Low or the HPFP CEL don't clear it, having this stored code will help your case with the Mini dealer in regards to covering it.

 

The extended warranty is VIN specific but more than likely.

http://www.*********************/for...extension.html

 

Well, I got a P15DF code today. officially the fuel pump. Car is running super rough and I'll try not driving it until my fuel pump comes in.

 

I take it you're not covered under Mini's extended 120,000 mile or 10 year warranty? I have heard reports that a change was made to the HPFP's internals when the N18 was released, lot a good that did!

There will be a lawsuit for that as well, lol!

 

Nope they only recently added a bunch of 2010 models. Not that I think i have a right to money. Probably would've been fine if I wasn't Stage 1 when it started failing.

 

Fuel pump fixed my issue. Thanks guys.

 

That's great news!! Now you can have fun

mQubed Motorsport, Manic Tuning Dealer