Despite moving to a higher elevation (@5k), and losing 3psi of boost - My 04 R53 runs great. However, I've begun to notice a significant "flat spot" or brief hesitation when hitting the gas from a dead stop before the car accelerates. It doesn’t stall. Just a brief lag.
I am not that familiar with drive by wire or fuel injected cars for that matter, but was wondering if anyone can suggest a cause or remedy for this?
My Mini is modded with CAI (3.5" × 6" K&N cone), 380 cc injectors, 15% pulley, new NGK colder plugs and silicone wires and a 210 Adrian tune. The car has always fired right up on the first turn of the key and always been maticulously (OCD) maintained.
Do I need a re-tune?
Any suggestions would be appreciated.

 

Sticky BPV maybe? Try zip tieing the actuator on the valve closed and see if that makes a difference.
I installed a Detroit Tuned BPV a couple of years ago. It's advertised as giving a faster boost build-up due to a stiffer spring that closes the valve. I didn't notice any difference - except a lighter wallet.

 

Thanks. I'll give it a try with the zip-tie trick (again).
The last time - I had an issue with the car surging and lagging upon acceleration while driving - So I bought an aftermarket BPV (not DT) which was advertised to have a stronger, more robust spring. But I tried zip-tieing the actuator first to see if that was the problem. As it had turned out; the surging issue was due to a loose ground connection on one of the BUS.
I still have that new aftermarket BPV stored in a parts box somewhere. It'll certainly be convenient to have if it turns out to be the issue with my current BPV.
Thanks again for the tip!

 

Update: I tried the zip tie trick. Unfortunately the car ran like crap when doing so/testing.
I'll try to dig up that new BPV and install it when I can.

 

At 5,000 feet elevation your AFR is now off due to lower oxygen concentration. Have Adrian look at it again.

 

Thanks.
Adrian was my initial thought too.
I really dislike not having a suitable safe place to work on my Mini out here. E.g: changing out a BPV in a vacant parking lot.
This car is drawing too much attention out here = One of the top states for car break in and theft.

 

Not so much as an update. But I do find it interesting ...
I'd recently changed out my lower engine mount (trying to solve a different issue), and added a powerflex insert to the large end. I already had the powerflex insert on the small end of the mount for years but now having both ends "upgraded" with powerflex bushings, I've noticed a difference in my off the line acceleration.
The lag I had as described earlier, is nearly/entirely gone.
Although I don't make it a habit - I can easily launch the car and chirp/smoke the tire from a dead stop with no intended hard acceleration.
My previous (replaced) stock lower mount only had a little over 8k miles on it and really didn't show any concerning sign of deterioration.
I'm rather impressed with the added powerflex bushing combo.

I also feel that @cooper48 's recommendation to have @adriancl have another look at my current tune deserves some merit.

 

Curious to know if you feel any additional engine vibration (particularly at idle) with the poly bushings?

 

I don’t have experience with the inserts in the lower mount, but I can say that there is a noticeable increase in NVH at idle with the full bushings.

I ended up ditching the Powerflex bushings for a Vibra-technics lower mount a few years ago because I was having issues with the poly bushings softening too much when they got hot (or so I think). In that case, the inserts may have performed better for me.

 

At first - no.
Now having put 115mi since then,,,, I'd have to say - yes.
Although, I'm not exactly or throughly convinced its caused by the bushing alone. Something has caused my exhaust system to rattle horrendously at idle. The car doesn't shake/vibrate but I can feel the exhaust pipe underneath me shaking and rattling now.
But yeah - I think you may notice a little bit more vibration with full poly bushings. From my experience though - not much.

 

A very late update as to the "lag", NVH and exhaust rattle.
The lag : I almost considered/went with installing one of those electronic devices that splice into the ECU (?)/gas pedal that enhances throttle response but I didn't. With the combination of powerflex engine mount inserts and having replaced my upper mount with a Vibratechnics - The car launches and pulls like a rocket! Absolutely 0 lag.
NVH : Given the combination of upgraded mounts as listed above - might be a bit overkill for a family daily driver. At cold idle the car will vibrate intensely. Especially felt at the steering wheel until it warms up. Vibration at idle is felt throughout the car whilst sitting at a red light. The wife may not like this. But if you're all about reliability and performance and don't mind the added vibration...
The rattle : I had posted a thread regarding experiencing
my exhaust rattling. After changing out all the hangers, upgrading all the engine mounts - as it turned out my CAT had finally broken loose. Undetected (by me), it must have been gradually failing over the years. I rarely drove the car hard to notice the slight noise or decrease in performance. Just gas mileage - Until the internal CAT finally broke, making the car almost unbearable to drive.
Having replaced the CAT with a good used, low mileage OEM, coupled with all the upgraded performance mounts - I've never imagined or remember my Mini exhibiting so much power than before. Perhaps now taking advantage of the 210 tune I had had done not long ago. In addition; I'm seeing a crazy if not unbelievable increase in gas mileage.
No lag. Instant acceleration. More power. Seemingly more fuel efficient.
What more can I say?

 

Nice to hear about those mount inserts. I bought a set a few months ago and just haven't installed them yet. This good review of them is the inspiration I need!

 

Thanks.
Yeah - The lower powerflex dog-bone inserts (IMO) made an obvious noticable difference. With the addition/replacing the upper rubber (pre-faclift) engine mount with the Vibra-Technics, was crazy night & day improvement. Hit the gas from stop =(although I try not to smoke the tire), the car will instantly launch.
The only thing I would advise against (for a daily driver), is if you have the early model with the side strut tower vibration damper; I would not add the poweflex inserts for that particular mount. From my experience - They made my Mini shake like a construction site rock sifter. So much so, I had to remove them the same day I installed them.