I've notice that the car (02 MCS, 15%, cat-back, shark 93) doesn't pull as hard some days compared to others. One day it will pin me back into the seat and others I don't get that feeling. Vacuum is always -18 to -20 in/hg and boost is always in the 12-13 psi range so I don't think it's a leak issue.

Brand new plugs and belt.

I'm also pretty sure it's not weather change as its been pretty consistent here lately.

Any insight would be helpful.

Thanks!

 

What's the mileage? Could be fuel filter, dirty injectors or a failing fuel pressure regulator.

 

Just under 80k. Fuel filter was replaced in 07.

 

Since you just had it appart, I would double check the vac lines...especially around the bypass valve. Might be a longish shoot...but since the wires, etc were all unplugged...just make sure they are all plugged in securely. Heck, I bet you already did it but I figured, it's worth a shot to suggest.
Any idea if the o2 sensor (pre-cat) has ever been replaced?

 

Never had the o2 replaced (according to the receipts I received when I bought the car). Everything seems plugged in and in working order. I actually noticed this issue before the head swap.

As I can tell there are no vacuum leaks. I tried listening with a hose to my ear and all I could hear was a very slight rushing of air near the throttle body, but I'm guessing that is just the air moving past the butterfly. I'm going to pick up some carb cleaner and spray it around there to see if it affects idle at all.

One thing I did notice is the passenger side intercooler boot was twisted about 1/4 to 3/8 inch. Also, whenever I put on the intercooler in the past, the driver side boot would twist while tightening it (bottom half would slide out about a half inch while tightening the top). I went ahead and filed down the clamps about 1/8", sanded the driver side horn mating surface, and cleaned the boots so they're not slick with oil.

Vacuum is still the same (-20 in/hg), but boost climbs right up to 15psi now. I'm not sure if the higher boost is because of my "fix" though. Today is rainy and cool, so I'm thinking the air is more dense causing higher boost.

Thoughts?

 

Rain will increase the effectivness of the IC...just like a water sprayer on the diverter!
If the boost is still higher than expected when the temps are normal...it may indicate a bit of a restriction somewhere...perhaps on the exaust side....
I'd also look around the IC gaskets... Since they are a bit odd looking... Reach under. The ic, and make sure the gasket is well fitted, and not pinched...then maybe the part near the bypass valve...check it for wear...it is plastic...grayraven had a post a while back...something had worn a hole in it...resulting in a bit of power loss...a bit of boost leak just before the intake.....it was found when the sc was swapped out.
As for the o2 sensor...it should throw a code...it might be pending, but not yet set...a good reader will tell you. I think mini expects them to last about 10 years...100,000 miles, and some cars got the warrenty on the sensors extented due to premature failure (I know my 05' got a letter to this effect).

 

One thought...maybe un-shark it for a few days...then see if the problem remains.... I have read that with the shark, the timing is advanced pretty far...so maybe the power loss is from the knock sensor or something kicking in?

 

Never got the actual injector. I'll have to see if the previous owner still has it.

 

Since they can only be used on one car...they should...they are tied to the Vin# at first use.

 

The previous owner actually just did a Conforti flash back in 03, so no shark was used. Really the only thing I can do is have the dealer reflash it, but then I would be out the Conforti software, plus whatever the dealer charges to reflash it.

 

We'll it was dry and warmer today and I'm still getting 15-16 psi at peak so

SAY TO BOOST LEAKS

 

I spoke too soon. I did find a boost leak but that still doesn't help. It almost feels like the car is running at 75% throttle when I'm WOT... It's really frustrating me.

I thought it might have been the hose I put on the FPR was leaking during boost once it was heated up, so I threw a zip tie on it and it didn't fix anything.

I also notice at partial throttle, when the car is running good, it's very smooth acceleration. I can see the boost climb up to 10 psi really quickly and the car has some 'go' to it, even at 50% throttle. When it's running "bad", I need to be at 75%+ throttle to get the same response/acceleration. Watching the boost gauge it's not nearly as smooth either. This is with a DTBPV.

 

Hmmmm....there is a great debate about reseting the compute, but since you rebuilt the motor (close to it anyway) maybe you need to do it, or as the dealer would say reset adaptations. The final thing you could do is get a reflash by the dealer......have you gotten enough driving to get some freash gas into it? Also if the reset thing is bs ( then again you did have the battery disconnected for a week+, if the reset doesn't matter)it might take a couple tanks of gas for the ecu to adapt and re-learn.
Short of paying a shop a few $$ to trouble shoot/diagnose it ...might be a good next steep if no suggestions come in. But I know if you do this at a mini dealer...you car will almost always get a reflash...to freshen things...(they usually don't list it on the bill), then they will check stuff. That is why flash tools are do popular...heck the shark was the first thing to have the capability to reflash it self to the car when needed.
The 02 sensor is out of the running for an issue..it is only used at partial throttle...not at wot when you have issues....

 

Yea I've gone through a couple tanks, all premium gas. I really would rather not take it to a stealership. Hell, they probably won't even be able to "duplicate the problem". The car still pulls, just not as hard.

Is it possible for the car to store codes without the SES light coming on?

I've been thinking of some possibilities such as a caliper slightly sticking at random intervals or the throttle body not opening all the way.

 

I did some more testing today. After the car reached operating temp, I gave it part throttle in 4th gear at 3000rpm and it pulled "good". About 20 minutes later, after some highway driving, I put it in 4th at 3k rpm again, and at part throttle, it wasn't pulling nearly as good.

I'm going to check all 4 brakes to see if they're sticking at all. Also going to shake the pcv to see if it it still properly working.

Could lack of an aftermarket intake cause this problem?

 

My guess is is a caliper was sticking enough to make your car feel sluggish, the pad/rotor would be very hot/smoking, and it would only be a problm for a few miles. The fact it seems to do it warm, but pulls fine cold might be a useful piece of info.
A good odb2 reader can tell you codes that are sometimes just "pending". The light will turn on, I think, if the code has been set....it may oray not have to be emmisions related...I am not sure.
The fact the car hesitates when running closed loop, as opposed to open loop, when it is cold is interesting.....
An aftermarket intake would give you a bit more power...and a bit of sound, but it should not IMO cause this issue.

 

Yea I was thinking a sticking caliper would give me more symptoms that just powerloss. The loss of power in both closed and open leads me to believe it doesn't have anything to do with oxygen sensors.

The reason I bring up the intake would be potential heatsoak of the stock box, despite it being of plastic material. Just a shot in the dark really.

Ill bring the car to Autozone to get scanned, as well as check the PCV (although I don't think a clogged PCV would give THAT much power loss).

 

The power loss...would it feel like a yo-yo?
There is a long thread about the yo-yo...some software on some cars get it...the best solution for cars that get the dreaded yoyo, is newer software...sometimes resetting the adaptations seem to help, but the tool to let you do that is $$. It generaly takes 2 or 3 tanks of gas for the computer to re-learn after software reset...my guess is you motor is cleaner than it was...and maybe the car advances the timing too far, senses an impending knock, then retards it momentarily....the mini retards the timeing on a per cylindar basis...seperately if you will. It might be a flakey sensor too...it is it bit beyond my knowledge, but it is interesting.

 

Nah I'm not getting any yo-yo symptoms. It is interesting about the timing though. Perhaps after the car is well-warmed, the higher IAT plus the advanced timing of the Shark is causing detonation?

I would just hate to lose the Shark if I don't have to. Although that would give me an excuse to get a real tune

 

Since you are in mass, have you ever talked/visited Greassy's in Worchester (I can never spell it)?
I think he will be out of town next week, but it might be worth a visit/call when he gets back. His prices are much better than the stealerships, and he just moved to a new location. He might have some thoughts...he also is a founder of the massmotoringclub.com, a mini centric board kinda similar to this, but local in nature to mass, used for mostly planning group events and social stuff, but some mechanical threads too.

 

I took the car for a 10-15 minute drive this morning starting with a cold engine. Did a few good pulls around town. Pulled back into the garage and pulled the plugs and this is what I found (plugs are in order 1-4)






Looks like a lot of detonation, based on the white specs. I think I'm going to have the dealer reflash the ecu. My stongest guess is the timing advance is just too much.

 

All that crud make is difficult to see where the color change is on the straps. If it's at the base of the strap then you have too much timing....Is that where the color change is ?

I would definately consider a reflash of the ECU and strart fresh w/o that shark flasher.

 

It was part no. 15




Specifically the green gasket had the raddish.....made the attach hole adjacent to it elongated. MINI Parts Depts stock this green gasket as it is a know problem area and seems to fail around 80-90K miles. Greasy's stock it too I think, and may even have stock the whole piece.




Cant say I had sperratic performance variances though from day to day or hr by hr. Once it was buttoned up correctly with new tube and gasket I did notice improved throttle response. I had the DT BPV in there for about a year now and barely noticed a difference from the stock one.

I notice the difference now since this part was replaced. So this gasket had to have been leaking.

 

2 Months later...........

I just installed my Alta intake and Brisk DR12S plugs last night and this is what my BKR6EQUP's looked like. I haven't pushed the car at all over the past month, just normal driving really. These have about 3000 miles on them. There are about 6 darkened threads on them, so I was in definite need of colder plugs.



I'm curious about the inconsistent coloration on the ceramic from plug to plug.

What I have noticed is much smoother performance and quicker throttle response with the intake and plugs. The car did still feel slow, however. Ambient temp was 85 out, so maybe that accounted for something.

Also, check out the discoloration on the insulator. 2nd from bottom one:


What is that about? Just too much heat?