Ok, so I don't think I'm jumping to conclusions here. Let me know what you think.

The car is an 03 Cooper, 95k miles. For a while it's been experiencing issues that have been described in the Sticky at the top of this forum. I haven't gone through that whole sticky though. The bits that I did go through didn't seem to have much helpful information. Someone ought to think about cleaning up some of the clutter in that one.

It's had a loss of power. Fuel economy has gone down. We used to be able to get mid 30s easily and up to 38 if the trip was all highway. Now, I have to really struggle to get 32mpg. Usually I end up settling for 28. If I have to use the AC, the car damn near dies at a stop light when the compressor kicks in. And the same thing happens when I start it up in the morning. It starts up, and then falls on it's face. It doesn't die, just stumbles pretty bad. I don't have any idiot lights or codes or anything.

I'm suspecting something is up with the fuel system because I was on a week long business trip this week and when I got back to the airport, it took considerably longer to start up, suggesting it isn't maintaining the fuel pressure.

I made sure I was at Stage 0 and changed the air filter, plugs, wires and coil. From what I could tell, there isn't anything else to do for a tune-up. I also changed out the fuel filter, total PITA but it needed to be done. The only other thing that could be done is a new cat and O2 sensors. I don't think the cat is clogged because the exhaust flow doesn't seem all that bad. I can feel it coming out of the tip from over 3 feet away(not the most scienific, I know. but...). And if the O2 sensors were going, you'd think there'd be a code/CEL.

Anyway, is there some sort of check valve for the fuel to help maintain the fuel pressure? Or could this just be a fuel pump wearing out. I know on an old Volvo turbo of mine from way back when (it was a Tuesday, not sure if you knew that), I installed a high flow fuel pump with the rest of the system being stock and saw a dramatic increase in fuel economy. I went from 23mpg, which was normal to 28mpg, and that was with me driving like, well...a kid. I don't know if it was atomizing the fuel better or what, but I swear it worked.

Thoughts? Anyone else have any experience in this? I don't have a fuel pressure gauge to slap on. I wonder if Harbor Freight has one.

 

Maybe try some injector cleaner.

Mark

 

Since you are not having any codes or lights on the dash, I guess the O2 Sensors are good.

And generally speaking the fuel pump is electric, and so for the most part, it either works, or it doesn't work.


When was the last time you changed the PCV valve ?

Found here in engine compartment.

IMG_0783.jpg?t=1248553124

Look like this:

IMG_0785.jpg?t=1248553203

Here is part bag from MINI - Costs 20 dollars. ( *May be different Part No. For a Cooper )

IMG_0784.jpg?t=1248553272


Should be changed every 30K miles....if not you will eventually experience all the things you mentioned, and ultimately total engine failure......

INFO FROM A SOURCE I USE ON OCCASION:


The PCV valve is perhaps the oldest emissions control component to be installed on production cars and light trucks. The PCV routes partially burned gases (called "cylinder blowby gases") from the crankcase back into the air induction system, where they're reburned in the combustion chamber.
Over time, oil and gasoline build up as sludge inside the PCV valve assembly, plugging up the valve and increasing crankcase pressure. A worn PCV valve or breather element causes heavy engine sludging, poor engine performance and stalling. Symptoms of PCV valve deterioration include:
Excessive oil consumption and leakage. The increased crankcase pressure forces oil through seals and gaskets.
Air filter contamination. The increased crankcase pressure forces PCV vapors through the breather element, depositing oil and hydrocarbon particles on the air filter itself.
Poor idle quality and hesitation. A sticking PCV valve does not fully close, allowing "false air" into the combustion chamber that dilutes the air/fuel mixture.
Most manufacturers recommend replacing the PCV valve every 30,000 miles. However, check for signs of a plugged or sticking valve when you're inspecting the air filter and engine compartment.

 

Actually about 20-30 years ago before detergents were added to fuels and fuel injectors were at their infancy, this was a viable solution to some of the problems OP mentioned, but today injectors are not as easy to clog up anymore due to improved design....IMO fuel injector "cleaners" are pase, but would opt for something like slick 50 fuel system cleaner/lube instead.

 

Grey Raven, thanks. I'll check it out for sure. I had noticed a bit of an oil leak last time I changed the oil, but never thought the two could be related. I thought it was just from the car getting some age to it, and running Royal Purple. On the aforementioned Volvo, I switched to fully synthetic oil, and all of the sudden, the seals weren't so dry anymore. Would you think that seal would need to be replaced? Or should I try replacing the PCV and see if it stops seeping?

 

Ha, knowing my wife if it didn't get changed under warranty, it didn't get changed.

 

Betting you could do wonders with a good scan of your system. Any good diagnostic shop will do this for $50. Just get the print out and see what is out of speck. Post all your codes and values and we'll try to help.

If you try injector cleaner, try Techron.

YD

 

np, on a bad note our cars can be real oil seapers.

Had my oil pan gasket replaced at 75K miles.

As was my main bearing seal on the pulley side same time.

My maunual transmission filler plug had to be snugged up too.....

It will probably still seap oil no matter what at this point, so replace the PCV valve just the same.

Dose your local MINI Cooper Club have their own mechanic by chance ?

 

Or better yet, get yourself a Scanguage II. They are pretty cheap, and you can leave it velcro'd to the dash and monitor your water temp, Air intake temps, Amp readings, and other data w/o having to buy 300 bucks worth of guages and pods to mount them in

Hooks right up plugged into the OBDII port by your left foot well.

 

I caught my car nearly dying at a stoplight and had the presence of mind to look at my scan gauge. Unfortunately the only useful diagnostic value I got out it was a MAP pressure of about 10psi at well below idle. So something had to been pretty out of whack to get to that point...


EDIT from the grave:

This can happen when an engine runs at low speed, it jsut isnt turning enough to pull any vacuum,

 

Reason I ask is that when my wife accidentally put in regular the mileage went down dramatically and took a few tanks of premium to get the computer back on track.

 

That is one thing that my wife was very diligent about. I only fill it with Shell 93.

Yo's dad,

If I don't have a CEL, would I still have a code?

 

I just got it in the mail and put it on last night. I went for a quick drive and didn't notice a difference. I didn't drive it to work today, but when I start it up cold, we'll see if it quickly falls on it's face. I'm not terribly optimistic.

Any other ideas?

 

So I figured I'd give it a chance. But having driven it for a while now after installing a new PCV valve, there's been no change.

I cant be the only person with this issue.

 

You're not alone..... mine has almost the exact same symptoms. I just started searching the forum this afternoon and found your thread.

The only other thing I have come up with is to put my factory 15" wheels back on. The car currently has 17" wheels. I don't have much hope of this helping but the calculated diameter went from 24.0" to 24.3" when I changed them (probably 4 years ago).

I'll be watching this thread closely hoping the smart guys chime in....

 

Yeah, I got a little fuel economy back when I put 15s on. But that has since been negated by the problem getting worse.

I'm on the road right now(with the car at home), and I'm going to make sure to see if it takes more cranking than usual to fire up when I get home. To me, that will pretty much confirm that it's a fuel issue....or fuel is part of the issue.

 

the summer gas swap over hasn't helped me at all ; hard cold starts worse fuel economy , stumbling at stop signs on occasion . oddly when it switches back over the car will be fine .

 

I am having almost the same issue as you but when driving it falls on its face then the power comes back on hard and feels like someone rear ended me. Happens in any gear and worst when the engine is hot.

I have no fault codes and unsure if gas mileage has changed.

 

Holy thread from the dead.

I ended up starting a new thread. It's below and details what the problem was. I haven't seen the issue since the work mentioned in this thread was performed. Apparently bad intake manifold gaskets are a common problem in the N/A Coopers.

https://www.northamericanmotoring.co...my-tail-2.html

 

My issue is similar but I did not have all of the symptoms. Up until recently during morning start ups, I would typically have a difficult start. But, after new plug wires, ignition coil, O2 sensors, that smoothed out mostly. But what continued is the following: Upon starting, car goes to its normal RPM of ~900, then dramatically ramps down to ~600. During this sudden drop in RPM, car rumbles as if it's going to stall... Then RPMs increase to ~900 again. No stall and can pull away. Otherwise, car runs and idles fine. Seems that for a brief moment, the engine can't maintain its vacuum and starts to falter, but something jolts it to life. Will be swapping the PCV valve tomorrow and hope it helps. Any thoughts in general. It's not affecting overall drivability, but I would like to get to the bottom of this frustrating issue.

Regarding the PCV swap, any good technique from those who have done it? I want to avoid damaging the hose that runs off of it, which appears rigid after the initial portion of the run. I'm thinking of disconnecting the screw that holds it in. Then, with it in hand, I'll weasel it out of the hose - employing some WD40, if necessary.

Thanks!

 

You're pretty much following the same steps I did and getting the same results I did. I would highly recommend checking your intake for leaks. On my car and a lot of other Minis, from what I've heard, the intake manifold gasket deteriorates and allows un-metered air in, causing your motor to run lean.

Of course the dealer claimed they'd never heard of this happening. Whatever.

Anyway, good luck.

 

Not a DIY job, I take it... Anyway, when it was done, did the issue get resolved? Do you think the PCV valve I intend to swap could have a hand in allowing this loss of vacuum in this small window of time I've described?

 

The PCV valve is easy and cheap and it's definitely not going to hurt. But I rather doubt that it will completely eliminate you issue....based on how similar it sounds to my experience.

It may seem a bit extreme to to perform a leak test on the intake, but if it prevents you from having to rebuild the head like I had to, it would be a very worthwhile investment.

 

The gaskets themselves are cheap but getting at it seems a little annoying:

http://tis.spaghetticoder.org/s/view.pl?1/07/01/73

I have the same exact symptoms as you (rpms dip down after starting the car, then back up and its fine for the rest of the drive). Will be picking up a PCV valve tomorrow to try that first. Did you put your PCV valve in yet? Any improvement?

What year MINI are you driving? Manual or auto? I wonder whether it's related to the CVT software in mine.

 

Put the valve in a couple of weeks ago. No improvement. However, I'm told it's a worthwhile thing to do just for maintenance sake as the valve can get bogged down in oil, etc. My old one seemed perfectly fine, however. Shook it and it made the appropriate sound, but still replaced it. Who knows... Mine's a 2002 MINI Cooper. Automatic. Sounds like it could be computer/software related. Not too concerned anymore, as another problem developed.

My post from yesterday:

Whaddya think? Noise issue (front end) ...
Ok, I have this sound coming from the front of the vehicle (grinding or scraping) that occurs when I accelerate beyond a certain point. Then when the gear changes, it goes away; actually, it may or may not occur with gear changes. However, it does seem that way... Of note, the sound only lasts a brief second, then disappears until the next "aggressive" depression of the accelerator.

Here's my question: In my research, I've come up with possible causes. These are: 1) heat shield issue. The mechanic did seem to warp the heat shield when he needed to gain access from the front end to remove an old O2 sensor; 2) engine or transmission mount; 3) stuck caliper; 4) pre-cat O2 sensor aluminum shield (not sure we have one of these); 5) exhaust mount; 6) front wheel bearing; 7) something with the air intake system; 8) something going on with the transmission.

Hoping it's #8, as still have warranty on that from tranny replacement ~ 1 yr. ago. or #1, as the mechanic will have to remedy that for $0 as he caused the damage.

Any input on the likely cause, IYO, is appreciated...