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2008 Mini Cooper S hatchback,Automatic,Mello Yellow
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Discussion Starter · #1 ·
I have a Mini cooper R56. That I have painstakingly rebuilt. Now it is a year later. And was wondering, as I know everything on it is correct and done correct I.E. timing marks lining up and the car idling fine and such. That if bad gasoline could cause horrendous backfiring? Or if it is something else? Like my cat convertor or something.
The Car sits in a garage and starts and runs in there. It was running fine and has sense the changing of the timing chain. I drove for 4 or 5 miles. Now the gas in it by that time was about 11 months old. After about 4 miles or so it started backfiring when driving it.
So to be concise as there are a number of factors involved does anybody know off hand if having bad gas would cause such a issue? or if it is another problem that I have.
To me everything checks out fine in the garage at idle and what I also foolishly did was fill my gas tank when I was driving that day. I added gas to the fuel tank that was at 3 bars before I filled it up.
Now I was just wondering if that my be what I am dealing with or if someone knows. another angle? I check my turbo actuator vacuum hose. among having new spark plugs. I did swap a coil pack number 3 for a different one I had in the garage. It seemed to take the backfiring when I let off the pedal away or it could be just putting the throttle peddle through the motions that did that.
Would a bad vanos or phaser create something like that? with all things considered it sounds like it would. No leaks coming from the vanos area. would it be a vanos or phaser that I would change first. I inspected the phaser and the dots line up! but the vanos I had replaced a couple of years ago and it was not the real expensive one. but ran on the car for a while before doing the timing chain. And posed no problem.
I know what I am asking here alot of it is auto logic diagnostic type stuff. Of course I am gonna take it in. Just did not know if I am making a mountain out of a mole hill considering that it did have bad gasoline in it for a year.
And if that is the problem. WELL everyone knows that has a cooper S that it does not like to be in one spot running(certainly like a garage without say a fan? I don't know).
Point is what do you mini cooper lovers and driver think I should do? all around. I have a full tank of gasoline. It does not backfire at idle. 70 percent is new gasoline 30 percent is old and possibly bad being 1 year old inside my tank without the car running.
Or should I have the tank dropped and drained to begin with? and lastly just take it to a mechanic and have him run diagnotics and the full works at a premium. And tell me if the car is able to be saved or just junked?
Timing marks are dead on. so mechanically it's on the money.
Just a lot of late aftermath of changing a timing chain right under a budget over a year. is what I think.
anything would help. and it is nasty cat type backfire. but it's is redone in stock form. meaning new turbo borg warner, stock intercooler.
would a new turbo cause that issue if it were cracked or something. I paid for a what a retail borg goes for on the market. but nothing is perfect.
It would not be the blow off valve I hear it when I let off the gas.
It does have new piston rings would that make compression and seal so tight that I would have to consider getting a new cat over it? can a mechanic tell if a cat is good or bad or exhaust system for that matter?
I know that the phaser gear does need to be computer set when a timing chain is replaced. But that computer setting is for it to work efficiently from what I am aware of and would not cause backfiring to the degree I am experiencing. further more it did not backfire in the first five miles after starting it. Could that just be preserved fuel in the lines that were not exposed to the same thing the rest of the fuel in that tank was over the course of a year?
Please help?
 

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07 R56 S
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When does it back fire...I pulled valve cover one day for routine check chain tension......found rocker arm laying atop head...could not reinstall ....dealer quick diagnose bent valve WRONG....bad lifter...major backfire is built in warning....go to easy basics diag before before entertaining techno babble....G Luckl
 

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the cooper s n14 and n18 engines dont like weak fuel for sure,, ie i have had to put some super market cheap fuel in mine from time to time and it makes it back fire on over runs and causes a lag spot under 2k as well,, they really need to be 98 or above ron,,, what happens is higher ron fuels burn lower and more dense ie more rich is fuel molecules and a better deeper burn,, when lower octane fuels or gone off lower fuels cause it to lean out and when on over run can cause a mismatch in fuel and air mixtures it also can cool the upstream 02 sensor as well and ecu keeps trim on air added all over the place,, so yes fuel can cause this,
so can wrong spark plugs ie these engines do best with what factory say,, a lot of people stick iridium spark plugs in thinking a harder plug is a good move,, trouble on these engines the coil packs not man enough to run these plugs,, and causes dead sparks ie a cylinder dont ignite its air fuel mix in the cylinder then this gets pushed out in to the cat when the next cylinder exhaust stroke ignites it ,
also a faulty injector will do same thing where get drips of fuel on dead strokes,,
also as moneydump says and i have seen many cars around 100k with broken cam post lifters,,
also vanos sprocket sticking will cause same thing,
and another one is pcv system dumping to much oil in to inlet manifold ,,,
also valve stem seals cause smoke and misfires off exhaust valves but this oil drip goes hard on valve seats and causing compression issues ,
this all said you need to be able to read the can see what its doing on fuelling
cooper s 2007 live data running right 2.png
cooper s 2007 live data running right.png
etc some screen shots of a cooper s 2008 just after i rebuilt it and everything is where you want it for reference

bare in mind this was within 30 minutes of first run seen the car again after 6 weeks and all were still perfect,, notice the smooth running's if you have two that are miles out then thats the cylinder playing up,, also combine this with smooth running ie if one is not matched with rest then thats the issue,
i used autocom cdp plus for live data runs,, it also will allow you to reset the adaptions ie learning for the vanos sprocket and 02 sensors and fueling,, you were slightly misinformed about there is no reset processes after a rebuild,, most deffo is and is really a must do and need something dealer lever like autocom,, link below for very cheap ones
good luck trying to find the issue without a diagnostics tool , fresh fuel in it would be my first job,, ie pull rea seat out and remove tank sender unit and pump the fuel out,, or pull the fuel pipe to the high pressure fuel pump and add a inline pump to it another way link below for universal pump,
pump
 

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2008 Mini Cooper S hatchback,Automatic,Mello Yellow
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Discussion Starter · #4 ·
Wow this is a lot information. It has been one heck of year. With all kinds of stuff going on. I decided to send it in today. Down to the automotive shop. I getting a diagnostic. and will know this money. And will certainly share what it was. I tend to agree with everyone here. although I did repeatedly check the timing and valve train for disturbance and everything was according to hoyle. I think it may be gas hopfully. It might be something different and will just have to wait to find out what the verdict is. As of now. when I went out there and started it up it was purring like a kitten. Over this last year I have had to learn all kinds with this car and when they loaded it up on the wrecker truck it sounded good. It was just when I let off the gas around idle type RPM.
Not to say it was not serious but I will be letting everyone here know. Bad Gasoline in a high compression engine producing a situation of back fire. I owned the car it's whole life and it would be a first.
And I'm no expert mechanic but did work on it more in depth then any other time I owned it. Some of what got it there has been people here. And were gonna find out this Monday. And some time in future will be back to talking about good and healthy backfires.
 

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trouble with back fires on a engine that has a cat on it is the cat gets blown part over time and thats another can of worms,
 

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2008 Mini Cooper S hatchback,Automatic,Mello Yellow
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Discussion Starter · #6 ·
Another can o worms. I hear that. I checked timing spot on. Checked into the list of parts the scanner looks affordable I probably won't be able to set the adaptations but will at least know. The Place I took it to did not know what the problem was and did not charge a fee for it either.
IT COULD BE ANYTHING. but it would at this point behoove me to check some of those values with my Bavarian techniq equipment. I know it has fuel voltage and stuff like lambda. I will just have to look into it. started it up today for about a hour and drove it around the block a couple times and in the high school parking lot a couple time.
At idle it does not make a backfire at all. It maintains a consistent idle and goes through it's idle functions without a problem. Example it adjusts during AC use and calms down after a set amount time after first turning it on. The idle does not fluctuate. With that said combined with going around the block. In first gear of course or second don't know it's automatic.
It does not backfire. so about 15 miles per hour or 20 if it is flat ground. Uphill it will backfire once or twice and in the later gears I have not tried but know it probably would.
Anyway I can burn the tank of gas off it might take some time. but if it is bad gas.
So I stopped running the car today. Then pulled the valve cover and checked the timing again, Just in case the shop I took it to might of done something else. My timing mark is still there on the harmonic balancer (lined up with the oil pan gasket).
I continued to pull the spark plugs after not seeing any rocker out of place(wanted to do a tac hammer on the rocker test I DID NOT!) Nothing seems remarkable.
After looking into each of the spark plug hole's with a flashlight. (I really need some sort of camera scope) 1,2,and 4 look like the standard smear of grease for running the car sense re doing the timing and head gasket. But the number 3 looks like it has maybe a 1/2 a tea spoon of liquid(I see reflective not shiny like moist tell me it is a drop of something) on top of the drop of liquid not much but diffininatly where the backfire may be coming from(could it still be bad gas water not burned?) . Now I know I need a camera.
Someone here said a fuel drip. That would be heaven sent if that is what that was.
With liquid in mind it could be anything. I am smart enough to know that just because the coolant is maintained it's level sense putting the new coolant in does not mean it could not be that. Or worse yet blow by. A issue that is common with most standard type ring sets. And not so common with mini cooper original plastic wiper sets. Standard mahl is what I bought and replaced the rings when I went into the engine.
I don't know what it is at this point but was referred to shop that is better equipped to handle my problem.
Which I will look into to.
Until then I can at least rest knowing that my one car garage is freed up and can move the mini if I have to as long as I idle it to the front of the house on the street.
But yea they could not help me really. I live in the middle of farm land. And most garages only do minor stuff or stuff on John Deere tractors and stuff. Farmers probably like much of the UK.
 

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2008 Mini Cooper S hatchback,Automatic,Mello Yellow
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Discussion Starter · #7 ·
I got a borescope and took photo's of the inside of my cylinders. Number 3 being the one with the most accumulation of oil or water or fuel. don't know what it is. I will also post another pic of my lower side cat converter through the lower O2 sensor. And also a pic through the front part of the exhaust and in the tail pipe later. I due have to retract what I said about the amount of liquid in the number 3 it is not a 1/2 a teaspoon it is not even a quarter. A better view of it would be the closer image of number 3 cylinder. In the tear drop shape there is a ouline that is light reflective. It would be where the light outline breaks and is just black. Showing the amount of accumulation of liquid. also included are the other cylinders. keep in mind I did plastic brillow pad scrub the tops of the pistons and that the mini cooper pistons will have a dirty smear to some degree even though this is about 50 miles into it running counting the stand alone engine running time. Due to the fact that it renders oil vapor from the valve cover via the fuel tank send back and intake introduction from the valve cover tubes. To which I have left in the stock configuration. Until problem is solved and I will add the oil catch can.
cylinder 3.JPG
cylinder 3 closer.JPG
uppercat.JPG
 

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2008 Mini Cooper S hatchback,Automatic,Mello Yellow
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Discussion Starter · #8 ·
And here are the cylinders 1,2,4 in that order
cylinder 1.JPG
cylinder 2.JPG
cylinder 4.JPG
 

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2008 Mini Cooper S hatchback,Automatic,Mello Yellow
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Discussion Starter · #9 ·
The bore scope was slightly hot on the tip even though it had been 24 hours sense I ran the engine. The backfiring did not seem to effect the cat from the top view of the membrane(honeycomb matrix inside the Catalytic convertor).
The other exhaust manifold I was running the day it started backfiring was the JCW manifold. The manifold for the JCW has a connected passage for the 1 and 2 cylinders to go to the turbo. The 3 and 4 are connected as with the stock cooper S N14 manifold. But unlike the JCW manifold the 1 and 2 cylinder have there own passage to the turbo.
In either case the passage to the turbo is adjacent to the number 3 cylinder runner.
In either case with either manifold I used or am using(presently using the stock manifold.) The RPM cut down very quick when I let off the gas in park gear. So I have to slowly add gas by pressing my foot down on the gas pedal in order to maintain RPM. And when I lift my foot the RPM does not float all the way down to idle; it goes down faster like something is causing it(perhaps a piston not firing).
And that is what is strange. That at idle it has no problem maintaining anything. So the computer if it were like my foot would be adding gas to a point then having to reset it proverbial foot to grasp ahold of the RPM that it is maintaining.
This leads me to believe that it is not advancing like it should. Considering it is after 2000 rpm that I have problems maintaining any type of RPM.
And like someone here said it tends to be under 2000 rpm that backfiring occurs. My backfiring occurs at around 1500rpm everytime. Unless I have actually drove it like before up a hill forcing gas while the car is accelerating it is backfiring.
And at 1500 rpm it happens both directions. While I am accerlating past 1500 sharply or when I let off after holding a consistance 3000 or so Rpm. At which point I let of the gas at 3000 rpm and it goes past 1500rpm on down to idle speed again.
Anyway RPM goes down quickly from anything over 1500Rpm. But not so fast that it is causing a droning sound or anything.
And that dash of fliud it would be good to know what that is. I wish it were as good as it sounds on paper. That it could be bad gas with condensation from water in the gas after the alcohol burned up in the 3 bars worth of gas that was in the Car for a year; plus the 2 gallon tank reserve that does not show up on the gas gauge. So about 5 gallons total.
Mixed in with another 8 gallons of new. A 13 gallon tank if I am correct.
That the water gas mix is coming out of the injector and the gas is getting burned up and the molecules are collecting on the piston surfaces. But not exactly showing up in one lump sum.
Thing is.....it is the number 3 cylinder adjacent to the runner that dumps into the turbo.
I wish there was somewhere else I could look with the bore scope that might give me more evidence.
 

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2008 Mini Cooper S hatchback,Automatic,Mello Yellow
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Discussion Starter · #10 ·
I figured out the problem. It was 3 of the direct injector Teflon seals were absent when I pulled the fuel rail. Forgot to put them on after alllllllll that stuff I had to do sense June of 2019 until about a month ago when I resolved the problem. thankfully I did not try to buy a new HPFP. and man does it wind out now that everything I did and brand new everything in there working fine.
 
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