2004 mini cooper 1.6 wont start, fitted new plugs, plenty of spark, good fuel pressure at injector rail, injectors testing ok, compression a bit low on number 4 cylinder,checked vehicle with snapon solius pro no codes showing,im baffled

Did you test for spark? I would check spark and fuel pressure. OK, here's a little bit of working theory that'll help you to see the ‘why’ of the Noid light test.

Whether you're testing a No Start Condition or a Misfire Condition, you'll need to know if the cause of the problem is a lack of fuel. When your GM 3.8L (Buick, Chevrolet, Oldsmobile, Pontiac) does not start, it will be either because of a lack of fuel or spark. The same thing goes for when your GM 3.8L equipped car or mini-van is misfiring... that specific engine cylinder isn't contributing to engine power because it either lacks fuel or spark.

Now, since the above two conditions (No Start and Misfire) can be caused by any number of things... one of the things that has to be eliminated, from this list of possibles, is the fuel injector not getting power or the injector pulse signal (On/Off switching signal) from the vehicle's Computer.

This is where the fuel injector Noid light test comes in handy, because you're able to visually see if both of these signals are present or not. If no flashes, then now you know that you have to verify that the connector is getting power (12 Volts) and the injector pulse signal.

One thing to keep in mind, is that the fuel injector Noid light test does not test for a BAD fuel injector. But, is the first step in verifying if the fuel injector is BAD or not. For the fuel injector test tutorial.

Check for spark at 1 or more plug wires. If no spark, possible crank sensor/computer/fuse/wiring. Check for injector pulse. Remove 1 injector harness and install test light between the two terminals of the harness and crank engine. Test light should flash if computer/wiring ok. Make sure check engine light comes on when key in on position for bulb check. If no light, look for blown ECM fuse/s

OK IF YOUR YOUR SURE YOU HAVE SPARK AND FUEL THEN THE PROBLEM IS AIR OR COMPRESSION I WOULD THINK COMPRESSION DO A QUICK COMPRESSION TEST AND I THINK YOU WILL FIND THE PROBLEM IS A BROKEN TIMING CHAIN ONE OTHER POSSIBILITY IS A PLUGGED CATALYST BUT FOR BOTH BANKS TO BE PLUGGED TO THE POINT IT WILL NOT START IS VERY RARE GOOD LUCK (WHEN YOU SAY YOU HAVE FUEL DO YOU MEAN THE FUEL PRESSURE IS GOOD AND YOU HAVE INJECTOR PULSE OR JUST THAT YOU HAVE GOOD PRESSURE THE INJECTORS MUST PULSE AND HAVE AROUND 45 TO 60 PSI (RULE OF THUMB) FOR IT TO START ) USE A NOID LIGHT TO TEST INJECTOR PULSE OR IF NOT AVILABE SUBSTIUTE A 194 BULB AND BEND THE WIRE TABS FROM THE BULB DOWN AND PLUG THEM INTO THE INJECTOR HARNESS (NOT RECOMMENDED FOR ASIAN OR EUROPEAN CARS ) THIS LIGHT WILL BLINK WHEN CRANKING OR RUNNING IF YOU HAVE INJECTOR PULSE

For a no start , cranks over ok. be sure you have fuel pressure at the fuel rail first, before checking the injectors. There should be more that 40 psi at the rail... if not .. you might have a fuel pump problem. Even if you have fuel pressure at the fuel rail... the next thing I would check for,,, is spark !! Make sure you have spark at the spark plugs. The order would be... fuel pressure first and then spark , , then injector pulse. !! Then plugged exhaust.... then bad fuel then engine timing. The injectors have power to them all the time. The PCM controls the ground to the injectors. So you would have to monitor the ground side of the injectors. So checking injectors is kinda complicated. Hope this helps you. Good luck.

Do any cylinders fire at all? You have the three requirements (comp., spark, fuel) for a properly timed engine to kick right off. You may have to re-check your timing marks. First check your injector circuit. Pull off one injector connector. With key on, one of the injector wires should have power. Check with a test light, should be steady voltage. Now check the injector ground circuit: Put the black lead of the test light on the positive post of battery and probe the injector connector wire that did not light up. Have someone crank the car. If working properly the test light will be blinking when cranking. If this test checks out, the injector circuit is working.
One last: Does your Cooper have a distributor, or is it distributorless ignition? If it's a distributor, maybe you are 180 off-pull dizzy off and rotate 180 degrees and replace.
Well, if all else fails, check your timing marks again. Good luck.

Pull your O2 sensor and see if it fires. If so you have a clogged cat.

Well, it sounds like you have spent lots of money on parts, if nothing else!

Before we get started, please review this article: What Else Could Be Wrong?

First, keep in mind that "NEW" and "GOOD" are not the same. If they were, we would have no use for the word "WARRANTY". One or more of your "new" parts could be causing the problem. so please follow these instructions and disregard what is "New" and what is not...our goal here is to find out what is NOT WORKING. I have seen a lot of misdiagnosis because of getting these confused.

You first need to isolate the system. You are missing FUEL or SPARK or COMPRESSION. To get your engine to start, you must find out which of these is missing. You can check for spark by pulling one of the plug wires off of each coil and putting a screwdriver up into the boot and hold it about 1/2 inch from a metal part of the engine while someone cranks the engine over for you. You should get a bright blue spark. When I say 1 wire from each coil, it goes like this: (I am assuming you have the 2.2L engine...you didn't say) Cylinders 1 and 4 are on 1 coil and cylinders 2 and 3 are on the other. So you need to check spark on 1 and 2 or on 3 and 4 -or all 4 if you want a really good test, but you must leave the second cylinder for each coil connected while you test the other. (ie. Don't have #1 and #4 disconnected at the same time) If there is no spark, then we need to diagnose your ignition system.

If you have good spark, then check for fuel. The only way to do this correctly is to get a fuel pressure gauge and connect it to the service port on the fuel rail. It should go to about 50 PSI and then drop off to the specification of 41 to 47 PSI after the fuel pump times out. If there is no fuel pressure or the fuel pressure is less than this, then we need to diagnose your FUEL DELIVERY system.

If the fuel pressure is OK, then you need to check for injector pulse. This is controled by the FUEL INJECTION system. This can be done with a regular test light and a couple paper clips. Disconnect 1 of the fuel injector connectors. All of the injectors have a GREY wire going to them. This is the injector POWER circuit. If you connect the test light between the negative battery post and the grey wire, the light should light up when the ignition switch is turned to the ON position. If it does not, then we need to repair the injector power circuit. If the power circuit is OK, then connect the test light to the grey wire using the paper clip and connect the other end of the test light to the other wire at the injector connector. (Wire color varies depending on which injector you are working with.) The other wire at the injector is the injector CONTROL circuit. The PCM grounds this wire to fire the injector. When you have the test light hooked up, have someone crank the engine over. The test light should "Blink" on and off. (This blinking on and off is what is called the injector pulse) If the power circuit is good and the test light does not blink when it is connected between the power circuit and the control circuit, you need to find out what is wrong with your injector control...it will require a computer scanner that can read the data stream to diagnos. At least by this time you will know if the fuel injection system system is either causing your problem or it is not.

If everything is OK up to this point, (You have good spark and you have good fuel pressure and you have injector pulse) The only thing left is really bad spark plugs or cylinder compression problems. Pull all of the spark plugs out and check them real good. If the electrodes are badly worn you will have to replace them. If you are not sure, you may want to replace them anyway. Use a compression gauge to check the compression on each cylinder. You should have a minimum of 100 PSI on each cylinder. The highest cylinder should be within 20 PSI of the lowest cylinder.

By the time you have gotten to this point, you will have found what is missing. You may have found the actual cause or you may need to do further diagnosis, but you will at least know which system is causing the problem so you know which way to take your diagnosis.

p0301 is Cylinder 1 Misfire. Check fuel injector,Spark plug, plug wire, ignition coil.

p0326 is the Knock sensor (Combined with above code I'd check the fuel injector on #1 cylinder)

try spraying some easy start into the air intake while someone operates the starter if it trys to start you have a fuel system fault have you checked fuel pressure at injector rail you need to do this using gauge and check against volvo spec if low it will never run if ok check feeds to injectors using multimeter if no feed check relevent fuses if ok using multimeter check continuety of injector wireing back to ecu if it did not try to start using easy start check timing belt is ok and engine has compression

If the plugs are not wet, you have a fuel problem. Check the fuel pressure, if low, the system is unable to purge itself and the last two injectors on the fuel rail are vapor-locked. If the fuel pressure is low you probably have a problem in the tank. There is a flexible line connecting the fuel pump to the steel line that may have a rupture causing the low pressure condition. Or the fuel pump may be bad.

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