Can an Engine Have High Compression And Still be Flooded?

[marvin5881]

Hey guys,

I'm currently troubleshooting my car, 1995 BMW 318is. I keep hearing online to check if my engine is flooded, it makes sense since I've been cranking my car for long periods of time without it starting while troubleshooting so the injectors have been firing for awhile (I have lifted up the fuel injectors and confirmed they fire upon cranking). People will always say that a flooded engine causes low compression, low enough for the engine not to start, but my cars compression in its cylinders ranges from 120 - 190 PSI. Does this mean I can rule out a flooded engine?

 

[supton]

It's possible to wash the oil off the cylinder walls and lose compression, but, I don't think it's that common to do. And you can tell because it cranks super fast. But I don't think all flooding causes this issue, flooding can be just too rich to ignite, but still have good compression.

Is it not running at all, or is this an intermittent issue?

Do you have spark? Is it timed correctly? I'm wondering if a timing belt has jumped a tooth or something. Can you check for codes?

Used to be (probably still is) if you hold the throttle wide open the ECU will cut fueling so as to deal with a flooded engine.

 

[talest]

Originally Posted by marvin5881
Hey guys,

I'm currently troubleshooting my car, 1995 BMW 318is. I keep hearing online to check if my engine is flooded, it makes sense since I've been cranking my car for long periods of time without it starting while troubleshooting so the injectors have been firing for awhile (I have lifted up the fuel injectors and confirmed they fire upon cranking). People will always say that a flooded engine causes low compression, low enough for the engine not to start, but my cars compression in its cylinders ranges from 120 - 190 PSI. Does this mean I can rule out a flooded engine?


Does your car start?

 

[marvin5881]

Hi thank you for the swift answer, Supton. The car isn't running at all, really, the car hasn't ran in 13 years. I've been slowly replacing fluids and brittle plastics and bad parts on and off for 6 months now. I do have spark, and the car doesn't have a timing belt. Apparently timing is never the issue on these cars. I can check for codes by pumping the accelerator pedal five times but it give the code 1444 which means 'all clear'. Considering that I have fuel and spark and high compression, I'm starting to think maybe the fuel pump isn't giving enough pressure. I noticed when I saw the fuel injectors eject fuel, the spray looked kinda weak. Could that be a factor?

 

[supton]

Bad spray pattern, sure. Raw gas won't ignite. But I'd think it'd at least hit once in a while, especially if sat for a few minutes (to let it vaporize).

Hmm, wild guess here, maybe pull the fuse for the fuel pump, pull the plugs, crank it a few times to dry it out. Put plugs in but leave fuel pump killed. Spray a small amount of gas or something flammable into the intake. See if it will at least fire. If it won't do that then I'm thinking spark is off somehow, maybe off by 180 somehow.

 

[WyrTwister]

Any way you can check if ignition timing is correct ? Mechanical spark advance ( if it has mechanical ) stuck the wrong way ?

If you have a fuse that feeds the fuel pump , remove it while testing & spray something combustible into the throttle body & see what it does .

 

[talest]

Originally Posted by marvin5881
Hey guys,

I'm currently troubleshooting my car, 1995 BMW 318is. I keep hearing online to check if my engine is flooded, it makes sense since I've been cranking my car for long periods of time without it starting while troubleshooting so the injectors have been firing for awhile (I have lifted up the fuel injectors and confirmed they fire upon cranking). People will always say that a flooded engine causes low compression, low enough for the engine not to start, but my cars compression in its cylinders ranges from 120 - 190 PSI. Does this mean I can rule out a flooded engine?


As stated, spray in starting fluid and try to start with pedal all the way down to the floor and see what it wants to do.

If your car is not starting it is either because of no spark, no fuel, no compression, or improper timing.

 

[mk378]

Is the gas in the tank fresh? Does it smell like fresh gas?

I've never heard anyone say "a flooded engine causes low compression." Liquid of any sort in the cylinders will take up space and raise the measured compression. If flooded with fuel the spark plugs would have liquid gasoline on them when you take them out.

Do what the others said-- disable the fuel system, crank for a time with the throttle wide open to clear any flooding, then see if it will fire on starting fluid.

 

[mattd]

If the compression varies that much then you have some fuel washes cylinders or a mechanical issue with the low cylinders. That is way too much of a spread.

 

[Srt20]

Holding the throttle WOT will cut fuel. No need to pull any fuses or disable fuel system.

 

[marvin5881]

So the car does fire, once I got a new computer put in the car a week ago, I started noticing that every once in a while I would hear the engine start to speed up while cranking (but not enough to start). Before I put in a new computer, it would never do this. Now, I can go to the back of the car and there will be white smoke billowing out of it. The smoke smells strongly of gasoline, so the spark plugs are in fact working. If I put starting fluid in the upper intake manifold, the car will get right to the cusp of turning over but not quite there yet. I bought a spark plug tester that will light up when you crank the car and all four ignition coils passed the test also.

The fuel in the engine is new also so that isn't a problem. For this car I have also tested the camshaft and crankshaft sensors, cleaned out the ICV too. The car has a new battery that I make sure has 100% charge before I start using it for troubleshooting.

I did get a really beat up looking fuel pump from the junkyard though, planning on changing it out either way tomorrow. Also, the engine sounds pretty healthy when cranking, no sounds of metal hitting each other or anything like that, I suppose it if it was a bad engine I'd be able to hear it. When I get home today, I will try removing the plugs and fuel pump fuse and try cranking it to possibly get some excess out. Maybe now that I have a confirmed good Computer/DME, the result may be different.

 

[heynow]

Originally Posted by mk378


I've never heard anyone say "a flooded engine causes low compression."


Same here.

A flooded engine doesn't start because the excess fuel causes the spark plugs not to fire, not because the compression is lower.

 

[andyd]

Do you have the original ECU, why did you replace it? when you had the plugs out, were they wet? How old is the gas you're using? How much? Is this an M 10 engine? Have you had the cap/rotor/ wires off and cleaned up?

 

[WylieCoyote]

Your problem is a strange one, but sounds timing-related to me. Just wanted to give you two items of caution to keep in mind while you're trying to get this car running.

Be mindful that since you're getting fuel and it's not being burned, it's going somewhere. 2 experiences in my life taught me where it goes when it doesn't burn in the cylinders.

In high school auto shop class, the kids in the class before mine cranked an old ford pickup endlessly, and finally, enough gas collected in the exhaust and they blew the axle-back portion of the exhaust completely off the truck.

When I was in my 20s, working in a Pontiac / Olds / GMC service department, the outside temps dropped far below 0, and a 1989 Olds Toronado was towed in with a no-start condition. The technician foolishly cranked it endlessly, after the owner had already cranked it endlessly, and they blew the oil pan off the engine, and a fire ensued inside the shop.

Please be careful, and mindful of allowing an unknown quantity of fuel to enter and engine and remain un-burned. Your problems could suddenly get a lot worse.

 

[sloinker]

Are you sure you are getting spark? If so then timing can be an issue. Do you have compression in all the cylinders. Are you getting any explosions anywhere? Out the intake etc...find your timing marks and check TDC on #1

 

[marvin5881]

I'm positive I am getting spark, I used a spark plug test light and the screw driver test to confirm that. Honestly, I was guessing the old ECU is bad so it's in the trunk right now.I was guessing the ECU was bad because the fuel injectors weren't firing at the time. Because it is a 1995 BMW 318is it doesn't really have any anti-theft measures built into it so as long as I can find the same model ECU (which I did) then it will work in other BMW's it isn't key or vin locked. I am getting compression in all of the cylinders it ranged from 120-180PSI.

The gas I'm using is two months old. And the BMW has an M42 engine, I'm not sure how to check timing on this type of engine, though. On the bimmerforums they all usually never mention timing in troubleshooting these cars, maybe that's the missing link. Also, I will spray starting fluid into the upper intake boot and it will back blast out of the same boot that I sprayed fluid into, one time hot blue flames shot out. Needless to say I've been reluctant to use starting fluid since even though that gets the engine to turn a lot faster than gasoline

(Edit) I am looking for the timing marks now

 

[WylieCoyote]

That sounds like valve timing is jacked up.

 

[mk378]

Check for spark plug wires in the wrong order. Backfiring almost always means something is considerably out of time.

You can use a timing light on a car that doesn't start. Cylinder 1 should be firing close to TDC when cranking.

 

[marvin5881]

Spark plug wires are in the correct order, I pulled the spark plugs out and cranked it about 30 times with the throttle body open. Then I sprayed a bit of starting fluid in each spark plug hole. I put the computer/DME relay back in and cranked and the engine sounded close to starting about twice and then after that, nothing.

 

[sloinker]

If you have compression and spark and fuel then all that is left is timing. Is the distributor moveable? Have you tried rotating it on it's axis backwards and forwards 90 degrees? Does it even have a distributor. If not you may need to look at cam and crank sensors if #1 is at top dead center and aligns with your timing mark it should fire.