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Kerry_BMW
07-09-2003, 03:17 PM
Hey guys,

I have a '98 318is, I did a compression check on it the other day, I'm wondering what the compression accross the cylinders should be. I found the #4 Cylinder to be lower than the other three.

BMW is trying to tell me they hooked it up to their computer and it said there's nothing wrong with the head. I found that the compression was:

185psi on #1
185psi on #2
185psi on #3
165psi on #4

It seems to be worse when the car has been at normal operating temp for a while. The car will noticeably vibrate at idle. This is my first 318, they're telling me it's normal for the 4 cyl models. Which doesn't make sense to me, cause shouldn't it be easier to balance a 4 cyl engine? My 325 runs smooth, and it's 10 years older.

KIRASIR
07-09-2003, 03:49 PM
m44 is notorious for rough idle, just get used it.

Having said that I would definitely double check the 4th cylinder.

What's the milage on the car?

SL

Originally posted by Kerry_BMW
Hey guys,

I have a '98 318is, I did a compression check on it the other day, I'm wondering what the compression accross the cylinders should be. I found the #4 Cylinder to be lower than the other three.

BMW is trying to tell me they hooked it up to their computer and it said there's nothing wrong with the head. I found that the compression was:

185psi on #1
185psi on #2
185psi on #3
165psi on #4

It seems to be worse when the car has been at normal operating temp for a while. The car will noticeably vibrate at idle. This is my first 318, they're telling me it's normal for the 4 cyl models. Which doesn't make sense to me, cause shouldn't it be easier to balance a 4 cyl engine? My 325 runs smooth, and it's 10 years older.

Kerry_BMW
07-09-2003, 04:09 PM
The car has 101K on it now. What is the common cause for the rough idle?

djcontra
07-09-2003, 05:06 PM
Originally posted by Kerry_BMW
The car has 101K on it now. What is the common cause for the rough idle?

Check the plug on cylinder 4, and also check the wires. Maybe even replace the plugs and wires to see if that corrects the idle.
Do 318's have distributer caps? Check to make sure it's not worn, those are inexpensive to replace if it is. If the rough idle bothers you a lot, you could play with the idle control valve and tune it to your liking.

p.s. i've never worked on a 318 engine, but those are just some general things to check from my experience with other cars.

Kerry_BMW
07-09-2003, 05:30 PM
The plugs are good, as are the wires. The M44's have a distributorless ignition system. It's not a constant vibration, only after it's been at normal operating temp for a while.

Those factors would not contribute to low compression. I'm hoping no damage has been done to the head or the block. The car may have overheated excessively before I baught it, do the blocks warp easily in M44's?

dtthiaga
07-09-2003, 06:23 PM
I had the same problem with my 97 318is (1.9L 4 Cycl Engine).
When BMW hooked up the computer, but it said nothing was wrong.

I pressured them a lot, and they finally opened the motor up and found some problems. It was under warranty though, and they fixed the problem.

Do the e36 Self Diagnostic Test on your Dash. There is a code for Over Rev and Over Heat.

Kerry_BMW
07-09-2003, 06:45 PM
Originally posted by Kerry_BMW
The plugs are good, as are the wires. The M44's have a distributorless ignition system. It's not a constant vibration, only after it's been at normal operating temp for a while.

Those factors would not contribute to low compression. I'm hoping no damage has been done to the head or the block. The car may have overheated excessively before I baught it, do the blocks warp easily in M44's?

How do I perform said test?

Adriano
07-14-2003, 10:35 PM
Your dealer is full of shit!!!!!!!!!!!!!!
Those guys don't know there ass from the hole in the ground!
I ran nitrous and got carried away. Yes, I was a moron and ran lean (120 shot) and bent an exhaust valve. Anyways I broght it in to the stealer and they told me nothing was wrong even though I had to hold the gas down to keep it from stalling. Anyways $85 later I decided to do a compression test. 185 from cylinder 2,3 and 4 and 35 on number 1. All they know how to do is hook up there damn computer and if it shows nothing, then there is nothing wrong. Anyways I went back to give em shit and they told me it idled rough BECAUSE I HAD THE NITROUS INJECTOR AFTER THE MAF UNIT INSTEAD OF BEFORE IT!!!!!!!!!!!!! WTF???:mad: :mad::mad: I almost pissed my pants laughing infront of 4 other customers!
185 sounds right but the 165 is bad. You will want to do a dry and a wet compression test to see if it is your valves, head or pistions. The engine SHOULD NOT IDLE ROUGH (sorry KIRASIR, they run very smooth). There is definatly something wrong with the car and the computer (diagnostics) will not tell you anything! Sorry to be the bairer of bad news bud. I ended up doing a M3 swap.

Kerry_BMW
07-14-2003, 10:56 PM
I've been fighting with them for two weeks now. They keep trying to tell me there's nothing wrong with it. Yet I did the test three times to make sure before I brought it in, sure enough, every time the #4 cylinder was at 165PSI. Does anyone have a page in some Mitchel manual I can tell them to reference to show them that this is not normal? Cause I'm tired of people who don't know what is going on telling me that there is nothing wrong with it. All they do is get in it, drive around for 10 min, come back and say the car is perfect. No shit Sherlock, you think if it was that easy to notice the problem I would have purchased the damn car after the test drive? How 'bout NO Scott!!

My car is completely stock. I figure that the previous owner, or the dealer overheated the car and it ended up warping either the block or the head. I assume when this happens there is a place on the block that it commonly happens before the rest goes. Anyone happen to know if this is the #4 cylinder, or the cylinder closest to the firewall?

Any help here would be greatly apreciated.

KIRASIR
07-15-2003, 03:56 AM
I would have to disagree on that one with you too. I'll even post tomorrow a BMW bulletin on the rough idle problems with m44.

Having said above, I am not saying that 165 compression in the 4th cyl. is normal. Something is leaking and it will only get worse.

SL

Originally posted by Adriano
The engine SHOULD NOT IDLE ROUGH (sorry KIRASIR, they run very smooth). There is definatly something wrong with the car and the computer (diagnostics) will not tell you anything! Sorry to be the bairer of bad news bud. I ended up doing a M3 swap. [/B]

Adriano
07-15-2003, 12:51 PM
Again, you must do a wet compression test. Dump 3 teaspoons of oil in each cylinder and do the test. If you compression becomes good (within 10 psi of each cylinder) then this means you have fried your rings. If the compression does not change with cyl #4 then you have a bad head gasket or you bent a valve.