Engine dies at idle.

[Mordan]

Hello!

I have had trouble cold starting my M20 engine last morning. It was parked outside. The air was cold and damp. It wouldn't start. Starter would make noise.

After lots of finicking with sparks plugs, removing them and drying them. I could start again, but only if pushing on the gas pedal. The engine would die if it fell below 1500 RPM. Once hot, the engine would run fine at 1000, but very badly below that. It idles like there is a huge air leak, such as when the oil cap open. But there is no air leak except a small drip of oil at the rear oil seal. I just removed the idle by playing with the screw on the throttle. everything else was fine. No changes except an increase in fuel consumption on the highway. It might be fuel loaded with water.

But now I have a hard time starting even in the garage. I checked the following

igntion coil (Bosch TCI) : primary 1.2 ohms dropping to 0,8. Secondary resistance 5600 ohms. Something is amiss here. I have the secondary resistance of a motronic coil and the primary resistance of a TCI coil. My engine is Motronic.


the ICV reads 40ohms cold and 44ohms hot. 40 is the good value. Is my ICV done? I have 12,2 voltage on the ICV. The ICV is 3 pins L shape. Haynes says when removing the electrical connector, RPM should shot up to 2000. But when I do, RPM falls a little. Is Haynes correct?

I checked the igntion sensors and both have 950 ohms which is good. I couldn't get the 100 000 ohms resistance though. My engine model has the TDC sensor at the front linked to the 15pin connector. Haynes says you can't test it and is not used for igntion.

The only obvious issues are an oil leak on the rear crankshaft oil seal (small air leak I guess) and a hole on the exhaust silencer.


So if you have a M20, please let me know where should I look for. thank you. I would say ICV, but I don't like the ignition coil either.

[tim eh?]

Hello!

I have had trouble cold starting my M20 engine last morning. It was parked outside. The air was cold and damp. It wouldn't start. Starter would make noise.

After lots of finicking with sparks plugs, removing them and drying them. I could start again, but only if pushing on the gas pedal. The engine would die if it fell below 1500 RPM. Once hot, the engine would run fine at 1000, but very badly below that. It idles like there is a huge air leak, such as when the oil cap open. But there is no air leak except a small drip of oil at the rear oil seal. I just removed the idle by playing with the screw on the throttle. everything else was fine. No changes except an increase in fuel consumption on the highway. It might be fuel loaded with water.

But now I have a hard time starting even in the garage. I checked the following

igntion coil (Bosch TCI) : primary 1.2 ohms dropping to 0,8. Secondary resistance 5600 ohms. Something is amiss here. I have the secondary resistance of a motronic coil and the primary resistance of a TCI coil. My engine is Motronic.


the ICV reads 40ohms cold and 44ohms hot. 40 is the good value. Is my ICV done? I have 12,2 voltage on the ICV. The ICV is 3 pins L shape. Haynes says when removing the electrical connector, RPM should shot up to 2000. But when I do, RPM falls a little. Is Haynes correct?

I checked the igntion sensors and both have 950 ohms which is good. I couldn't get the 100 000 ohms resistance though. My engine model has the TDC sensor at the front linked to the 15pin connector. Haynes says you can't test it and is not used for igntion.

The only obvious issues are an oil leak on the rear crankshaft oil seal (small air leak I guess) and a hole on the exhaust silencer.


So if you have a M20, please let me know where should I look for. thank you. I would say ICV, but I don't like the ignition coil either.

my ICV totally packed it in but the idle never got that bad on mine.

it does make a sound when it is working - a fairly high-pitched hum/whine/whir.

next time i drive i will pull my icv connector and see what it does, i know mine works.

i would for sure check the distributor cap and rotor for this.

if you can get it idling again on a drier day... here's something to try-
get a spray bottle and fill it with water and set it to mist. with the car idling spray water all over the distributor cap (edit- you have to take the black cover off of course, it's tight in there :()... if it stalls chances are your cap is cracked.

that's all i got... someone else?

[russiankid]

Have you tried cleaning the valve?

[Mordan]

Have you tried cleaning the valve?

yea I did. Well you will never know what was the issue.

I decided to open the valve cover because I had rebuilt the head 1000 miles before and nearly all the rocker arms had no play...

I still haven't done it back it again, but that must the cause.

[Tiger]

Is this valve manually adjusted or hydraulic lifter? Check your timing chain and see if it is aligned.

[M20Turbo]

yea I did. Well you will never know what was the issue.

I decided to open the valve cover because I had rebuilt the head 1000 miles before and nearly all the rocker arms had no play...

I still haven't done it back it again, but that must the cause.

Hey Mordan...... how is the M20 running/starting?

[Mordan]

Is this valve manually adjusted or hydraulic lifter? Check your timing chain and see if it is aligned.

it is the goo'old rocker arm engine bro.. so pretty... (old pic before rebuilt,, now it is spotlessly clean)

http://www.mordan.biz/bmw/valves_1.jpg
belt driven.. aligned...

M20Turbo. i will start the car tomorrow.

[Mordan]

Hey Mordan...... how is the M20 running/starting?

ok it is starting much easier now.

but it is making an awful lot of ticking noise. I decided to tweak the clearances without a feeler gauge.. as it is a pain in the ass and I wanted to learn to do it with the intuition.

however the engine seems to be much more aggressive now. I read a post about the M30. it said a little higher clearance = more noise but more power. is that true for the M20 as well?

PS i did not drive as I'm doing a rust job.

PPS do you have a trick to set the clearances? do you always remove the fan and fan shroud. any special tool to move the crankshaft?

[Ross]

I suggest you retweak the clearances, this time using a feeler gauge. You are playing with fire by not measuring valve/rocker clearance.
With the spark plugs removed you can sometimes turn the engine over with the fan nut, or you get it from underneath, or use the starter.
I set 'em to the loose side for a better idle.

[Mordan]

I suggest you retweak the clearances, this time using a feeler gauge. You are playing with fire by not measuring valve/rocker clearance.
With the spark plugs removed you can sometimes turn the engine over with the fan nut, or you get it from underneath, or use the starter.
I set 'em to the loose side for a better idle.

i used the feeler gauge once and then set the clearance on others comparing the one set at 0.25 mm with the feeler. but due to inexperience, I failed.
when I rebuilt the head, i did all the clearances with a gauge. it took me awhile and it was with the head out, which is much more confortable.

loose side. you mean 0.28mm?

thx for the tip

[Tiger]

If the valve is too tight, it holds the valve open. Valve adjustment is usually done with warm engine, check Bentley for more info.

I would also double check your timing chain alignment.

[Mordan]

I would also double check your timing chain alignment.

wouldn't have mis-alignment destroyed my engine?

or only if I rev the engine in the red?

[Tiger]

Massive misalignment would but I think one teeth won't... one teeth will cause rough idling and performance. Since you are going to take the valve cover off... why not double check it?

[Mordan]

Massive misalignment would but I think one teeth won't... one teeth will cause rough idling and performance. Since you are going to take the valve cover off... why not double check it?

because when I first started the engine after the rebuild.. it was smooth in idle :)

and I just started the engine. it is smooth and all. just loud clicking noise... which means too big clearances on some rocker arms.
seriously.. just a pain to remove the things to check the alignment which I know is 100% sure aligned.

yesterday when clearances were 0, no clicking noise. just a dying idle when engine was cold. it makes sense right... since the rockers are wearing hard on the camshaft all the time, some rockers probably even pressuring the camshaft because of the vavle and its spring

[M20Turbo]

ok it is starting much easier now.

but it is making an awful lot of ticking noise. I decided to tweak the clearances without a feeler gauge.. as it is a pain in the ass and I wanted to learn to do it with the intuition.

however the engine seems to be much more aggressive now. I read a post about the M30. it said a little higher clearance = more noise but more power. is that true for the M20 as well?

PS i did not drive as I'm doing a rust job.

PPS do you have a trick to set the clearances? do you always remove the fan and fan shroud. any special tool to move the crankshaft?

Okay Mordan, I'm sure you have been here before http://www.bmwe34.net/Wiki/tiki-index.php?page=Valve+adjustment

I do remove the fan/shroud (plastic radiator cowling), mine is easy to remove, I have an electric fan that I attached to the cowling, so I disconnect the electrical connection and the two pins at the top of the cowling and out she comes. Then I have room to use a socket wrench on the vibration damper to hand turn the crankshaft clockwise to check/adjust the clearances, also remove the spark plugs. I adjust the values with the engine cold. 0.25mm (9.010in.) Forced induction = more power...:D

[Mordan]

it is all done! thx for the tips

run smooth without ticking now.

only real issue is the oily sprocket...
oh and the bad paint job from the previous owner.. also the green tape.. they had to replace the pressure switch wire. it is not good looking but I will fix it when I find a new wire harness for cheap.


http://www.mordan.biz/bmw/bmw_e30_head_clean.jpg
http://www.mordan.biz/bmw/bmw_e30_oily_sprocket.jpg

[Tiger]

So was the valves too tight or loose?

[Mordan]

So was the valves too tight or loose?

the valves? the rocker arms were too tight on the valves head and the camshaft. due to running in I guess.

then I set rockers too loose and it was ticking loudly. now they are right. :)