e30 m20b20 warm start question..

[Brdjo]

Hi to all, I have some problems with warm start.

I have a 1988 320i m20b20 (motrnoic 1.3) that starts fine when cold, but starts hard (cranks about 2-3 seconds) when hot. If I start it in the morning it starts immediately. When at operating temp (after driving to work), if I turn it off and then try to restart, it will start right up. However, if I let it sit 30 minutes to a couple of hours, it takes some cranking to fire up (will sometimes kick when cranking but takes much longer than is normal). When it does start, there a fuel smell in the exhaust like it’s running rich... only on start up. When it’s running, it runs fine; smooth, good idle, good power.

I was pretty sure that's was the faulty CTS, so I bouth a new one, but nothing changes. Old one was Bosch 946, new one is Calorstart by Vernet WS2587 for opel Vectra, salesman said it;s a same CTS? Is this true?

Did some measurements off new CTS:

Outside temp is 7-9ºC.

stone cold - 4000 ohms
operating temperature - 200 ohms
15 min after turning off - 260 ohms
30 min after turning off - 360 ohms
1h after turning off - 630 ohms
2h after turning off - 1600 ohms

same thing is on the ECU terminal side..

From ECU to the CTS comes 4.95v, ECU number is 0 261 200 172.

Past repairs till now:

new fuel pump -7 months ago
cleaned fuel tank -7 months ago
new fuel filter -7 months ago
cleaned injectors and tested -3 months ago
new spark plugs (NGK ZGR5A) -7 months ago
new spark plug cables -7 months ago

Do u guys have any idea what next to look for, is there anything else that play a role in warm start up?

[Brianmoooore]

All the symptoms of a leaking injector. Get a £10 fuel pressure meter off of ebay and connect it up, and see what happens after the engine is stopped.

[Brdjo]

Thanks for quick reply, I did call the guy who cleaned them to ask for test results.. He did a leak test and it was all ok.. but definitely i will check for leak my self...

[Brdjo]

Did fuel pressure test today...

After turning off engine - 2.5bar
After 30 min drops to 1.5bar
After 1h - 0.7bar
After 2h - 0.4bar

So tomorrow I will instal one way valve near fuel rail, just to be sure thet are injector are the problem.. Off course I will check FPR just in case..

Fuel pressure must not go below 2 bar when not running?

[Brianmoooore]

Fuel pressure remains constant at 2.5 bar when the engine is running, but this is relative to the pressure in the inlet plenum, not atmospheric pressure, while your gauge is measuring with reference to atmospheric. With the throttle wide open, the pressure in the inlet plenum won't be much below one bar, but when the throttle is snapped shut, the pressure in there will momentarily drop to nearly one bar below atmospheric, and the fuel pressure should also drop dramatically to just over 1.5 bar. This will recover quickly, as the plenum pressure rises, and with the throttle closed, you will see around 2 bar on the gauge.
Your pressure is definitely falling off too quickly. This can be leaking away in one or more of five ways.
1/ A simple leak in the fuel supply pipe, rubber or metal, including filter, between the pump and the fuel rail.
2/ An internal leak in the FPR, allowing fuel to pass into the small rubber pipe that goes to the inlet plenum.
3/ An internal leak in the FPR, allowing fuel to pass into the return pipe to the tank.
4/ A leaky non return valve in the fuel pump.
5/ One or more leaky injectors.
1 to 4 can be determined with two fuel pipe clamps, and by examining the small pipe for the presence of fuel. If these all pass, then it's 5.

[Brdjo]

Brian thanks for your help, appreciated it...

My fuel pressure is et 3 bar when engine is running.. FPR is Bosch 0 280 160 249, 3.0...

Today I instal an non return valve, to fuel supply hose near fuel rail and gauge, so with that I eliminated pump, fuel filter and hose..

Started the engine, warum up, turn off... Results are the same:

After turning off engine - 2.8 bar
After 30 min drops to 1.8 bar
After 1h - 0.9 bar

Also, after turning off engine I removed the hose from FPR and put a paper below it to check for leaks, none was found on either side (return side and vacuum side).

Pulled out the dipstick, do not know if I imagine it or not, but there is some petrol smell in oil...

So it has to be the injectors.. Now I am worried about piston rings, I did 7000 km like that...

[aimlessrock]

unless you have had the injectors overhauled recently (last few years) why not just buy a set of used injectors, have them cleaned by injector tune and then fit them?

[Brdjo]

Non overhaul whatsoever..

Now I must find which one is leaking, and replace them..

To me it;s seems thet losing 1 bar in 30min is much? what should i expect 2-3 leaking injectors?

sorry for my english, and thanks for your help..

[aimlessrock]

Non overhaul whatsoever..

Now I must find which one is leaking, and replace them..

To me it;s seems thet losing 1 bar in 30min is much? what should i expect 2-3 leaking injectors?

sorry for my english, and thanks for your help..

just replace the lot, it they have not been touched since they left the factory they could be leaking or clogged etc.

Put a post in the wanted section for a set of B20 injectors and then send them to injectortune for a full rebuilt (abour £10.00 per injector).

This may not solve the problem but at leat you can rule out the injectors out and they will likely make a noticeable difference to the running of your car.

[Brdjo]

aimlessrock I did that 3 months ago

So, this is new, my FPR do not hold pressure, I remove rail and injetors from the car today and only place thet is droping fuel after was pressurize is FPR return. Applied pressure was 2 bars, and he could not hold it..

All injctors did not make a single drop of fuel. Just in case I sent injectors to guy, who did cleaning and changing filters in them 3 months ago, and hi is going to pressurize them to 3 bars and let them seat for a night.

But!!!

Yesterday, after driving my car and leave it for 1h, I come back and first run the fuel pump from reley pins (87-30) in hope to build preser inside rail, tried to start it up and he did the same think like before..( only wants to start with two short cranks or one longer when warm)..

Also i noticed the same problem is there when is sunny outside even if the engine is stone cold.. So he only starts right when engine is cold and air is cold.. I have some visiling when cold on air intake, sound like vacuum leak, will check that for sure and keep you posted.. Can vacuum leak make that kind of mess?

Thank you all guys for helping, appreciate it..

[Brianmoooore]

I have some visiling when cold on air intake, sound like vacuum leak,

Failed inlet manifold gasket makes a whistling noise. Use a metre length of garden hose to probe around the manifold to head join, with the other end of the hose in your ear.

[Brdjo]

I will check for vacuum leak as soon as possible, injetors are out of car for now.. I do have a video made 2 day ago on that whistling noise, here it is

[Brdjo]

Good news from guy who tested injetors.. All injetors are fine.. They hold 3 bar presure for 4h.. No fuel drops no pressure drop..

So I will put spare FPR on rail and put all back in..
I am still confused, ok my fuel pressure is droping to 0 over night, and yet car starts good in the cold morning, but in warm morning (or 1h after driving) not so good, longer cranking, no revving to 1200-1500rpm and back to 700rpm if warm.. Also i did try to run fuel pump few seconds before cranking and same think happens...

And ofc vacuum test is a must, for that whistling sound when cold..

[Brdjo]

New FPR is done the trick.. Tnx all for help..

In this year I planing on taking care of my m20b20, maybe upgrading to b23 but for now will just gathering information.. cheers

[aimlessrock]

good to hear you got it sorted. Why not look to fit a modified chip in the ecu?..i did this to my B20 and it gave it much better mid range grunt and slightly better mpg.

[Brdjo]

Personally I am not fun off chiping car,is there some "plug and play solution" or?

[aimlessrock]

Personally I am not fun off chiping car,is there some "plug and play solution" or?

see the below mate,

http://www.e30zone.net/modules.php?name ... c&t=187893

Fitting it is easy:

http://www.e30zone.net/e30zonewiki/inde ... ting_Guide

[Brdjo]

I did saw something like this when I was in US, very interesting.. Definitely worth trying I was planing on rebuilding the engine and maybe then buy some.. Ofc if shipping is possible to Serbia.. aimlessrock thanks for info.