E30 316i M40 - Start problem after turning off for 10/15mins

Hello all,

 

Firstly, Thank you for having such a great source of information for Bimmer Drivers, great insights and knowledge! :)

 

This post will be long as I've been browsing the forums, Haynes manual and couple of Mechanics minds, in order to puzzle this problem out, so I've tried a few things which I will list to help in Diagnosing the problem...

 

Car: H reg (10/1990) 316i E30 M40 engine....yeh yeh I know. :shifty:

I believe it's Motronic 1.3

 

Car History: Bought about 3 1/2 years ago off an elderly chap in a nice part of Bristol 43'000 miles £280! Pale red (post sunshine red) colour. 12 months MOT. Gem! No service history or owners manual, perfect bodywork condition (apart from the paint fade) No sign of modification, Interior spotless, no wear on the seats, origional fire extinguisher under the drivers seat! All electrics working!

Has passed all 3 MOT's with only minor bits, emmissions very good!

I don't remember exactly when this problem started, I believe it wasn't present when I first had the car, I think it apeared about 2 1/2 years ago, I used it to and from work (2 miles 5 days a week) and 126 mile journey to london almost every weekend.

First sign of trouble: One day (aprox 2 years ago) I was driving past reading (motorway 65 MPH..Very casual) and it cut out for a split second (not electrics but power; as if I took my foot off the Accelerator quickly). Took it to a BMW garage; mistake; they changed a missing breather cap, charged about £60, then wanted £140 to change the fuel rail. :eek I declined as the problem didn't bother me much.

 

Now I want to fix it! Ok, so the problem is like this:

 

When the car is started from cold (ambient temp now around 5 degrees C), misfire putt putt, then straight away fine, idles high (1500rpm) for a min, slowly comes down (seems like a normal start for an old car). Misses only very slightly (I've become picky in my quest for purrrfect running;)), can only feel it if you have hand on top of engine.

When warm, missing seems to be more prominent: At the 1/4 mark - 1/2 mark on Temp gauge, most prominent missing, car idle's at around 700-750, then at 1/2 mark idle properly at 800 +_50rpm average missing. Now if I stop the car, it will start fine if I start it within a minute, if however I wait 10-15 minutes it takes a few cranks, then idles low (550-600rpm) and grumbles a bit - I think this is because it's logged a fault code and sets ICV at standard or something. If you wait 30 mins, it takes even longer to start, sometimes having to crank alot, then stop then crank again. So the engine is turning over fine, it's recieving spark, but my thinking now is that it's not holding fuel at the rail. I've read of this problem, not had by many, but no-one seems to have solved it! I bought a hose clamp to clamp the fuel return line about 15 inches from the FPR, then turn it off and try it in 30 mins, but it made no substansial difference, I then clamped the return line while the car was running and it seemed to cure the misfire and idle increased, I then clamped the fuel in line and it still ran! So I think the fuel clamp is not stopping the fuel and possibly when I half clamped the return line, it increased pressure in the fuel rail making it run properly.

I have been through the haynes manual, but it's a little hard to follow as it simultaniously talks about 3 different fuel pump systems, and I seem to have a mix of 2! I've been on RealOEM but for my car it doesn't seem to have an exploded view of the Fuel pump, as I'm now thinking that it is probably the check valve letting the residual pressure out of the return line. I have looked at the fuel pump/sender unit under the back seat, I'm a bit hesitant to pull it out to see if it has a check valve if I don't need to. There doesn't seem to be any other pumps...I've checked under the carpet in the boot...the haynes manual is confusing as it says some models have a transfer pump.

I just bought a Ediabas/Inpa interface with software and 20-16pin adaptor to read the codes, but alas it's earliest model is Motronic 1.7, which I believe is on the M42 wonder motor. So I'm returning that as the seller told me it worked on all E30's! I'm thinking of getting a normal code reader, as BMW want about £130 to read the codes! Nutters!

 

Replacement parts (in last 2 years):

 

Radiator (leaked slightly, couldn't stop with Rad Sealant)

Cam belt (47'000 miles)

Fan blade

Distributor cap and Rotor arm

 

Replacement parts (last 2 months):

 

Oil (and filter) 10w-40 Castrol Magnitech (err spelling)

Fuel filter

Spray bar OEM (on top of Cam shaft, also replace valve cover seal OEM)

Spark Plugs (NGK) - Old one's looked slightly reddy brown...perfect?

HT - Leads

Rotor arm

DME Relay

Fuel Pump Relay

Coolant temp sensor

All vacuum hoses apart from ICV to Throttle body (looked and felt fine..plus £35 more that I didn't need to spend)!

Air filter

Both Upper and Lower intake manifold gaskets

Small fuel hoses between FPR and metal fuel line and between fuel in metal fuel line and fuel rail.

Thermostat (has never worked properly...didn't realise...now temp reaches mid point)

...Therefore coolant...twice

Clutch kit (LUK) standard

Gearbox oil and Diff oil

Exhaust clamp

Checked Guibo...looks in great cond!

Accelerator cable (don't want it to snap)

Both V belts

 

Adjusted:

 

C-O mix when I didn't know what it was (about 2 years ago - muppet), now I adjusted it (without any equipment) to see if it made any difference to Idle, made it slightly richer (clockwise) and it runs at proper Idle. Before this adjustment it flew past it's last 3 MOT's on emmisions.

 

Cleaned/checked (in last 2 months)

 

ICV T-shaped 2 pin (ran slightly smoother, did the unplug test and Idle increased as it should...not quite to 2000rpms but significant)

Seafoamed the intake through a seperate piece of Vac hose into just past the butterfly, stalled and left for 10/15 mins, lots of smoke, runs slightly smoother.

Cleaned the injectors whilst changing the Intake gaskets.

Put a screw driver on each injector and pressed other end to ear to check for consistant clicking...perfect, like a swiss watch.

 

Other considerations:

 

I have tried a bit to tackle the slight ticking noise which I don't think is related but I'll expand as I know M40's are renound for oil pressure/flow depriving camshaft's of lube...It ticks on and off during warm up (occasionally there is a clack which is seperate as sometimes it stays a little longer than the tick but then quickly dissapears) in the same sort of timing as the injectors, when it's warm it only ticks quietly a bit at around 2000rpm. I suspect valve guides and possible slight cam wear, but when I changed the spray bar the cams looked good, and it rev's to just inside redline. So I may do the job in a year or 2 when I have to tackle the cam belt as you have to do the belt when you do the shaft/hydraulic lifters...etc.

 

My choices as I see them...Get OBD codes read, get decent fuel hose clamp, check residual pressure. If fault is electrical, could be Puse sensor? No Knock sensor present, I've heard someone with a similar problem had their fuel pump changed and checked FPR with no improvement, but if no codes then I could get it fuel pressure tested?

 

I apologise for such a long post, as you can see by the replaced/cleaned parts I have been through a few options, but before I go any further I thought I'd post at thread just in case anyone could assist in my hunt for purrfect running as I'm driving through europe in June and really want to get it fixed!

 

Kind regards to anyone who is patient enough to read such a long post!:jaw-dropping

 

Thank you.

Hi, which problem did you have? Was it the hard start and Misfire or was it the tick and knock? Or both? I don't have a cam senso or a crank sensor but I do have a pulse sensor which I believe works a bit like a crank sensor, thanks for the response!