E28 528i No start/Idle

[AlessiRocks]

Yeah it's brand new but trying the other 2 AFM still gives the same results. I tried adjusting it, at least I hope I was turning the right thing, and it didn't do much. It still sounded like a slight misfire and lots of white smoke was coming out.

If it sounds like a misfire but when checking the timing it seems to be correct then what could it be. Has the distributor gone bad therefore sending a bad spark or not sending it at the correct time which leads to there being a lot of fuel and running rough? I mean like there aren't many other things it could be. Fuel system is new in nearly every part and it has been tested to be at the correct pressure, compression is good, vacuum lines are all sealed and new, most of what has to be tested and replaced has been done. Only things left are really the coolant temp sensors, distributor and not really much else apart from maybe a faulty ECU which I doubt. The coolant sensor thing confused me because there are 3 in the coolant housing, I think I have on but I still need the other 2, the bigger one and the one that has a different connection from the other 2.

[dworthy]

Okay, as for those temp sensor:
1) The brown one is the Thermo time sensor
2) The blue one is the DME sensor
3) The single wire is for the gauge in the Dash.

So to test the thermo time switch, there should be some small writing on the nut portion. Should look like 35C 12S, which means below 35 Degree C and will run for 12 Seconds.
You can test the DME sensor, and you can use a DVOM. Set to resistance, it should be 20C 2100-2700, and as the temp rises it will get lower resistance.

[AlessiRocks]

Oh then I might have the correct ones. I have the Blue and the Brown one which I managed to find. The one I don't have is the single wire one but if it's for the gauge then i'm not going to worry about it. Thanks a lot for your help, it definitely cleared any confusion with the different sensors. Will come back with the results.

[E39MGirl]

It's good that your car is now running, the idle air bypass valve is notorious for causing no start/difficult start and cars that start but then immediately stall.

That said, it is now time for some photos of your injection system please so we can be more specific with our advice.

As Dworthy pointed out, the AFM mixture screw (the only adjustment on the AFM) should not be touched unless you have an exhaust gas analyser - it does not adjust your idle speed! The factory sets the AFM idle mixture screw to provide mid-range CO2 exhaust readings and the only way it should be fine-tuned to a particular car is with an exhaust gas analyser. If you have played with that screw on the new AFM without using an exhaust gas analyser, you will now need to take the car to someone that has an exhaust gas analyser to adjust it to its correct settings.

Euro spec Bosch L Jetronic and very early Motronic injection systems with the auxiliary air valve (AAV) have an idle air bypass screw on the throttle housing. That screw is the only screw you use to adjust the idle speed. We need some good pictures of your injection system (particularly that throttle housing) to determine if it has the idle bypass screw. As your car is running the AAV there should be a bypass screw.

What commonly happens is cars develop vacuum leaks over time and idle faster than they should, and rather than fix the vacuum leaks people start to wind in the throttle bypass screw to lower the idle speed. Eventually someone replaces all of the vacuum hoses as you have done and the car suddenly has a very low idle speed because the screw has to be wound back out again. Send the photos before you touch any screws on the throttle housing – the throttle stop screws should not be adjusted. If your car doesn’t have the bypass screw it is possible someone has played with the throttle stop screws, but don’t touch them until we get a good look at what is going on.

Lots of white smoke is caused by burning oil, lots of white steam by condensation in the exhaust or burning coolant. Fuel injection or ignition issues are very unlikely to be causing white smoke. If enough oil is finding its way into the engine from the crankcase there will be a lot of white smoke, the car will run roughly, the spark plugs will keep fouling and eventually the car won't start. If the head gasket has gone you will be smelling coolant in the exhaust gas (it will smell sweet) and your car can run roughly too.

We will need actual compression readings (not, the compression is okay) on each cylinder to be able to help you out more specifically from here (and those photos).

[AlessiRocks]

I will take some photos. Maybe a short video could help.

I did play with the screw but returned it to the exact same position since I left a mark but i'm sure someone around has an exhaust gas analyzer so I will borrow one. Haven't touched any other screws so I will not touch them until you advice.

The white smoke smells a lot like fuel and considering we had to change the oil because it thinned due to all the fuel in it i'm guessing it is something to do with not burning properly. Coolant levels have not gone down either, although it could be that oil is getting in but the smoke doesn't seem blue and oil levels don't go down either.

Hopefully my friend wrote down the readings because when I can't work on the car he has done some things for me, hence why sometimes I don't provide certain results. But he knows what he is doing. I know he said one of the cylinders had a slightly lower compression but no more than a 5% difference. Otherwise I will get the readings myself and report. Photos will be on the way.

Thanks a lot for your help. It is much appreciated and hopefully the engine gets to run soon.

[dworthy]

My thoughts on the white smoke were more of the car hasn't ran in a long time, so you have moisture buildup. Normally when that happens, it can be cleaned out by running the car for 20-30 minutes, and help to drive it around too. I was just going to leave no comment on it as I am sure it will go away with time.

[AlessiRocks]

Took some pictures and a video. Hope they are of help. As a sidenote I checked the oil and it was full of fuel again. And the smoke is definitely not moisture, it has a heavy smell of fuel and is definitely too thick. Even after some running time it persists.

Also my temp sensors consist of a yellow one and a big brown one therefore the sensors I bought weren't the correct ones.

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Here is a link to the video: https://www.youtube.com/watch?v=XCqCUT1MoyI

I really don't know what could have caused this to start happening literally overnight.

[MIKYZZ4]

Is that the throttle position sensor pictured in photo-#1?
If so, have you checked for bent pins, or substituted another used part to test operation?

[AlessiRocks]

Will check but I think the pins were good. I could try and look for another TPS to test.

It's weird how such a simple system is giving so many problems haha.

[dworthy]

With that much extra fuel I am still thinking the cold start valve is leaking. Yes the yellow connector is for the DME, and in picture #3 you can see the idle set screw. You don't see too many euro E-28's with A/C, but if it was purchased in Spain, then I can understand.

[E39MGirl]

There are many reasons why it might just start happening overnight, and especially if the car hadn't been driven much before you bought it. It's quite common for a car to sit in storage for a long time, run okay initially and then start to develop problems. If the car was already running really rich then the plugs would foul on a drive and the next time you went to start the car cold you would have problems.

As Dworthy pointed out, the idle speed adjusting screw I was looking for is in picture three. It is the screw in the alloy 'tube' just behind the hose clamp holding the crankcase vent hose to the rocker cover. It appears to be well and truly screwed all the way in (and looks like it has been that way for a while) and you may need to remove the housing and screw complete, and soak that screw in a lightweight oil to get it moving again. At least then you will then be able to screw it out a bit and get the idle speed up.

After that, next tricks.

Get a clean white piece of paper and hold it behind your exhaust tips with the engine running. Whatever is causing the 'smoke' should be deposited on the paper after you have held it there for a while (make sure your garage door is open!) and it will be easier to get an idea of what is going on. I would be surprised if the paper ends up being wet given the temperatures in Spain over the last few weeks. If the oil is heavily contaminated with fuel then it will burn quite readily and cause both white smoke and a fuel smell, and you will get residue of the oil and fuel mix on the paper. Let us know the results.

Warm the engine up a bit. Either get a good solid pair of pliers like a set of 'vice grips' and clamp them onto the piece of fuel hose that goes to the cold start injector, or remove the injector from the manifold and start the car with the opening in the manifold securely blanked off. If the car suddenly starts to run better your cold start injector is leaking as per our previous comments.

These are a simple system and it will be something simple. At the moment this is a big problem though because continuing to troubleshoot with an engine that keeps diluting its oil so badly will end up doing damage to rings and bearings. We need to sort out the over-fueling issue asap.

[AlessiRocks]

Well it definitely is not the cold start injector because I blocked of the line and no change and considering this was tested a few months back then i'm sure this is not the problem.

I adjusted the screw back out and it helped a bit but still too much fuel. At least it now idles smoother and better.

The paper did get slightly wet but there wasn't any residue left on it. The smoke did still however smell like fuel and the paper did too but there doesn't seem to be any oil on the paper.

So since i'm not really sure what to check i'm going to think back which maybe I should have posted some more story to help. So we picked up the car and brought it home, then drove it around one day and left it in the garage. The next day the car wouldn't start due to there not being fuel so the fuel pump was changed and maybe I should have remembered to say this but the Fuel Pump Fuse was blown and was changed together with the Fuel Pump. Until the fuel pump arrived, which took a week, I cleaned the engine bay and the only things I disconnected momentarily were the intake up to the AFM and the AGR valve I believe it was but everything went back together as it started. I cleaned a bunch of oil from the valve cover and the rest was just dust. The vacuum line from the FPR was changed the day the car got home and shortly after we changed that vacuum line, the car started to become difficult to start, the FPR currently is new. I can't really remember anything else that was done to the car before it started giving issues.

Maybe the return line is clogged from a piece or something of the old FPR?

I can't believe how well the car ran before it got home. Well and not to mention the luck of being able to get home.

Also would like to say sorry for taking time to reply and thank everyone who has given feedback on what it could be. I really appreciate it.

[E39MGirl]

The good news is that if there is no oily residue on the paper, oil consumption is not too bad. It's good to double check the cold start injector and now it is done we can rule it out completely. With your idle speed now within spec it will also make it easier to trouble shoot some more.

Next trick. Get a large (preferably 20ltr/5gallon) clean fuel can and a piece of rubber fuel hose long enough to reach from the FPR to the fuel can. Disconnect the return line at the FPR and connect one end of the long piece of fuel hose in its place, then put the other end in the fuel can. Start the car and see if it runs better. This will tell you if the overfuelling problem is because the return line is blocked in some way. When you have finished the test you can just pour the fuel from the fuel can back into the tank. If the car runs perfectly with the return line disconnected we can start looking at obstructions along the return line, if it runs the same we can rule a return line obstruction out.

A blown fuel pump fuse could simply be old age, but it could also be because the fuel pump was getting very tired or working too hard.

You will need to post a photo of the 'AGR' valve you mentioned. You are probably thinking of an EGR valve, which I don't think that model had. I don't even recall any of these being fitted with air injection so I doubt it is a one way valve for that either. You might be talking about an evaporative purge valve from the charcoal canister - the canister that traps fuel vapours from the fuel tank. It's possible that if the evaporative system purge valve wasn't working before, the canister was full of fuel and when you 'disturbed' it excess fuel is now being drawn into the engine. This isn't likely to cause that much overfuelling for that length of time, but we can check it easily.

[dworthy]

+1 get the return line checked.

That car doesn't have the purge valve, for it is controlled by the water temp, and you would see in the previous photos the 2 vacuum lines coming from the thermostat housing.

[ptarditi]

First to nit-pick L-jet was used on US spec Bimmers in the '70s, (I was certiified for that system) (e12,maybe even e3,9) second try ohming out the sensors that have connectors on the intake manifold support, crank and rpm(i think).

[AlessiRocks]

Well just tried disconnecting the return line and putting a new line that went into a bottle but still nothing. Car runs rough as it's been doing. Although now the idle has gone crazy again.

Here is a picture of the valve I was talking about.
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I was looking around but there aren't any crank or rpm sensors although the intake manifold support does have inserts for them they just don't seem to be in this model.

I swear this car is driving me crazy haha.

[ptarditi]

Sorry, sensors are on front of engine,reference is from toothed sprocket. try cleaning the pick-ups.

[AlessiRocks]

Solved! It was the ECU. We found one from another car and now the car is running perfectly. Thanks to everyone for the help!

[E39MGirl]

Excellent news! At least you now have a solution.

If I recall correctly didn't you try another ECU early on though? Was that other ECU bad as well do you think, or was it only part of the problem and having fixed everything else the good ECU can finally run the engine correctly? Probably impossible to know one way or the other I guess without getting the other ECU you borrowed and trying it on the car again.

Anyhoo, good result and good that you got back on here to let everyone know!