[Question] BMW 540 1998 M62B44, idle to 6000 RPM...¨

[polo16v190]

Hi everyone,

I just finished to rebuild the M62B44 (pre-VANOS, with the throttle body controlled by cables). Everything was ok for 10'000 km until yesterday. When I started the car, It begin by raising the RPM very fast, and if I didn't stop immediatly the engine, it could reach the redline.
I don't understand, because everything was ok until now. I think that, on that engine, it means that there is a big air leak, because the fuel pressure is regulated by the air entering in the engine.
You have to know that the engine's RPM raise to 3000 RPM and more (I stop the engine immediatly) EVEN if the throttle body.... is closed...
Is it possible to have a big air leak IN the intake manifold?

I didn't find any subject or a similar problem on that forum, neither on the other forums.

Do you have any suggestion ? My mechanic doesn't understand, and before taking the car to BMW Dealer, I need to know if someone knows what is the problem.

Thanks for your time.

PS : As you see, english is not my mothertongue, sorry if it is not easy to read.
Thanks!
John

PS2 : A photo for the eyes
DSC_0243.jpg

[Plattus1000]

Grüezi, hoy Zama! That sucks. I'd check your throttle sensor, fuel pump and throttle body for the correct voltage draw.

Good luck man.

If you can't fix it, das hash dé has a gah. (spelling is incorrect)

I hope you get answers. Tschús

[polo16v190]

Hi! Thanks for your answer.
Funny, something tells me that you know from where I am ^^.
Anyway, I can't check it, because my throttle has cables, so there is no voltage, or throttle sensor (or are you talking about the plug on the side of my throttle?)
Fuel pump is ok, new from the last month

[Plattus1000]

Throttle position sensor?
I'm not an expert. You explained everything well. I simply don't know this engine enough to help you.

I've been going to Schweiz every year for the last 10. Friends and family there and Spain. Love the Swiss culture. Come vist someday. I'll put you up for a few days and you can see Seattle.

Seriously, good luck. Zug? Or Zurich? No, Lucerne.
Geargrinder is also rummored to visit in Schweiz for his job. Probably stashin his gold in Liechtenstein "FL"
This is only my theory,based on no information to lead me to that conclusion.

[XAlt]

Post in the main e39 section.

[polo16v190]

Throttle position sensor?
I'm not an expert. You explained everything well. I simply don't know this engine enough to help you.

I've been going to Schweiz every year for the last 10. Friends and family there and Spain. Love the Swiss culture. Come vist someday. I'll put you up for a few days and you can see Seattle.

Seriously, good luck. Zug? Or Zurich? No, Lucerne.
Geargrinder is also rummored to visit in Schweiz for his job. Probably stashin his gold in Liechtenstein "FL"
This is only my theory,based on no information to lead me to that conclusion.

I'm from Lausanne. In the french part of Switzerland^^.
Oh yes, keep in touch if someday you're near Lausanne^^.


I will post my message in the e39 main section, as the last message suggests. Thanks for your answers guy

[dme88]

You have a mechanical throttle, so nothing there. Have you checked the ICV? Disconnect it in closed position, and try again. If it's not the ICV you have a massive air leak.

Air leaks are easiest found with a smoke machine. But in you case one should be able to spot it just by looking. Is the PCV valve tight? Did you forget any gaskets?

[qcdstick]

Before getting too crazy, Have you checked the throttle linkage and ensured the throttle body is able to close completely? Easiest thing to do to start would be to pull forward on the lever where the cables attach, it shouldn't move in that direction if the TB is indeed closed.

[Plattus1000]

I'm from Lausanne. In the french part of Switzerland^^.
Oh yes, keep in touch if someday you're near Lausanne^^.


I will post my message in the e39 main section, as the last message suggests. Thanks for your answers guy

I would enjoy the visit! It would be fun to hear YOUR Schweizer Deutsch. Gruyere, Vevey, Ch, de Chillon and Saas Fe were all amazing last time I was in your area. I'll visit, ganau.


The main forum has more "Augen" eyes and the chances are better to find the solution.

Ábientot

[polo16v190]

You have a mechanical throttle, so nothing there. Have you checked the ICV? Disconnect it in closed position, and try again. If it's not the ICV you have a massive air leak.

Air leaks are easiest found with a smoke machine. But in you case one should be able to spot it just by looking. Is the PCV valve tight? Did you forget any gaskets?

First, thanks you for your answer. In fact, the ICV is new and working. We can see that it is working by removing the plug and replug it. I will go to my mechanic today, and ask him to use a smoke machine. The PCV valve is new too (it comes in one part and was buyed in my BMW garage). I didn't forget a gasket I think. The car was running smoothly and very good for one month, and one day (2 days ago), the problem came. The hose are new too (done a complete rebuilt the most clean rebuild I can). Ok for the air leak, I'll check it today. I think that the only position of the air leak must be near the mastervac. I didn't see a other position after the Throttle Body for a air leak.

Before getting too crazy, Have you checked the throttle linkage and ensured the throttle body is able to close completely? Easiest thing to do to start would be to pull forward on the lever where the cables attach, it shouldn't move in that direction if the TB is indeed closed.

The linkage are good, and the throttle body is closed completly, when the throttle is released. I will recheck that todayand keep in touch.

Thanks for your answers.


Other question : Is it possible to have a massive air leak by the mastervac? I know that in the M62, the fuel rate is totally control by the air entering in the engine (by the ICV which play that role of regulator). It is opssible to have a air leak in the mastervac, and that force the engine to rev?

[geargrinder]

I'm from Lausanne. In the french part of Switzerland^^.
Oh yes, keep in touch if someday you're near Lausanne^^.

Nice. I almost took a job in Lausanne (at IMD) way way back in the day. In hindsight, probably a mistake, I probably really should have. Money was going to be hard to survive on was the problem.

I don't go anymore but Platts is right, used to go all the time, sometimes every month... up North indeed where they speak Schweizer Deutch but I can't speak a word really. Spent good part of our honeymoon in Suisse, including a tour that started in Geneva and went up into France to Chamonix where a friend has a place, then back around through Martiny and around Lac Leman. Gorgeous part of the world. Got another friend who lives outside Geneva, always wants me to come back over and visit... really need to do that sometime... Anyway...

Is it possible to have a massive air leak by the mastervac? I know that in the M62, the fuel rate is totally control by the air entering in the engine (by the ICV which play that role of regulator). It is opssible to have a air leak in the mastervac, and that force the engine to rev?

Maybe translation problem? Don't know what mastervac is?

[qcdstick]

Other question : Is it possible to have a massive air leak by the mastervac? I know that in the M62, the fuel rate is totally control by the air entering in the engine (by the ICV which play that role of regulator). It is opssible to have a air leak in the mastervac, and that force the engine to rev?

I'm no expert, so someone feel free to chime in if I'm wrong. The fuel rate is controlled by the air entering the engine by design. But the car only knows about the air entering the engine that passes through the MAF, correct? Therefore, a vacuum leak occurring after the MAF, would indeed allow more air into the engine, would not result in the engine adding more fuel (beyond possibly what little the ECM can compensate for based on the O2 readings) because it is unmetered air. This would result in a lean condition, which would cause stumbles and rough running, not a runaway idle condition.

Am I incorrect in my reasoning here? To my mind, it almost has to be a problem with the throttle body, return spring, linkage, bypass (ICV) etc. to result in this condition. I.E. too much metered air is getting through or around the throttle body specifically.

[adm750]

here's a really dumb question Polo....the floor mat wasn't pushed up or bunched up on the throttle pedal was it ???? I know you posted that it is free and returning properly....but was that after pulling that floormat back to check it (I'm wanting to use that "puzzled look" emogie here...)
.....seems very odd to run 10K km's with no issues, then all of a sudden she goes to WOT with no prior indications of a problem....
Does the car still do this when you try to start it or does the condition have you concerned enough not to start it again till you find an issue...?
all the best,

tony

[HoZy]

Vacuum leak won't make it rev to 4500rpm because it'll be un-metered air for the MAF & it'll stall unless your MAF is also faulty & it's running in closed loop.

I know this for a fact because I once started the car with the IACV not on my manifold & it didn't rev like crazy, it stalled just after starting.

I'll say your throttle isn't shutting completely or your pedal/cable is stuck.

In this day & age with YouTube you would think more people would record a video on their phone & upload the problem...

Cheers
Mat

P.s- If you built the motor & you think it's vacuum. Remove the inlet manifold, ccv & throttle to check. It's not actually a hard job to do any of that.

[ViolinARC]

+1 on the video. It is easy and will give us a better idea of what is happening...

I agree that it sounds like a stuck cable since it's not drive-by-wire...

[polo16v190]

Nice. I almost took a job in Lausanne (at IMD) way way back in the day. In hindsight, probably a mistake, I probably really should have. Money was going to be hard to survive on was the problem.

I don't go anymore but Platts is right, used to go all the time, sometimes every month... up North indeed where they speak Schweizer Deutch but I can't speak a word really. Spent good part of our honeymoon in Suisse, including a tour that started in Geneva and went up into France to Chamonix where a friend has a place, then back around through Martiny and around Lac Leman. Gorgeous part of the world. Got another friend who lives outside Geneva, always wants me to come back over and visit... really need to do that sometime... Anyway...



Maybe translation problem? Don't know what mastervac is?

Hey! You know my country very well. It give me pleasure, keep in touch if you come one day here, to visit Lausanne or around the Lac Léman. Yes, beautiful part on our earth. The Scheizer Deutsch is very difficult. Don't think that every swiss can talk with that language, at school we're learning the normal german (and english ^^), but not the swiss german, that is very but very difficult, even if we are strong in german. You have to come back one day, to rest, with the mountain .

Mastervac sorry, maybe is it a word in french. I was talking about the brakebooster, just after the brake pedal. (See à the end of the message to know what's going on with my M62).
Thanks

I'm no expert, so someone feel free to chime in if I'm wrong. The fuel rate is controlled by the air entering the engine by design. But the car only knows about the air entering the engine that passes through the MAF, correct? Therefore, a vacuum leak occurring after the MAF, would indeed allow more air into the engine, would not result in the engine adding more fuel (beyond possibly what little the ECM can compensate for based on the O2 readings) because it is unmetered air. This would result in a lean condition, which would cause stumbles and rough running, not a runaway idle condition.

Am I incorrect in my reasoning here? To my mind, it almost has to be a problem with the throttle body, return spring, linkage, bypass (ICV) etc. to result in this condition. I.E. too much metered air is getting through or around the throttle body specifically.

I think that you're reasoning very good, and I'm ok with that. Anyway, you have to know that I check every hoses, and I find no leak before the MAF. I find after the MAF no leak with the smoke machine ,but a little near the brakebooster, that was I think the problem why the engine as revving so high. An addition to your reasoning, is that the ECU, in year 1998 was maybe not as sensible as today, and it could not make a very good regulation, even with the O2 sensors (don't forget that I'm in Europe, and that I have only two O2 sensors, where you, in America, if I'm not mistaken, you have THREE O2 sensors).

here's a really dumb question Polo....the floor mat wasn't pushed up or bunched up on the throttle pedal was it ???? I know you posted that it is free and returning properly....but was that after pulling that floormat back to check it (I'm wanting to use that "puzzled look" emogie here...)
.....seems very odd to run 10K km's with no issues, then all of a sudden she goes to WOT with no prior indications of a problem....
Does the car still do this when you try to start it or does the condition have you concerned enough not to start it again till you find an issue...?
all the best,

tony

The car now isn't running anymore. to answer to you, know that I disconnect the cables (cruise control and throttle cable) to be absolutly sur that nothing can enter IN the engine by the Throttle Body. Thanks for your answer and see the end of the message to know the problme

Vacuum leak won't make it rev to 4500rpm because it'll be un-metered air for the MAF & it'll stall unless your MAF is also faulty & it's running in closed loop.

I know this for a fact because I once started the car with the IACV not on my manifold & it didn't rev like crazy, it stalled just after starting.

I'll say your throttle isn't shutting completely or your pedal/cable is stuck.

In this day & age with YouTube you would think more people would record a video on their phone & upload the problem...

Cheers
Mat

P.s- If you built the motor & you think it's vacuum. Remove the inlet manifold, ccv & throttle to check. It's not actually a hard job to do any of that.

Inlet Manifold was removed, and I find one gaket that was nor correctly set by the learner at my garage, when I give my BMW for the service of the 10K. Anyway, CCV is new (you're talking about the part that is at the rear of the manifold?) and the throttle is now disconnected to be sure that it is completly closed. The engine is not reving anymore but (!) it is not starting too. See the end of he message.

+1 on the video. It is easy and will give us a better idea of what is happening...

I agree that it sounds like a stuck cable since it's not drive-by-wire...

First of all, thanks for all your messages. I didn't answer to them while the week but I was reading them.
Now, I have seen what could be the problem.

1) There was a little leak near the "brakebooster", a hose was not totally good. It is strange because it was new, maybe I've done a mistake while I was installing it? I don't think so, but the problem begins one day when I give my BMW to the official dealer.

2) It was a learner, that has done the service on my car. There was a error in the ECU at the tester in the garage of the official dealer, it was a error about the "crankshaft speed sensor" (the part that is counting the RPM of the flywheel). The learner replaced it but yesterday I have noticed... That the was not the plate (!) that ensure that the sensor is at a sufficiant distance of the flywheel of 0.55 cm +- 0.2. Results, the sensor has touched the flywheel and not working anymore because we can see that it is damaged.... I don't understand because I can run the car very good for 15 minutes, the time that I need to come back to my home from the garage...

3) There was a error in the ECU yesterday about the camshaft position sensor. I've ordered a new.

4) because I didn't know what to look for, I have done all the compression and all my cylinder (without a difference) are at 13 bar (=188PSI)
5) I've got the spark. The engine is ok

Now the leak is removed, the throttle body is closed, on monday I will replace the little plate and the CPS (crankshaft position sensor), the camshaft position sensor and try again. If it is not starting or something else, I will post a video to give you a better view.

Thanks you so much for your suggestions!

[geargrinder]

Wow. So yeah seems clearly your no-start is either the crank sensor mistake, or, the cam sensor.

Here's a question for you - I wonder if the trainee might have confused crank sensor and cam sensor? So he replaced the crank sensor when really it was the cam sensor error that you still have?

Excellent compression, that's very good sign.

Good luck, be interesting to see what happens when you get the sensors back in.

And FYI, we don't have 3 O2 sensors, we have 4 - which = 2 per side.

Each side of the engine has one normal O2 sensor before the 'cat' (aka catalytic converter / catalyst) and then one O2 after the cat.
But the 2nd ones don't do anything with mixture or running the engine, they are really only there to 'set the alarm' if we are polluting too much and the catalysts are not doing their job.

[polo16v190]

Oh okay, you've teached me something. I was sure that you have more O2 sensor anyway, because your laws are more strong than ours about the air pollution.
Here is the news:
1) all sensors have been replaced
2) The engine cranks but doesn't start, because there are NO spark.

--> I'm thinking about a ECU or EWS out of sync. Because :
a) If I disconnect the Cam Sensor, the engine starts but run very badly
b) If the sensor is connected, the engine is not trying to start at all, because of no sparks.

I think that it could be only 2 things :
1) The immobilizer, that won't let the engine start
2) The ECU or EWS out of sync, because the learner remove the battery with the key in position 2.

That what I think, but now I know that the sensors are working good because the ECU got the good information. If you have maybe a other idea? I think I'm right but I'm not sure. I have to sync with DIS or INPA, I'm installing it now and will tell you if it is that or not, maybe it could help someone one day.

John

[geargrinder]

Nope. Definitely don't waste time w/ EWS.

If the engine runs at all the EWS is fine. Plus you'd get EWS errors.

But good news is youre really close... If engine runs badly w/ cam sensor disconnected... but not at all with it connected... its the cam sensor for sure. It is 'supposed to' run badly w/ cam sensor disconnected.

Did you use a cheap / non-dealer replacement sensor? See this guys comments.

https://www.bimmerforums.com/forum/s...or-Replacement

[polo16v190]

Ok I agree with you except for one point.
My engine doesn't start AT ALL, it means that there is something else no? Like DME?
By running poorly, I meant runs with backfire in the intake.

Anyway, you're right, it is the only part that I don't get from BMW. I ordered it now, and will have that original part from BMW on thursday.
I will comme back if there is news or if it is fixed. Thanks for the post, I didn't find it.

Thanks!

[geargrinder]

Wait...

My engine doesn't start AT ALL, it means that there is something else no?

But you said...

a) If I disconnect the Cam Sensor, the engine starts but run very badly

Confusing.

You mean "doesn't start at all with sensor connected"... well yes the aftermarket sensors are reported to be so bad that sometimes they don't work at all. I haven't had first hand experience but a number of guys have reported they are really that bad. So it isn't totally surprising...

HOWEVER to be fair and open minded... could be you have some connection/wiring problem on the cam sensor? One that only impacts when the sensor is plugged in? Have you checked the plug (socket) for it to see if it all looks clean and in good condition?

About DME - these DME's almost NEVER fail on their own. EVER. I mean sure I'm sure there's some .01% case where a DME failed but its unheard of normally. The one known issue is if the thermostat connection leaks and coolant gets pushed down the thermostat wire into the DME connector and then corrodes the DME connector and inside of the DME... but aside from that... they're pretty bulletproof.

[polo16v190]

Yes you're right, it was confusing because I'm writing fast without reflexion. I'm a little bit tired of that project, it took me so much time and now, doesn't work.
Anyway.

To be clear : When the new camshaft sensor (non original part) is disconnect, the engine runs very poorly and stop immediatly with backfires.
And yes, it doesn't start at all when the sensor is connected. It try not to start because there are no sparks. I'm sure you're right about the quality of the sensor.

To be fair, the wiring are good and there are no connections that I forget. To do the thing good I will take in count you're sentence "could be you have some connection/wiring problem on the cam sensor? One that only impacts when the sensor is plugged in? Have you checked the plug (socket) for it to see if it all looks clean and in good condition?"

--> I will clean, check again the cables and wiring for the sensor, replace the sensor by a original BMW sensor. If with the new sensor and the cleaning it doesn't start, i will try the DME thing.

I know you're right and that it is very rare for the DMW to fail. The learner, however, took the battery off WITH the key in position 2, I remember, I just didn't get the time to stop him when it took away the battery ground cable of the battery. It's why I was sure that it is out of sync.

Thanks for your time! Will post the news tomorrow!

EDIT : I will check the little cam sprocket (for the sensor signal), by removing the upper engine cover. Maybe there is a problem there or is not aligned because it slept?

[polo16v190]

Hi again to all.
so here is the news. The winner is : DME88.
I was lost, I've tried everything. So I have sent my fresh rebuilt BMW 540i to... BMW.
They find a monster leave leak. In the manifold, because I have forgotten the seals between the engine and the bolt of rhe manifold (I think that you see what I'm talking about.

Now the car is running good. cylinder smoothness is good.
My last problem is now that it is running a little bit rich.
I think that my fuel pressure regulator is dead.
i will replace it with the MAF, (the total air needed is a little bit to high, as the idle speed air needed, in INPA).
Thanks a lot to all of you. It was very important for me to read you every time that I was posting a message.
Thanks to the forum also, because of the DIY's and all the information that we can find.

good night.
John

[johnnylud3]

I see you found the answer to this. I was going to respond saying I has the same symptoms when I had massive vacuum leak. The boot to the TB was half on and leaking massive air.

[Dolsey056]

I actually have had my throttle stick on me twice. and its the cable getting bound up under the cover. Im not exactly sure why yet which is why i searched throttle issue. All I can think is its getting bound up with the cruise control cable and the cover. mine is a 98 540i