Super Slow 535i

[sockoiX]

Got a 1991 535i 5 spd, under 173k miles. Did all the basic tune up, new temp sensor, afm, o2 sensor, basically everything is new. Valves adjusted and no bad ticking noises. Was very happy to have no CEL's or any lights on the dash. Runs quiet and smooth. Decided to take her out for a test drive, its terrible! 1st gear and pedal to the metal, it crawls slowly from 2k to 5k rpm and zero power. Tried 2nd and 3rd it would just crawl and bog at times. Around few blocks and it decided to stumble hard and was barely able to drive it back home and park it. What gives? Fuel pump?

[paperplane94]

Try a stomp test anyways and see if anything comes up.

[ZenitramNaes]

Fuel pressure?

[zubbie]

could be anything.

fuel pump
vacuum leak
bad afm
injector

[bmwdirtracer]

If the car is just slow - and has no misfiring, spitting, or other odd behaviour - then I would tend to think of an AIR problem - not fuel, not spark. Inadequate fuel tends to make an engine misfire, and stall. A spark problem (like bad cap, rotor, or wires) tends to cause misfires and spitting.

But a completely clogged air filter, or a stuck-closed AFM door, or a clogged exhaust all cause the engine to not be able to pump air - which makes it slow, very, very slow.

For testing, I'd first advise making sure the AFM door opens easily, removing the air filter, and then if no solution is found there, you might wish to try unbolting the exhaust, in front of the cat (as I recall, that's possible on your 535) {I would recommend you soak those exhaust bolts with PB Blaster, at least 1 day before you try undoing them)

I likely won't see further replies on this thread, because I hang out in the General Mechanical Forum; you can PM me, or post in the Mechanical forum, if I can be of further help. (Many pro BMW techs are in the Gen'l. Mechanical forum}

[Dash01]

Have somebody rev it up when warm, check exhaust pulses at the tailpipe. One of my 535i cars (bought for $700 since it would hardly start or develop power) turned out to have some blockage in the passenger side exhaust pipe or cat. Clogged cat - poor power = rotten fuel economy, etc.

I confirmed this with a laser thermometer from Harbor Freight--pistol grip type that shoots a red dot and measures temp.--a very handy tool, as is $3 HF mechanic's stethoscope. With stethoscope you can listen to individual injectors, relays, bearings, whatever.

Also, pull the dissy cap, use fine emory paper and clean the rotor and pips, pull the plugs and do the same & set gap.

Fuel & air filters are cheap and easy.

[E38740iMD]

Have somebody rev it up when warm, check exhaust pulses at the tailpipe. One of my 535i cars (bought for $700 since it would hardly start or develop power) turned out to have some blockage in the passenger side exhaust pipe or cat. Clogged cat - poor power = rotten fuel economy, etc.

I confirmed this with a laser thermometer from Harbor Freight--pistol grip type that shoots a red dot and measures temp.--a very handy tool, as is $3 HF mechanic's stethoscope. With stethoscope you can listen to individual injectors, relays, bearings, whatever.

Also, pull the dissy cap, use fine emory paper and clean the rotor and pips, pull the plugs and do the same & set gap.

Fuel & air filters are cheap and easy.

pic of 2 said tools!?

- - - Updated - - -


pic of 2 said tools!?

nvm i found it

[sockoiX]

I'll pull the exhaust out and check, and obviously run it without the exhaust if theres a difference as well. Don't got a fuel pump pressure gauge yet :/ On laid off budget as I had several job interviews and want this car to be reliable once hired (finally)

Have checked for leaks many times over especially with carb cleaner. I'll see the AFM flap movement making sure it opens. I just pulled the tank out and where the fuel pump sits in that black box chamber...it is full of rust particles in it...several handfuls of those! Now the tank is clean just need to dry it out while I pull the exhaust out since it'll give me more space under there. Good idea on laser thermometer!

[Binjammin]

I'll pull the exhaust out and check, and obviously run it without the exhaust if theres a difference as well. Don't got a fuel pump pressure gauge yet :/ On laid off budget as I had several job interviews and want this car to be reliable once hired (finally)

Have checked for leaks many times over especially with carb cleaner. I'll see the AFM flap movement making sure it opens. I just pulled the tank out and where the fuel pump sits in that black box chamber...it is full of rust particles in it...several handfuls of those! Now the tank is clean just need to dry it out while I pull the exhaust out since it'll give me more space under there. Good idea on laser thermometer!


If you have rust in your tank, the first thing you should be doing is figuring out why, then solving that. If the problem is a rusting tank, replace the tank. I wouldn't run the car at all if you have rust in it, as that will kill a fuel pump in short order. In addition, you very likely have a clogged fuel filter, and that's probably giving you your issues.

[ross1]

If the car is just slow - and has no misfiring, spitting, or other odd behaviour - then I would tend to think of an AIR problem - not fuel, not spark. Inadequate fuel tends to make an engine misfire, and stall. A spark problem (like bad cap, rotor, or wires) tends to cause misfires and spitting.

But a completely clogged air filter, or a stuck-closed AFM door, or a clogged exhaust all cause the engine to not be able to pump air - which makes it slow, very, very slow.

For testing, I'd first advise making sure the AFM door opens easily, removing the air filter, and then if no solution is found there, you might wish to try unbolting the exhaust, in front of the cat (as I recall, that's possible on your 535) {I would recommend you soak those exhaust bolts with PB Blaster, at least 1 day before you try undoing them)

I likely won't see further replies on this thread, because I hang out in the General Mechanical Forum; you can PM me, or post in the Mechanical forum, if I can be of further help. (Many pro BMW techs are in the Gen'l. Mechanical forum}

Easier to check for restricted exhaust with a vacuum gauge. Hold revs DEAD NUTS STEADY at 2500-3000(# doesn't matter, STEADY does) and watch vacuum reading. Dropping vacuum is indicative of restricted exhaust, most likely melted cat unless you've managed to kink a pipe.
This engine could also be starving for fuel.

[BMW IDFR]

I agree with a post above about the AFM, Did you try to clean it or something?

[shogun]

Does this 535 have EML? = fly by wire instead of a bowden cable to the throttle valve? If so, it could run in limpmode.

[Binjammin]

Are you guys mental? He says he has a tank full of rust....


:confused This sounds exactly like a clogged fuel filter...

[zubbie]

Are you guys mental?...

That's a rhetorical question right?

[Binjammin]

That's a rhetorical question right?

Around here? Always.

[sockoiX]

Do have the EML. It comes on and off right away when starting the car. Have swapped the eml system no change. Will do the vac gauge when I put the tank back in to check for clogged exhaust. The surface of the tank is clean, just the inside the tank is rusty some areas. Already cleaned it out. New fuel filter, the fuel feed line dropped out pure orange/brown :/

[sockoiX]

Update: did the vac gauge to test for clogged exhaust. It is extremely stable at the 3k rpm for 30 sec. Getting cel that goes on and off when revving it or holding the rev. Emission (lambda) Control. Runs and revs okay, really rough idle after all that work and parts replaced. Gunning it on the road felt like jogger is overtaking me (still slow at high rpm and feels so flat lacking of power)
Makes me wonder if the eml light either on or off, it's stuck on limp home mode?

[shogun]

I see, EML. What do you mean by : "Have swapped the eml system no change", Details please?
Did you clean the throttle valve? Not where the air passes thru, the motor on the throttling valve. Often this is the problem, the brushes of the motor get stuck because of the dirt.
I made a nice photo of such a motor https://imageshack.com/i/0wthrottlevalvej
2 weeks ago we had another member here with EML problems, read this http://forums.bimmerforums.com/forum/showthread.php?2088509-Is-it-possible-to-have-NO-idle-air-control-valve&highlight=EML

[E38740iMD]

Hey shogun, my 1990 535i has eml but it drives by cable. Is it because mine is a manual trans

[sockoiX]

Shogun - I have a newer EML motor, actuator and throttle body. They're clean and the throttle valve is also clean. EML light comes on for 2-3 sec then comes off. I had to take the original EML apart on my car to inspect everything and saw that the wire brush on the throttle body, bent and some of the wire arms were missing. Put a newer one that is in good condition, it may be off just a bit to throw things off whack.

[sockoiX]

Unfortunately I just got fed up with this EML system. I'm going to either sell/part this 535iM or put in non-EML throttle system in. Too much hassle with that EML thing :/

[E38740iMD]

:confused

who said that was the problem. take care of the tank first

[MyFirstProject]

Unfortunately I just got fed up with this EML system. I'm going to either sell/part this 535iM or put in non-EML throttle system in. Too much hassle with that EML thing :/

I'm in denver. How much are you looking to get for it?

[sockoiX]

PM me your offer. I paid 1,100 and put quite good amount of new parts on it, new AFM, o2 sensor, cap/rotor, temp sensor, plugs. Needs body work on the front passenger side.

The tank is took care of since cleaning it out and re-installing the newer pump has crossed out the potential problem related to fuel/air issue which turns out to be the EML system is gone for good.

[Binjammin]

my full time project to restore it.


http://assets.sbnation.com/assets/1384167/yuck_imdone.gif

.

[sockoiX]

Lol :P

[sockoiX]

Posted 2 pics. One is the non-EML harness out of a 1988 735i. The other pic is the ICV, intake tube and related hoses to connect the ICV, below intake mani, and crankcase vent, accel cable/pedal shaft (the foot pedal wasn't able to yank out), and lastly the throttle body with TPS (from a 1990 735il).498310498311

Tomorrow will post progress and final pictures. Hopefully after all that work done and the EML may be the main source of a super slow 535i EML car. Ain't giving up!

[sockoiX]

498388498389
In progress of removing the EML.
498390498391
Noticed the non-EML harness round socket connector is completely different from the EML harness :/

[MyFirstProject]

http://assets.sbnation.com/assets/1384167/yuck_imdone.gif.


.

[sockoiX]

498393
I had to push out the pins as the car is male and the non-EML harness is also male...got me stumped. Couldn't find anything online regarding to this so any advice about how I should clean/fix that up would be greatly appreciated.
498394
So far the current state of the non-EML is now on the car! Intake tube is wrong :/

Started right up, no CEL's. Shook for a bit and smoothed out a bit. Gave it a drive, could tell the big difference and the almost dead EML system really made me appreciate this car with the conventional throttle :)

[MyFirstProject]

Why is there no fan on the engine?

[sockoiX]

Took it off to do the valve adjustment and put a new CPS in. It'll be put back on soon.

[coolvegase34]

Sounds like the Maf sensor. I had the same model and year car that you have and that was the problem. I hated working on that engine

[zubbie]

M30's don't have MAFs

[sockoiX]

A new AFM is on my M30 and it works...have a older one that also works so that issue is looked on. Pretty soon will tackle on the wiring on the connectors since the E32 and E34 harness uses different style connectors.

[coolvegase34]

That is correct. But they still have an Maf sensor. Mine was converted to an Maf

[sockoiX]

Miller maf?

[Binjammin]

That is correct. But they still have an Maf sensor. Mine was converted to an Maf

No, they have a VAF: Vane Air Flow meter. A Maf is a different type of flow meter, the two are not interchangeable and the two terms mean completely different things.


Miller maf?

Is a waste of money?

[sockoiX]

Not at all, have been seriously considering of investing in getting the miller maf kit

[Binjammin]

Not at all, have been seriously considering of investing in getting the miller maf kit

It's a waste of money.

Get a chip with an aggressive tune? Make X power.

Get a miller maf? Has to come with a chip too, make X power again.

The trouble is that the VAF really isn't a restriction like everyone thinks it is. The m30 will pull the same amount of air with a maf as a vaf, so all the magic happens in the tune. If you like parts on your car that require periodic cleaning and don't make any extra power, well, then sure, it's not a waste of money at all. Other than that?...

[zubbie]

but you get 2 ms better throttle response with a MAF.......

[Binjammin]

but you get 2 ms better throttle response with a MAF.......

:rofl

[coolvegase34]

Yes it was a miller Maf. Whatever the correct term is, it is an air flow sensor. Change the airflow sensor which is $200 for the part and you may have solved the problem

[sockoiX]

Okies you all make a good point about the miller maf. Since it only changes out the AFM with minor performance improvement. A turbo set up would be more better choice?

I finally took the 535i out for a long drive. It's slow! Still....
Flooring it and it just crawls like a turtle. Rechecked for vac leaks and fuel. Idle stays steady. I'm guessing the valves might be worn out or the eccentrics. Will source a compression tester and go from there. I did notice a big change from .012 to .010 in terms of idle was really rough and felt like a very hot cam.

[Binjammin]

Change plugs cap and rotor and wires?

[sockoiX]

Already did :/

[Binjammin]

:dunno Try unplugging things and see if anything changes it. Coolant temp sensor? AFM?

Did you ever check fuel pressure?

[sockoiX]

Coming back here
So far new fuel pump it's giving perfect fuel pressure. 120 psi on all cylinders on compression test. Different coil and afm still make it run rough. Readjusted the valves to .008 on the camshaft not on eccentrics. Still rough and plugs are wet with fuel. Idles perfectly just shakes and grumbles when stomping the pedal. New throttle body gaskets and vacuum holds strong at 7" at idle.

[demetk]

Coming back here
So far new fuel pump it's giving perfect fuel pressure. 120 psi on all cylinders on compression test. Different coil and afm still make it run rough. Readjusted the valves to .008 on the camshaft not on eccentrics. Still rough and plugs are wet with fuel. Idles perfectly just shakes and grumbles when stomping the pedal. New throttle body gaskets and vacuum holds strong at 7" at idle.

120 psi looks low. What does 7" at idle mean? Is that vacuum?

[ross1]

Coming back here
So far new fuel pump it's giving perfect fuel pressure. 120 psi on all cylinders on compression test. Different coil and afm still make it run rough. Readjusted the valves to .008 on the camshaft not on eccentrics. Still rough and plugs are wet with fuel. Idles perfectly just shakes and grumbles when stomping the pedal. New throttle body gaskets and vacuum holds strong at 7" at idle.

Have you checked for RESTRICTED EXHAUST????
I suggest you revisit post #5

[sockoiX]

Forgot to add, I got the muffler off, just the cats on there. No change and with just the cats the flow is very strong.

- - - Updated - - -

Yes 7" vacuum at idle. Holding the rpms here do maintain higher vacuum and doesn't drop off.

[ross1]

Forgot to add, I got the muffler off, just the cats on there. No change and with just the cats the flow is very strong.

- - - Updated - - -

Yes 7" vacuum at idle. Holding the rpms here do maintain higher vacuum and doesn't drop off.

7" is way too low. The muffler isn't likely to be a flow restriction, cats commonly are.

I don't understand what you are saying with your last sentence.

[sockoiX]

The vacuum will go up around 10-15" and hold well doesn't keep going up or down so I assumed the cats are good.

[DrCharles]

Idle vacuum with a stock M30 cam should be around 15-17 inches. Even with my 275 Asymmetrical Sport Cam from Metric Mech. I had 13-14"...
Are you sure you're measuring at a manifold source, not a ported vacuum source?

[sockoiX]

Definitely like to have that similar range not 7"
I'm teeing it off from the FPR vacuum line that comes from the bottom of the manifold.

[Binjammin]

Idle vacuum with a stock M30 cam should be around 15-17 inches. Even with my 275 Asymmetrical Sport Cam from Metric Mech. I had 13-14"...
Are you sure you're measuring at a manifold source, not a ported vacuum source?

It's an m30b35, I don't think there are any places to take vacuum that aren't direct from the manifold.

[ross1]

The vacuum will go up around 10-15" and hold well doesn't keep going up or down so I assumed the cats are good.
Well, 10" or 15"? If it's not restricted, exhaust or intake, then I'd start to suspect valve timing is wrong. What is your history with this car? Bought this way? suddenly happened? recent head gasket job perhaps?

[sockoiX]

Checked the crank and cam, they're aligned. I decided to readjust the valves again to 0.012 instead of 0.010 and the compression went up to 140 across the board. Going to button up the motor and crank it. Also going to replace the hose for the purge valve just in case. I bought the car when it was running much worse. Drove it 120 miles home, it just shakes so bad (engine not wheels) and got 6mpg. Have been working on it for 3 months now slowly replacing all the vital parts and tune up. Converted it away from EML, was stuck on limp home mode and swapped other EML parts no luck. The swap really made a difference. The PO didn't know squat about BMW's and didn't even bother fixing it, basically tossed it aside and I nabbed it for cheap knowing its going to be a project.

[demetk]

Good to know. Maybe vacuum will increase now.

I'm curious as to how you checked cam alignment? Did you look at the cam sprocket?

[sockoiX]

Vacuum increased to 8" :/ am pretty stumped now.
For the alignment of the cam and crank I found a pic guide to help. Getting the crank to TDC and I also saw that certain hole on the cam sprocket and bolts line up perfectly then the first cylinder lobes point towards the pistons

[demetk]

Double check to what vacuum port you are connecting the vacuum gauge to.
Also make sure the gauge is reading correctly.

Here's my check of cam timing:

1. Harmonic balancer to aligned to O|T mark.
2. Cam lobes on cylinder 1 pointing down.
3. Then check cam alignment by looking how that sprocket bolt lines up with that imaginary green line.

http://i31.photobucket.com/albums/c375/demet_/bmw/engine_03bcamsprocketalignment.jpg~original

4. Since this is a new bimmer for you, you also need to verify that the dowel pin is in this position at TDC.

http://i31.photobucket.com/albums/c375/demet_/bmw/engine_02a.jpg~original

[Binjammin]

Double check to what vacuum port you are connecting the vacuum gauge to.
Also make sure the gauge is reading correctly.

Here's my check of cam timing:

1. Harmonic balancer to aligned to O|T mark.
2. Cam lobes on cylinder 1 pointing down.
3. Then check cam alignment by looking how that sprocket bolt lines up with that imaginary green line.

http://i31.photobucket.com/albums/c375/demet_/bmw/engine_03bcamsprocketalignment.jpg~original

4. Since this is a new bimmer for you, you also need to verify that the dowel pin is in this position at TDC.

http://i31.photobucket.com/albums/c375/demet_/bmw/engine_02a.jpg~original

At 140psi in the cylinders now, he's got to be damn close, or the car wouldn't even run.

[sockoiX]

Good news :D
Ordered a set of 4 nozzle Bosch rebuilt fuel injectors. Plugged them in and boom the M30B35 comes back alive. Idles so smooth and revs mad! It ain't the super slow 535i. The original single pintle injectors were so nasty and caked with soot. The micro filter were clogged with rust.
Will post pics soon!

[Binjammin]

Rust? :confused

[demetk]

Good news :D
Ordered a set of 4 nozzle Bosch rebuilt fuel injectors. Plugged them in and boom the M30B35 comes back alive. Idles so smooth and revs mad! It ain't the super slow 535i. The original single pintle injectors were so nasty and caked with soot. The micro filter were clogged with rust.
Will post pics soon!

Yeah baby. I'm confused with the rust part also. If it is rust maybe it came from the tank?

[Binjammin]

For rust you need oxygen. Water accelerates the process, but I can't imagine how that much water was in the fuel lines. I'd believe maybe carbon buildup, but even then, I think the screens on injectors are brass or bronze...

[DrCharles]

It's an m30b35, I don't think there are any places to take vacuum that aren't direct from the manifold.
On the 80's big-six there are two ports on the throttle body, one on top and one underneath. Don't remember which is which, but one is ported and one is manifold. They connect, through various emissions valves/vacuum hose spaghetti, to the advance and retard diaphragms on the distributor. The OP has a '91 so I don't know if he has that setup or not.

Re: rust, most gasoline today has 10 or even 15% ethanol. Water is miscible in alcohol so there can be quite a bit of corrosion (rust) over time. Thought the injector tips were stainless though...

[Binjammin]

On the 80's big-six there are two ports on the throttle body, one on top and one underneath. Don't remember which is which, but one is ported and one is manifold. They connect, through various emissions valves/vacuum hose spaghetti, to the advance and retard diaphragms on the distributor. The OP has a '91 so I don't know if he has that setup or not.

Re: rust, most gasoline today has 10 or even 15% ethanol. Water is miscible in alcohol so there can be quite a bit of corrosion (rust) over time. Thought the injector tips were stainless though...

The e34 doesn't have a distributor, just a cap and rotor. No vacuum advance. No vacuum ports on the throttle body. the vast majority of fuel in the US is e10, e15 isn't really on the market much. That's 10% methanol, how much water do you think would be suspended in it? It's not like you would have the meth evaporate, leaving just the water in the lines. The water will stay suspended in solution.

Why would stainless rust?

[DrCharles]

OK, so my '80's big-six vacuum hose knowledge isn't relevant. Thought it might help. Forgot that DME replaced L-jet sometime in the 80's.

It's ethanol, not methanol, and I didn't say that there would be "much" suspended water, hence the "over time" part. I'm not curious enough to research how many ppm water are in E10 gasoline.

Who said stainless would rust? I certainly didn't. Did you miss the "though" at the end of my post? That implies that if stainless, they would not rust, of course!

[Binjammin]

I'm just trying to figure out how OP could have rust in his injectors, and yet still have them work enough to run the car. I think it's just carbon buildup.

[ross1]

The e34 doesn't have a distributor, just a cap and rotor.



That meets the definition of distributor very well. Though timing is controlled electronically this certainly is a "distributor". Vacuum advance is a peripheral function on some distributors.

[Binjammin]

That meets the definition of distributor very well. Though timing is controlled electronically this certainly is a "distributor". Vacuum advance is a peripheral function on some distributors.

This is true, but I look at it like... even distributors with fixed advance you can change the relative angle to adjust base timing, the m30 isnt. Potato potato though, as older m30s had vacuum advance distributors. How far the m30 advanced! :rofl

[demetk]

How far the m30 advanced! :rofl

Cutting edge if you ask me. :)

[sockoiX]

Looking into the original injectors microfilter, i see black/orange particles. Hopefully find a new tank one day before too long. Have a new fuel filter, fuel pump and screen in place. Do plan on driving it more finally! Let my E36 take a break ;P

504223504224

[93FIM5]

120 psi looks low. What does 7" at idle mean? Is that vacuum?

We're at 5000+ft of elevation, that's going to affect compression numbers.

[ross1]

We're at 5000+ft of elevation, that's going to affect compression numbers.
Then you can add about 12% to that for correction. 134psi, pretty sketchy
7" vacuum at idle is WAAAAY too low.