Strange engine problem... [Archive]

BM-BOY

07-21-2005, 01:14 AM

Hello again!

This time I seem to have a bit of a problem, which is going to be quite hard to explain/understand...

Basically, when I am accelerating, something seems to be holding back - almost like a blockage in fuel or something - and instead of smoothly going through the rev range, it has a bit of a splutter. On tick-over, it's fine, but even gently accelerating, between 2-4500rpm, it feeles quite jerky. If I put my foot down, it is more apparent, and the splutters are much closer together, but after about 4500rpm, it pulls nice and smoothly again...

Sorry about the vague description, it's not something I have experienced before, and cant really tell what it could be. Any ideas would be greatfully appreciated...

Jose

07-21-2005, 02:06 AM

When was the last time you changed your fuell filter or checked your distribution cap or Ht leads for leaks ? Check this and you plugs before looking further.

BM-BOY

07-21-2005, 05:35 AM

Well to be honest, I haven't. But I have only had the car a few weeks, and was waiting for a spare weekend to do all that...

It has been mentioned to me that maybe I picked up some crap from my last fuel stop, and thinking about it, the problem has only been since I last refuelled, but I always use the same filling station, which is a large, well known company, and I have never had a problem like this before with any other vehicles...

632 Regal

07-21-2005, 12:40 PM

525SEI BRIT

07-21-2005, 04:09 PM

Had the exact same symptoms shortly after I bought my 525 changed the fuel filter ASAP and even though it looked like new. Never had a problem since.

Also try not to run around on empty to much as the pump located in the tank will be more likely to pickup all the **** at the bottom. If you’ve got a metal filler neck, ill guaranty there will be loads of metal shards setting in your tank. Not good news!!

Hello again!

This time I seem to have a bit of a problem, which is going to be quite hard to explain/understand...

Basically, when I am accelerating, something seems to be holding back - almost like a blockage in fuel or something - and instead of smoothly going through the rev range, it has a bit of a splutter. On tick-over, it's fine, but even gently accelerating, between 2-4500rpm, it feeles quite jerky. If I put my foot down, it is more apparent, and the splutters are much closer together, but after about 4500rpm, it pulls nice and smoothly again...

Sorry about the vague description, it's not something I have experienced before, and cant really tell what it could be. Any ideas would be greatfully appreciated...

BM-BOY

07-22-2005, 02:04 AM

Thanks guys...! Guess what I'm doing this weekend!

1995 525i

07-22-2005, 07:58 AM

replace the plugs and definetly check the electrical connectors as Jose recommended. Read up on the standard maintenance items on our cars and DO THEM...you will regret it if you dont get a handle on the car right away.
I've replaced the fuel filter, oil filter, gotten new plugs, had the injectors professionally cleaned but I still get the surge when I hit the gas. It doesn't pull uninterrupted. the dots represent the smooth acceleration and the x repsresents the hessitation.

......x........x............xx..................

the only I can think of is the fuel pump but those things are expensive. What do you think?

BM-BOY

07-22-2005, 08:16 AM

Strangely enough, my drive into work this morning was trouble free... even the dashboard was working correctly!!
There is nothing more annoying than intermittant problems - I mean, how are you supposed to fix something that isn't always broken?!?!?

1995 525i

07-22-2005, 08:34 AM

Jason

07-22-2005, 11:37 AM

Barrabas

07-27-2005, 04:06 AM

Barrabas

08-02-2005, 03:17 AM

I am not sure but I feel that the engine runs better when it has not reached operating temperature. Maybe a temperature censor for the fuel system is defective?

BM-BOY

08-02-2005, 02:33 PM

Well... this problem has increased to being so bad it is barely driveable. Now, the only way to accelerate smoothly, is to either tickle the throttle gently, up to 1500 rpm, or to put your foot flat on the floor, and keep the revs up higher than 4500 rpm.
Obviously, you cannot drive "normally" like that, so this is starting to get on my nerves...
I have just changed the fuel filter, and the first few minutes after, driving wasn't too bad, but it has now got to be as bad as before...
Can anyone suggest anything else, as i am tearing my hair out now...??

LMUNick

08-02-2005, 02:56 PM

I'm not super familiar with the big sixes, but it seems to truly be either a fuel or ignition problem. Other thoughts: fuel pressure regulator, crank sensor, airflow meter??? How does it idle? Does the driveability vary based on ambient temperatures?

Interceptor

08-02-2005, 05:02 PM

I am not sure but I feel that the engine runs better when it has not reached operating temperature. Maybe a temperature censor for the fuel system is defective?
I have the similar problem:
- poor performance
- higher consumption
- stalling

All this is much more noticable when the engine reaches operating temperature! When cold, I can drive it normally without reaching 3000 rpm. After it warmed up, I find my self being forced to push the throttle harder to achieve the same level of performance. I find it utterly frustrating! I must note that this wasn't happening when I bough the car, it started a few months later.

Are we cursed? :)

Jose

08-02-2005, 05:35 PM

You could also check the blue tempsensor on the thermo housing, if it´s not giving the right temp info to the brain, the brain could read the engine as cold and keep injecting too much fuel choking the engine as a result. Didn´t you have a read out on error codes at your locall dealer or BMW specialist ? Also, does your car have a O2 sensor and is that working properly ? Good luck mate. Keep us posted.

Barrabas

08-03-2005, 03:01 AM

I have recently changed the O2 censor, did not solve the problem. Regarding the tempcensor feeding the brain, that was what I meant in my earlier post. Maybe thats it? Maybe error codes reading is the way to go?. Thanks for your suggestions, please keep them coming

BM-BOY

08-03-2005, 04:27 AM

Hello again!

On my way into work this morning, my car started coughing and spluttering so bad, i had to pull over because it was completely undriveable... it was also backfiring quite badly... when i pulled over, the engine idles fine - nice and smooth, abouth 750 rpm... however if i try revving the engine, it splutters all the way through the rev range now.
I managed to get home, just by keeping the revs below 1500 rpm.
I wonder whether this is an ignition problem of some sort - as the backfires would suggest it isn't sparking correctly... I am gonna have to sort this out asap, but don't know where to start... should i buy spark plugs and leads, or could it be a blocked injector? when i changed the fuel filter last night, i drained the fuel into a clean bucket, and when i looked afterwards, i noticed quite large pieces of what looked like grit or gravel...

HELP!!!!

Barrabas

08-03-2005, 06:27 AM

wow!, seems that your problem is much worse than mine. I have pity on you BM-BOY.
I was just out driving and it is a bit cold around 17 degrees Celsius and rainy outside (Norway :( ) and the problem (uneven acceleration) is not so distinct in this weather. Maybe just a coincidence.

SRR2

08-03-2005, 07:20 AM

You don't mention having done a Stomp Test. You'd better try that right away and note the results.

BM-BOY

08-03-2005, 01:03 PM

What the hell is a Stomp Test???

You'll have to forgive me, but this is my first BMW and I am not a mechanic...!

That said, I have just checked my spark plugs, and they all look new, and the HT leads dont look perished...

What else can I try? I really don't want to have to pay a garage if it is something simple, but I dont want to have to keep borrowing my brothers' old Mini to get to work, cos I like having power steering, electric windows and a stereo!!!

SRR2

08-03-2005, 01:12 PM

It's a way to read the fault codes out of the ECU. There are plenty of references for the procedure and codes. You can search these forums for more information.

Oh hell, you're having enough problems, I'll do it for you:

http://www.bmwe34.net/E34main/Trouble/Engine_codes.htm

BM-BOY

08-03-2005, 01:18 PM

Hey thanks for that! I'll go and have a look now...

BM-BOY

08-04-2005, 02:28 AM

It seems the Stomp Test doesn't work on my car... I guess because it is the early model, and I cant be bothered to start taking out my dash as well...

Time to call the garage... :(

BM-BOY

08-06-2005, 03:47 PM

Garage had car all day friday - still none the wiser... Only thing they said was some of the wires under the engine looked like they had been chewed by mice!!

BobHarris

08-06-2005, 05:45 PM

It seems the Stomp Test doesn't work on my car... I guess because it is the early model, and I cant be bothered to start taking out my dash as well...

Time to call the garage... :(

Stomp test only works on US cars.

You said that the car ran better after you changed the filter but soon went back to poor running?

It strikes me, that the fuel rack or an injector could be blocked. When you changed the filter the fuel in the rack drained back bringing the blockage with it. The car was fine until the blockage was sucked back.

Or I could be talking bolllocks. :D

All the best

Bob

SRR2

08-07-2005, 10:29 AM

Do you have a non-US car? Mine (until tomorrow!) was built in 11/88 and the stomp test works on it. Are you SURE you followed the instructions to the letter? Are you sure your CEL is working? There's a lamp test mode... rats, I can't recall where the instructions are for that. I think it's something like holding in the CCD clear button and turning on the ignition to the run (without starting) position. This cycles the lamps and gauges. It's sort of humorous to see all that stuff going on like some whack video game.

BM-BOY

08-08-2005, 02:30 AM

Mine is a UK model... I wouldn't know if the test works or not, because I have been having some issues with the dash recently as well. But I did follow the instructions, and absolutely nothing happened.

I also thought it may be blocked injector or something like that, because I had been driving with this intermittent problem for some time, and thought some **** may have passed through the filter...

But someone earlier mentioned the fact it only happens to them when the car is up to temperature, and I am now wondering whether the same goes for me - and that replacing the fuel filter didn't really help, because after I had taken the car out on a test drive, it was going just as bad as before by the time the engine had warmed up...

Anyway, gonna give the garage a call lunch time, to see if they have found anything yet...

grave77

08-08-2005, 04:02 PM

I thought I would share what I have recently got with my car, in the thread I posted few days ago http://www.bimmer.info/forum/showthread.php?t=12877 ...later I replaced the fuel filter, already replaced the fuel pump, I have another DME which I installed and I also borrowed an AFM from my dads car for test. and nothing changed ... when the car is cold it accelarates like a blast ... but when hot the maximum RPM is 4500 with choking all over, I have tried to notic the exhaust colore ... there is nothing emmited ...no black smoke no smell ... I even disconnected the O2 sensor and the temp sensor and reset the car without them so it wont be included in the DME program but nothing changed ... I had the same problem like the hesitation betwen 3000 - 4500 then smooth again just like the beginning of every one of you. now I just dont know what would it be. and I'm simply running out of options .... crank sensor sounds logic but what would cause it? I dont think its electrical ( sparks ) cuz its not smelling gas nor exploding in the exhaust ... and since the idle is smooth then injectors r fine ... some one told me that its a blocked catalytic converter ... no one replied to this comment yet ... finally I have blocked the return pipe from the fuel regulator and it didnt change anything. I hope this will give some hints to get closer to the problem ... thanks for all your posts guys .... good luck for all of us ...

grave77

08-09-2005, 07:24 AM

well I would like to add something new today ... car doesnt start ... takes too long to respond .. but when it works it responses very well ... no choking no nohing .. but ... just in an instant ... it just stops ... as if you switched the engine off ... today when I was back from work ... engine was choking with the RPM needle droping down around 700 - 1000 RPM .... while I have manual tranny ... the engine RPM should remain the same almost ... but the drop is more than the slowdown in the engine while choking ... also ... when I stopped at the traffic light it just stopped .. I started it on again then drove back home ... not daring to step it more than 4K RPM ... or it will choke ... still no smell of unburnt gas or smoke. ""for more information only about the situation"".

grave77

08-09-2005, 07:30 AM

Jeff ... I think the problem is way far beyond those stuff ... as some guy here said ... its a curs ... I thought I had this problem only .. but seems like many owners of an M30 engine had it ... good when cold bad when warm ... reaching the fatal ending I'm suffering from ... I was going to ask about the crank sensor and the feedback sensor on the highvoltage wire at the distributor. they are the area am doubting now... any comments Jeff?

BM-BOY

08-10-2005, 06:57 AM

Hmm... Sounds like you have a slightly different problem, but nonetheless frustrating.:(

Well rang the garage last night... STILL no news... :(

grave77

08-10-2005, 01:37 PM

thats so strange ... I'm doing some reading in the bently manual ... maybe something might ring a bell ... but anyway I bought a new fuel filter ... its already time to change it ... and I got mercedes benz high voltage coil .. it has better skin than the BMW ... same shape .. as the BMW 535i coil cracks quicker than this one I got .. I will check the hammer and the distributor ... in general I will replace the old parts in my engines area and see what will change.

grave77

08-18-2005, 03:29 PM

well ... I would like to say that the problem in my car was solved .... I'm not quite sure about the dimming happening between the 3K - 4K RPM ... but the choking was due to the bad CPS ( crank position sensor ) located at the front of the engine ... it was loose and then I think the sensor died too ... paralising the car from starting. now I replaced it and everything is back fine !! :) hope this would help ... sure my thanks goes to Javier who was a great help ... and to all bimmer guys too ... chears

BM-BOY

08-21-2005, 04:00 AM

My car has been fixed!!!
Picked it up friday night - They have replaced the dizzy and rotor arm, but he said one of the injectors needed cleaning as well... I recon it was probably just the injector causing the problem, but never mind... I BACK ON THE ROAD!!!

EonPeon

08-21-2005, 06:19 AM

Sorry, but am I stating the bleeding obvious by saying:- "How about taking the car into a BMW dealer for a service?"

Now I KNOW I'm going to get a LOT of flak for even suggesting the car goes NEAR a BMW 'stealership', but surely these guys should know what they're doing? And while you might pay more per hour than average, surely it's worth it because they know what they're doing and so (in theory) should get it done quicker.

Surely it's a false economy to be running your car while planning to fix it yourself next weekend, when it could take you HOURS to figure it all out and still run the risk of screwing up a very-expensive-to-replace piece of finest German engineering?

If taking it back to a genuine BMW dealership is too much bear, at least seek out a good independent motor mechanic who specializes in BMW...

I'm lucky enough to have two such service places I know in Sydney...

One services ONLY BMW, the other does ONLY European cars. Check your local Yellow Pages...

All the best,

Ian

grave77

08-21-2005, 09:16 PM

whats the dizzy and rotor arm? any other names?

emw525E34

08-22-2005, 12:42 AM

I've replaced the fuel filter, oil filter, gotten new plugs, had the injectors professionally cleaned but I still get the surge when I hit the gas. It doesn't pull uninterrupted. the dots represent the smooth acceleration and the x repsresents the hessitation.

......x........x............xx..................

the only I can think of is the fuel pump but those things are expensive. What do you think?

If you have done all the above. You missed the most likely culprit. The MAF. It probably had flat spots on them.. You might start by taking it and the intake elbow out for a good clean with Carb cleaner. I don't know if the MAF for '95 model had any serviceable modules in there but for the M20/M30 engined AFM, there is a lot that can be done. The ....x..... will become ......:............:......
or just clean pull all the way to the redline. I doubt if the fuel pump is dying. You will get serious dip in rpm if the pump is struggling to hold the 45psi it is asked to.

BM-BOY

08-22-2005, 02:34 AM

whats the dizzy and rotor arm? any other names?

Distributor cap and rotor arm... The bit the HT leads connect to...!

"How about taking the car into a BMW dealer for a service?"

If I could afford £80 an hour labour, I probably would take the car to a stealer, but until I win the lottery, I'll use my local grease monkeys...

onZedge

07-26-2007, 12:39 AM

My Wife is having the big surge going uphill problem as well. I am currently performing a 150K mile SUPER TUNE-UP which includes bench testing, changing, flushing, greasing, lubricating, measuring, sniffing, adjusting EVERYTHING, as well as regular Inspection I & II stuff and beyond.

Firstly, I have no diagnostic codes (except 1444 no-fault code). Questionable things found so far: bad WOTPS (replaced), coil secondary reads 9.2K ohms (not replaced - yet), cylinder identification sensor reads 0.05 ohms (not replaced - yet), distributor cap coil tower to button reads 33 ohms (replaced), Terminal R unloader relay contact (SPST) 0.6 ohms (not replaced - yet), DME relay coil reads 125 ohms (not replaced - yet), fuel pump relay coil reads 80 ohms (not replaced - yet), anything rubber attached to the intake manifold was rock hard and replaced, all fuel pressure and return lines were replaced, injectors were backflushed and re-ringed. Every connector in the engine compartment has been cleaned/lubricated with CRC QD and CRC 2-26. Low beams suck big time.

Major things left to do are fuel pump/regulator flow and pressure tests and inspection as well as battery/starter/alternator testing and cable cleaning.

I suspect the surge problem is going to be either the coil or something not yet mentioned in this thread. THE FUEL PUMP PICKUP SCREEN OR CRACKED PUMP DISCHARGE HOSE (in the fuel tank). If not, it's on to the Motronic DME...

Also, somebody mentioned a Mercedes HO coil. Where to get? What P/N?

Ferret

07-26-2007, 02:35 AM

If I could afford £80 an hour labour

I pay nearly that for my local indy, where you from?

The local stealer here wants £120/hr + tax.

onZedge

07-27-2007, 12:37 AM

OK, checked fuel system and these are the results:

Engine off, Fuel Pump Relay socket jumpered with pushbutton, I got 48.5 PSI (failed - should be 43.5) and >40 oz. of fuel from the return line in 30 seconds (>29.6 oz. is OK) and it held 42 PSI for 20 minutes (OK).

Engine on @ idle with vacuum, I got 43 PSI (failed - should be 40-41)

Engine on @ idle without vacuum, I got 49 PSI (failed - should be 46-47)

I also noticed a random spike in pressure, coincident with a slight hunt at idle. The fuel return line is clear, so I guess I have a bad FPR.

I did a search here on the surging M30 problem and realized that I better recheck the CPS gap as well. A new coil will also be on order as soon as I can get a part number and source for that Mercedes-Benz High Output coil I saw mentioned here somewhere. Can anyone help me out with that? I want to get a handle on this problem before it gets...well...out of hand!

BFEINZIMER

07-27-2007, 01:31 PM

whats the dizzy and rotor arm? any other names?

oh yea thats the whatcha-ma-call-it and the gottafixit

scary my 535 doesent have these probs just the hot start

genphreak

07-28-2007, 08:41 AM

Distributor cap and rotor arm... The bit the HT leads connect to...! If I could afford £80 an hour labour, I probably would take the car to a stealer, but until I win the lottery, I'll use my local grease monkeys...You're crazy letting anyone unqualified touch it. BMW would run a test over it and tell you which sensors are dead. You can do all this yourself as easily as most garages can (unless they know BMWs). For a quick fix, nothing beats experience. Otherwise follow the electrical test procedures in the Bently for every sensor and check for loose pipes and boots in the intake- damaged sealing surfaces, a dodgey AFM, incorrect plug gap, stable fuel pressure... it pays to do it all methodically, taking care to learn before doing things the wrong way, and get it running right. Do it bit by bit, planned, and post pics to get help from the more experienced people on forums like this- they can be extremely helpful - better than a stealer with the right attitde and equipment AND unlimited budget. :) Nick