Jerky Acceleration when pedal to the metal

[Bilito]

Went for a top down ride and found a few places with no one around and I decided to floor it off the line, it hesitated, gasped, then took off, went herky jerky up thru the gears, flooring it after each gear change, same thing all the way to 4th never went into 5th. I wanted to see what it could do. The engine at that time was not fully warmed up and by that I mean the temp needle was only midway between pointing straight up and out of the Blue mark.

A little later when the temp was warmed up to normal and I mean the temp needle was now pointing straight up, which seems to be the normal for this car, I did the same test and it was much smoother with just a little hesitation here and there.

So what can be causing this, I assume there will be a code, because the engine check light came on before I did any of this, I sorta expected a light because I still had a small amount of roughness right after start for about 30 seconds or so after we changed the valve cover gasket.

Bill

[Blacklane]

Sounds like bad VANOS Seals. Check out the Beisan Systems website.

[rf900rkw]

I suspect it is something much more mundane. A failing coil or a MAF problem. The M52 VANOS does not have the same failure symptoms as the M52TU. Nor is this an IAC problem. Start with the basics. The light is on. Read the codes!

- - - Updated - - -

Taking all of the different symptoms that the OP has spread across four or five separate threads,. I'm suspecting a dead MAF.

[Bilito]

I plan on getting the codes read first thing in the morning.

[bluptgm3]

Look for codes…but did you have - Tire slip with ACS+T light?


Sent from my iPhone using Tapatalk

[Blacklane]

I suspect it is something much more mundane. A failing coil or a MAF problem. The M52 VANOS does not have the same failure symptoms as the M52TU. Nor is this an IAC problem. Start with the basics. The light is on. Read the codes!

- - - Updated - - -

Taking all of the different symptoms that the OP has spread across four or five separate threads,. I'm suspecting a dead MAF.

After I saw who posted this, I thought the same thing. The car is new to him and he's been chasing several issues, most of which point to a vacuum leak or a bad MAF. I'm sure the previous owner was happy to unload it.

https://www.bimmerforums.com/forum/s...2#post29806002
https://www.bimmerforums.com/forum/s...8#post29810798
https://www.bimmerforums.com/forum/s...0#post29811380

[Bilito]

Hi Guys, I am back, just had my codes read at the auto part store, here is what was found

P0170 Fuel Trim, bank 1

P1188 No definitions found, consult repair manual

This morning as usual it ran very rough for two minutes and then smoothed out,. it even accelerated very jerky, but once it was fully warmed up it ran perfect.

[rf900rkw]

Those are both fuel trim codes. for bank 1. This is consistent with a vacuum leak or similar problem, but not conclusive.

[Bilito]

Your suggestions please,.In my mind is removing the throttle body and the intake manifold, replacing all the vacuum lines to and from the ICV, cleaning the ICV, and everything that looks grimy and replacing the oil separator and the pvc valve (my brother seems to think the intake manifold gasket is leaking)
I am trying to make a list of the assorted gaskets, vac lines, and other parts.
what happens if I disconnect and reconnect the various sensors one at a time while the engine is running that are easy to get to that are on the top of the intake tubing and throttle body, I can see three of them

[Bilito]

OK I found a list of all BMW code and this is what I found
P1188 Fuel Control Bank 1, Sensor 1

P0170 Fuel trim Bank 1

So what sensor are they talking about and where is it and how do I check it?

[328 Power 04]

There likely isn't a problem with a sensor. Also there very likely isn't a problem with ICV, not sure why you insist on it too much. You have a large vacuum leak most likely. You will need to inspect the rubber boot going to the throttle body, and the hose going down from it. After that, a smoke test will discover all the other leaks the best.
There is a chance that your mass air flow sensor is bad, but I would still verify that the intake tract is sealed first.

[saneesh8]

If you are removing the intake (all from my memory when i did the water pipes years back),

1) Replace all the gaskets for Intake manifold, ICV, DISA etv,
2) Fuel injector O-Rings
3) All the vacuum lines.
4) Check coolant pipes.
5) Check the elbow for any cracks / leaks.

There is a vacuum port under the intake which is closed with some kind of cap. If it is bad, it can cause leaks.

I had to remove the intake of my 2000 2.5 because of the coolant leak at the water pipes. When i was there, i also replaced the OFHG, cleaned the alternator air vents etc. Please see below.

https://www.bimmerforums.com/forum/s...-DIY-with-pics

Also my car had a hick ups at high RPMs. The fuel filter was the issue. Changed it and it fixed it.

[328 Power 04]

He has the single vanos engine. The above do not apply too well.

[saneesh8]

Oh ok.. didn't knew about it..Thanks..

[Bilito]

OK, the big rubber elbow with the accordion pleats is almost brand new, we took that thing and stretched it out every which way no cracks anywhere, so I think the issue is down stream from that, the hose going down from the elbow looks to be suspect, it is old, where does the other end go?

The only things I can get at vacuum wise at this point is the throttle body, which is a two piece deal, if I remove that I should have a little more access to all the lines under it.
What is a smoke test?

[saneesh8]

Smoke test is the best method to find the leak. I never had to do it, but saw some videos. One of them was, after taking out the MAF, inject smoke and see where the smoke is escaping. Search for youtube videos on smoke test and you should be able to find it.

The below links are for my car. Try this for your car . From realoem, Engine->Vacuum control. You can see the vacuum lines diagram.

http://www.realoem.com/bmw/enUS/show...diagId=11_2682
http://www.realoem.com/bmw/enUS/show...diagId=11_6225

[Bilito]

Thank you for the tips on smoke, my bother told me he heard that party stores have something call smoke in a can, it sprays out smoke for parties, I never heard of anything like that, gotta check that out

[nevan]

Thank you for the tips on smoke, my bother told me he heard that party stores have something call smoke in a can, it sprays out smoke for parties, I never heard of anything like that, gotta check that out

If you are so heart-set on getting smoke tested, I recommend taking it to a reputable shop. My experience has thought me that it's rather how you interpret findings that counts (not just about cars but it also applies to life in general)... Or I would even recommend starting with simpler test like spraying brake cleaner if you haven't done it already...

It seems like you have quite a bit of things to sort out... And I noticed that you are in Miami, why not take the car to Randy for an expert advise, just a thought...

[Bilito]

who is randy? where is his shop located?
BTW I am not heart set on smoke testing I just heard about it

[bluptgm3]

I believe that is the pre-catalytic converter O2 Sensor in bank 1 head pipe collector.
How many miles on the O2 sensors, as they are 100K service replacement items.


Sent from my iPhone using Tapatalk

[Bilito]

I assume they are original equipment, the car has 92K miles

[Bilito]

In my continuing effort to find these vacuum leaks, this morning I tried the carburetor spray on all the areas of possible vacuum leaks. I did not get the engine to speed up at any one point, but I did get a sorta sucking sound here and there around the throttle body. It was a sound like you get when sucking from a straw at the bottom of an empty glass of soda, it was not steady, I would spray, it made the loud noise, then the noise stopped, I sprayed again, no noise, I waited a few minutes sprayed again the noise was there but just for a few seconds then it stopped, I think that is a vacuum leak around the top area of the throttle body. There is two sensors there. The photos are just a reference, the sucking sound was in that area and it did not last long enough for me to pin it down and the motor still ran very rough for a few minutes until it warmed up.

fullsizeoutput_1d4c.jpgfullsizeoutput_1d4e.jpg

[saneesh8]

Good find. Since all the hoses are checked out, the housing gasket is bad?

Just checking. When the car is idling and you open the oil fill cap, is it slight vacuum ?

I think you better do a smoke test. Check with some nearby shops.

Good luck

[Bilito]

AHHH, I forgot to check around the oil fill cap, I will do that right after lunch

[Bilito]

I sprayed around the oil filler cap, nothing, so I attempted to open it to feel for a vacuum and I could hardly turn it and when I did open it the Engine almost quit, stuck it back on, engine ran, lifted it off again, engine almost quit, put it back. I guess it is safe to say the vacuum system is working pretty good. Seems to me with that kind off suction any small leak would make a loud hissing sound. What else can cause all the rough running and herky jerky acceleration until the engine is fully warm? Once fully warmed up it runs perfect.