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Still Suffering from hesitation/bucking even after VANOS seals? Look Inside!

224K views 411 replies 128 participants last post by  Cibby600 
#1 · (Edited by Moderator)
My car has suffered from a slight hesitation when taking off and under load, and also when suddenly accelerating under load at low rpm's up until 3k in 1st through 2nd even well after 3k miles on the beisansystems.com seals.

So I went in and looked at the MAF, cleaned it and also inside the connector I crimped down the pins inside so it would grab the receiving end pins better--that helped but the hesitation was still there.

Just 3 days ago I decided to clean and evenly crimped (using a pick) down the pins inside the connector for the exhaust VANOS solenoid; I took it for a spin and lo and behold the hesitation was pretty much gone! A few days went by and the more I drove the car the more low end torque it developed and it revved up smoother and smoother.

Yesterday, I did the same thing to the intake VANOS solenoid connector. Took it for a spin and the car felt as if the DME was relearning it's VANOS adaptations all over again! (felt sluggish at the beginning and started feeling stronger about 3 to 6 minutes later) 30 miles later the car feels great! and there is absolutely no hesitation under any circumstances!

The hesitation was caused due to shoddy and loose contact between the solenoid and it's receiving end [VANOS solenoid contacts]-- In other words

I believe that the issue is this..........

The contact width are set to the high side of the spec. The signal that is traveling across these contacts is quite weak. In other words, the current draw is very small. The device of interest, is not receiving the full signal strength from the PCM. Hence the sluggish performance of the VANOS. The best analogy that I can think of: Measuring the resistance of a conductor with a DMM. You will obtain one value when gently touching the conductor with the leads and a different reading when you press hard.
The pins inside both pigtails were spread open for some reason unknown to me.

The new found torque and instantaneous throttle response caught me off guard yesterday during a on and off drizzle when I punched it at 2750rpm in 2nd gear-- The rear end of the car kicked out to the side as if it had an LSD! (yes, I always drive with traction control off--at least when I can remember to turn it off.)



This is my MAF connector but the same concept applies to the VANOS connectors since they are the same in design.

You basically wedge a pick at the top and bottom of the filaments inside closing them together. Not all the way obviously but enough so that when it is plugged in it will open slighly and grab/bite the pins on the receiving end.

I've already done it to the image above. I don't have a before picture but the filaments were spread open and did not form a perfect rectangle as they do now.

Now after you have done so; Now when you are about to connect the pigtail you can feel some resistance ( which indicates the pins have a much better contact with the solenoid pins ) whereas before they simply just slid in like butter; Almost as if they were sliding into a void.

This trick would also work for MAF, DISA, IAT, Alternator pigtails, and all pigtails with the same design throughout the car.

Here's what Rajaie--Owner of besiansystems.com--had to say.

Congrats on the find and repair!
Thanks for sharing this important info!

I have not heard of this before. It seems reasonable it could be a problem.
There have been owners that complained of a hesitation that the vanos seals didn't resolve.

Some owners replace the vanos seals and receive little or no benefit. I know if they have another performance related problem they won't receive the benefits of the new seals until the problem is resolved. But in some cases it seems they have no performance problem. I've always wondered in these cases what is going on. Maybe what you found is a relevant cause.
Spray cleaning connectors with electrical contact cleaner is a good idea. But I had not considered crimping the pins.

Did your pins seem excessively open?
Which reminds me I need to detail my engine bay...

Lets try to keep this thread strictly on the topic at hand

For those who don't bother with searching [and newbs]...

For a in-depth VANOS walk-through

http://www.beisansystems.com/procedures/vanos_procedure.htm

To purchase

http://www.beisansystems.com/products.html

E46 besiansystems.com support thread

http://forum.e46fanatics.com/showthread.php?t=524336
 
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#78 ·
Hey guys, in addition to cleaning the contacts, did anyone re-grease the seals of the connector (not the contacts) with white grease?!
 
#84 ·
did this quick fix this morning... I was sceptical as hell, but said what the heck, its a free mod right? Im still not 100% sure if I feel the difference, I had bucking even after I did the VANOS rebuild. I THINK I still feel the bucking, but it seems to be less. I'll post my final determination after a couple days of driving.
 
#88 ·
You need to take the intake manifold on the M3's, then all the connectors are in plain sight. Simply disconnect and crimp the ones that have the same style plug as the ones pictured.

look up DIY's for both the intake and exhaust camshaft sensors for M3's to find out where to find those.
 
#90 ·
EXCELLENT info... I had planned on repairing my VCG in early Spring, when it warms up. I have spent DAYS reading and re-reading this forum... You guys are awesome. But I keep seeing stuff I need to fix! :ben:

I do have a mildly fluctuating idle so I figure I might as well do the Vanos seal repair while I am replacing the VCG. Then reading up on that and its related threads and posts lured me here. Great info!

So it looks like a complete tune up, clean the ICV, replace Vanos seals, VCG, plugs and tweak the connectors. I wish it was 70 degrees out in the garage... I'd be out there now.
 
#91 ·
Just so you'll know

I had a little bit of a hiccup at idle at 80K miles and added in the Vanos seals and rattle when I did my VCG (which incidentally was in like new shape when removed). After this work, I can still get a bit of fluctuation in idle speed. So there are no guarantees.
Always post your mileage so we have some idea of where your engine is in its history.
 
#96 ·
maybe we have the same problem

I have a manual with 87K.
When partial throttle above 3K rpm, my car stutters, with erratic power slightly, but in an annoying fashion. Full throttle usually pulls strongly and evenly.
Is this what you have?
When did you last do plugs?
I did full vanos, injectors, O2 sensors, and camshaft position sensors, and fuel pump and filter without effect.
 
#97 ·
Plugs and valve cover gasket were changed about 5000 miles ago. I pulled the one plug off of the vanos and used contact cleaner. I drove after that and it ran great. Couple of days later the problem came back however. It seems to be intermittent. When I have it, it is more than a slight stutter. I have not pulled the DISA yet. Anyone have these symptoms with a bad DISA?
 
#100 ·
I know this thread has been going on for a long time but I'd like to say top dollar to the guy who posted about cleaning the connectors!

I cleaned and crimped the vanos exhaust connector and camshaft connector as they were next to each other and it has made a big difference. from 1,500 to 3,000 rpm the pull has increased a lot and the engine runs much smoother through the rpm range. The engine note has changed as when you floor it now it doesn't get bogged down, just sounds a lot more free'er flowing. I also think gear changes are less clunkier and smoother (might be in my head though that). Car has had 100 miles covered since diy. I'll be tackling the intake vanos connector this weekend.

Not left car running upon first start up to see if it has cured the irratic idle when cold. will try tomorrow morning I think.

Just to let people know how much work I have done on my car to solve the low end torque issue:- cleaned all intake, maf sensor, ICV (twice), Camshaft sensor (intake), TB, has B25 inlet manifold mod (increasd power top end), spark plugs, new fuel filter, new juel pump.

Fingers crossed this has worked, not checked mpg yet.

Dan
 
#104 · (Edited)
In for pics. Have no idea what you're talking about.
Can't edit the original post anymore but here's a pic. Should be pretty self-explanatory on what needs to be done--stick a pick in the seams just above the filaments and close them until they are nice and square as shown below.

 
#105 · (Edited)
I tried this on my car. Beware. This didn't do anything for me personally as far as benefits go, but what it did do was made the pins on my vanos solenoid and MAF come out. If you work on your car a lot and unplug certain connectors, the connectors sometimes lose their ability to retain the pins in their respective bodies once this mod has been performed. No biggy but the pins are so fragile it's easy to change the shape of the pin and/or bend/break the delicate tabs that hold them in.

I'm sure these connectors are standard throughout the auto industry and I can't imagine them needing this type of service or failing to the point where contact is intermittent.
 
#106 · (Edited)
I tried this on my car. Beware. This didn't do anything for me personally as far as benefits go, but what it did do was made the pins on my vanos solenoid and MAF come out. If you work on your car a lot and unplug certain connectors, the connectors sometimes lose their ability to retain the pins in their respective bodies once this mod has been performed. No biggy but the pins are so fragile it's easy to change the shape of the pin and/or bend/break the delicate tabs that hold them in.

I'm sure these connectors are standard throughout the auto industry and I can't imagine them needing this type of service or failing to the point where contact is intermittent.
If you're careful then this wont happen. It only happens if you pry in too deeply into the recess and if it does it's an easy fix. It all depends on the build date and harness used as well as history of the car. I've seen some E46's that benefited greatly and some that didn't.

Also just because the auto industry uses them and are the standard doesn't mean they are impervious to defects. Just look at the rear sub-frame fiasco :rofl: so that's a moot point.

On the bright side there's nothing to loose for trying this out. It can only reward if not leave you as before. Win-Win situation if you ask me.
 
#107 ·
The subframe issue is based on a proprietary design for one single BMW model. It's not an industry-wide part like a bolt or an electrical crimp connection that is shared among all bmw models as well as models of other makes as well. It likely isn't even limited to just cars. The same crimps are found at radio shack. Apples and oranges.

It may not hurt, but all I'm saying is for people to be careful they don't pop the pins out or damage them beyond repair. Cause then your problems could suddenly become a lot bigger.
 
#115 ·
Hmm...interesting. I feel as if a DME flash can help this go away too. Either way, it's worth a glance on everyone's car to check. I'm sure this happens to less than 10% of all E46s. Could replacing Vanos Solenoid help this?
 
#118 ·
My car has suffered from a slight hesitation when taking off and under load, and also when suddenly accelerating under load at low rpm's up until 3k in 1st through 2nd even well after 3k miles on the beisansystems.com seals.

So I went in and looked at the MAF, cleaned it and also inside the connector I crimped down the pins inside so it would grab the receiving end pins better--that helped but the hesitation was still there.

Just 3 days ago I decided to clean and evenly crimped (using a pick) down the pins inside the connector for the exhaust VANOS solenoid; I took it for a spin and lo and behold the hesitation was pretty much gone! A few days went by and the more I drove the car the more low end torque it developed and it revved up smoother and smoother.

Yesterday, I did the same thing to the intake VANOS solenoid connector. Took it for a spin and the car felt as if the DME was relearning it's VANOS adaptations all over again! (felt sluggish at the beginning and started feeling stronger about 3 to 6 minutes later) 30 miles later the car feels great! and there is absolutely no hesitation under any circumstances!

The hesitation was caused due to shoddy and loose contact between the solenoid and it's receiving end [VANOS solenoid contacts]-- In other words
I have the exact same symptoms. Car has 54,3xx on the ODO and I've only owned for a week. Did the above today and took it just around the block. Need to take it out and see if there is a difference. All connectors were in great shape, no corrosion or signs of abuse. In fact, the damn thing looks new. I will report back, hopefully I am one of the success stories.
 
#119 ·
Hey! i have a similar problem! slight hesitation when taking off and ever so slightly gittery when stopped at lights, junctions ect. (auto box) it sounds fine in neutral. i took it to the shop and the first thing the guy did was open the oil cap! the car cut out and he said it was an air problem! that the engine was taking in air through air breather manifold or somewhere else! dose this sound right or has anyone had a similar diagnosis?? thanks!
 
#120 ·
I just bought an E46 a few weeks ago it's a 1999 328Ci, and i'm suffering terribly from bucking and performance/hesitation issues when it comes to acceleration. I thought it was the spark plugs, nope. I learned about the MAF sensor, so I cleaned it. Still after cleaning the MAF sensor and replacing old spark plugs I'm having the same problems. I'm somewhat mechanically inclined and love DIY options, could you break down this topic a little bit more I'm a noobcake at times. I'm not familiar with the VANOS system.

One thing I have noticed that when I have this loss of performance, I've tried shutting the car off while in movement and starting it back up and it temporarily solves the problem. I don't know where to go from here :(
 
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