Hesitation/Jerking

[jbailer]

Bone stock, when I brake for a 90* turn and then hit the gas, the car does this lurching for a few seconds like it's on and off the gas. It does the same thing if I brake for a really bad dip in the road like at a bad intersection and I'm going straight. Anyone else have this? Any ideas? My first guess would be fuel pressure related or sloshing but I get it even when the tank is full.

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[Chef jpd]

I had the same issue when stock. Went away with the Tune+.
I did notice when it happened it was only on very light throttle, a little more pedal and it smoothed out.

 

[jbailer]

Thanks, I'll give that a try. I'm not usually very light on the throttle though. If anything I was thinking the opposite, I may have been on it a little too much but I let up when it jerks like that.

 

[jbailer]

Nope, problem is definitely not from being to light on the pedal. I didn't think that would be the case since I'm not usually very easy on it. In fact when I went slow it was no problem at all, it's when I'm more aggressive on it.

It's not every turn either. There are 2 spots I drive that it always happens, both have a bump. There is a left turn that I'm going up a hill and the road I turn onto goes slight up hill with a gradual bump in it. The second place is at an intersection, I know you've all seen these where the intersection grading isn't very good and there are all the marks in the road on the far side where people's cars dug into the pavement. On that One, I'm going straight, I brake to slow down a bit and as soon as I go over the bump I speed up. That's when the jerking starts.

 

[Juben]

The only surging that I've ever felt that's similar to what you're describing was because of the BPV opening and closing in succession. Under certain conditions and lighter throttle, it'd feel like it was surging on and off much like you've described. Is there anywhere that you could pull over before one of those spots and unplug the BPV then drive through like normal? If so, just don't go ham on the throttle (snap on and off of it) and drive it like normal. If the problem goes away, then that'd show you it's something in the tuning/BPV scheduling.

 

[jbailer]

The only surging that I've ever felt that's similar to what you're describing was because of the BPV opening and closing in succession. Under certain conditions and lighter throttle, it'd feel like it was surging on and off much like you've described. Is there anywhere that you could pull over before one of those spots and unplug the BPV then drive through like normal? If so, just don't go ham on the throttle (snap on and off of it) and drive it like normal. If the problem goes away, then that'd show you it's something in the tuning/BPV scheduling.

Hmmm interesting, I'll have to test that. 1 of the spots is right down the street from my house so I can definitely try it. When you say unplug it, you mean the electrical connection correct?

Not sure what you refer to as light throttle. I'm definitely not WOT, normally probably hitting about 5 psi there. Is that ok? As long as I'm not going 20+ I'm fine right?

 

[Juben]

Hmmm interesting, I'll have to test that. 1 of the spots is right down the street from my house so I can definitely try it. When you say unplug it, you mean the electrical connection correct?

Not sure what you refer to as light throttle. I'm definitely not WOT, normally probably hitting about 5 psi there. Is that ok? As long as I'm not going 20+ I'm fine right?

Yeah, I mean unplug the electrical connector on it. Mine would do it around 5-7 psi at probably 30% throttle. I was probably 1/4 of the way down on the gas and it was even more noticeable under heavier loads, e.g. pulling a hill. Just don't get in it and floor it with the BPV unplugged. It won't cause it to blow up or anything, but it'd cause some nasty compressor surge. When you let off the throttle (with it unplugged), do so in a gradual reduction kind of way, i.e. ease off of it instead of just immediately lifting off of it.

 

[jbailer]

Yeah, I mean unplug the electrical connector on it. Mine would do it around 5-7 psi at probably 30% throttle. I was probably 1/4 of the way down on the gas and it was even more noticeable under heavier loads, e.g. pulling a hill. Just don't get in it and floor it with the BPV unplugged. It won't cause it to blow up or anything, but it'd cause some nasty compressor surge. When you let off the throttle (with it unplugged), do so in a gradual reduction kind of way, i.e. ease off of it instead of just immediately lifting off of it.

Justin, if this is the case, you think it is a bad or leaking BPV? Depending on the weather, I'm hoping to try it out tomorrow.

 

[jbailer]

This is odd, the problem has been very consistent so far. Yet this morning I unplugged the BPV and went around the corner close to my house. It only happens when I'm making the left there (going out). The first trip it didn't do it so I thought, that must be it! I decided to turn around, come back and try it a second time. Sure enough, it didn't do it again. I was feeling pretty good about it. Then I went back home and plugged it back in and took my wife out to lunch, it didn't do it that time either...

Is there any chance uplugging the BPV and plugging it back in made it start working again?

 

[TheLion]

This is odd, the problem has been very consistent so far. Yet this morning I unplugged the BPV and went around the corner close to my house. It only happens when I'm making the left there (going out). The first trip it didn't do it so I thought, that must be it! I decided to turn around, come back and try it a second time. Sure enough, it didn't do it again. I was feeling pretty good about it. Then I went back home and plugged it back in and took my wife out to lunch, it didn't do it that time either...

Is there any chance unplugging the BPV and plugging it back in made it start working again?

Sounds like valve flutter as Juben stated. I upgraded the BPV to a Boomba BOV which is ECU controlled. It functions these same, but doesn't leak or flutter as it is pneumatically powered by boost / vacuum sources (which are controlled via a solenoid operated manifold plugged into the ECU).

They also over a BPV variant, so you have the same benefits but maintain the silent operation. Another solution is the DV+ upgrade kit, which is cheaper. Basically the DV+ kit upgrades the stock BPV plunger to again eliminate these issues. The DV+ kit looks completely stock, also maintains factory ECU control but like the Boomba solution, eliminates leaks and fluttering.

Although there may be another source as well. When I was running the Brisk RR14S plugs, I noticed a lot of "on / off" oscillation in power. Felt like misfiring, but there were no codes, the timing curve was smooth. Nothing on the ECU was registering anything abnormal. After 2 drive cycles (100 miles), it seemed to all but disappear. So I reset the ECU again and sure enough it came back. After another two drive cycles it seemed to "optimize" out. I even noticed it once I switched back the OE plugs, but to a much lesser degree (barely detectable) which also optimized out after 1 or 2 drive cycles.

Which brings me to the point that perhaps you have a plug or two out of spec on the gaping? These TDI engines seem to be VERY sensitive to plug gaping, design and how deeply they are projected into the chamber. For example with the Brisk RR14S I have constant rough idle and low throttle hesitation, just did not work well with them (they are more recessed than the OE plugs, so I believe they were causing erratic ignition).

 

[PewterCam]

This is odd, the problem has been very consistent so far. Yet this morning I unplugged the BPV and went around the corner close to my house. It only happens when I'm making the left there (going out). The first trip it didn't do it so I thought, that must be it! I decided to turn around, come back and try it a second time. Sure enough, it didn't do it again. I was feeling pretty good about it. Then I went back home and plugged it back in and took my wife out to lunch, it didn't do it that time either...

Is there any chance uplugging the BPV and plugging it back in made it start working again?

What kind of tires do you have and how cold has it been? If you have summer only tires that may be the culprit. My summer tires get rock hard in temps below 40* causing the traction/stability control to kick in like crazy and cause a strange lurching action when accelerating out of low speed turns. When I shut the stuff all off the traction and stability crap the car would not only drift around the turns without trying but also lightly spin the tires just touching the throttle in a straight line. Once the tires get a little heat in them they regain grip and the problem goes away.

 

[jbailer]

Sounds like valve flutter as Juben stated. I upgraded the BPV to a Boomba BOV which is ECU controlled. It functions these same, but doesn't leak or flutter as it is pneumatically powered by boost / vacuum sources (which are controlled via a solenoid operated manifold plugged into the ECU).

They also over a BPV variant, so you have the same benefits but maintain the silent operation. Another solution is the DV+ upgrade kit, which is cheaper. Basically the DV+ kit upgrades the stock BPV plunger to again eliminate these issues. The DV+ kit looks completely stock, also maintains factory ECU control but like the Boomba solution, eliminates leaks and fluttering.

Although there may be another source as well. When I was running the Brisk RR14S plugs, I noticed a lot of "on / off" oscillation in power. Felt like misfiring, but there were no codes, the timing curve was smooth. Nothing on the ECU was registering anything abnormal. After 2 drive cycles (100 miles), it seemed to all but disappear. So I reset the ECU again and sure enough it came back. After another two drive cycles it seemed to "optimize" out. I even noticed it once I switched back the OE plugs, but to a much lesser degree (barely detectable) which also optimized out after 1 or 2 drive cycles.

Which brings me to the point that perhaps you have a plug or two out of spec on the gaping? These TDI engines seem to be VERY sensitive to plug gaping, design and how deeply they are projected into the chamber. For example with the Brisk RR14S I have constant rough idle and low throttle hesitation, just did not work well with them (they are more recessed than the OE plugs, so I believe they were causing erratic ignition).

Thanks for that explanation. I was very good with superchargers in the V8 world but turbos and DI are both very new to me and turbos seem a bit more complex. Some day, I'll crack some books and learn a little more. Until then, it's a bit of a struggle not knowing what seems to be pretty basic TDI mechanics.

After getting this car, I went on past Ford performance/reliability and quickly jumped into mods and it was running great! After all the ecoboom scare, I decided to back them all out except for the ATM intercooler and oil CC. I've even gone back to the stock plugs and they are gapped very precisely even though like most others they weren't from the factory.

I have an extended warranty and since this is my only car and DD, need it reliable and I don't want to shell out thousands of $$ since Ford had some issues with the early build EB engines (which mine is).

Now this is stupid because I would love to go with the Boomba BPV that you mentioned and it sounds like that might solve this issue. I saw it when they released it and really liked what they did. However, I'm 100% sure that my Ford dealer would blame any issue on that BPV if it was aftermarket. They are very ignorant when it comes to modifications. I don't mean that in a derogatory manor, just literally.

So, I could take it back to the dealer and they could drive it around and waste my time and probably say they couldn't reproduce the problem or they won't be able to fix it. That brings me forward to the point I know I will get to sometime anyway and that is back down the mod path and forgo the warranty. Especially seeing some of the new developments like the HPFPs that will soon be available and some of the new turbos, I really love how that new turbo from Turbonetics looks. Plus I see guys like Justin (Juben) that has been running tuned for a long time on an early build with many more miles than mine. hmmmm

 

[jbailer]

What kind of tires do you have and how cold has it been? If you have summer only tires that may be the culprit. My summer tires get rock hard in temps below 40* causing the traction/stability control to kick in like crazy and cause a strange lurching action when accelerating out of low speed turns. When I shut the stuff all off the traction and stability crap the car would not only drift around the turns without trying but also lightly spin the tires just touching the throttle in a straight line. Once the tires get a little heat in them they regain grip and the problem goes away.

Thanks! I know what you're talking about. Before I got rid of the stock Pirelli summer only tires last fall, when the temps got to around 40* driving got real interesting even on dry roads. Now I'm on Conti DWS 06 that get great traction. I'm positive it isn't a traction issue but really appreciate any insights.

 

[Chef jpd]

Ill second the Lion's suggestion. I forgot to mention that when I tuned my car, I also added a Turbosmart BPV (mechanically controlled) as well as a Tune + WGA. The stutter was never there after the tune, but I,'m not sure if one or all of the mods fixed it.

 

[jbailer]

Ill second the Lion's suggestion. I forgot to mention that when I tuned my car, I also added a Turbosmart BPV (mechanically controlled) as well as a Tune + WGA. The stutter was never there after the tune, but I,'m not sure if one or all of the mods fixed it.

Thanks John, I had similar results although this stutter just started happening. I have the Turbosmart Kompact Shortie Dual Port BoV that I had on the car until I got scared off. To be honest though, I really like the concept of how the Boomba BPV works since it is still controlled by the ECU. I think this really will be the solution, I just need to work up the nerve to forget the warranty, get the Turbonetics Turbo, Boomba BPV and new HPFP and see what she can make on pump 93. It's just so hard to give up that warranty. Especially since I purchased the extended. :(

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