Hiccup from Stop When Hard Accelerating AFTER Engine is warmed

[matreyia]

OK folks... I have solved the hissing sound, but the hiccup still persists. Here is the summary:

From full stop, hard acceleration in any drive mode results in hiccup... this happens AFTER engine reaches operating temperature. It does not do this if cold start and before reaching 160F. This leads me to suspect the PCV Solenoid hose is not working correctly since the PCV solenoid activates only after reaching operating temperature and not otherwise. This hose/solenoid comes out from the firewall and connects directly to the throttle body and the RB external low side catch can hose connects perpendicular to this hose at the mouth of the throttle body.

This is what has been done so far:
1. Replaced all hoses and connections, clamps and couplers to all possible hose connection points on every engine and turbo part.
2. Replaced with brand new throttle body.
3. Cleaned all PCV valve adapters.
4. Replaced crankcase sensor.
5. Ran Fuel Cleaner for e85 tank.
6. Reset all adaptations in MHD
7. Battery is 100% level, all connections checked and tightened front and rear.
8. spark plugs new.
9. spark plug wires, new.
10. replace both camshaft sensors.

This is what will be done next:
1. replace PCV hose/solenoid
2. check transmission fluid level.

This problem manifests in any drive mode and regardless of traction control on/off state.
Again...only after operating temperatures are reach does it begin to hiccup and only hard acceleration from full stop.
It does not hiccup AFTER going into motion no matter how hard I slam on the pedal.
It does not hiccup from full stop IF I feather the pedal conservatively and ease into motion.
The engine feels and sound super strong, stable, smoother in idle, in park, or in drive with the brakes depressed, or in reverse with brakes depressed, and after it is in motion and under WOT. When in motion, throttle response is predictable and stable... only from a dead stop after operating temps reached does it hesitate under hard pedal press.

The last option is contacting my tuner to check the tune and logs.

Any ideas welcomed.

 

[matreyia]

And...done. No more bms filter or fake m3 cowl modification.

View attachment 37636

And...nothing has improved. Still hiccups after reaching operating temperatures under hard pedal press. So much for new spark plugs.

 

[martymil]

The reason water got in is because you cut the cowl to short and didn't use the rubber strip on the edge you cut.

I drive my car in the rain wash it regularly and never had water enter the spark plug area.

 

[matreyia]

The reason water got in is because you cut the cowl to short and didn't use the rubber strip on the edge you cut.

I drive my car in the rain wash it regularly and never had water enter the spark plug area.

View attachment 37639

Yep

 

[Cruizinmax]

I don't have a specific answer for you as to why but in the first data log from post 14, the reason you felt a "bog" was caused by your car's ignition timing fluctuating. It went from 10* advanced to -4* retarded and then started feeding timing back in. I think what you're feeling is in your tune and not a mechanical issue per se.

I hate seeing threads like this where people randomly replace parts without testing them to see if they've actually failed. Car parts aren't magic. If they fail, they can be observed prior to replacement. You can see if something is cracked and leaking. Solenoids can be tested for resistance to see if it's an open circuit or shorted. Ex. Before you replace you vanos solenoids, can you look in your log and see if the cams are following the DME commands? If they are why would you think the solenoids need replacement? Sorry for the rant. If you haven't checked it out, the Diagnose Dan channel on YouTube is very good at showing the diagnostic process and explaining the "why" in a real world environment.

 

[matreyia]

I don't have a specific answer for you as to why but in the first data log from post 14, the reason you felt a "bog" was caused by your car's ignition timing fluctuating. It went from 10* advanced to -4* retarded and then started feeding timing back in. I think what you're feeling is in your tune and not a mechanical issue per se.

I hate seeing threads like this where people randomly replace parts without testing them to see if they've actually failed. Car parts aren't magic. If they fail, they can be observed prior to replacement. You can see if something is cracked and leaking. Solenoids can be tested for resistance to see if it's an open circuit or shorted. Ex. Before you replace you vanos solenoids, can you look in your log and see if the cams are following the DME commands? If they are why would you think the solenoids need replacement? Sorry for the rant. If you haven't checked it out, the Diagnose Dan channel on YouTube is very good at showing the diagnostic process and explaining the "why" in a real world environment.

I would tend to agree with your assessment. But it is strange how this only happens AFTER operating temperatures are reached... like from 160 F and above. The very same conditions that purge solenoids operate under.

 

[Cruizinmax]

There are timing corrections in play at lower temperatures. I also noticed that the AF ratio goes slightly lean when you snap the throttle open. It's also possible that the DME is retarding the timing to keep the engine from stalling. Again I think this could be addressed through the tune.

Can you pinpoint when this started? What was changed just before the car started exhibiting these symptoms?

 

[matreyia]

There are timing corrections in play at lower temperatures. I also noticed that the AF ratio goes slightly lean when you snap the throttle open. It's also possible that the DME is retarding the timing to keep the engine from stalling. Again I think this could be addressed through the tune.

Can you pinpoint when this started? What was changed just before the car started exhibiting these symptoms?

I have sent these logs to Twisted. We will see what he says/does. It isn't any hardware issue as literally all components are new... HPFL, LPFP stage 3, Fuel Filter, Fuel Lines, MAP, TMap, camshaft sensors, crankshaft sensors, hoses, clamps, motor oil temperature sensor...

 

[matreyia]

There are timing corrections in play at lower temperatures. I also noticed that the AF ratio goes slightly lean when you snap the throttle open. It's also possible that the DME is retarding the timing to keep the engine from stalling. Again I think this could be addressed through the tune.

Can you pinpoint when this started? What was changed just before the car started exhibiting these symptoms?

Twisted will look into the logs today. He did say that it is normal for timing to reduce as load increases. But there is something this normal range imho. We will see what's up. Other than this issue...the car is 1000% badass. Response, power, stability...all dope.

The other day, I was taking a night drive when the fwy was deserted and first an AMG S63 sedan wanted to have a little run... I guess because my top was down and I have a normal looking 335i with no crazy spoilers... So I let him go past me for 3 seconds and then just floored it and zipped right by him like he was jogging... did this 3x with zero strain on engine.
After the AMG returned to normal speeds, a Charger Hellcat rushed up behind and started to do the vroom vroom gesture, so I knodded and he floored it...super loud car with a crazy whine... I let him go past me 3 seconds and floored it and also passed him up..again did this 3x's, then he had to exit and waved as he left. Overall, pretty friendly racing on a coronavirus deserted 8 lane highway. And no... I did NOT do with on any curves. Hell no.

So I tell you...I love this car. Just need to solve this little tiny minor annoyance and it will be perfect. I daily drive the car and it feels like a normal stock car...until you mash the pedal. Then you shit your pants.

 

[Cruizinmax]

Twisted will look into the logs today. He did say that it is normal for timing to reduce as load increases. But there is something this normal range imho. We will see what's up. Other than this issue...the car is 1000% badass. Response, power, stability...all dope.

The other day, I was taking a night drive when the fwy was deserted and first an AMG S63 sedan wanted to have a little run... I guess because my top was down and I have a normal looking 335i with no crazy spoilers... So I let him go past me for 3 seconds and then just floored it and zipped right by him like he was jogging... did this 3x with zero strain on engine.
After the AMG returned to normal speeds, a Charger Hellcat rushed up behind and started to do the vroom vroom gesture, so I knodded and he floored it...super loud car with a crazy whine... I let him go past me 3 seconds and floored it and also passed him up..again did this 3x's, then he had to exit and waved as he left. Overall, pretty friendly racing on a coronavirus deserted 8 lane highway. And no... I did NOT do with on any curves. Hell no.

So I tell you...I love this car. Just need to solve this little tiny minor annoyance and it will be perfect. I daily drive the car and it feels like a normal stock car...until you mash the pedal. Then you shit your pants.

It is normal for timing to decrease as load increases but that should happen smoothly. Not a 14* swing over 1/10 of a second. Something else is at play here. I don't know what BMW terminology would be for this but it looks like it needs a bit more tip in fuel as there is a large rush of air when you snap the throttle open and fuel isn't keeping up. The RPM's are so low the o2 sensors are going to have a hard time picking that up. It would be super easy to test if we could make changes in real time and not have to flash a map for every little change.

 

[matreyia]

It is normal for timing to decrease as load increases but that should happen smoothly. Not a 14* swing over 1/10 of a second. Something else is at play here. I don't know what BMW terminology would be for this but it looks like it needs a bit more tip in fuel as there is a large rush of air when you snap the throttle open and fuel isn't keeping up. The RPM's are so low the o2 sensors are going to have a hard time picking that up. It would be super easy to test if we could make changes in real time and not have to flash a map for every little change.

Perhaps the Port Injection Map should be updated to allow for this sudden load request.

 

[Cruizinmax]

Perhaps the Port Injection Map should be updated to allow for this sudden load request.

I wouldn't think so. The is far before any boost is built so there should be no port injection flowing at this point.

 

[matreyia]

I wouldn't think so. The is far before any boost is built so there should be no port injection flowing at this point.

Today, i will take out the VRSF CP, renew the o ring, teflon all bungs, seal the 3.5 map sensor as best I can... vrsf is notorious for quality control issues. And I should have a brand new purge solenoid installed. It is just getting worse and worse... like whatever is failing is actually getting to the point of total failure... the car now feels like it will die upon acceleration after warmed up. When cold... it is absolutely perfect in every way. Throttle is perfect no matter the acceleration when cold.

 

[matreyia]

Ok..installed the new purge valve solenoid and car runs like a swiss clock. I was correct after all. No more hiccuping from stop light when warmed up. If things return to previous bad state, I will update immediately. Will keep fingers crossed. So far drive about 40 miles mixed driving.

 

[dcafs]

Ok..installed the new purge valve solenoid and car runs like a swiss clock. I was correct after all. No more hiccuping from stop light when warmed up. If things return to previous bad state, I will update immediately. Will keep fingers crossed. So far drive about 40 miles mixed driving.

Good to hear you may have found a solution.....what a frustrating problem.

I too have noticed a jerky hesitation when opening up throttle in 2nd gear after engine is warmed up, so I may have to replace this sensor too.

Keep us posted as to whether the fix stays or not. These engines are notorious for fooling us for a little while that things are fixed only to pop back with a vengeance as you have found out...lol.

 

[Cruizinmax]

How have you tested the failed part? Is the solenoid not opening/closing?

Is your PCV teed in where the fuel vapor return goes? Just curious if this may have something to do with how your PCV is routed as you were also having issues with that just prior to this issue.

 

[matreyia]

How have you tested the failed part? Is the solenoid not opening/closing?

Is your PCV teed in where the fuel vapor return goes? Just curious if this may have something to do with how your PCV is routed as you were also having issues with that just prior to this issue.

I may have spoken too soon. I replaced the purge valve solenoid and also reflashed to linear throttle mapping as suggested by Twisted and the car runs like butter.
After a hundred miles of driving mixed conditions, I decided to test it by reflashing to original throttle mapping and though it was a little less, it was certainly still there. So I must conclude that this is as you suspected - a tuning issue.

So, I will switch back to linear throttle mapping to drive a perfect car for the time being and then in a couple of months, when finances allow, I will do another custom tune with V8bait to try to fix this issue, AND get more power out of these high flow PureS2 turbos.

 

[matreyia]

Good to hear you may have found a solution.....what a frustrating problem.

I too have noticed a jerky hesitation when opening up throttle in 2nd gear after engine is warmed up, so I may have to replace this sensor too.

Keep us posted as to whether the fix stays or not. These engines are notorious for fooling us for a little while that things are fixed only to pop back with a vengeance as you have found out...lol.

Be advised, this is not a sensor. It is a purge solenoid valve controlled by the ECU after temperatures are reached so that it can proportionately release hydrocarbon vapors to be burned in the combustion chamber. Though the car drove noticeably better after replacement, it did not completely fix the hiccup issue after warming up engine...when flashed with stock throttle mapping in MHD.

 

[matreyia]

OK. I contacted Sutphine transmission tuning and informed him of my hiccup situation and that I am about to get a new tune from v8Bait when he has an opening just so compare any differences. Rod sent me an adjusted trans map that literally fixed my hiccup situation so... now the car is indistinguishable from stock smoothness. You would not be able to tell the car was modded in any way...until you press the pedal deep - then you shit your pants.

I am looking forward to testing out this new upcoming tune. Hope to push the boundaries to 650whp or as close ot 700 as possible. Should be a hoot.

 

[dcafs]

OK. I contacted Sutphine transmission tuning and informed him of my hiccup situation and that I am about to get a new tune from v8Bait when he has an opening just so compare any differences. Rod sent me an adjusted trans map that literally fixed my hiccup situation so... now the car is indistinguishable from stock smoothness. You would not be able to tell the car was modded in any way...until you press the pedal deep - then you shit your pants.

I am looking forward to testing out this new upcoming tune. Hope to push the boundaries to 650whp or as close ot 700 as possible. Should be a hoot.

Were you getting the hiccup from 1-2nd or 2-3rd from a start?

 

[matreyia]

Were you getting the hiccup from 1-2nd or 2-3rd from a start?

1 to 2nd. Only after warmed up engine. It was a combination of the trans and the engine tuning that caused the issue. It is now 95% gone. The only time it comes back and backfires is from a stop and I suddenly slam the pedal all the way to the floor in D mode.