Surging issue, dumping boost around 12 psi

[Special K]

Does anyone else have a light surging or hesitation under moderate (but not full) throttle? Particularly in manual mode while in 2nd or 3rd gear. The waste gates will also flutter and dump boost sometimes when this happens. RPMs will fluctuate by 50-100 but once at a steady speed (around 65 mph) the car smooths out, but once you decelerate it starts back again. It also did it on the track at Apex. Looking for other cars to help document the issue.

 

[italianjoe]

Does anyone else have a light surging or hesitation under moderate (but not full) throttle? Particularly in manual mode while in 2nd or 3rd gear. The waste gates will also flutter and dump boost sometimes when this happens. RPMs will fluctuate by 50-100 but once at a steady speed (around 65 mph) the car smooths out, but once you decelerate it starts back again. It also did it on the track at Apex. Looking for other cars to help document the issue.

Kevin, did Bryan do a recording and send to the engineers to see if there is an issuse?

 

[Special K]

Kevin, did Bryan do a recording and send to the engineers to see if there is an issuse?

He hasn’t been able to get it to happen yet. I compiled a short video of it happening on the track but it’s too hard to tell on the video.

 

[BtwoG]

Yes, it happens to my car as well. I rode in 4 or 5 new GTs at the Rally and none of them had the issue. Steve the delivery guy suggested getting a video, but I haven't done so yet. I'm planning on going to the dealership after the holidays

 

[DakotaGT]

Could it be a fouled plug? Or would the computer always recognize a misfire condition? I have no idea what all the symptoms might feel like on these particular cars, with a fouled or partially-fouled plug, but I know we’ve all heard that these cars are a bit prone to that.

 

[fjpikul]

Fouled plug causes code. Usually caused by not running car long enough to fully warm up.

 

[Special K]

Yeah, I don’t think it’s a fouled plug. It feels more like erroneous sensor data causing an air/fuel issue. I also don’t think is a problem with the waste gates specifically, more like the computer makes bad decisions based on the bad data... if that makes sense.

 

[nota4re]

Of course, taking it in to a GT-experienced shop is probably the best advice. If for whatever the reason that is inconvenient/impractical, you can datalog some of the PID values - O2 signal, fuel trim, boost, MAF, timing, etc. If you look at these values (and potentially others) when the problem occurs, you can get a really good idea of what is going on. This is probably what the shop is going to be instructed to do anyway.

 

[Special K]

Of course, taking it in to a GT-experienced shop is probably the best advice. If for whatever the reason that is inconvenient/impractical, you can datalog some of the PID values - O2 signal, fuel trim, boost, MAF, timing, etc. If you look at these values (and potentially others) when the problem occurs, you can get a really good idea of what is going on. This is probably what the shop is going to be instructed to do anyway.

It’s in the shop now, but I’m looking to see who else is having the issue to try and help expedite a resolution.

 

[Simon]

Where ?

 

[italianjoe]

Of course, taking it in to a GT-experienced shop is probably the best advice. If for whatever the reason that is inconvenient/impractical, you can datalog some of the PID values - O2 signal, fuel trim, boost, MAF, timing, etc. If you look at these values (and potentially others) when the problem occurs, you can get a really good idea of what is going on. This is probably what the shop is going to be instructed to do anyway.

That's what I would do as well.....we can also record the event and send team data to the engineers to review.

 

[Special K]

It’s at Sanderson Ford in Glendale, AZ.

 

[BtwoG]

All,
It was a beautiful day here in Atlanta and I got the NFGT out in the mountains. This was part of the route we did at Rally 12.5.

Here is a link to a video where the waste gates are dumping boost. We tried both auto mode and manual mode, as well as normal and sport mode. It did it under all the different conditions. As Kevin said, it happens at part throttle (about 15-25% throttle). You can hear it in the video at the following time indexes 0:07, 0:35, 0:52, 0:58, 1:31, 1:45, and 1:55. I noticed it at throttle lift, maintenance throttle, and on throttle, but mostly on throttle.

Here is a second video. You can hear the flutter at 0:09, 0:14, 0:20, 0:30, and 0:36.

Unfortunately Atlanta's one and only certified dealer sold their GT and no longer works on them. The closest dealer is in SC now.

 

[Simon]

please share the video link

 

[Special K]

My car has been since sent back to Multimatic for this and wheel creaking issue, but before it was sent back, a Ford engineer came down to Arizona and documented the issue. Hopefully this will be resolved soon.

 

[Gene Cassone]

Concerning certified dealers already giving up working on NFGT. Suspect there will only be « regional « service centers in the future !

 

[medici78]

That's unfortunate that even Bryan hasn't been able to figure it out. If he can't do it, nobody (well, nobody outside the factory) can. However it's also good to see Ford and Multimatic stepping up to make sure it's taken care off.

 

[nota4re]

Frankly, it doesn't seem like that difficult of a problem to diagnose and fix.... and it is a shame that Ford/Multimatic have to return to home (Canada) in order to resolve. Then NFGT regulates boost pressure through control of the wastegates where the ECU can regulate target boost pressure electronically by controlling the pressure needed to open the wastegate(s). In addition, there is a blowoff valve whose function in normal operation is to relieve boost pressure when the throttle plate is closed. Due primarily to the odd sound - which is more of a chirp, I suspect that the problem is either at this valve or elements leading to the functioning of this valve. Normally, this is completely mechanical so I would suspect that the valve itself is sticking and/or there is a vacuum leak in the control circuit.

 

[BtwoG]

While that certainly makes sense, I doubt both blowoff valves are bad. Its probably not obvious in the video, but you can hear the bleed off oscillating between the 2 turbos. So perhaps your suggestion of a control circuit vacuum leak makes most sense.

Frankly, it doesn't seem like that difficult of a problem to diagnose and fix.... and it is a shame that Ford/Multimatic have to return to home (Canada) in order to resolve. Then NFGT regulates boost pressure through control of the wastegates where the ECU can regulate target boost pressure electronically by controlling the pressure needed to open the wastegate(s). In addition, there is a blowoff valve whose function in normal operation is to relieve boost pressure when the throttle plate is closed. Due primarily to the odd sound - which is more of a chirp, I suspect that the problem is either at this valve or elements leading to the functioning of this valve. Normally, this is completely mechanical so I would suspect that the valve itself is sticking and/or there is a vacuum leak in the control circuit.

 

[italianjoe]

Frankly, it doesn't seem like that difficult of a problem to diagnose and fix.... and it is a shame that Ford/Multimatic have to return to home (Canada) in order to resolve. Then NFGT regulates boost pressure through control of the wastegates where the ECU can regulate target boost pressure electronically by controlling the pressure needed to open the wastegate(s). In addition, there is a blowoff valve whose function in normal operation is to relieve boost pressure when the throttle plate is closed. Due primarily to the odd sound - which is more of a chirp, I suspect that the problem is either at this valve or elements leading to the functioning of this valve. Normally, this is completely mechanical so I would suspect that the valve itself is sticking and/or there is a vacuum leak in the control circuit.

You would think that by monitoring PID'S that you could capture the data needed to find an issuse but it's not that easy if an input sensor is within a certian parameter then there is no failure, however there could be a programming issuse causing this. Case in point if all inputs to pcm are correct and within perameters the pcm could be commanding an output to do something it's not suppose to......and this will never trigger a check engine light on because the pcm monitors inputs not outputs to certain degree. Technicians are not allowed to alter settings nor do we have the capability to. This would be the job of an engineer. Hope this makes sense?