Problems w/ Whipple - GT500 Injectors

[Vapour Trails]

I'm looking to hear from any whipple owners who have moved to GT500 injectors from the wimpy little Ford GT injectors that came with the whipple kit - Did you have drivability issues after the swap?

I had a very good tune in terms of power/drivability/safety then I swapped the injectors and had my tuner email an updated tune using the published injector specs. It should have been fairly plug & play.

Now the car stumbles badly at low rpms, especially when cold. The AFR will initially go lean when you give throttle, the engine will stumble, then as you let off the AFR goes very rich. Basically low rpm operation results in a wildly swinging AFR. I'm now on my 4th tune revision and the problem remains. In boost the engine feels strong, this seems to be a transient fueling issue.

I found a post on modular fords where redfury (RIP) that tuning the GT500 injectors with the whipple manifold was tricky.

http://www.modularfords.com/forums/...er-Injectors?p=1068689&viewfull=1#post1068689

 

[Witt]

I responded to your question in your thread on the HPTuners forum.

 

[Vapour Trails]

I responded to your question in your thread on the HPTuners forum.

These are the specs I provided

he has sent a few revisions but the problems remain. He opened up a GT500 tune and copied the specs for the latest tune update.

 

[BruceH]

I have them in mine. Until the car warms completely there will be some stumbling. After it's completely warm it's 99.9% gone. The stumbling happens during the transition from open loop to closed loop. If you monitor your stft in real time it's easy to see. If you are using sct the gt500 injectors are a drop down in the software.

 

[Vapour Trails]

I have them in mine. Until the car warms completely there will be some stumbling. After it's completely warm it's 99.9% gone. The stumbling happens during the transition from open loop to closed loop. If you monitor your stft in real time it's easy to see. If you are using sct the gt500 injectors are a drop down in the software.

And you are ok with that stumbling Bruce? I cannot stand it, granted mine may be worse than yours. Often it feels like the engine is going to stall. In cooler weather, using the 160F t-stat, it oftens takes 10+ mins to finally reaching operating temp, so this is a problem.

So with the SCT you can choose between different injectors with a press of a button?? So you have not been custom tuned for the GT500 injectors?

 

[BruceH]

And you are ok with that stumbling Bruce? I cannot stand it, granted mine may be worse than yours. Often it feels like the engine is going to stall. In cooler weather, using the 160F t-stat, it oftens takes 10+ mins to finally reaching operating temp, so this is a problem.

So with the SCT you can choose between different injectors with a press of a button?? So you have not been custom tuned for the GT500 injectors?

It's a drop down for my tuner with his software. I think of the stumbling as the motor being "cold blooded". It was quite common with carburated motors back when I started driving in the 70's. In fact I just had a discussion about this last night. Basically it feels like a carburated car with a bad accelerator pump. The nice thing is it goes away. I just make it a point to be real careful in traffic the first few minutes of driving. After that it's pretty much gone.

 

[hammeron]

It should have been fairly plug & play.

vapour, i have the whipple HO and just swapped the 32lb/hr injectors for the 47's. it was not plug and play, as far as the tune is concerned. my fuel trims were off and i'm currently fine tuning the transfer curve. so far it's running very smooth and i haven't noticed any issues. i haven't driven off though until it's been fully warmed up, so we'll have to see about that...

 

[StangPower05]

Same issue here. My tuner. John Lund, said its an issue when using these particular injectors on a GT. I forgot why he said theres an issue running them, but there is. Mine is 100% once warmed up. There shit when cold.

 

[stang910]

Only issue I had from a remote tune was throttle tip in. The AFR would go high 15's and I'd get a hesitation for just a split second. I later had it dyno tuned and all the drivabilty problems were gone.

 

[Vapour Trails]

I drove the car a little further today, got it up to operating temp. The drivability is much better, but it still goes lean on tip-in and hestitates in boost a bit.

Aside, do you guys notice that your fuel pressure at idle increases about 5 psi from cold idle to heatsoaked idle? Just noticed this today, and it is especially hot. Just want to rule out some other sort of problem.

 

[Vapour Trails]

Aside, do you guys notice that your fuel pressure at idle increases about 5 psi from cold idle to heatsoaked idle? Just noticed this today, and it is especially hot. Just want to rule out some other sort of problem.

I went back to my old tune and injectors today and the car is back to normal. The fuel pressure is a constant 29 psi, regardless of heat soak. My tune was jacked up somehow. I also noticed my exhaust tips were turning grey.