Hey guys, long time lurker but new member. Quick rundown of my setup: 2014 GT with the Stage 1 VMP Gen2 blower kit. Only other mods are Lethal's off road-x and over axle pipes and the NGK 1 step colder plugs. I'm running VMP's tune for the kit. I have a part-throttle surge issue that I can't seem to get figured out. From about 2500-3000 RPM at maybe 45% through 75& throttle the car wants to surge and I can hear what sounds like the surge coming from the throttle body. Normal driving and WOT are fine. Car pulls like a beast, but that part throttle surge issue still remains. I've taken apart the intake and put it back together multiple times and checked my other connections. Next step for me is to take off the throttle body and reseat that along with the CAI again. Has anyone had an issue similar or can recommend a fix?
Coyote TVS surge issue
- Thread starter TVS_gtcs
- Start date
I have a GEN one stage 2 VMP tvs i get slight surging at highway speeds when barely applying throttle. I got a updated tune from him last year (man im lazy) that is suppose to help.
He's also mentioned numerous times that JLT is coming out with something that is suppose to stop that but i have yet to hear anything about the "fix"
Do you have the ability to datalog? What is the bypass valve doing when it does this? Is AFR stable? Timing stable? Manifold pressure stable?
My first guess is that there's something going on with the supercharger bypass under those conditions. You could force the bypass valve open with a zip-tie, then drive it and see if it's still surging in those same areas. If it is then you can eliminate the bypass as the issue.
I had the same thing happen to my VMP TVS '14. No matter what I did, it was always there. Did a lot of research and ultimately found that it was because of the JLT intake. I pushed the filter all the way in, all the way out, bought the fresh air inlet foam, blocked the thing off entirely, etc. Still was there. Found that it surged the least when the air inlet was completely blocked, and the filter was as far back of the CAI tube as possible (opposite of pushing it in as far as it could go).
If there is any vacuum in the inlet where the blower bypass actuator is referenced to (the vacuum line going to the bypass actuator), then the bypass will begin to open during periods of high load (this results in loss of boost and hp since it's just recirculating that air).
Conditions that could cause this are:
- Dirty air filter
- Inlet, throttle body, air filter box or inlet tube too small
Conditions that could cause this are:
- Dirty air filter
- Inlet, throttle body, air filter box or inlet tube too small
Nothing is dirty, the kit is brand new. Nothing is too small, it's assembled kit from VMP. I've datalogged several times and sent it to Justin. His best guess is that at that particular load range and that particular RPM band it's trying to shift from vacuum to boost. I think it's the JLT as well.
I think the only other choice is the 127 mm carbon intake. This issue seems to be hit or miss really, i had the JLT on my car when it was NA with no issues but it's a well known issue with those too. Just depends i guess. I'll have to play around with the intake and filter position
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