Removed blower and returned to stock no power 2500 to 3500 rpm

[racingmason]

Well, the time had come to sell the 17 Kenne Bell and move onto something new. The car is returned to stock and it runs great except for between 2500 and 3500 rpm there is no power randomly and going WOT the engine sits at that rpm and then randomly will accelerate normal after some time.

I’ve triple checked for vacuum leaks and can’t find any. What kills me is that it’s intermittent and doesn’t happen all the time. Sometimes it happens when the factory vacuum/boost gauge (I know it’s inaccurate) reads 0 and other times when it reads 5 inhg. To me it acts like there is a vacuum leak but I can’t find it if there is one. Unless the IMRC are plugged in backwards but I don’t think that matters.

Ive done a crank relearn and there no codes present.

I’ve checked for vacuum leaks all around the manifold, fuel rail, and all hoses going to the intake manifold.

I’ve changed plugs back to factory Motorcraft plugs.

confirmed throttle body operates appropriately after returning it back to stock.

I don’t have my SCT anymore so data logging is not an option.

Part of me just says trade it in tomorrow and not deal with it but I’d like to be honest about it with the dealership.

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[Andy13186]

How did you put the stock tune on if you dont have the SCT?

 

[markmurfie]

Sounds like a traction control, clutch, or torque limit issue, with it being random. I say if you are ready to trade it in and move on, do so and don't look back.

 

[racingmason]

How did you put the stock tune on if you dont have the SCT?

I flashed it back to stock on my SCT 2 months ago when I started returning every tj inch to stock. I slowly worked on it as it is not a daily driver. I had a shop perform a crank relearn for me.

 

[racingmason]

Sounds like a traction control, clutch, or torque limit issue, with it being random. I say if you are ready to trade it in and move on, do so and don't look back.

That was my first thought along with me not being use to drive a 400 hp car vs one making over 900.

 

[EFI]

between 2500 and 3500 rpm there is no power

IMO that's the effect of going from a twin screw supercharged engine that brings in a shitload of torque early to a high revving relatively small V8 that is pretty much gutless under 4000rpm.

 

[mindo389]

Ah, just bring it in and trade it. Let their tech figure it out... With all of the aftermarket items you installed, are you going to leave them on the car?

 

[racingmason]

Ah, just bring it in and trade it. Let their tech figure it out... With all of the aftermarket items you installed, are you going to leave them on the car?

It’s completely stock and everything is sold except the catless kooks headers and GT350 exhaust.

I thought it was me going back to a NA motor but when you hold the throttle down at it sits at 3500 rpm for infinity something is limiting power.

 

[EFI]

It’s completely stock and everything is sold except the catless kooks headers and GT350 exhaust.

I thought it was me going back to a NA motor but when you hold the throttle down at it sits at 3500 rpm for infinity something is limiting power.

Ah, well there's your issue. It's not going to run right with stock calibration and this level of modifications. Can you not put the OEM manifolds and cats back on?

 

[racingmason]

Ah, well there's your issue. It's not going to run right with stock calibration and this level of modifications. Can you not put the OEM manifolds and cats back on?

They are not on the car. The car is stock. Those parts are sitting in my garage waiting to be sold. The car is 100 percent stock.

 

[BrianGT2015]

Well, the time had come to sell the 17 Kenne Bell and move onto something new. The car is returned to stock and it runs great except for between 2500 and 3500 rpm there is no power randomly and going WOT the engine sits at that rpm and then randomly will accelerate normal after some time.

I’ve triple checked for vacuum leaks and can’t find any. What kills me is that it’s intermittent and doesn’t happen all the time. Sometimes it happens when the factory vacuum/boost gauge (I know it’s inaccurate) reads 0 and other times when it reads 5 inhg. To me it acts like there is a vacuum leak but I can’t find it if there is one. Unless the IMRC are plugged in backwards but I don’t think that matters.

Ive done a crank relearn and there no codes present.

I’ve checked for vacuum leaks all around the manifold, fuel rail, and all hoses going to the intake manifold.

I’ve changed plugs back to factory Motorcraft plugs.

confirmed throttle body operates appropriately after returning it back to stock.

I don’t have my SCT anymore so data logging is not an option.

Part of me just says trade it in tomorrow and not deal with it but I’d like to be honest about it with the dealership.

If you bought a used car at a dealership, then shortly after buying the car it had issues, and you found out it was a race car before, or had been raced or what have you. The sales man, manager, and what not is going to look at you and say, "it's not our problem, sorry buddy.." a car dealership will flat out lie to someone's face and give them very false hopes when selling a car. Screw that dealership and let them deal with the fall out. I had tried to bring a car in for warranty work, told them what was wrong, what needed to be replaced, showed them what needed to be replaced. They kept telling me its covered under warranty but they had to charge me a diagnostic fee of 75 bucks to get a tech to come look at it and diagnose it. I told them there is nothing to diagnose and if it part didn't need to be repaired and I was wrong about the issue ill pay for the whole service out of pocket. No go. Point is, screw that dealership and the I would feel bad. They do not give a damn if they rip someone off, get a young stupid buyer into a high interest loan he doesn't understand how bad of a decision is it. Okay, off my soap box.

 

[Shadow277]

Sounds like a traction control, clutch, or torque limit issue, with it being random. I say if you are ready to trade it in and move on, do so and don't look back.

He probably doesn't want to screw a person over which is admirable.

 

[BrianGT2015]

He probably doesn't want to screw a person over which is admirable.

I understand that. Man, I just can not stand a used car salesman. I have never met one that's been transparent with me or honest. I even throw in a few dumbass statements just to see if they will tell me the truth about stuff and nope. Have not had one answer a question truthfully yet.

 

[Nuked]

Knock sensors plugged in? IAT harness (not sure what KB uses) removed and back to normal?

 

[Dfeeds]

You said the rpms just sit? If it's actually not budging and then feels underpowered that 100% sounds like traction control. I shut mine off after it nearly got me rear ended in the snow. It's prevented me from revving the car passed a certain rpm on a couple of occasions. But maybe I interpreted your post wrong.

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