Fuel cut?? S5 calibration

[Mysterio]

I'm using a stage5 calibration on my 87 dodge shelby charger from you guys. I am having a problem hitting a HARD fuel cut at the top end of 4th gear at around 5000-5500 rpm. Power loss light comes on, it dies completely like a HARD fuel cut.

I'm assuming it's got to be a computer related fuel cut. If it was just the pump lacking on pumping ability it wouldn't turn the power loss light on and cut out that hard for a second and then drive fine right afterwards.

So my question is. Can one of you guys tell me EXACTLY what the possible causes are for the computer causing fuel cut?

[iTurbo]

Have you checked the codes and verified you are actually getting 45 (overboost)?

[Mysterio]

Have you checked the codes and verified you are actually getting 45 (overboost)?

I never have gotten a code 45, and I never said it was overboost.. It's the same type of fuel cut like when you hit overboost. But it only happens at 5000-5500 rpm in 4th gear when I've already been at full boost for like 15 seconds already. And I'm runnin a 3 bar map so 15 lbs of boost shouldn't be overboost. And it holds 15 lbs of boost steady according to my gauge.

[MiniMopar]

Does the tach drop to zero when the cutout happens? If so, then it's the HEP signal being lost. Otherwise it sounds like the rev limiter or overboost. What is the overboost cut out set to in this cal and how are you controlling boost? Being a custom cal, it may not quite behave as a stock cal as far as code are concerned depending what has been done to it. I've seen some weird stuff in Blueberry mods for example.

[Mysterio]

Does the tach drop to zero when the cutout happens? If so, then it's the HEP signal being lost. Otherwise it sounds like the rev limiter or overboost. What is the overboost cut out set to in this cal and how are you controlling boost? Being a custom cal, it may not quite behave as a stock cal as far as code are concerned depending what has been done to it. I've seen some weird stuff in Blueberry mods for example.

I'll have to do it again and watch the gauges a bit better and see exactly what happens. I'm controlling the boost w/ a manual controller which is set at 14-15 lbs. The cutout should be like what? 24 lbs with a 3 bar map right? The HEP is BRAND NEW. And it was doing it w/ the old HEP before that one went bad. So it's not the HEP itself causing it if that is the case it would have to be something in between the hep & LM.

[MiniMopar]

The 3-bar can read up to 29psi or so, but that has nothing to do with where the overboost cutout is set in the cal. This is a key thing they should have told you when you got it.

[turbovanman²]

And thats why he's asking here, to find out what Cindy sets them at,

[MiniMopar]

Oops...sometimes I forget to look at which forum I'm in...

[turbovanman²]

Oops...sometimes I forget to look at which forum I'm in...

Well if you quit touching your noodly appendage,

[Mysterio]

Haha. I posted here figuring Cindy or someone could give me a little breakdown of exactly what things can cause the computer to fuel cut so I know where to look at can narrow things down.


Correction though. I am running a stage4, not a stage5. Sorry. But according to their website max boost on the s4 cal is 29 psi

[Mysterio]

FWD Performance can't contribute at all with this situation??

[turbovanman²]

FWD Performance can't contribute at all with this situation??

Probably best if you call them.

[Mysterio]

Probably best if you call them.

Yea I figured but I didn't want to :P I guess I'm going to have to though.

[moparzrule]

Does it do it in fifth gear? Any other codes?
And you are running a 3 bar MAP sensor correct? Because if you are still using a stock 2 bar that would explain this. In fourth gear you have a higher load, so it will make a touch more boost, maybe just the right amount to trigger overboost.

[Mysterio]

Does it do it in fifth gear? Any other codes?
And you are running a 3 bar MAP sensor correct? Because if you are still using a stock 2 bar that would explain this. In fourth gear you have a higher load, so it will make a touch more boost, maybe just the right amount to trigger overboost.

I'm not sure if it does it in 5th gear or not. I'm getting a code for my o2 sensor & speed/distance sensor. I don't think either of those would cause it to fuel cut or overboost though?

I'm running a 3 bar map. Ran the wiring for it myself according to minimopar diagrams, I'm fairly confident I wired it in correctly. The overboost for the computer should be like 29 lbs though right with a 3 bar map. And I'm only running 15 lbs.... That doesn't make much sense.

[MiniMopar]

29psi is the absolute max pressure the 3bar MAP can measure. The overboost cutout limit it set in the cal itself and generally this is something you would discuss with the vendor. If left untouched from stock, it comes out to around 21psi after the 3bar MAP refactoring.

[moparzrule]

Bad O2 sensor would put it in limp mode, causing overboost cutout at 15 PSI no matter if it's a 3 bar MAP or not. There's your problem.

[MiniMopar]

That also depends on the cal and which constants were scaled. Left alone, they will cutout at 21psi. It could be that, though. These don't have a staging mod, do they? If so, a bad speed sensor can trick the cal. Which O2 code are you getting? Do you have an O2 gauge? The S5 cals sometime run rich for folks.

Like Simon said, I would just call up Cindy.

[WickedShelby88]

Yeah that could be speed sensor, O2, or a boost spike causing a boost cutout. Definitely find out by calling and seeing where your boost cutout is set. It seems to be harder and harder to troubleshoot where that gremlin under the hood is hiding the more mods you do.

[moparzrule]

If it was the speed sensor with a staging limiter issue, it would do it in all the gears. I do not believe cindy's cal have a staging limiter anyway.