Fuel cut with Mapecu

[oldsking]

Alright guys I ran ito a problem. Took the car out for a drive and ran into some fuel cut issues. I have checkd my map fuel table and it looks good, no ridges or valleys, its a steady increase. When I roll into the gear it spools smooth, kinda rich and aroud 7-10lbs its pops and there goes the engine light (Code 34)

I have no idea why I am having this issue, I checked my plugs yesterday and they were all nice and tan.

Here is what I have in specs,

560cc injectors
T70 turbo
Fuel pressure set to stock with a vacuum source on the top of the throttle body
SX performance fuel pump

What are the usual cause of fuel cut? What is weird is that in boost it will be rich and when it revs a bit higher and throttle it some more it stops and hits fuel cut.I need some help

 

[SupraSean]

What are your afr like? thats alot of turbo for 550's..

 

[oldsking]

Is it really? I was thinking that but I read it would be fine.. hmm afrs in transition are 10ish to 11 so its rich but then it cuts out quick. They may have maxed out?

 

[oldsking]

Drove home tonight and it was cooold and tried to boost a bit, it was running rich and ran rough it then hit fuel cut. Could this be some sort of boost leak? I didn't check when I got home but will check my intercooler pipes. The top ones are tight but I need to check under the car still.

 

[gurley0916]

Boost cut is triggered by the frequency value that you enter, If i remember right any value above 3600 in the cells trigger fuel cut, check to see what your values are at. If possible could you post a pick of your tune so that I could see the values. Like screen shot and paste it into paint and post it up?

 

[oldsking]

Not a problem, I showed the fuel map with the logged runs to see which values were being used and none of the ones used were near the 3600 mark. Now at the 0 to 5psi range the car showed a 10-11 afr on my wideband right before it hit fuel cut on this tune. Ive hit 10psi before on this car before so I am thinking there must be some sort of leak possibly?



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[CyFi6]

Considering you are speed density, boost leaks cannot cause fuel cut. Do you have any way of monitoring the emulated AFM frequency output (not familiar with he map ecu)? Fuel cut will happen around 1500 hz, but depends on other factors including coolant temp, throttle position etc, but for a general rule of thumb around 1500 hz you will see fuel cut.

 

[CyFi6]

Fuel pressure set to stock with a vacuum source on the top of the throttle body
(

This is a problem. The throttle body ports are ported vacuum, not manifold vacuum. You need a dedicated manifold vacuum source for your FPR, otherwise when you get into boost, the fuel pressure wont rise properly. Connect the proper vacuum source to the regulator and you may find that you will begin to run richer, which will allow you to pull some more fuel from the table, and in turn raise your fuel cut level.

 

[gurley0916]

Like I said before the stock ecu sees fuel cut at 3600hz with the mapecu. This is the condition that I have seen multiple times when I have tuned. The mapecu is not speed density and only relies on the manifold pressure reading. I recommend resetting your ecu and see if the problem persists. Im assuming this condition has just arrived and your tuned hasnt given you problems in the past?

 

[oldsking]

@ Cy, I rechanged back to the factory location for my fpr that's on the metal piping by the manifold and not to much change, still rich then cuts.

@gurley, I've run this tune before and the car never cut out, this tune was given to me and said to hold up to 25psi but when i saw the zeros it scared me but those channels were never used.

So guys think I need a better vacuum source and maybe I'm dumping to much fuel?

 

[oldsking]

For vacuum are you guys running vacuum blocks off the stock manifold? Currently the port in the back is being shared via my mapecu and boost gauge. And I just thought! That port is supposed to feed the vacuum tubing under the manifold for the vsv?

 

[gurley0916]

I dont know about that vacuum line question. What are u running for the intake air sensor? I know mapecus can change there tune alot on when air temp changes drastically. Ive had to make tunes for people cause the tune changes 5 to 10 percent richer just cause the air got cold.

 

[oldsking]

Yeah when its file my car does not run as smooth. For the IAT I have it wired so it reads 32f all the time, this was recommend by mapecu. I think my vacuum is having the issues also like when it boosts the fuel pressure may be going down and not building like its supposed to but my afrs are rich

 

[CyFi6]

http://www.cygnusx1.net/Supra/Library/EPC/291410/catalog.aspx?F=1708&P=3

That's the stock vac line setup, the rear port in the manifold should be feeding the heater valve and the cruise control. You can tee off this for your boost gauge and map sensor.

Did you reset your fuel pressure after you changed the vacuum source? It should have reduced your idle fuel pressure. If you had a bad vac line to the map sensor you would likely run leaner rather than richer under boost. View all the data inputs to the mapecu and make sure they all make sense and are in a normal range.

I guess I am not really understanding your issue here, if you are running rich why aren't you tuning it out? The richer you run the closer to fuel cut you will be.

 

[oldsking]

Okay so maybe I'm retarded and have to much fuel being dumped! I have been thinking its leaning out and increasing the fuel at the point and that may have made it worse. I'll post a pic of the fuel map in 3d mode so you can see the increases as I may have them to far up.

 

[wardog]

Try to lower your fuel pressure i had mine set to 25-28 with vac on when i had my 550s. I made 430rwhp at that pressure on my maft pro and still was at -25 on the main scale on the maft pro.