seems my TT SEFI wont turn past 6K
symptoms remind me of the burnout pop you hear on turbo cars


A/F is solid 12:1 . FAST and MSD rev limiters disabled. timing 28 .
was running 93 octane ,switched to 100, no difference, just a tad fatter.
making 20# boost went down to 12# no difference
150# injectors and big aeromotive pump so fuel isnt a problem
45#FP boost referenced regulator

I dont see full spool until 4500-5000 so turbines arent choking
changes in boost didnt affect it so I doubt surge
105MM wilson TB, elbow and intake conversion.
brodix227cnc heads and intake
.630 mech roller .200 long valves plenty of spring.
keep in ming this getup was built and tuned by myself, with lots of
professional help with the component selection.

ANY ideas are greatly appreciated

 

first of all nice setup

Second, when you say FAST are you using a fast stand alone? If so are your table axises not configured to go beyond 6k?

 

thanks for the reply and compliment

I have the RPM rescaled to 8k
I think the default was 7K

the XFI is my only fuel control
power-adder controls disabled
I'm using the fast harness with IAC (its unhooked)
msd digital 6 dipswitches are set 8cyl, revlimit and start retard disabled
the green loop is intact

 

Crank trigger or are you firing it off of the distributor? Is the rotor phased correctly?

 

using the crank trigger for a crank position sensor
crank reference angles are all good
I have modified my non advance style MSD distributor by
cutting off 7 of the reluctor tabs and installed set screws to adjust the
reluctor 20degrees ahead of the rotor for a cam position sensor
I have been told that the FAST will run sequential without a cam sensor
so I unhooked my distributor once. seems like throttle response was the only difference I saw. I assume it guessed where #1 was?
I phase my rotor at my average timing and drill a hole in the cap to
check it with a timing light

Im sure its something DUMB that I have overlooked or maybe a tuning issue

 

Are both of the rev limiters off in the XFI? The low and high limit set to 8000 or so? The XFI has to have a cam sensor signal for sequential. If it looses the signal it will batch fire. The cam signal should lead your crank signal by 10 degrees or so. Which it sounds like it should be. The injection point is adjustable in the XFI by the way. What is your crank trigger air gap?

 

ahh
thanks for the info on the XFI

I have the high/low power adder on 8&9K with locked timing just in case
the only rev limiter I see is in the spark functions menu
I have also rescaled the timing rpm table to correspond to the fuel table

air gap on crank trigger is .020 or so
I have had the ignition apart and readjusted with the same results

the engine pulls strong
the thing just gets to 6k then "pop"
I held it there once and it surges between 5&6k
it just wont rev past 6K
the boost climbs a tad more on the datalog but the rpms drop
kinda making a backwards loop instead of the forward ones you normally see

keep picking guys I'm sure someone will figure it out

 

Have you tried a .060 to .070 air gap?

 

will do
I drove it back from lunch so I'll try that before I leave work

thanks again for all the ideas

I swear it acts like a rev limiter tho

 

What do the plugs look like?
What kind?
What gap?

Closed loop? If so, what kind of O2 correction are you getting?

IS the FP keeping up?
I've had that problem with platinum plugs in my Turbo Buick. Got rid of them, went to AC's, and gapped them at .025". Engine was "sour owl ****" on the dyno with Ac's gapped at .032. Closed up a fresh set to .025, and picked up 70FWHP.

Just throwing out some ideas....

 

I think I may know where your problem lies.
Hook up your laptop, open Ccom WP XFI, go to View -->System Configuration-->Operational Parameters and look for "Fuel Cut On RPM" and "Fuel Cut Off RPM". The factory sets a low rev limit. Check it out!

I always set the crank trigger air gap to .060" FYI.

 

ooooops.....

if all else fails read the instructions

I ASSuMEd the fuel cut off RPM was a fuel pump control
since I am using a toggle switch this wouldnt have mattered
"the fuel cut-off will prevent the injectors from firing until the engine
drops below the value specified in fuel cut-on"

since the default setting was 5700 I am almost positive that this is the problem. this also explains the lean "pop"
I have set it at a conservative 8500 & 8600

dam its after 11:00 and I like my neighbors
guess I'll have to terrorize the morning yuppies to find out

 

Please report back as I am having a similar problem...

 

drove it this morning

it got too sideways so I had to shortshift

but from what I can tell, this was the problem

I go to lunch at 11:30 so I'll repost about 12:00

 

too sideways HA! no such thing hahaha jk

glad to hear these guys were able to solve your problem. got any more pics of the car? looks like a flawless setup, i really like your design on the plubming!

 

WOW!!! Like somone else posted nice setup!!!!

i love new projuects but there always seems to be a little glitch the first few days of driving that will make you nuts trying to figure it out.... but in the end all teh time and effort pays off and in your case it was just a shortshift away LOL

post a few more pix of your setup and what car its in!!

Blake

 

Feels like a cutoff because that's what it is.

 

WOW!!
what a rocket!!
just starting to get happy at 6K

andereck, your checks in the mail

LTLHOMER, based on the fact yours goes fat on stumble, I suspect
you have a spark issue. since I have no experience with BS3 I would hate to speculate, but it is probably some simple setting in your EFI config, or maybe
ignition box. a friend of mine had a similar issue with a digital6 MSD box.
turned out he had the cylinder select on odd-fire 6cyl. ran fine
till about 6500, but with 2 extra firing impulses per rev, the rev limit came sooner. simple mis interperetation(sp?) of the instructions...like my problem

heres a link to my homepagehttp://home.nc.rr.com/streetrodz/home/
its free and small

 

Easy to check stuff like this is to load the car in gear and drive up to the cutoff and see if it's there everytime. Then chances are it's a table that didn't get changed.