New FAST install, reads way too lean??? sensor's good

[S351 R]

Just finished the install of new B2B FAST on a '89 Mustang 393ci N/A(using a White plug&play interface) and got the car running, even with a decent idle, but Actual AF reads only in the high 15.'s, except briefly when blip'n the throttle.

Using the "L" function, it has put VE values as high as 150 for that cell. When Closed Loop is enabled above 1500rpm, it still max's out the O2 Correction (+/-24.6 on a 25% max) This has only rev'd in the garage to 2500 or so thus far.

Manually increasing VE numbers at Idle from 70 to 95 didnt impact Atual O2 at all.

I have laser temp'd the headers and each tube is about as hot as the other suggesting that I don't have a dead cylinder.

I have inserted the O2 sensor in both sides of the h-pipe and similar results for each side. An exhaust leak at the shorty header/h-pipe is possible, but on both sides?? and how largeof a would it have to be?

The UEGO voltages match (connected and disconnected) as per the Manual.

So here I am with no further things to try. The only nagging thought is the small cam produced a lumpy idle with the stock computer that sure sounded a lot bigger - this always seemed odd - installed wrong?

FWIW, bought the car in current setup (sans FAST), drove well, was weak on HP but good on TQ (only run to 5K 360rwhp, 430rwtq), figured it had to do with the small cam to begin with.

Pls, any trouble shooting ideas are appreciated.

 

[RickWI]

Some basic thoughts. I assume the config screen has the correct size injectors. I assume your injector opening time is set to 1. I assume temp correction tables for water and air are correct. I assume your UEGOS readout on the dashboard is between .45 and .48.

 

[norbs]

Turn off the closed loop. look at the plugs right now, check if there black or clean. IF the a/f is 15 :1 and the plugs are black you have a problem or huge ehaust leak.

 

[S351 R]

wow! thanks for such a quick response.

Yes the fuel calc should be good: 393 listed, 30# inj, 1.0 m inj opening etc.

I checked 6 of the 8 plugs (tight on back drivers side ) They were all clean white to a little tan at darkest on the porcelin, strap was sorta chalky white, and the base ring had some carbon.

Although I did rev a little during trouble shooting, it definitely had a chance to sit on idle in open loop registering the 15.8+ at the time I shut it down.

The base program came from my other Ford TFI car with 351 and S-trim. Appropriate changes were made in the fuel calc etc., and except for a very hard start (plenty of cranking and ended up giving it throttle to get it going) I was able to get it to a pretty good idle pretty quickly.

So 1st, Im surprised it would idle and rev as decent as it did albeit for a limited time with a real 15+ reading. And 2nd, the short time I played with VE, nothing seemed to impact the reading at idle.

*One other potentially important glitch is: MAP reads around 45kpa on dash at idle and properly displays the cursor in AF and Spark table, BUT it shows around 20kpa on the VE table, (RPM is fine). I suppose I could eyeball 45kpa without the cursor and see if that VE cell changes something.

Hey thanks again guys.

 

[norbs]

Just for a hunch here.........reinstall the software, or use the dos version. Just to confirm the readings are similar on the ve. Are these low impedance injectors? what is the base pw at idle? does the pw change with changes in ve?

 

[S351 R]

I'll give the reinstall a try tonight, although I dont have a clue how to get started in DOS though. I may also plug in another laptop which already has FAST loaded and see if there is any change.

I will look at PW, but noticed yesterday that duty cycle was at like 3.5% or so. Ive got 30# FMS "red tops" in there, so they'd be high impedance. FAST doesnt distinguish between these does it? The program I overwrote with the changes was for 72#ers...

I'd also add that before with stock EEC, we had one of the Autometer A/F ratio gauges, and while those are very narrow, it appeared to function normally sweeping back and forth like every other one I've seen. So this leads me to believe that things should be good enough mechanically...

While a reload may solve everything, the more I was thinking about the mis-aligned VE cursor glitch, if the computer is actually trying to adjust cells down at 20kph, it will never effect the appropriate cell at 48kph, which would explain why even at closed loop at 2K rpm, nothing really effected AF. (FWIW, VE #'s for idle and the little reving I've done are around 68-72)

I shoot ya an update later on. I appreciate your interest on this.

 

[S351 R]

Well, things appear to be solved.

1st I pulled off the stock EGR from the manifold and borrowed my blockoff plate from the other car. In my limited understanding of the Ford EGR valve, I still don't think it should've had an effect just because it was unplugged since the vacuum line was still attached.

Hooked up different computer and bingo, all was operating like it should. VE around 60's, Actual AFR low 13's with the same for Target.

Then hooked up old computer, and the misaligned cursor problem remained, but the AFR was fine. Reloaded software and that fixed it.

Bottom line seems that the EGR played a big role if AFR when not being run by stock EEC, and it was just bad luck to have the VE table glitch at the same time.

Thanks for all the input, and now just to get it to start before cranking for so long. Off to the search button...

 

[norbs]

Glad you got it figured out.

 

[norbs]

I think the high impedance have an opening time of 1.8-2ms. The fast has no way of knowing that. The idea of low impedance injectors is quicker opening times to allow the injectors to run at lower pw when needed. I would change your opening time to @least 1.5 secs on the high impedance style injector.

 

[S351 R]

I may play with it a little, but ever since I removed the EGR and used a block off plate, it behaved as I would have expected it to. (I still dont see how the EGR made that much difference with vacuum off, ie closed...)

I know that my first FAST came from ASSC for 36# (high imp) with a 1.0ms opening time, which seemed fine as well. It was actually when I switched to the 72# lows that I had to bump up the ms opening. Anything below 13.9 volts running and the injectors got lazy and lean at idle. The hotter the engine (and thereby the alternator and wiring and higher resistance) the lower volts went. 1.3 seems to be a good fit for the 72's on a 351W.

Now I'm busy learning what a N/A stroker motors likes... Any gouge or reference material for this?
Thanks norbs