hot start problem

[dthompson]

I'm struggling with a hot start problem. I have 160lb FID injectors, but the following items have been scaled in half: maf transfer, cid, injector slopes and injector break point. I did not scale the FN367 injector offset versus voltage, not sure if I should have or not? The car starts fine when the ECT is less than 170ish deg. When its closer to 185-190+, it doesn't do anything but turn over (doenst light off even a little). If I wait a few minutes and let it cool down some, it will fire right up. I have messed around a lot with the FN348A Cranking Fuel PW vs ECT table. Is there some other reason why the engine wont crank when its hot?

65534......0.598 <-
200.........0.598 <- I have moved the top two PW values everywhere from 0.43, 0.45, 0.50, 0.55, 0.60, 0.65, 0.70
150.........0.598
70...........0.702
40...........0.952
20...........1.465
0.............2.075
-20..........3.455
-65536......3.455
-65536......2.881
-65536......2.881

I've even tried going lower than .43 on the top two rows , but it didnt work either. The data I received from FID says that the min inj time is .43 seconds. Base timing has been verified at 10deg with the spout unplugged.


89 thunderbird sc
427 sbf twin 6266, t56 magnum
AFR 205CC
SCUI small hydraulic roller cam 22X-22X@.050
160lb FID injectors
L1C (5.0 thunderbird eec)
QH and BE

[decipha]

nope the offset doesn't get scaled

if it does it only when its hot then its probably fuel boiling in the rails. You can kick up the fuel pump prime time to see. Just seen you are using BE you won't have access to it. Best bet is to prime the key a few times when hot to verify that way.

[dthompson]

I can give that a shot, I think you can control the fuel pump prime in BE with the scaler Z_FPTM fuel pump disable time. I've messed around with it in the past. Its set to 1 second like the factory now.

I'm running a 4303 pump and a 20 gallon fuel cell, trickflow (aeromotive fuel rails), and no hood right now. It was only 82deg today when I was messing around with this thing. Just seems weird to me that I can get it to crank when the ECT is 175, but not when 185. Like its running and the ECT is 185deg, I shut it off for 30seconds or so and then try to crank it right back up, but it wont fire. I like your theory, but how does a factory car ever fire back up. They run a lot hotter than 185 and dont have this issue. I'll try to shoot the temp of the fuel cell next time too, maybe the fuel is hotter than I realize.

[91GTman]

I had a hot start problem as well. I'm running A9L2 with a 3 second fuel prime. I also made adjustments in the top rows to test and ended up finding out it wanted more fuel. I went from .25 @ 180 up towards 1.0 @180 (dont remeber exact value atm) and was able to get it starting hot consistently. This is with 80lb dekas

[dthompson]

Im still struggling with this issue. I messed around with the fuel pump prime stuff and have ruled that out. Tonight I replaced the remote TFI module (with heat sink compound) and it didn't seem to help. Ive increased the cranking PWs upwards of over 1ms now and it still has the hot start problem. Now it seems fairly repeatable that once the engine is warm, I can turn the key and the starter will spin for as long as you hold the key. Then the second time you turn the key, the engine will fire instantly. This seems weird to me. It almost seems like an ignition issue to me, like on a stock SC DIS when you crank it and it starts on the third try, its the crank sensor... kind of reminds me of that. I think the coil is ok, it ohms out at .7ohms across the primary side and 8660ohms between power and spark terminal. And the TFI is new. So that leaves the distributor pickup? Any help is greatly appreciated.