Starting over , need help
Have a GM performance 383 crate engine. I can provide the cam details, but it is a 325HP, 440 ft-lb and seems to have a mild cam. Something like .45 lift and like 190/208 (this is not exact) duration. I have been driving vehicle and for the most part have had good luck. It is now hot in Texas and seems maybe things have changed. I have erased everything and am starting over. Reason why is on start from engine that has been sitting overnight (~80-90 degrees ambient outside) I have to turn key on, then off, then on for it to start within 3-4 turnovers. when it starts, it will rev up to ~1500 RPM, start to settle down, then do the surge thing where it will drop to ~800 RPM then down to almost dieing, then surge back up and keep cycling like that for 3 to 5 times until it kind of settles down. Upon initial installation, I did not have this problem, I could set IAC steps in the 3-10 range. This makes me belive with what is happening now, something is loose, came loose or something. I looked to see if I can see any vacuum lines unhooked, nope. When it settles to about 1000 RPM idle, timing is at 12 degrees like GM said to set it. I have tried to set IAC but I am having issues with the surge towhere it starts to lower, RPM drops, IAC steps take off increasing ~20 steps then starts going down, RPM drops, IAC steps shoot up ~20 again. Until engine gets warm, I cant get IAC steps to adjust properly. I looking over other posts here, I have increased afterstart on 20 and 65F up to 20 and seemed to help when engine was warmed up, but after engine cooled down, it is back to doing what I have described. I have not had any fault codes until now. I have a P0130 wideband and a P000. I need some help. What do I do next?
It seems like starting issues are the worst...not going to try to advise right now, but I'm sure others that view your post will want some basic info:
- Which FiTech system do you have
- What fuel delivery system? FiTech, inline pump, in-tank pump?
- Do you have a fuel gauge to check the pressure?
- Timing control: is it managed by the FiTech ECU? You mentioned initial is 12*, is that with/without vacuum advance? Initial timing is always set without...with the vacuum line connected it should be in the mid-high 20s.
- When it's running, is the AFR reading changing or is it stuck at a value like 14.7?
- Current readings from Handheld concerning all the 7.Cranking Fuel settings.
I will make a comment on your idle speed...it should probably be set to no higher than 750 for a mild 383. I'm running a 383 with larger cam and automatic trans and that's what mine is set at with no issues. If you need to have it idle at 1000, then there's something else going on. Actually, there is one thing you could try...it's a computer...reset it. Make sure you save the current CAL from the ECU so you can go back if needed, or get the settings from it, but then try loading the default V8 CAL and go through the setup instructions. Don't forget to set the PWM to 100 all thee places if you're not using a PWM controlled fuel pump and disable the Fan if not using the ECU to turn it on. Good luck!
If reloading CAL file doesn't work, Flash the ECU using the ECU programmer. May need to enable it in the display menu.
TTthanks thanks thanks guys for responding, Yes, there are all kinds of things you need to know so just ask. I have the 600HP system, I bought a 255lpH intank pump from Fitech and it is controlled from the Fitech unit. No, no fuel gauge, I replaced the lines from the 3/8 lines out of the tank with AN06 lines all the way to the fitech and back. I have a 100mic filter before the unit. Ttiming according to GM manual says NO vacuum advance at all. Using MSD all in one unit and vac diaphram port closed off. So 12 is hard timed and at 4K RPM, it is like 32 or close. No no timing from ECU. On AFR, I just went out and started it, For 3-5 seconds it stayed at 14.7 then started oscillating with the idle. Idle drop to like 5-600 at that low range, AFR peak out around 19-20 when RPM go up to around 13-1400 AFR down to around 14 AFR target is at 13.4. Crank fuel settings: Prime fuel 259, C rank fuel for 20, 65 170, all at 0, afterstart 20 at 0, 65 at 25, 170 at 0, warmup all at 0. On the reset issue, I think that is what I did. I went to the loads and did a load of the V8 default to basically start over. I see something I dont understand. WHen I would go in and set the afterstart like at 20 for both 20 and 65, when I would go back in and look at it, it would say 0. this is after I would set, turn off key, let display go away, turn back on key and go to look at setting. Not there. I REALLY appreciate this.. Im 60 and have recently gotten into vehicles. Rebuilt a 79 vette and now working on this. So I know enough to be dangerous but also old enough to know I dont know.
have you checked for a vacuum leak around the intake and throttle body gasket, what is the lobe separation on the camshaft fitech like at least 112 lobe Sep. 13.4 should be good for 383, you cant go off gm timing specs with a after market cam, find out what cam it is and have you distributor curved for all in 36 degrees at what the cam specs for from cam manufacture. what is your duration @.50 I would guess your cam setting should be #2 or #3 I would try more timing, check for vac leak you need at least 8 to 10 inches of hg, finally last set iac to around 10 with set screw on the throttle body, worked for me on my dual 1200 power adder.
I dont know how to check for vacuum leak, exceept to look for hoses that have come loose or split. I have heard something about the "smoke test" but dont know how that works. This is a crate engine. All I can tell you on cam is it has .431/.451 lift 196/206 duration at 50. My vacuum, according to the fitech is around 14, it has absolutely no lope to it. The timing is what GM says to set it to, and that is what I did. My problem is I cant set IAC until engine get up to operating temp and from what I understand, I should set it when temp is normal outside (like 80 to 90 degrees)
Hi Dave, are you referring to a manual that came with your new engine? Anything that says forget vacuum advance for a street driven vehicle is wrong. Please read the attached .pdf file on SBC timing. Here's the easy way to set the timing...adjust the timing so you see 36* when the timing is all in and accept whatever the initial is. With the tame 383, even if it's 14-16* that's fine as long as the starter does not have a hard time turning the engine over and the total is 36*. If the MSD came with bushings, you could also change it out to lower the initial back to 12* and till have the 36* total. Then, PLEASE hook up your vacuum advance to manifold vacuum, not ported vacuum. This will put your timing in the mid to high 20s..and that's good. The attached paper will explain why. As for your settings not staying in the handheld, remember that you need to press the button to send the change to the ECU...you will get a pop-up saying it was saved.
When you were setting up the FiTech, what cam did you select? If not Cam 1, I would change to that. Any other cam selection might be way rich, to the point the FiTech can't trim it out...just a thought. Also, as others have mentioned, vacuum leaks will play havoc with idle. Being a crate engine, hopefully the intake manifold was sealed correctly. When checking for leaks you usually spray something like starter fluid or carb cleaner around the base of the throttle body and where the intake meets the heads. Problem is, you're looking for the RPMs to change if the fluid is sucked in...and your engine is already fluxing so it could be very difficult to tell if there was a difference. Just out of curiosity, do you have the PCV valve hooked up? Again..good luck!
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One more question...the FiTech intank pump will not work with PWM, did you set these settings to 100? My brother burned out a pump because the FiTech default setting is not 100.
And one more piece of info on Cam selection from the FiTech site: Cam selection is based on vacuum load of the engine. Cam 1 is for 15Hg or above, Cam 2 is for 10Hg to 15hg, Cam 3 is 8Hg to 10Hg, Cam 4 is 8Hg to 6Hg. These are estimates and you may need to switch between them if the vacuum load is between two different cam settings to get the engine to run better for your application.
I know you mentioned 14Hg...but I would still try Cam 1 as FiTech tends to tune to the rich side with its VE tables. And if you're already at Cam 1, then raise the idle AFR to 14 or a little more lean and see what happens...you're not going to hurt it. If you don't have a vacuum leak, and if the pump is providing the correct pressure (Austin will tell you to get a gauge...because you just don't know otherwise), then it's the ECU sending the signal to spike rich and lean...oh...Austin will also ask that you take a 30 second log file of the ide and make it available through Dropbox. That could be very helpful.
OK, I have just ordered fuel pressure gauge and will install that. This evening will start over with the default V8 cal and set cam at 1 I have generally been setting at 2 or 3. But it makes sense with the cam being mild and high vacuum. Will keep you guys informed.