palehorse77

First off this site has been so helpful and I thank the many that have always provided such valuable input to keep this American Traditions alive and well. With that being said - I'm hoping to get some input on 2 issues.

Car (Lovingly Known as the Thunder Chicken!) suddenly started cutting out at high RPMs and then shortly thereafter the Opti crapped out. So I thought for sure that the new opti would resolve the stumbling/cutting at high RPMs, but it continues. The opti rotor arm had literally exploded so the car wouldn't start. Car runs like a raped ape now aside from the intermittent stumbling. I had a new FPump in there in 08' and very rarely drive this cherry so that nearly new pump didn't fair well for long really (maybe 5k mi.).


1. My first question is - I plan to install the Racetronix pump kit and don't intend to do a AFPR. I'm using 30# set of ford FI's. Longtubes, LE2 cam/heads, 52mm, 1.6 RR, all that schtuff. I haven't even checked the FPressure on a hard launch as I'm certain it's the pump quitting as I'm putting down 424 TQ and HP at the rear ( at 5k above MSL). From what I've read it has to be the pump quiting. I just want to be sure that the new pump with stock pressure (as it's tuned for) will solve this issue. Really just looking for a confirmation. BTW should I upgrade wiring? (seems un-necessary pushing this HP with the larger pump)

2. Herter did the tune. It was originally tuned for the MileHi city and I've reflashed (from Bryan) when I moved back to MSL=1200. Thing is it's always (both locations) tried to go to a low idle of 5-600 when I hit the brakes. Until I come to a complete stop at which point it will return to a 8-900rpm idle. Really annoying as I end up trying to keep the rpms up while braking. Any ideas as to what could be causing this? Not sure if the vaccum from the power brakes is acting as a catlyist for this low rpm or if maybe a weird cags issue? Any input would be appreciated.

timnfxr

Did you experience symtom #2 before the 1st tune? In either tune, were any of the DFCO values changed?
Specifically, "DFCO Disable RPM Threshold" and "DFCO Disable MAP Threshold" would be worth checking.

Lt1son

As far as fuel pressure cutting out---it would be very easy to hook a fuel pressure gauge up tape it to windshield and go--or even disc. vac line from regulator and see what it spikes at---my car was doing the same thing on a decel after my ****ty mailorder tune from a source i wont name---i had it dyno tuned and the guy said the IAC counts were way off and once he tuned it that was fixed--good luck

palehorse77

So I took it for a spin with the FP gauge and what a f'NG mess that trip was. It ran like a top for the first maybe 3-5 minutes (cold) and then progressively started to SHi0T upon me like it never has aside from the when the opti rotor literally exploded after 84k miles. I had to let it cool down twice to get it home. During that first 3-5 minutes the fuel pressure ramped up to 50+ on demand. So I don't feel like it's a fuel pump issue at the moment. It would progressively miss as it warmed up and seemed to get worse as I applied more throttle but ran well enough to get me home.

If I had made the CLASSIC mistake of not aligning the dowel on the opti with the cam I'm thinking it wouldn't run well wether it was warm\cold open/closed loop ect... Can anyone confirm that? If so I'm thinking that ol' boy is right and I just need a good dyno-tune. Next step is to run the scanner/datalog on her.

Thx again for the input.

palehorse77

Tim -

The low idle issue has occurred since the motors inception.

Deceleration Fuel Cut Off. Hmmm - That sounds legit based on the issue. Threshold seems too low. I'll see if I can get Brian to review this thread and reply I believe he still has my data.

Injuneer

Your injectors sound too small. 424HP Aat the rear wheels equates to almost 490HP at the flywheel. I'd think you would need 36's running at stock fuel pressure. Then bring it down from 5,000 ft and it should be well into the mid-500's at the flywheel.

What was the fuel pressure at say 5,500RPM and WOT?

palehorse77

My injectors are exactly as those shown as 30# in the imaged linked below.
I would say low 50's at WOT - It doesn't seem reasonable that it the pump as it shouldn't have been able to give me the couple good pulls as it did before it warmed up....?

I'll get the dyno sheet in hear as well. Fred can you provide input on the opti question regarding the dowel alignment?

http://www.allfordmustangs.com/forum...ctor_guide.jpg

palehorse77

Dyno Pull

I have the BIN file as well from Herter for both locations. Can I open a .bin like an xml file to review parameters? Perhaps I should reflash the car. I believe I did reset the computer ( believe it was just a 15 min. period with no batt.).

Thanks again for the input.

timnfxr

You can open the BIN file using the tuner software used to create it (i.e. TunerCat, etc.) and examine the values from the tables, without a connection to the car. I don't think you can open a BIN file as XML, at least not with TunerCat which I'm familar with.

palehorse77

https://www.hightail.com/download/OG...aFJZY1JYd3NUQw
= Datalog from June 21 before I replaced the opti but cutting out was occurring.

Opti Carnage

palehorse77

Guys, I think I just realized the issue if not discovered a big clue - I just realized I had a data log I hadn't reviewed and it shows some disturbing stuff - No knock retard ever - desired idle of 3000+ ect.... I'm thinking I either need to reflash or need a new CPU all together?..... I see now why when I got out of closed loop it shat upon me so suddenly - I'll definitely reflash, rescan and report back!

My trial of tuner cat was up so I'll have to get it on the work cpu and check it tomorrow regarding the DFCO.

https://www.hightail.com/download/OG...a0RLVlg0WjhUQw

Injuneer

Assuming that you were responding to my comments/questions:

I understand they are 30psi Ford injectors rated at 2.7 bar (39.15psi), which will flow 31.62 #/HR at the LT1's stock 3bar (43.5psi). And in my opinion, they are marginal for a 490HP (flywheel) engine. A good guideline is to multiply the flywheel HP x 0.07 to get a decent size injector for the engine. 490 x 0.07 = 34.1 #/HR. That assume a brake specific fuel consumption (BSFC) of 0.476 #/HR/HP and a limit of 85% duty cycle.

Yes, you may have a more efficient tune, or you may have a higher than stock fuel pressure, or you may be pushing the injectors closer to 100% DC. But you indicate that your dyno numbers are at 5,000-ft above sea level, and you are now running the engine at 1,200-ft, so its over 500HP.

If you have "low 50's" as in 50psi, at WOT, and a stock fuel pressure regulator, there is something wrong with your fuel system. It's designed to run at 43.5psi, and the GM spec is 47psi max. Does it hold "low 50's" at WOT ABOVE 5,000RPM?

If you put the Opti dowel pin in the wrong "deep" hole, it's going to be 120 cam degrees (240 crank degrees) off, and I doubt it would run. But it's possible to have the pin in a "cloverleaf" hole close to the correct dowel pin location, and it would probably run semi-OK, but not great.

palehorse77

Checking it tonight - idles at 50PSI and reving takes it back down to 43PSI - it is idling super low tho - like 400RPM - CPU min I'm assuming.

Also - screwdriver test passed on all injectors... Getting frustrated.

Tried to reflash and winflash cont. to give me errors trying to read PCM - but the Scan9495 tool works great to read it. I don't know what I'm looking at on a lot of these values tho... And this is just reving in the driveway - afraid I'll toast this thing under load as it gets hot quick... Really getting worried (PISSED) now.

Injuneer

The target idle speed is whatever is programmed in the PCM. There is no lower limit.

Fuel pressure should rise as the throttle is opened, not drop. Stock idle would be 43.5psi WITHOUT the vacuum compensation line connected (41-47psi acceptable) and pressure should drop proportional to intake manifold vacuum when you reconnect the vacuum line. I'd suspect less than a 5psi drop with an aggressive cam.

Revving it in the driveway is not the way to test fuel pressure. It's has to be under max load to reach max fuel consumption.

By any chance, do you have an Aeromotive fuel pressure regulator? Have you checked the FPR vacuum compensation line for leaks or wet fuel?

palehorse77

Fred - FPR is stock for now.

So I took the new opti off today as I strongly suspected it was the issue after doing some more datalogs and poking around.

The F'n dowel pin was loose! It basically came off with the opti..... Clear polishing where the opti wheel was hitting it from both sides as it kept the opti within a 3-5deg. range. Which totally explains why it ran so well for a period when it was probably lodged in a solid position. I've JB welded it back in.

I also didn't realize that it was fairly common for an opti rotor to blow up after 6k RPMs which explains my last failure (which was an AC Delco w. maybe 25k). Yes I put a 10k$ motor in I'm going to rap out over 6k occasionally if I freaking want to. Seriously considering LTCC or similar solution!

I'm still thinking my fuel system is next on the list as the pressure seems too high at Idle and the FPR is hissing when the pump primes quite noticeably. Pressure is @50PSI at idle and goes down with increased RPMs which makes sense so I'll see how it reacts to the new solution first. Suggestions on any solution? MSD, ACCEL, DyanSpark, Cardone, LTCC or otherwise?