AO

Problem solved... sort of.

I was going to shark tune the car, so I pulled out my spare ECU and began opening it up. When I got it open I noticed that it had Ken's S300 chipset installed! No wonder I had exactly the same results when I swap ECUs.

I rummaged around inside my ECU bin and found the original stock chip. I install that chip in my spare ECU, then install that in the car.

I just got back from taking it out for a quick spin and idle is a little bit rich (13's) but cruise seems to be about right, but now when I go wide-open throttle, I am now getting low 12's or upper 11's. The car runs very smooth with this set up. I think I'm going to leave it like this for now.

Woohoo!

PorKen

You can pull some of the idle/cruise (and a touch of WOT) richness out with the MAF CO screw - CCW leans. (380 is the usual center.)

PorKen

Do you have a spare front fuel pressure damper? In the video it kinda looks like it's not well damped at idle? Maybe the FPD is stück partway open?

GregBBRD

The really perplexing part is that you think I have the time/interest to make things up.

You, obviously, have a product with the potential to melt pistons/ruin engines.....hopefully only in isolated situations. You can make jokes, you can attack me personally, or you can go figure out what is happening.

You've spent considerable time doing the first two. Now that you have another vehicle with the same exact problem, why don't you try to go figure out what is defective with your chips?

Cosmo Kramer

Seeing that the best you can get is 40 psi of fuel pressure that's not a surprise. Stock chips are designed for 38 psi under load and S300 need 48. For whatever reason your car wasn't creating the fuel pressure required for Kens chips. Did you end up putting a new 87 fpr on it or are you still using the adjustable one?

On my 85 when it was supercharged I ran 24 lb injectors with an FMU and at full boost I would hit 100 psi fuel pressure with the stock pump, so the pump should be up to the task.

Leave it alone for now and get your track days in, but the fact that you couldn't get 48 psi under load is quite puzzling.

PorKen

AO put in a a new(?) '87 FPR = 3.8 bar = 55 psi w/o vacuum (stock 2.5 = 36, fixed above).

OTR18WHEELER

Now it's getting interesting. (cue cat fight sound effects)

AO

FPR is brand new Bosch unit. Pump is brand new Bosch. The only thing I've not touched is the filter which I will do next week.

It's a head scratchers why I can't get the fuel pressure.

PorKen

Front damper?

mark kibort

and this is why I use STOCK stuff! it works and you can tweak it in ways you almost are assured you cant hurt the car's engine!

just think if you were doing your tests on the road with a 400rwhp stroker motor with a 11:1 combustion. those tests at 14:1 AFR would have put a hole in the piston and you would be out a $15k engine

I knew it had to be something simple the stock stuff doesn't screw up that bad and the dampers and things don't anything that major to effect AFRs that much.

mark kibort

AO said he is getting 48psi with the Stock Fuel regulator? new pump? should be good ... fuel filter has no bearing.. that's going to be a flow problem at WOT and high RPM if it is totally clogged up.
fuel damper? that has no bearing on anything but damping out the fuel pressure pulses.

mark kibort

LOVE it!

that splitter looks perfect! you can extend it later if you want now too, using those supports. nice work!

The "home dyno" is nice! it works, right?? so nice to do things on the driveway that most need a dyno to do. if you get a skilled foot, you can go full throttle in 4th and hold the RPM at near almost any high RPM for a few seconds.

weird you are at about 42psi at WOT and it backs down to about 38 to 40 at idle.

could just be the fuel regulator issue. the pump is more than capable of producing 75psi, as I had on the holbert car with stock injectors and the stock 5 liter.

I think the fuel pressure regulator might be the issue.your vacuum seems to be working as designed .... see how it ran back up to about 48psi when you shut off the engine?
the fact that you are at 12.5:1 at wot, is good thing and you are in good shape......... did you track the car in the old form at 14:1?

AO

It is stock, except the chip. I'm a firm believer in Ken's stuff, just unclear why the 87 FPR which is designed to run at 45psi is not working for me. It's brand new. Perhaps it's a bad/wonky FPR?

I;m just glad I took time to check and figure out what was going on.

Thanks! It was a good suggestion.

In a pinch, it works. The biggest issue was the neighbors complaining about the noise. Woops! That car is LOUD!

As I mentioned, it's a brand new Bosch FPR. Not some aftermarket POS. I'd be willing to try a KNOWN good FPR to see if it that is the issue or not. But the important thing, is that the car is now driveable.

I never drove the car on the track with the 14-15:1 issue. I did, however drive it when it was 16-17:1 which just made no power.

Hopefully the motor didn't suffer. Certainly seems okay, but time will tell.

It is weird how the FP rises after shutoff.

PorKen

Unless it's stuck or clogged.

(Or if the front damper was replaced with a FPR, by accident!)

55 psi. 3.8 bar. Jeez. There are so many numbers thrown around in this thread...

Fuel pressure should go up to 55 or more for a while after shutdown with no vacuum and warm fuel. (Spec is 55 ±3 psi, -3 cold, +3 hot.)

GregBBRD

I've fixed cars that had the FPR in the front damper position.

None of those cars would run, at all. The fuel hits the backside of the FPR "seat" and is dead headed....because there is no pressure on the other side to "lift" the seat.

Of course, every time this occurred the FPR was new. Perhaps an old worn out FPR would allow a small amount of fuel to bypass?

I've seen fuel filters that were allowed to "dry out" be very restrictive. And, of course, tank strainers can get so restricted that they won't pass enough fuel. The problem with either of these items is that things tend to get worse, when the car is run. I'd think that the performance of the car would have deteriorated as the day went on, at the track.

Fuel pumps that are restricted from either end tend to be really noisy as they struggle to pass fuel. Does the pump sound like it is straining to pump?