BC

You know how some people have problems that they fixed and then when someone has an unrelated problem they think the same thing would work? Well, thats me now

I replaced my fuel reg with an aftermarket one. I'm not suggesting aftermarket, but maybe just a newer one.

Just a thought. Otherwise it could be something electrical, which you are already on the hunt for.

byrdman454

BrendanC, where did you get your fuel regulator? Did you replace both driver and pass side regulators?

Was your Euro doing the same as mine?

k1woods

Mike - Remember that your S4 has an O2 sensor that will correct/compensate to some degree a failing MAF. I'd bet that the both MAF's are out of spec - just that one is better than the other.

- Kevin
84 928 S2

BC

My euro was stumbling upon accelleration from a stop, Almost stalling. Thats why I said it the way I did above.

I used a reg I bought from 928spec. The hesitation has not come back, but I think it was a combination of quite a few things.

FlyingDog

Brendan, are you running single or dual fprs? If single, how did you bypass the driver's side fpr?

John Speake

Hi Mike,
If it is still running very weak at less that WOT, with a "good" MAF then the O2 loop must be faulty.

Try and monitor the volatge across the O2 sensor without disconnecting it from the loop. Volts should swing around from 0.3 to 0.9 in normal operation, engine at normal temp

BC

Sorry, I forgot to answer that. I run the Adj on the passenger side. I rerouted all the vac lines, and simplified them ala Porken.

The driver's rail gets a new dampener, and I don't have the vac lines hooked into the dampeners at all. Only the regulator. I took most of the fuel line stuff out of that rear area. It was rusted anyway. So the fuel comes up to the front dampener, and then back out both rails into the regulator, and then into the return pipe.

It was so tempting to do more customization, but as you see in my sig, the car needs to stay drivable.

byrdman454

John,
This Euro does not have the O2 sensor hooked up. The aftermarket fuel control module has been removed from the car. This car should be running the same as it did orginally.

BrendanC, do you have the procedure from Porken about simplifying the fuel system? Did you remove the damper in the front of the engine too, since you have replaced the driver's regulator with a damper. Did you use the '85-'86 damper or did you buy something else? Where did you buy it?

Thanks

_Thomas_

Hi I have gone through all of that with my '84 928 S 5sp ('Euro'). When I bought the car the fprs were pressed short to (permanently) increase the fuel pressure. After I had the MAF recalibrated the car was running much too rich (CO was not adjustable to below 2 % anymore) and I had to buy new fprs which then again brought the car very close to a lean condition (for low throttle). I wish at the time I had bought adjustable fprs.
BTW: I was told because Porsche Switzerland stopped importing 5sp 928 S around '85 because of the annoying lean running-hesitation (with autos it was less noticeable).

From what I read quite a few people have replaced the original fpr on the driver's side with a fuel damper and the fpr on the passenger side with an adjustable fpr. Can somebody list the exact parts (part numbers) which are needed for the modification. Some pictures of the installation would also be nice.

Jadz928

Thread on AFPRs
Had a lean condition. Bumped fuel pressure to 40psi. All is well.

Before doing this, replaced MAF and calibrated, flowed injectors and relpaced orings and rubber hoses to fuel rail.

_Thomas_

Jadz928 that looks like a neat solution. What make is that AFPR? and why does it have electrical connections? Did you have those fuel lines custom made or can they be ordered somewhere?

Jadz928

I think it's an Aeromotive FPR. The elec. connection is an FP sender to an analog gage in the cabin. The hoses were cut to length by me, fittings and hoses sourced from Goodridge.

_Thomas_

Did you remove the vacuum control in the process?

byrdman454

_Thomas_
Here is the info for the adjustable fuel pressure reg (pass side rear) and the damper which will replace the regulator on the driver side rear. These part numbers are from 928 Specialists. The damper is used on a '85-'86 32V US 928. You could also buy the damper under its Bosch number instead of paying Porsche to sell it to you.

928.110.198.01.A (adjustable reg) and 930.110.602.00 (damper)
Damper is actually Bosch P/N 0280161021

_Thomas_

Hi do you mean this one:
Adjustable Fuel Pressure Regulator 80-87
928SP.4500

in the description it says ".. They are adjustable, and the rate of pressure also rises with vacuum for even better throttle response. ... "

does that mean I could set the base fuel pressure like stock (I don't need an increase there) but still get a higher fuel pressure at low throttle openings? do you know how much the increase is?