blade7

Is the adjustable fuel pressure regulator supplied by Lindsey Racing the only one that will fit into the fuel rail or are there options from other suppliers ?

Humboldtgrin

Not that is any cheaper if that's your worry. And what type of fuel pressure regulator fitting into the fuel rail do you have? There are two types. Personally I'm using the LR billet fuel rail set up because I had two stock fuel rails leak in a row at the seams on the top of the rail where the mount is attached to the rail. Something to consider.

bw993

My preferred 951 AFPR is the Holley p/n 512-503. It's a 1:1 rising rate FPR like the Bosch and looks completely stock. Another AFPR that works well with the 951 is the SPA Turbo p/n VLRPF201. I had all three AFPRs to test on my 951 and decided that the Holley was the best fit and easiest to adjust. It was also the most consistent in terms of accuracy. The SPA and Lindsey were comparable. The Holley was $170 new, Lindsey was $195 and the SPA was $89.

Hope this helps.

blade7

Thanks very much for the replies. At the moment I have a Bosch 3 bar fpr fitted and idle fuel pressure is a bit low. Where I'm located I wouldn't get much change from $250 for the Lindsey version. That wouldn't be so much of an issue if it is my fpr that is at fault.

V2Rocket

blade the 944S/S2 FPR appears to be a direct swap to the 951 rail and is 3.5-3.8 bar...maybe try that?

bw993

I assume that you are checking your fuel pressure with the vacuum line disconnected. In my experience with multiple Bosch 3bar FPRs, I have seen their accuracy vary from -1.5 to +5 PSI. Usually, they are calibrated to be on the high side of 3 Bar.

blade7

I am checking with the vacuum line disconnected. The Holley adjustable fpr mentioned earlier seems to have been discontinued. Changing the old fuel filter soon to check that's not a restriction.

blade7

Thanks, wonder if that might be too much pressure and overload the injector drivers though ?

blade7

I changed the fuel filter and it made no difference, idle fuel pressure with the fpr vacuum hose disconnected and plugged is 42 psi. afr is fine during warm up, on boost and on part throttle, but mixture is lean at hot idle. I searched and found a post where fast951 said he ran 60 psi idle fuel pressure?

Humboldtgrin

Do you have an exhaust leak from the headers to the turbo?

blade7

No leaks between the head and the turbo, tiny leak under the car where I removed the first silencer but the cars run fine with that for years. With the fpr vacuum pipe connected the idle fuel pressure is 36 psi, is that too low?

topley

I'd love to hear if you find the issue... I've been chasing that as well. I have healthy AFR's pretty much everywhere but hot idle. I've pressure tested from the intercooler inlet and it takes about a minute for it to go from 10PSI to 2-3 psi and the air seems to be coming out the oil filler cap... I can find no other leaks. Idles (840rpm) at 16-18 AFR. High 10's-11 WOT boost. FYI I have the Lindsay adjustable FPR.

blade7

Hello topley I suspected the original worn AFM, but replacement with a better condition used one made no difference. I'm wondering now if it's something faulty in the DME computer. Can you borrow one to try ? Also what fuel pressure are you running with the Lindsey adjustable FPR ?

topley

Well, here's where I'm also cheating... I have a Vitesse MAF and a Vitesse turbo. I have tried 2 different DME's and KLRs with no change. My MAF voltages are perfect so it doesn't seem like its an electronics issue. I'm 42-44 PSI at the fuel rail with no vacuum. It has every hallmark of a vacuum/boost leak, but I can not find anything obvious.

blade7

When I had a split boost hose on a different car it misfired on boost. I've also tried bypassing the ICV with no effect.