Recently I had done a lot of work on my car. In forth taking it to scoffs for a power reading. The fuel was fine to about 20 psi. Then my turbo went bang, my issue is I've replaced a t25 tomcat with a t2 to get the car running. Running 7psi it's lean 13.2@ wot. Cars had a new fuel pump, new fuel filter, adjustable malpassi fuel reg set at 6 psi. Carb spec, 120 main, 0.9 ac, 1.7mm needle valve, second stage 1.3mm. Wtf is going on? Why is it lean
sensor calibrated wrong? exhaust leak before sensor, inlet leak, misfiring, blocked jets?
Good shouts ill check thosejust strange it's not been touched since scoffs and now it's lean when the fuel was perfect
might be a leak between the new turbo and manifold or downpipe.... maybe eve the elbow.
FPR issues? Down the years I've read no end of woes folk have had with non-OE adjustable FPRs.
i thought the best spoke of way of running 20psi+ was with an adjustable fpr as standard isnt upto it?Originally Posted by Trevhib
it is but also a fixed fpr with a different enrichment ratio will also do the job, that's what i run
Just seems strange as it was literally fine at 22lb with the T25 and as soon as the t2 went on it's 13 + afr @wot with only 8lb boost. I think it's more likely a leak on the exhaust downpipe/elbow. Although it will be worth just checking the fuel pressure again to be sure.
it is but also a fixed fpr with a different enrichment ratio will also do the job, that's what i run
.
by different enrichment ratio do you just mean fettling the carb? Just iv seen a few people complaing of the carb emptying at 18/20psi so your saying a good working standard fpr should be ok if carb is set up right
I can't remember what the different problems were with aftermarket FPRs. Something to do with the way they worked with the GTT fuel return system, problems with rising rates, basically the setting up. Most went back to new OE IIRC as they seemed to be fine for high boost engines as long as they were set up correctly. I'm sure some of the gurus here remember. Brisgy or Ashy specifically I seem to recall doing this.
Maybe all that stuff has been worked out in recent years and/or maybe Josh's issues have nothing to do with his aftermarket FPR at all. It's just what came to my mind when I saw the malpassi mentioned.
Last edited by Trevhib; 03-06-2013 at 18:05.
James my car was emptying the bowl with a standard fpr after 20psi, because the engine breathes so well. Nothing to do with the carb being set up incorrectly. I've found a big leak on the elbow/rear housing joint.will seal this up and all will be sound more than likely.
my fpr is a rising rate one, the standard fpr enriches at 1:1 air/fuel, my fpr is 1:1.5 air/fuel, enough with an efi pump for 25lb manifold on a 1.7 needle valve.
most standard frp are no good for 20lb or above high up in fourth after a standing start.
Never heard that before Phil but sounds absolutely plausible
Well we have a few hours this afternoon to try and solve this issue, we have since found a carb/manifold gasket missing and also an exhaust leak at the turbo elbow.
Both made the car run better but it was still the same with the afr's 13's with only 8lb boost???
The fuel pressure is at 5psi on idle then it drops to 2psi as soon as the throttle is touched, is this normal?
What happens if you turn the boost up? Does the fueling go richer or even more leaner?
We haven't had the balls to do that yet
Sorted, it was the carb, swapped it for mine and hey presto, just been out and wound the boost upto 18lb afr's were in the 11's untill 6.8k then they start to rise to 12.2 haven't gone all the way past 7k yet, will leave that for the rollers.
doesn't half shift for just 18lb boost
1.7mm needle valve?
Drill it to 1.9mm to keep safe in all conditions
Carbs suck ass! Fecking hate them!
tried that and it runs really badly with the increased fuel pressure, bogging down heavily between gears and puffing black smoke on bumpy surfaces, I even tried one of those land rover valves that are already 2mm and it was exactly the same, my car fuels well beyond 7k at 24lb manifold, with a 1.7mm needle valve.
It is however lower c/r than josh's car.
Indeed they do
The 1.7mm needle valve is ok with the raised pressure..the problem is elsewhere. Possibly main jet blocked or something is a miss with the enrichment block
Yeah your right brigsy, but that carb is a ****ter to idle when cold aswell. Phil's carb is perfect.
Oh and the fuel pressure is at 5 psi base so maybe can squeeze another 1 or 2 in there.
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