These are from a GS-R powered del Sol that I just installed a DRAG 3 kit on. The kits 100% stock, motors 100% stock. Fuel system consists of a Jackson Racing intank fuel pump (he was previously supercharged), DRAG in-line pump inbetween fuel filter and rail, and RC310 injectors... with a Vortech 8:1 FMU and AEM adjustable regulator. Base timings at about 13 degrees. The plugs shown have about 10 minutes of driving on them, with a few WOT runs. The car was very hesitant at certain points, like a bad "sputtering", and then when the boost would build... it would rocket off for a bit, losing traction throughout the top of second gear at a mere .45 bar.

From what I know, these plugs look like the motors VERY lean, but I do not see how. Could it be a conflict between the two fuel pumps? ANY helps appreciated. Does the polarity on the in-line make a difference in fuel flow? The car idles fine etc... but like I said... has a bad stutter, and the plugs look like this:

EDIT: My friend just brought up an interesting point. The fuel pressure reads 45psi vacuum ON, and that gauge is BEFORE the inline pump!






[Modified by HybridKOOP, 7:46 AM 7/31/2002]

 

Yes, make sure the fuel pump(s) are wired correctly, otherwise you will have them working against each other.

 

yea looks lean. what were they gapped at?

 

Stock gap. Also... when the cars off etc.... and I just activate the inline pump, I can feel gas returning to the tank from the rail... so gas IS being pumped the right way that I know of...

 

check all your vac lines too, make sure the fmu is properly installed

 

My guess would be a clog in the fuel line, had a similar problem in my old car, but you say it sounds like its flowing fine,sorry I couldn't be more help.

 

Center outlet on the FMU is returning to tank.. "side" outlet on FMU comes from the rail... with a vac to the *row* of vacuum T's from 1 spot on the intake manifold. Could too many vac sources on 1 intake manifold outlet cause pressure differences? The boost gauge reads a perfect 6.5 to 7psi of boost.

I just really don't understand how 2 fuel pumps, a FMU, and 310cc injectors could run lean at 7psi.

 

here is a thread i started about plugs 6 weeks ago ... very useful info : https://honda-tech.com/zerothread?id=212116

 

Wow... some very useful info in there, thank you. Maybe the mere 3-4 miles I put on the plugs just isn't enough to properly gauge how the motors reacting to the boost. Just to be safe, I'm gonna crank the pressure on the 310's up to 55 atmospheric and pull timing out until I *do* see rich conditions on the plugs... good idea?

 

^^^