AngelP

Greetings all,
Recently had my injectors cleaned & tested while replacing a dried up O seal on the thermostat/coolant manifold. I had for a while been having a detonation problem on part throttle acceleration, which hadn’t been resolved by getting the rising rate fuel pressure reg. The bench test summary I received from Marren Motorsports indicated I had poor spray pattern on three injectors. After the reinstall the car has been running great(no more detonation), but I detected a distinct fuel smell after shutting off. Should have checked it right away, but let it go for about a week… luckily without consequence. Finally got around to it yesterday. Re-checked all connections to and from fuel rails, dampers, regulator with no sign of leakage. Last bit was the fuel pressure check at the rail.
Lo and behold the indicator was pegged at 60psi +. I’m stumped as to how this happened. The holding nut for the adj screw was tight when I re-adjusted. Can’t see how the cleaning would have affected this. I recall, when I originally installed the reg having to dial up some turns to get about 46 psi.
Yesterday had to dial back at least ten turns on the adj screw to get it back down to approx. 44psi. Any ideas on what happened??

Making an attempt at attaching my injector report for the curious.

Angel
89 GT

Gretch

The static pressure will be much higher than the idle pressure, because the engine vacume reduces the pressure "held" by the RRFR. Set your pressure statically by jumpering yout fuel pump relay, based on the specs in tha manual. If that is what you did, then I don't have any other answers for you.

AngelP

Should have mentioned that all reading were set at idle.

Gretch

I believe the correct procedure is to set initial pressure at static. Then let the vacume actuated regulator do its thing. That is what we do with the SC transplant.

Then if needed, ('cause with the huffin' surgery there are more changes to the fuel system than just a RRFR) tweak the pressure at idle for proper mix and smooth running. Then make sure the SFMU provides enough fuel at WOT to keep from vaporizing the engine.....compromizes.....compromizes. Tim's design got the fueling math correct for the 8PSI kit. My car runs very well through the power curve.

AngelP

Can't check the handbook now but I believe there are values for both static and idle. I may be off, but it was just my instinct was to set it while running. Thanks for the feedback..

Old & New

Perhaps a bit of crud found its way to your RRFPR.

Gretch

It seems to me it would have to be a big piece of crud to jam up the works such that the pressure in the system is at approximately the maximum of the fuel pump...

How was the car running? The injector firing logic limitations lead me to believe that clean stock injectors with 60 psi behind them would deliver a very rich mixture at idle.................

worf928

Angel! Welcome.

I thought you punted your Autothority chips after that Dyno day in 1999?

In any case, you are correct: there are two FP values. With a stock FPR you should see ~45 PSI at idle. Without vacuum (e.g. throttle blip, motor off, etc.) you should see ~55 PSI with a stock FPR.

One thing I'm not certain that you mentioned: Did you check to see if you have vacuum at the dampers and regulator? If you are seeing a higher-than-expected idle FP I would check vacuum first.

AngelP

That's what I would have thought too but it was running fine, other than the distinct fuel smell post shut-off. No sign of it burning overly rich.
Now after 40 miles with the re-adjust still fine. I'll run it hard on my way home because those early miles were while it was pouring cats&dogs this a.m. here in NJersey.

AngelP

Hi Dave,
It wasn't the chips but, as is evident now, dirty injectors causing the detonation during that dyno day. Still had good HP numbers though. The RRFP is now set at approx. 44psi (idle). I'll see how she does next couple of days, and also re-check vacuum.

worf928

And I had just put freshly Marranized injectors in my '91.

Yes you did. According to my spreadsheet you put down 289hp/295tq! (JV was apoplectic about his numbers - which we will not post here lest JV smite us from on high...)

Make sure you see the FP rise to ~53+ when you give the throttle a good blip.

I'm glad to see you gettin' back into it. (Haven't seen you around Cyberspace in a while.) Do you still have your VW?

AngelP

Dave,
Sorry to say I got rid of my 90 G60. At the time I changed to a more civilized '97 A4 1.8tq, which was subsequently swapped for a '99 Passat 1.8tip because my then new wife didn't drive stick. Actually at some point I'd like to pick up another G60 as a daily driver.

worf928

The G60s (and VR6s) are rare. Good luck finding a good one.
Wanna nice Audi TT (still under warranty) instead?