installed RC/Lucas 550cc injectors...car runs like crap now

[Brandon92DSM]

The title pretty much says it all. Im getting annoyed with trying to
make the car to run halfway normal. By far the worst problem is the
low RPM bogging/stuttering/bucking/whatever you want to call it. Its
very difficult now to pull away from a stoplight without this lousy
behaivior along with an indicated 10-20cts of knock on the logger.
Giving the car extra throttle from a stop is the only way to
somewhat smooth it out, but if the revs fall too low im in trouble.
The car smooths out ok after 2k rpms or so.

The car didnt have any drivability issues with the stock 450's, even
after ditching the stock 1G MAS for a GM MAFT blow-through a couple
months ago. I simply set the translator BASE knob to "2" per the
instruction manual (for 450cc injector compensation) and the car ran
smooth as it did off the showroom. Now with the 550's the car runs
like crap, and adjusting the BASE and IDLE knobs hasnt helped.

At this point I have to wonder if something went wrong with the
installation of the injectors, which is hard to believe since the
install went cleanly. I cant quite recall, but i seem to remember
noticing that the Lucas injectors where possibly shorter in length
than the stock ones. Could it be possible they are, and that they
are not seating into the intake manifold as snugly as the stockers?
(Causing vacuum leak maybe?)

At this point Im tempted to put the 450's back in just to enjoy a
car that drives normally, but wanted to hear any input anyone has.

Thanks,
Brandon

 

[missouri_dsm]

try disconnecting the battery for a few minutes to reset your ecu. Then set your knobs for 550's. Also check and make sure you plugged every thing back in(any plugs, hoses, etc.) If you have a boost leak tester, test for leaks. One more thing, make sure you see the little red light on the translator flash when you make adjustments, to make sure it is accepting the changes.

 

[xxREVERBxx]

What are your settings on your MAFT? I was having the same problems as you did but realized that my idle knob was to rich i leaned it out two clicks and it ran fine. Oh and the base knob was set for 550s. Try that out if you haven't already. Everything now feels alot better since i got my Stage-3 chip from Keydiver

 

[Brandon92DSM]

I tried setting the MAFT to AUX=0 BASE=C for 550 injector compensation but the car ran far too rich according to the O2 trims. right now the AUX and BASE are set for 600cc compensation and the O2's are somewhat in line during a 60mph cruise or so.

Honestly I dont know how to properly set the IDLE knob. The knob is set at 7 or 8 I think and of course the O2 trims are indicate rich (around 58-60) when the car is idling, but the car runs definitly worse if I attempt to lean the idle knob out any more than that.

Maybe I do have some leak problems. I would be interested in learning how to make a boost leak tester to troubleshoot that possibilty.

Oh yeah, the red LED lights up when I change the settings, so its definitly accepting the changes.

 

[missouri_dsm]

you wouldnt happen to have an aftermarket fuel pump would you?

 

[Brandon92DSM]

The fuel pump isnt stock. Its a Denso 180lph, OEM on the 3000 GT VR4. I was under the impression that it would plug and play with the stock pressure regulator. (unlike the larger Walbro or Denso pumps).

Ive never had reason to beleive the fuel pressure was seriously out of whack, although I couldnt say what it runs compared to stock.

 

[missouri_dsm]

do you have a check engine light? also you might check your timing. When is the last time you did a tune up?

 

[Dred]

If your o2 sensor is fine try what Missouri said. The ECU needs to recalculate the trims according in accordance to the new injectors. Btw, what are your trims at now?

 

[destrux]

I have the exact same setup, MAFT, 180LPH Denso pump, Lucas 550's, and I'm having the same problem. It ran fine with the stock 450's, and now it runs like crap with the 550's. I got the PTE/Lucas 550's brand new on ebay from a place I've bought alot of my other parts from and I know I installed them right... they fit perfectly, don't leak and the wiring clips are properly connected. I already checked for boost leaks also. With the maft set for 550's and the other knobs at 0, the O2 trims float around 50-60% at light throttle cruise and it goes to 32-40% O2 trim at idle and my O2 readings stay rich (.83 or so) at idle and after a few minutes of driving the O2 sensor will start cycling like it should be, but when it does my idle suddenly gets alot worse. Leaning out the idle seems to make no change to the trim numbers, but it makes the car idle worse and the throttle response is so bad it's not driveable. I can drive it around like normal with the idle and mid knobs at zero though and the car runs alright as long as I'm not idling, but the ecu is giving me those rich trim numbers and when I try to idle it runs very rich. I thought with larger injectors it was supposed to run leaner at idle because of longer dead time... and it seems like it's doing the exact opposite.

I also tried setting the base for 780's and 1000cc/min injectors to see if the injectors I got were the wrong size (since they have no markings on them that state the size). It ran too lean under normal driving at both of those leaner settings (so obviously they aren't 780's or 1000's), but it still ran rich at idle. The only thing I've yet to try is setting it for smaller injectors, but the place I got them from only sells 550's and bigger, so I figured there's almost no chance they're smaller than 550cc. Oh and I'm running 40 psi (so I should have to set the injectors as 600's on the MAFT to correct for the extra few pounds of pressure, which I also tried and it made no difference). Because of that extra few psi of fuel pressure I had my old 450's set as 480's on the MAFT and I had the trims perfect at nearly 100% and the car idled fine.

 

[missouri_dsm]

For those who dont know how to tune with a maft. Tune for your High trim first, dont worry about your other trims or anything else for that matter, atleast at this point. To do this, RESET YOUR ECU first. Now, set the knobs for what injector size you have. Now, all your trims(low,mid,high)will read 0 0r 100 depending on if it is a 1g or 2g. Now that we got that straight, More than likely your trims (especially your high trim) will be rich. That is why it is a base setting, it is supposed to run a little rich so it will be safe to run. After your high trim has settled, for 1g cars it will take about 30 min. of highway driving, adjust your base knob, dont touch any other knob, remember base knob is opposite of your other knobs. Turn your base knob ccw(conter clock wise) to make it richer and cw(clock wise) to make it leaner. Only turn it one click and wait for it to stabilize before you turn it more. after your high trim is at 100 or 0, you can move on to your other trims(low and mid). Do your low trim next then your mid.