RC 550cc Injectors = Bad Idle?

[Mist3r Spool]

I can't fix my idle issue. It has that mmmmmmBLURPmmmmmmmmmmBLURP tone. I've come across some info from Hahn Racecraft stating that RC 550cc injectors will cause a poor idle and low-end driveability so they offer 650cc/660cc Injectors to remedy the issue . I haven't upgraded my fuel pump yet (still waiting for UPS) and thought that may help smooth things out. Any takes?

 

[CrippleFight]

if you would provide us with some more descriptive information on your setup it would probably help you out

 

[Mist3r Spool]

My vehicle profile isn't descriptive enough?

 

[CrippleFight]

sorry....the page wouldnt show up for a while

at idle(no boost) the injector size shouldn't be your problem. Only at higher RPM's if you're hitting the fuel cut off. I would check the tuning on your AFC

 

[Mist3r Spool]

sorry....the page wouldnt show up for a while

at idle(no boost) the injector size shouldn't be your problem. Only at higher RPM's if you're hitting the fuel cut off. I would check the tuning on your AFC

I've tuned my SAFC-II and can't smooth out the idle. Generally should I be having it more on the LEAN side or on the RICH side, for <1000RPMS?

 

[Ultimatedsm]

Do -10 across the board first than try going lower and lower until your car idles. Don't go TOO low though. At -15 your car should idle fine.

 

[Mist3r Spool]

I've went as low as -17 with no luck, but I'll give it a try again. I should be idling at ~750 correct? Ive noticed that many DSMers have a 1K idle.

 

[DGajre777]

I've went as low as -17 with no luck, but I'll give it a try again. I should be idling at ~750 correct? Ive noticed that many DSMers have a 1K idle.

My idle is 650.

 

[steve]

II should be idling at ~750 correct? Ive noticed that many DSMers have a 1K idle.

If your running a stock ECU and your ISC is working then you should have a 750 idle. Many people misadjust their BISS and drive the ISC out of range so they can get a 1k idle and others have a chip or DSM link with a 1K idle replacing the stock setting.

Are you trying to describe an idle miss?

Steve

 

[Mist3r Spool]

If your running a stock ECU and your ISC is working then you should have a 750 idle. Many people misadjust their BISS and drive the ISC out of range so they can get a 1k idle and others have a chip or DSM link with a 1K idle replacing the stock setting.

Are you trying to describe an idle miss?

Steve

My idle sounds like it's missing, it has a faint pop-corn popping noise to it (when it "blurps"). I have a stock ECU and have my base idle set screw set properly. Do I want to set my BISS to idle @ 1K?

 

[steve]

Do I want to set my BISS to idle @ 1K?

No.

Steve

 

[Mist3r Spool]

My theory is that the new injectors, which obviously flow more, are flowing all the fuel out of the lines and my stock fuel pump and 130K old fuel filter isn't supplying the sufficient fuel for a smooth idle. That's probablly way off but it's just a thought. I'm gonna have to borrow an impact gun to get the banjo bolt off my fuel filter, it's very tight.

 

[weith1111]

I've taken that sucker off twice without one. Flare wrench on top and bottom, use the bottom one for leverage to turn the top, it will break free, trust me.

 

[steve]

There are flats on the filter housing on each end so you can put a wrench on the filter and another on the bolt. If you put the wrenches on right you can squeeze them together and crack the bolt loose.

Steve

 

[Mist3r Spool]

Thanks for the removal help. I initally tried the "squeeze" method and had no luck. My buddy was helping me and decided to try and break it loose with a 1/2" drive socket and pinched my hard line. So, I called up my buddy @ SlowboyRacing and ordered a Walbro 255LPH pump, complete SS fuel pump -> fuel filter line, fuel filter, and SS fuel feed line...Problem solved.

 

[Sharkcus]

Wow. You described my problem to a T

The only way I can get it to idle halfway decent is to raise my 1000k lo throttle point (safc) to +4% or more. I know that can't be right, with bigger injectors, I should be leaning it, not adding fuel.

I am going to change my fuel filter and send my injectors out for cleaning and balancing. I will let you know when/if I solve this issue. Chime in if your solution ends up fixing it too, I am curious to know.

 

[Mist3r Spool]

I leaned out the idle on my SAFC to about -13 and it seems to be better. I'm sure my 160K old fuel filter/fuel pump aren't helping so I'll post when I get the upgrades from SBR.

 

[Sharkcus]

any news?

 

[Mist3r Spool]

Holy Crap, it's been a while since I've been on this site. Everything looks totally different...sweet. Anyway as for the issue, I had it fixed and then I messed it all up. I've kinda ditched the car in the garage (for about 2 months). I installed a Walbro 255lph fuel pump, a complete SBR -6an tank -> fuel filter SS braided line, a new stock fuel filter, & a SBR -6an SS fuel feed line (Oh yah, the stuff above). Everything was fine until I decided to hack my maf. I read on RRE that it's not such a bad idea (according to their tuning for SAFCs...which was not so). I should've just kept everything as it is, but I always like to get my hands dirty. I need a FPR for sure, my 255 must be running the crap outta the FPR! As for the idle, it's still nasty, I need a base tune and a FPR and I'm sure it'll be fixed.

 

[FastGS-T]

my idle did the same thing, couldnt tune the idle at ALL everything else was tuned fine though... then i blew a head gasket just cruising and noticed one of my injectors was missing that little metal spacer ontop of the o-ring

 

[Mist3r Spool]

my idle did the same thing, couldnt tune the idle at ALL everything else was tuned fine though... then i blew a head gasket just cruising and noticed one of my injectors was missing that little metal spacer ontop of the o-ring

You mean the plastic spacer, right? So your car was spitting out fuel instead of injecting it into the combustion chamber? Dang, that stinks.

 

[MyBeatGSX]

Glad I'm not the only one with this problem. My idle has a horrible random misfire all the time; initial startup, hot start (even worse), after running for awhile, etc. It all makes no difference. After a long run when everything is good and hot, I can hear the unburnt fuel exploding in the exhaust. Mine also started with the installation of 550's. Right now I'm running -8% at idle then up to -18% in the higher RPMs. It drives and runs fine at all other RPM points, only the idle is off. Leaner or richer at idle makes it worse.

Vacuum is usually dead steady at 19in/hg when its misfiring lightly, although it will fluctuate a small amount (+/-1 in/hg) from slightly lower (18in/hg) when it gets bad. Overall I'd say the vacuum seems to be mostly uneffected.

The O2 voltage bounces just like it should.

Plugs and wires are brand new, fuel filter is brand new, no vacuum leaks, no boost leaks, no fuel leaks, all injectors are sealed, no preturbo exhaust leaks. After idling for 5-10mins I pulled the plugs and they were all in perfect condition with no sign of running too rich. The one thing that worried me was the #3,4 plugs had whitish colored ground electrodes (coolant?), the #1,2 plugs were textbook perfect. The idle is at ~750, +/- 50rpm. It misfires ALL THE TIME. I haven't heard a smooth idle since I put the injectors in.

All mods are in the profile.

 

[Sbeing1]

I have the SAME problem too. I have 550cc and my idle is at like 1300-1900rpm. I have everything else running good just my idle sucks ballz. Has anyone figured out whats the problem yet?

 

[Sharkcus]

Glad I'm not the only one with this problem. My idle has a horrible random misfire all the time; initial startup, hot start (even worse), after running for awhile, etc. It all makes no difference. After a long run when everything is good and hot, I can hear the unburnt fuel exploding in the exhaust. Mine also started with the installation of 550's. Right now I'm running -8% at idle then up to -18% in the higher RPMs. It drives and runs fine at all other RPM points, only the idle is off. Leaner or richer at idle makes it worse.

Vacuum is usually dead steady at 19in/hg when its misfiring lightly, although it will fluctuate a small amount (+/-1 in/hg) from slightly lower (18in/hg) when it gets bad. Overall I'd say the vacuum seems to be mostly uneffected.

The O2 voltage bounces just like it should.

Plugs and wires are brand new, fuel filter is brand new, no vacuum leaks, no boost leaks, no fuel leaks, all injectors are sealed, no preturbo exhaust leaks. After idling for 5-10mins I pulled the plugs and they were all in perfect condition with no sign of running too rich. The one thing that worried me was the #3,4 plugs had whitish colored ground electrodes (coolant?), the #1,2 plugs were textbook perfect. The idle is at ~750, +/- 50rpm. It misfires ALL THE TIME. I haven't heard a smooth idle since I put the injectors in.

All mods are in the profile.

That is EXACTLY my problem, although I cannot say with 100% certainty that it is my injectors because I did a bunch of upgrades all at the same time. I am pretty sure they are the problem though. However, I even sent them off to be cleaned. They came back with perfect flow results and did not need to be cleaned. I put new BPR7ES plugs in. I had the stock plug wires, so I just bought a nice set of Accell wires, but haven't gotten them in yet. I did a leak test, no boost leaks. Right now I have the turbo off for a rebuild, but it will be back on soon. If I set my SAFC at like +7 for idle, it seems to misfire a little less, but eventually it goes back to the same thing. Thats about %25 more fuel then they should be dishing out and it still misfires. Like you, normal driving is fine. If anyone gets any closer to figuring this out, post here. I'll do the same.

 

[MyBeatGSX]

I would love to hear the solution to this.

Today I tried playing around with the AFC. I went as far as -20% and +5%. Going leaner fixed it for like 2 seconds and then made it worse, it was dying out at -20%. Going richer had zero effect, good or bad. I'm completely stumped. Maybe its ignition related?