Fuel Injectors

I'm starting this thread because I couldn't find anything exactly related.

Today I installed some 42.5 lb injectors. I picked them up used, sent them out to be cleaned and flow tested (CODY Motorsports in Georgia, good reputation, nice work, highly recommended, reasonable pricing). I correctly modified my IFR table for the larger injectors. I also noticed how ugly the OEM injectors were when they came out (130000 miles on them)

The first thing I noticed - my idle roughness and sputtering was gone! The engine sits smooth as glass at idle again! It hasn't run like this in... two years maybe?

Granted that I still have some re-tuning to do before everything is right on, but the change was immediate and very noticeable. Weather was bad, I won't have any real reporting to make until April, but still this made a huge difference.

It makes me wonder - how many engines do you think need their injectors cleaned? I mean really, really cleaned? I was thinking I should have my old injectors cleaned (having them cleaned out of the car on a separate machine has no equal), then sell them to somebody else in the club who still wants stock injectors, so they can do an injector swap with minimal downtime (have nice clean injectors on hand), then they can send theirs on to be cleaned and send them on to the next person who needs them, rinse, repeat, continue...

I'm still completely amazed at how big a difference it made.

Funny thing is, we were having a lot of problems with my brother's car (455 with custom fuel injection). Finally this summer we sent the injectors to be tested (they were 12 years old) and they were filthy, barely working, some wouldn't even clean up. Turned out we needed 3 new injectors and now the massive 455 idles smooth as glass like it used to. It's amazing the things you can do with a custom fuel injection system on a big cam 455 But I should have looked to the injectors on my car sooner, having known that...

The short point of this long story is... how clean are your fuel injectors???

Congrats on the injectors.

How are your IPWs at WOT before and after the injectors?

Last time I was at the track (last summer) with my 3.2 I was 19-20 IPW at WOT. I think they were going static because no matter what I tried to fatten up the top end I never got any more fuel and I couldn't change my KR any.

I am only running my 3.4 pulley and I have snow tires, so any WOT runs are useless right now. Plus with the pouring rain yesterday I didn't get to WOT anyway. It'll be a while before I can WOT scan, but I need to re-tune my idle/cruise anyhow.

deekster_caddy wrote:

Last time I was at the track (last summer) with my 3.2 I was 19-20 IPW at WOT. I think they were going static because no matter what I tried to fatten up the top end I never got any more fuel and I couldn't change my KR any.

I am only running my 3.4 pulley and I have snow tires, so any WOT runs are useless right now. Plus with the pouring rain yesterday I didn't get to WOT anyway. It'll be a while before I can WOT scan, but I need to re-tune my idle/cruise anyhow.

mine hit 17 or 19 the last time I did a full scan (and Ive added ALOT more fuel since then), but people on the DHP board were saying that 22 is more likely static, not 19.

but then alot of guys say whenthey get to our stage running a smaller than 3.4 pulley, they needed the injector upgrade.

Drew, are you pretty much suggesting that while using a 3.2 or smaller pulley, the factory injectors cannot provide enough fuel (with or without tune)?

I ask because I am using a 3.2" pulley right now with the stock injectors and tune. I normally use a 3.4" Recently, I have had a MIL on for a lean mixture, but there was a probably a good month between when I switched to the 3.2 and when the MIL showed up.

You need to scan to truly find out.

Even with tuning, you can only flow so much fuel through the injectors. If the injectors are old and cruddy, you flow less fuel... also when they do go static (wide open), you get very different flow patterns and poor atomization.

From what I've been reading, 3.2 with supporting mods is about the limit for the stock injectors, might be over the limit. Only your scanner can tell us

If anyone's running a 3.2" without scanning, I say you're playing with dynamite.

interesting thread. but cant you just instal a after market fuel pressure regulator and fool the injectors into delivering more fuel? and btw deekster, will your stock injectors fit a 95 s/c rivi? if they do im interested.

robotennis61 wrote:

interesting thread. but cant you just instal a after market fuel pressure regulator and fool the injectors into delivering more fuel? and btw deekster, will your stock injectors fit a 95 s/c rivi? if they do im interested.

As long as you get your chipped flashed for the injectors it should work. But there will be no gain as your injectors aren't maxed out ( unless you have mods I don't know of)


As for the Adjustable FPR it will only by you a little extra if any pressure (at least in my expierence)

turtleman wrote:

Drew, are you pretty much suggesting that while using a 3.2 or smaller pulley, the factory injectors cannot provide enough fuel (with or without tune)?

I ask because I am using a 3.2" pulley right now with the stock injectors and tune. I normally use a 3.4" Recently, I have had a MIL on for a lean mixture, but there was a probably a good month between when I switched to the 3.2 and when the MIL showed up.

yes, thats what Im suggesting from what others have said.

I am still trying to tune out knock with my 3.25" pully. I dont have a 3.4" so I just dont get on it unless Im scanning for knock. Im trying to tune my knock out but I MIGHT be successful after my top end rebuild ( dont know if there are any air/vac leaks since my gaskets are shot). Until I get to that fix, I will just keep adding fuel until KR goes away, or my injectors go static.

of course with an intercooler, you can put off buying larger injectors until you drop lower in pully sizes. But thats alot more expensive than injector/fuel pump upgrades.

dirty injectors can cause a lot of tuning problems. My whole tune is now too rich, because all cylinders are getting the amount of fuel they are supposed to. You should see how gross the original injectors were.

My new opinion is that there's no point in tuning if you have 100Kmile injectors that haven't been cleaned/flow tested. Even with the stock injector size. Put some good injectors in, then look at your problems again.

deekster_caddy wrote:

......... I was thinking I should have my old injectors cleaned (having them cleaned out of the car on a separate machine has no equal), then sell them to somebody else in the club who still wants stock injectors, so they can do an injector swap with minimal downtime (have nice clean injectors on hand), then they can send theirs on to be cleaned and send them on to the next person who needs them, rinse, repeat, continue.........

I could be interested. I doubt my injectors have ever been cleaned, and are likely originals. May be the reason I have KR on a 3.6 pulley with my listed mods. Any ideas on $$$? Also makes me wonder how effective/ineffective regular use of injector cleaner is.

^^^^^^^^
Derek?

sorry Dave, I forgot about this. It'd probably cost about $100 by the time I send mine out, have them cleaned etc and then returned.

If you are interested drop me a PM and I'll get things rolling. My old injectors are all sealed up, sitting in a box on top of my tool box, ready to ship.

-D

Thanks Derek, looks like I have a similar option available to me for less, so I'll pass for now. I do like the concept of passing such a deal around the membership.

so Im not really decided on my next mod - maybe some more information would help me decide.

I was planning on the larger injectors - pretty cheap fix and I could probably run my 3.0" with them. But really its not the most "efficient' way to go about it. The cheap mans fix if you will.
Another option is the go intercooled. I kinda bit myself in the ass cause my ported SC doesnt have an intercooler outlet. Will that be a huge problem if I go intercooled? And would I still need the injector upgrade? or would the cooler air help me be able to run my 3.0" without larger injectors?

Im thinking with option 1 above, im basically going until I chunk a piston and then looking at rebuild/boring/higher compression/etc, but still probably never intercooled if I went that direction.
With option 2, it will keep my car more reliable (as AA always talks about, kinda the reason we both went with rockers and not a cam even though mine is hardly driven)and I only got 110K on it, not really enough for a rebuild but not really a young healthy new motor either. Im thinking since I went with reliability and rockers, this might be the better option. It will probably take me a year or more to save up to get all the parts though. It wont be the SS intercooler, Im going big as possible that will fit under the hood. Seen cars running low 12's or better with this setup (stock heads/block/pistons, rockers instead of cam, etc.)

decisions decisions.

that should work check the ZZP site and see what that says, im almost positive that you need a XP cam to run the 3.0

Quote :

my ported SC doesnt have an intercooler outlet.

Please explain this. The outlet is the same as any other SC isn't it? I have installed many ICs and never had any special SC.

You can probably run a 3.0 or smaller through an IC without doing a cam, but just remember the engine is simply a big air pump and the more air you can get in and out, the more power you can make. That is why cam and heads are a better investment for serious power making. Also why a Gen V Blower is better - it flows more air at cooler temps, but you still need somewhere for that air to go.

With an intercooler, you'll get a machined LIM, which should help flow if I'm correct. Do you agree, Derek?

I think the IC is your best bet. Go with ZZP's best core. The 3.0" should be easy to run, but also install the bigger injectors just in case.

Since I have not done these mods take it for what it's worth, but an IC will do a great job of preventing KR for any amount of boost the motor can use. It does not address the higher fuel need in any way. It seems like at about a 3" pulley or so, you run out of injector and thats if everything else isn't maxed out before even that like tuning and maf sensor. You can put the biggest IC on it you want but if you have a bunch of boost and no fuel, youre in danger again and probably not making the power you want. Personally, I would do the injectors and tune first.

AA wrote:

With an intercooler, you'll get a machined LIM, which should help flow if I'm correct. Do you agree, Derek?

I think the IC is your best bet. Go with ZZP's best core. The 3.0" should be easy to run, but also install the bigger injectors just in case.

go for the 60lbers over the 42.5lbers you'll like it much better

Quote :

go for the 60lbers over the 42.5lbers you'll like it much better

Why?

If you are talking about a machined LIM that's different. I was trying to figure out what a SC outlet was...

Also, having larger injectors than you need will hurt your idle/gas milage. Depends how big you go, 42.5s will get you a long way. They are also very resalable should you prove to need 60s.

AA wrote:

Quote :

go for the 60lbers over the 42.5lbers you'll like it much better

Why?

when more people in the 3800 modding scene switch to E85........... 42.5lbers just cant keep up

very good point travis