Injector problem

[norm8332]

I have had random idle misfires since my maggie/injectors were installed and 2 shops have told me it's being caused by the "large" injectors. When the cam went in it got much more noticeable. Of course it goes lean at idle with the misfires and smells like gas at the TP.

Anyone else with bigger ones have a similar problem?

I'm Willing to swap the injectors, but to what?
Livernois installed "60 lb" injectors, and short style is all I know about the current ones.

I'm sick of the rough idle/shake. It's not the cam, it's small, and the tune is good. Any help would be appreciated!!

[Crazy Paul]

Post up some good pics of the injectors and post any part numbers you see marked on the injectors.

[norm8332]

Thanks, I will. This is the only pic I have now. Not much use though.

[99-LS1-SS]

I'm not having the issues that you are having. I think we have the same injectors. Bosch LS9 style injectors?

[norm8332]

It looks exactly like these (with the blue plastic). I try to find a number on one.

7771

http://www.lingenfelter.com/mm5/merchant.mvc?screen=prod&store_code=lpe&product_code=rxs107fm&category_code=c257

[norm8332]

I don't think they are the ls9 style. I think they are Siemens brand. I can't see much more than the picture. They are really in there.

[99-LS1-SS]

I don't think they are the ls9 style. I think they are Siemens brand. I can't see much more than the picture. They are really in there.

Ah, well I'm not sure then. I wonder if an injector is "hanging"? Have you asked Rick or Andy if they have any ideas?

[norm8332]

Maybe I'll just order the ls9 injectors you have if they will fit mine. If I look at a scan mine start to misfire below 1.7 ms which is around idle for me.

[99-LS1-SS]

Greg has the LS9 injectors at a pretty good price. It might be worth a call to him. I wonder if your injectors just can't go that low reliably?

[norm8332]

Are yours the short ones like I have (if you recall)? Please check the picture at post #3. Thanks. Have these been available long?

[99-LS1-SS]

I believe they are the short ones. Here is a link to the injectors that I have.

http://www.lsxtune.com/shop/product_info.php/products_id/1694

I don't know anything about your injectors so your's might have this feature too. But, from what I understand the LS9 injectors are made for the Magnacharger applications because of the angle of the spray cone. This is a quote from Greg Banish on HP Tuners forum regarding his findings on the LS9 injectors.


A little more research shows that the LS9/A injector has a bent angle to the same spray cone. They end up targetting the same spot (back of the intake valve) on the supercharged engines, but from a different injector position in the intake.

If you install these in the conventional position on an LS1/2/3/6/7, you run the risk of targetting the spray at the port wall instead of the valve. The flow rate is there, but the wall film effects will be much greater. Can you tune around this? Sure, but it's going to take a bunch of work to the "fuel to wall impact factor" and "evap factor" tables to tame the transient response.

[norm8332]

I believe they are the short ones. Here is a link to the injectors that I have.

http://www.lsxtune.com/shop/product_info.php/products_id/1694

I don't know anything about your injectors so your's might have this feature too. But, from what I understand the LS9 injectors are made for the Magnacharger applications because of the angle of the spray cone. This is a quote from Greg Banish on HP Tuners forum regarding his findings on the LS9 injectors.


These are 51.72 lb/h, whats the ceiling (HP) on these? It even mentions improved idle. Did they directly connect to the wiring without adapters? I'm ready to do it. Do you know where I can get the flow rate tables for these?

Sorry for all the questions, but this idle issue is almost the last thing I need to correct before I have the car where I want it. I'm excited at the possibility of a smooth idle.

[99-LS1-SS]

I believe around 650-700 rwhp.

You can use the flow numbers that the ZR1 uses.

[Andy@SquashPerformance]

FWIW I have the same injectors but with a lumpier cam and don't have a misfire issue. They came installed from Livernois, but I believe they get them from Magnuson. I will check my idle pw when I go home tonight, but chances are that it's not going to be noticeable on my car.

Andy

[norm8332]

Livernois did the install in Dec of 08. I beleive my car was the first G8/ maggie they did, so I'm not sure what injectors they used. But they are bigger and slower than the the ls9 injectors. I was told they were Siemens 60#, but I never got a part#.

[gr8lover]

Sorry for the dumb question... How can you tell it misfires? just from the sound... or from dashhawk/similair???

[norm8332]

My wideband shows it lean, the engine shakes, the misfires are reported on all random cylinders. No vacuum leaks. to test, I temporarly forced it richer idle by setting the final min injector pulse to 1.7ms - misfires gone but cant drive it like that.

[99-LS1-SS]

Found an interesting link and quote while thinking about this thread.

Fuel injector calculator
http://www.witchhunter.com/injectorcalc1.php4


Saw the same Data on the TVS 2300,I believe it is more like 100hp in reality.

So for all those that think that 600 rwhp is not enough...Here is a little math

600 rwhp on a stick car is roughly 700 flywheel hp + 100 to turn the blower 0= 800+ flywheel hp.Now try to fuel 800 flywheel hp!

Then put 8-10 psi boost on the front side of the injector that has 60 psi on the back side and you get 50-52 psi on an injector that has a rating of 49lb at 60psi and all the sudden your injector size just shrank,alot!

[norm8332]

Maybe further research is warranted. I read on another forum that the ls9 injectors only flow 48lb at 58 psi and the fuel pressure can go as high as 87.0 psi at wot on the ZR1. Don't know if it is correct though.

[99-LS1-SS]

I believe the ZR1 statement is correct. I would be shocked if the LS9 injectors only flowed 48 lbs unless they are referring to the LS9 injectors flowing 48 lbs due to boost pressure?

If my injectors (LS9 style) are rated at 52 lbs @ 58 psi and I have 6.5 lbs of boost then realistically, I have 45.5 lbs injectors at WOT. Damn....

I've never had a BAP before so I'm not sure if they boost only flow or pressure or a combination of both. How does the BAP work?

[99-LS1-SS]

Finding the right injector seems walking on a knife edge. If you get injectors that flow enough up high, they don't usually have good low end manners and vice versa.

[norm8332]

I wonder if these would idle better.

http://www.compperformancegroupstores.com/store/merchant.mvc?Screen=PROD&Store_Code=FS&Product_Code=30572_1_4_6_8&Category_Code=GMGenIV

[99-LS1-SS]

The only problem I've seen with FAST injectors is obtaining the data for them. I'm not sure they have the data.

[norm8332]

Those were the wrong type anyways. Looks like no easy fix.

[99-LS1-SS]

Norm,

This corrects my guess on how much HP the injectors will support. What power level do you think you'll end up with?

http://www.camaro5.com/forums/showthread.php?t=85332

[Devilish34]

Brandon would flow matched injectors like fasterproms offer help or??

[norm8332]

I think I'll get them, I could always switch back if I want to later. If it will idle smooth with 550-600rwhp then that's good enough for me.

Thanks for the help.

[Andy@Livernois]

Norm, they are the blue stripe 60's in your car. The first thing I would look at is doing a test on all the wiring. Adapters are needed for these injectors, so that would be my first test. we use the same 60# injector in all of our maggie installs for G8's, Camaros, and corvettes as the LS9 injector is done at about 575 rwhp on a stick and about 530 rwhp on an auto from all of our testing. The 60# we use can go to the max of the 2300 (about 650 rwhp on an auto) but she's done after that...

as far as the misfire with these, unless we had a dead injector right out of the box, we haven't seen any issues down the road, although, how many times have the injectors been dry fired because of dead pumps? I would say it might be a good idea to sonic clean, replace the screens, and reflow...

And I agree with Brandon, not a fan of "modified" injectors like the FAST units.

[norm8332]

I've never had a BAP before so I'm not sure if they boost only flow or pressure or a combination of both. How does the BAP work?

I missed this, the bap basically only helps flow since the bypass valve in the tank still cracks at 58 psi or so as far as I know. It would be nice if the valve could be replaced.

[99-LS1-SS]

Brandon would flow matched injectors like fasterproms offer help or??

Flow matched is good but it isn't a factor in the volume of fuel being delivered. It only affects the consistency between the injectors.

[99-LS1-SS]

Brandon would flow matched injectors like fasterproms offer help or??

Flow matched is good but it isn't a factor in the volume of fuel being delivered. It only affects the consistency between the injectors.

[99-LS1-SS]

I think I'll get them, I could always switch back if I want to later. If it will idle smooth with 550-600rwhp then that's good enough for me.

Thanks for the help.

Unless you have the ability to adjust your tune I wouldn't switch between injectors unless they are the same size and make. It could dramatically alter driveability.


Norm, they are the blue stripe 60's in your car. The first thing I would look at is doing a test on all the wiring. Adapters are needed for these injectors, so that would be my first test. we use the same 60# injector in all of our maggie installs for G8's, Camaros, and corvettes as the LS9 injector is done at about 575 rwhp on a stick and about 530 rwhp on an auto from all of our testing. The 60# we use can go to the max of the 2300 (about 650 rwhp on an auto) but she's done after that...

as far as the misfire with these, unless we had a dead injector right out of the box, we haven't seen any issues down the road, although, how many times have the injectors been dry fired because of dead pumps? I would say it might be a good idea to sonic clean, replace the screens, and reflow...

And I agree with Brandon, not a fan of "modified" injectors like the FAST units.

Thanks for stopping in and clearing things up Andy. I think your suggests are a great starting point.

[norm8332]

Unless you have the ability to adjust your tune I wouldn't switch between injectors unless they are the same size and make. It could dramatically alter driveability.

I can put in the tables. And I have a wideband. Thanks for helping me out and get this documented for future users. Now I feel that I'm well aware of the limitations of the ls9 injectors. But, I'm still going to give them a shot for the street. I don't have a fuel system anyways. I was going to do a BAP again but this time put it on an RPM window switch instead of just boost reference so it would not engage unless really needed. I estimate this would cut down on it's use by 80% in my case.