I recently sent in injectors from a 3.4L Camaro engine to be cleaned and pressure tested. I was informed the injectors were unrestorable. I still have the 2.8L injectors, however I understand if I use them the engine will run lean, creating additional heat. At this point I am leaning towards using 17lbs injectors from Accel 150617. I am curious if others have used these injectors, and what there experience is especially concerning idle flooding.

quote Originally posted by aquamarine: ... I still have the 2.8L injectors, however I understand if I use them the engine will run lean, creating additional heat.

additional heat ?! that's crap. I ran my 3.4 for over 7k miles with the 2.8 injectors and it ran fine. Others may argue that it's not OPTIMAL, but it will run fine. Spend your money on other things

quote Originally posted by aquamarine: At this point I am leaning towards using 17lbs injectors from Accel 150617. I am curious if others have used these injectors, and what there experience is especially concerning idle flooding.

You'll be fine with 17-pound injectors in your 3.4L engine swap, as I thought I and TK had reassured you in your previous thread titled, "3.4 Injectors" (accessible via this link: https://www.fiero.nl/forum/Forum2/HTML/096664.html ).

I've not experienced flooding with those 17-pound Accel injectors in my 3.4L engine swap, and I'm at a loss to understand why you would expect that problem in yours.


If it puts your mind at ease any about this, be aware that 17-pound injectors are the standard injector size for GM's pushrod 3.4L engine.

quote Originally posted by PaulJK: additional heat ?! that's crap. I ran my 3.4 for over 7k miles with the 2.8 injectors and it ran fine. Others may argue that it's not OPTIMAL, but it will run fine. Spend your money on other things

Totally agree. Don't be afraid to use the stock ones. I used them for a very long time with no lean problems at all and it had a lot of mods. If you go 17# then do get a PROM. If not changing the PROM you are better of with the stock 2.8 ones.

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Red: TPI V8 + 6-Speed Yellow: Nitrous 3.4 + 4 speed Auto
304rwHP/366rwTQ

Thanks for the information...somehow I lost my prior listing.

So there is no issue with pushing the original 15lbs injectors beyond their duty cycle with the 3.4L engine? I assumed there must be some down side of using the original injectors with the 3.4 engine.

I have just finished changing out my injectors, I have a Fiero Factory 3.4 motor and it had the original 2.8 injectors, not to mention they had over 175K on them, the car ran poor.
I got some Tec help from a Injector remanufacturing Company out of Canada. Here is what they said. Factory 2.8 use a 83cc injector, the 3.4 uses a 91cc injector, they advised to make the change (as does the Fiero Factory) I swapped them out and the car came to life! The injectors rebuilt were my cost 37.61 ea. From Dakota Auto Parts, Sioux Falls, SD. I am now in the process of chasing down everything else. Good Luck, Don

Do not take this as trying to flame anyone but:

quote Originally posted by project34: You'll be fine with 17-pound injectors in your 3.4L engine swap,

Yep - he'll also "be fine" with the 2.8 ones. "fine" - yes; "necessary" - no.

quote Originally posted by project34: If it puts your mind at ease any about this, be aware that 17-pound injectors are the standard injector size for GM's pushrod 3.4L engine.

No Doubt. But the 3.4 swap into the fiero does Not use the STANDARD 3.4 engine. It uses the 3.4 long block with major 2.8 fiero parts (intakes, exhaust, throttle body, sensors, etc.) swapped onto it. But hey, if he wants to buy into it, then he should read all the threads that say you also need an adjustable fuel pressure regulator with the 17# injectors ... and don't forget all the ones that also say to add the MSD ignition box, and low restriction K & N intake to help "breathing". If you believe this theory, then believe it all, not just some of it. Heck, they are guys here that will probably even do some calculations to prove it with the math . All this crap will add $ Hundreds to his swap and not do much (although the MSD DID smooth the idle).

quote Originally posted by dakotamustang: ... and the car came to life!

My 3.4 had enlarged throttle body, ported and matched intakes and exhausts, all new ignition (including the $185 MSD box) and a new ATK long block (new compression). Putting on the larger injectors made no difference. If your car "came to life", there was something else wrong. Like maybe your 2.8 injectors with 175,000 miles on them were shot to begin with. c'mon - come to life on TWO #s of difference ?!

quote Originally posted by aquamarine: So there is no issue with pushing the original 15lbs injectors ....

How are you "pushing" the injectors ? You 've got the air going through the 2.8 fiero parts, fiero 2.8 engine sensors and the fiero 2.8 ECU controlling everything. (?!)

quote Originally posted by aquamarine: .... there must be some down side of using the original injectors with the 3.4 engine.

If you rev every shift to the red line and/or are using a turbo, then i'd have to say the stock injectors are on the down side - maybe even find some bigger than 17 # for a turbo.
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Man I hate to see people tell people asking for help to waste money - because it already happened to me. I bought 6 new 2.8 injectors for about $90 EACH when the swap was done (the guy doing the swap recommended this) and later bought the Accel injectors for $200 more (somebody else recommended that. The >$500 worth of 2.8 injectors with about 7k miles on them got THROWN AWAY because NO ONE here will pay much for them, even if you can find someone who wants them.

But what do I care ... my car runs fine. Buy what you want - believe what you want.

If I already had good 2.8 injectors (for free) and had guys telling me from experience they would be OK, I'd at least put them in and give it a shot ... before i had to throw them away ....

Put the 2.8 injectors in your car and drive it for awhile. Then go to a fiero meet and drive somebody's 3.4 with the 17 #. If the 17 # alone make you happy, THEN spend the money

[This message has been edited by PaulJK (edited 11-30-2008).]

Hey thanks everyone....at this point I will try my 2.8L injectors and see how they work they only have 60K on them.

quote Originally posted by PaulJK: Do not take this as trying to flame anyone but: My 3.4 had enlarged throttle body, ported and matched intakes and exhausts, all new ignition (including the $185 MSD box) and a new ATK long block (new compression). Putting on the larger injectors made no difference. If your car "came to life", there was something else wrong. Like maybe your 2.8 injectors with 175,000 miles on them were shot to begin with. c'mon - come to life on TWO #s of difference ?! If you rev every shift to the red line and/or are using a turbo, then i'd have to say the stock injectors are on the down side - maybe even find some bigger than 17 # for a turbo.

DITTO. Mine had FOCOA headerse too, CAI, under pulley, etc. I did send them for cleaning/blueprinting. Good 2.8s will work more than fine unless you change cam/intake mfld.

yes, 17# injectors are the "right" size for a 3.4 V6 making 150-180hp
from 180-200 19#'s are more appropriate - but 17's will still do
and, that is for an average duty cycle - as mentioned - 15's can be stretched to do the job - especially with a stock Fiero intake.

peak HP's & how many cylinders are the variables to use when determining injector size

I would be worried the engine runs a bit lean on start up until it goes closed loop and the fuel trims compensate.
Anyone have any wideband O2 experience with the 15lbs injectors on a 3.4L swap?

And what is wrong with an adjustable fuel pressure regulator to correct a lean open loop?

[This message has been edited by Hudini (edited 12-01-2008).]

The 15 lb injectors will work on a 3.4L as the ECM will adjust the pulse width according to the engine load. Where you will get into trouble with this size injector is at WOT. At WOT the O2 sensor output is ignored and the ECM uses a FIXED fueling table that is calibrated to the 15lb not 17 lb injecftor. Some may disagree but the 3.4L swap does require an ECM reprogram to work correctly.
My turbo 3.4L uses 24 lb Ford Motorsports injectors and the injector base pulse constant number in the ECM constants table had to be scaled to the new injector flow accordingly.

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87GT - 3800SC Series III engine, 3.4" Pulley, N* TB, LS1 MAF, Flotech Exhaust Autolite 104's Custom CAI 4T65eHD w. custom axles, HP Tuners VCM Suite.
87GT - 3.4L Turbocharged engine, modified TH125H
" I'M ON THE LOOSE WITHOUT THE JUICE "

So what was your new BPC with the 24lbs injectors?

If the ECM needs reprogramming who or where should that be done?. I just put in 19lb mustang injectors in my 3.4 swap. I plan on using the trueleo intake, but first need to pass smog (visual).

Is this something that Darth Fiero should do, or do I need to go to a dyno-shop and get worked for a few hundred dollars?

[This message has been edited by blkpearl (edited 12-01-2008).]

Blkpearl... Is your car running smooth with the 3.4L and the 19lb. injectors? How rich would you say at idle / wide open? Do you worry about smog (data) from the computer? - visual will be cake.


DOES ANYONE KNOW THE DIFFERENCE FROM A 3.4L DOHC INJECTOR COMPARED TO A 3.4L OHV INJECTOR BESIDES one being 17lb. and they other (I think) is 19lb.?

Car is not running yet. We are going to be bolting the engine/craddle this next week. So in a few weeks I will know alot more.

Hurry... j/k --- I bet you can't wait!


I'm a little further behind you. My long block rebuild should start this coming week at Hiperformer in Washington. I've prepped for everything else and gotten things ready for bolt-on--- just trying to get a head start on the final stuff.

Let us know how it is when you finished... I'm in SoCal too.. We are all interested (FierosWest Car Club)

I've got a curve ball for you guys...

Will injectors from a 3.4L DOHC work in a 3.4L OHV iron heads..... I believe the pound rating is different from the two ( OHV = 17lbs. and DOHC = 19lbs. Now I hear people using mustang's 19 pound and seem to be doing okay. The body's of the injector are exactly the same for fitting

I do have the Holley fuel pressure regulator for adjustment and a hi-flow fuel pump to fill those bad boys and I'm planning on a turbo setup for next winter but I will be running it N/A for the first year to get the kinks out. After Cali smog check I will adjust the computer to compensate for the new injectors. I'm hoping the output of my 3.4L OHV is around 180hp with 200 lbs of torque N/A. Before you bash me on the hp, I've done some mods internally to help the numbers and like I said, I'm hoping.. so we'll see.

So what do you think? Think it'll work or should I just be in the market for the OHV 3.4L injectors only?

They will work. I'm running 24lbs injectors on my 3.4L OHV with turbo. I'm working with Darth Fiero to get the tune now.

The Grooms remanufactured 3.4 that one of our members installed is running the Mustang 302 19# injectors without any adjustments on the regulator or prom. His mileage dropped from about 28 on a stock 2.8 to around 20 on the 3.4. It does run a little rich at idle, otherwise there are no issues. The drop in mileage is probably a combination of the larger engine and the injectors, but as I said, it's a very driveable combination.

Having said that, I spoke with the folks at fuel injector city and they said that the 17# injectors were the standard for the 3.4 engine. When asked about disk or pintel type injectors, he recommended disk due to the spray pattern. He said pintel emits a stream while disk emits a cone shaped spray. And he said there should be no issues with the prom but pressure might need to be adjusted at the regulator. Just another variable to the possibilities.

quote Originally posted by Hudini: So what was your new BPC with the 24lbs injectors?

From memory- around 170.

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87GT - 3800SC Series III engine, 3.4" Pulley, N* TB, LS1 MAF, Flotech Exhaust Autolite 104's Custom CAI 4T65eHD w. custom axles, HP Tuners VCM Suite.
87GT - 3.4L Turbocharged engine, modified TH125H
" I'M ON THE LOOSE WITHOUT THE JUICE "

quote Originally posted by fierofool: When asked about disk or pintel type injectors, he recommended disk due to the spray pattern. He said pintel emits a stream while disk emits a cone shaped spray. And he said there should be no issues with the prom but pressure might need to be adjusted at the regulator. Just another variable to the possibilities.

If he thinks that disc type injectors have a good spray pattern just watch this vid. The Lucas disc injectors ( also packaged by Tomko) have the poorest spray pattern. Looks at the three streams as opposed to the mist of the Bosch and the GM Multitec

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87GT - 3800SC Series III engine, 3.4" Pulley, N* TB, LS1 MAF, Flotech Exhaust Autolite 104's Custom CAI 4T65eHD w. custom axles, HP Tuners VCM Suite.
87GT - 3.4L Turbocharged engine, modified TH125H
" I'M ON THE LOOSE WITHOUT THE JUICE "

How do you know what spray pattern each individual injector is?.. Is it in the model code or is it the actual brand itself?

Thanks for the answers for before.

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OH... I TAKE IT THAT THE COMPUTER AND MOST INJECTORS WITH THE SAME STYLE CONNECTORS WILL COMMUNICATE TO EACH OTHER TOO, RIGHT?

[This message has been edited by unboundmo (edited 12-02-2008).]

unboundmo, it sounds like we are doing exactly the same thing. My engine will be running soon, and then I will work on the Turbo. After this works out and I like it, I will then do a rebuild and go with forged pistons.

I guess it's the likely story when you live in Cali..... stock look to pass smog and then we add all the bolt-ons.

Blk pearl - there are only a couple companies, it seems like, that actually want to help us with our V6s.. Ross pistons are "nice" and custom for around $99 per. That's what I will be using.. Connecting rods are hard to come by.. I'm going to try ARI for those. I couldn't find anyone else.
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Heads up for FierosWest club members Holiday party in Cali... I assume that you are in San Diego.. I know it's a drive to Long beach airport area but it'll be fun. 7pm on Saturday the 13th of Dec.

Dennis, there's just so much informatiion that it's difficult to determine what is the best combination. I think what the guy was saying was that the cone spray pattern atomized the mixture better than a stream pattern. I guess we just have to try something and see if it works for us. From all the discussions that have gone on about this subject, just about every combination has worked for 1 person, but not for another. Personally, I'm picking up a set of used 17's from a Grand Am engine to drop into my 3.4 transplant.

quote Originally posted by fierofool: Dennis, there's just so much informatiion that it's difficult to determine what is the best combination. I think what the guy was saying was that the cone spray pattern atomized the mixture better than a stream pattern. I guess we just have to try something and see if it works for us. From all the discussions that have gone on about this subject, just about every combination has worked for 1 person, but not for another. Personally, I'm picking up a set of used 17's from a Grand Am engine to drop into my 3.4 transplant.

I believe that you have chosen the easiest solution. The #17 injectors are the ones calibrated for the 3.4L and may work w/o any ECM adjustments. Almost any injector size from 17-#24 can be made to work but when you go sharply up in flow, then ECM recalibration becomes more necessary.

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87GT - 3800SC Series III engine, 3.4" Pulley, N* TB, LS1 MAF, Flotech Exhaust Autolite 104's Custom CAI 4T65eHD w. custom axles, HP Tuners VCM Suite.
87GT - 3.4L Turbocharged engine, modified TH125H
" I'M ON THE LOOSE WITHOUT THE JUICE "

quote Originally posted by fierofool: ...Personally, I'm picking up a set of used 17's from a Grand Am engine to drop into my 3.4 transplant.

Are they pintle type or disc?

I think they're disk. The garage does't know, the Chevy dealer down here doesn't know, but thhe injectors don't have that bonnet on them like the one you showed me. But he has 1 set from a 3400 Grand Am and one set from a Grand Prix or Bonneville 3400.

quote Originally posted by Raydar: Are they pintle type or disc?

most injectors are disc. Fiero is one of the few to ever use pintle types.
and, the only difference is the spray pattern - disc have a wider cone, pintle sprays a narrower cone.

and, I'm not sure about this - but, I do think that the injector holes on the stock Fiero intake manifold should be made bigger when using disc type injectors. I think the wider cone does spray the sidewall, and could inhibit atomization

Pyrthian, that was my thoughts too. Though I've never been into the intake area of a Fiero, I wondered if the injectors were set further away from the valve and needed a more direct stream. When I get the chance, I'm going to borrow a Fiero intake from someone and compare it to the 3.4 lower intake that I have to see how they compare.

quote Originally posted by fierofool: Pyrthian, that was my thoughts too. Though I've never been into the intake area of a Fiero, I wondered if the injectors were set further away from the valve and needed a more direct stream. When I get the chance, I'm going to borrow a Fiero intake from someone and compare it to the 3.4 lower intake that I have to see how they compare.

I'm having a little trouble understanding the concern about trajectory of the injector stream, considering that the 2.8 Fiero injection system bank fires instead of sequentially.

I put a 3.4 in my 87 in 2000 mainly with info on the net,with 3.4 injectors with an adjustible fuel regulator its cheap insurance I used the car as a daily for many years put 75-80 thousand miles on the car after the swap getting around 28 mpg. the car now has over 200 thousand miles on it and still runs fine. Just everything else is done so we are going thru her bumper to bumper and making it a fun toy. 15lb 2.8 injectors are just to small IMO the engine is .6 liters bigger you can't say it doesn't need more fuel. Lean is mean until you burn a hole in a piston. Just my 2 cents

quote Originally posted by fierofool: ...When I get the chance, I'm going to borrow a Fiero intake from someone and compare it to the 3.4 lower intake that I have to see how they compare.

I think I have an extra.
If I do, I'll try to remember to bring it to the meeting.

[This message has been edited by Raydar (edited 12-03-2008).]

quote Originally posted by randye: I'm having a little trouble understanding the concern about trajectory of the injector stream, considering that the 2.8 Fiero injection system bank fires instead of sequentially.

It isn't the sequense of firing. The thought is that the longer the passage from the tip of the injector to the valve seat, the more direct the stream should be. if you're spraying a cone pattern in a long passage, the cone will strike the walls of the passage, converting into a dense droplet. Liken it to spraying a garden hose with a wide pattern and inserting the nozzle into a foot long pipe. What comes out the other end would be a dense droplet rather than a fine atomized mist.

I agree on the manifold port area and think the common sense is true about the walls collecting the fuel instead of the air. I ported my plenum down to the lower manifold. Gasket matched. There are side walls that get in the way in the lower manifold.. Here's some before and after picture. I didn't think of the spray pattern then when I was doing this though. I was just think cfm flow.

quote Originally posted by fierofool: It isn't the sequense of firing. The thought is that the longer the passage from the tip of the injector to the valve seat, the more direct the stream should be. if you're spraying a cone pattern in a long passage, the cone will strike the walls of the passage, converting into a dense droplet. Liken it to spraying a garden hose with a wide pattern and inserting the nozzle into a foot long pipe. What comes out the other end would be a dense droplet rather than a fine atomized mist.

I understand all that.
What I still don't understand is why all the concern when 2 out of every 3 times any of the 6 injectors fires, it's squirting at, (or near), a *closed* intake valve...
Like I said, my understanding is that the OEM V6 injection system bank fires, *not* sequentially fires.

quote Originally posted by randye: I understand all that. What I still don't understand is why all the concern when 2 out of every 3 times any of the 6 injectors fires, it's squirting at, (or near), a *closed* intake valve... Like I said, my understanding is that the OEM V6 injection system bank fires, *not* sequentially fires.

well, firing at a closed intake valve is in fact what you are going for.

If atomization of the fuel wasn't needed, then why not just put a solid squirt of fuel direct to the valve? I think there's some benefit gained by not having the mixture turn back to a liquid because it's running down the side of the intake.

quote Originally posted by Pyrthian: well, firing at a closed intake valve is in fact what you are going for.

That's what I'm trying to understand here.
Since the 2.8 ECM bank fires the injectors, that means that a given injector fires fuel three times at a closed intake valve for every 2 turns of the crank.
Only on the third injector firing does the intake valve open. At least thats the way I'm understanding it.
Injectors for cyls. 1, 3 and 5 all fire at the same time and injectors for cyls. 2, 4 and 6 all fire at the same time in bank firing mode.
Doesn't that mean that fuel would collect at the intake valve from the first two firings of the injector?

I understand that sequential injector firing would be different, but that isn't the case with a 3.4 using the original 2.8 ECM and injector system.

Help me out here. What am I missing?

[This message has been edited by randye (edited 12-04-2008).]