I am getting conflicting answers as to which fuel injectors I should use in the new 3.4 engine I am installing in place of my 2.8. The 2.8 uses 15 lb./hr. injectors, but I have been told to use the 17 lb./hr. injectors in the 3.4. I was talking with West Coast Fiero today concerning flexplates, and was told that I might want to consider using 15 lb./hr. injectors because of the need to pass smog tests in the psychotic state of CA every two years.
Has anyone had any experience with this? I have ordered the larger injectors, but can change my order. I am not using the old injectors, obviously, so I will be getting new ones no matter what. I just don't want to buy two sets at 403.00 apiece...
The 17 pound injectors should be OK with the 3.4 L push rod engine. If you go to 19 pound injectors, it will be pig rich and require modifying fuel tables in your controller. I am running slightly detuned 19 pound injectors on a turbo 3.4 setup, and it was initially too much fuel but good for black smoke generation. That would make it difficult to pass a CA inspection.
The 17 pound injectors should be OK with the 3.4 L push rod engine. If you go to 19 pound injectors, it will be pig rich and require modifying fuel tables in your controller. I am running slightly detuned 19 pound injectors on a turbo 3.4 setup, and it was initially too much fuel but good for black smoke generation. That would make it difficult to pass a CA inspection.
Thanks for the comeback. I think the 15 lb. units might have a tendency to be too lean. So I guess I will take my chances and order a whole new set of 17 lb. units and install them. I would think that if an engine is run too lean, it could also create emission issues, so I will go with the happy medium.
I have been running my 3.4 conversion (In a 85) for 20 years...It has passed smog 8 times and I am using the original injectors because the 17 lb F-body injectors would not work with my computer- supposedly the 88 computer will run them.
The only problem I have is that at low throttle movements (Driving in 25 zones) it will jerk back and forth a bit...Driven hard it runs like a raped-ape. I now have an 88 computer but it has no cold idle- it runs at 1000 rpm cold or hot.....I will try swapping in those 17 lb injectors in the future
Originally posted by cvxjet: The only problem I have is that at low throttle movements (Driving in 25 zones) it will jerk back and forth a bit...Driven hard it runs like a raped-ape
I guess you have EGR working? You may want to (temporarily) disable that; if the car smooths out, then you have too much EGR... could possibly be reduced in the tune.
I had bucking at low load/RPM on my Fiero, and reducing the spark advance in those areas helped to alleviate the bucking. Also something that could be changed in the tune. You could do an initial quick-and-dirty test by retarding the timing 10-20 degrees (rotating the distributor). https://www.fiero.nl/forum/F...L/142133-5.html#p198
[This message has been edited by pmbrunelle (edited 11-30-2020).]
I have a 3.4 in my 87. its fully custom with cam, 1.6 roller tip rockers, bored TB Bored plenum, custom PPG style plenum, custom manifolds, etc etc. my 17 lb rochester injectors from a 93 camaro work fine, but in my case they barely haandle the needed fuel. there coming out anyway and 28lb are going in as im installing a vortech v1 sc set up.
I've used 19# Mustang injectors and the original 17# injectors that came in the 3.4. As said, the 19# will run rich, but with a stock Fiero ECM, the original 3.4 injectors are much worse. Injector size is determined by number of cylinders and horsepower. Six cylinders at 160 horsepower requires 17# injectors. The stock ECM will efficiently operate a pintle style injector. The BMW EV1 injectors flow 16.76 # which is slightly above the required 16.66 #. Not enough to cause it run rich.
Aren't you using the FWD 3.4? That engine has redesigned aluminum heads. Nothing about the Fiero engine (intake, emissions controls, etc.) is compatible with it. Worse... swapping the Fiero heads onto that block, in order to use the Fiero intake and plumbing, will result in about 7.5:1 compression. There's more to it than even that.
Of course, if you are swapping the whole thing in, as a unit, and retaining the LA1 heads, intake, and ECM, it should be pretty straightforward. Although it won't look "stock Fiero" any more. But then there's the California smog referees to deal with. (Can't help you much with those, since I live in GA.)
Aren't you using the FWD 3.4? That engine has redesigned aluminum heads. Nothing about the Fiero engine (intake, emissions controls, etc.) is compatible with it. Worse... swapping the Fiero heads onto that block, in order to use the Fiero intake and plumbing, will result in about 7.5:1 compression. There's more to it than even that.
Of course, if you are swapping the whole thing in, as a unit, and retaining the LA1 heads, intake, and ECM, it should be pretty straightforward. Although it won't look "stock Fiero" any more. But then there's the California smog referees to deal with. (Can't help you much with those, since I live in GA.)
Sorry. Hate to be the buzzkill...
I think that I had posted accidentally that this was the case, for which I apologize. I am using RWD 3.4. I received it yesterday and the first things I checked were tranny match up, starter location, valve cover fit, etc. It's all good. Thanks for the warning...
Originally posted by eti engineer: ... I am using RWD 3.4. I received it yesterday and the first things I checked were tranny match up, starter location, valve cover fit, etc. It's all good. Thanks for the warning...
Whew! Excellent! My apologies for missing your update / additional info.
I had 19# Bosch pintle-type injectors in my 3.4. (They were sold as replacements for a 98 Jeep 4.0 straight six.) Using a stock tune, IIRC, it ran rich until it went into closed loop, and then it passed a sniffer test just fine. (Georgia used to do a 2 speed dyno-roller test.) Even with a 272 cam, headers, big throttle body, etc.
But yeah... 17s would have been better.
EDIT -
quote
Originally posted by eti engineer: ... I think the 15 lb. units might have a tendency to be too lean. So I guess I will take my chances and order a whole new set of 17 lb. units and install them. I would think that if an engine is run too lean, it could also create emission issues, so I will go with the happy medium.
The real trick is finding 17# pintle-type injectors. The Fiero ECM is tuned for those characteristics. (Fierofool might have a line on those. I haven't talked with him about injectors in quite some time.)
I have been running my 3.4 conversion (In a 85) for 20 years...It has passed smog 8 times and I am using the original injectors because the 17 lb F-body injectors would not work with my computer- supposedly the 88 computer will run them.
Very odd. I ran a 1985 ECM in my turbo Fiero as it is the only one that has the software for positive pressure operation and it ran my 17 lb injectors just fine.
In any case, for a 3.4 in a Fiero the stock 17 lb 3.4 injectors are appropriate.
As with many things, the answer is "it depends". The required injector size will be dictated by the engine's power output. A good rule of thumb for 60-degree V6 engines (running on pump gas) is 1 lb/hr for every 10 HP. So if you think the engine will only make 150 HP, then 15 lb/hr injectors will probably work. But the 3.4 V6 was rated for 160 HP from the factory. So for a stock 3.4 (iron head), 16 or 17 lb injectors would be ideal.
As with many things, the answer is "it depends". The required injector size will be dictated by the engine's power output. A good rule of thumb for 60-degree V6 engines (running on pump gas) is 1 lb/hr for every 10 HP. So if you think the engine will only make 150 HP, then 15 lb/hr injectors will probably work. But the 3.4 V6 was rated for 160 HP from the factory. So for a stock 3.4 (iron head), 16 or 17 lb injectors would be ideal.
The engine will be making a little over 200 hp, according to the builders. So you're saying I might have to go even larger, right?
If it's actually producing that much power, then yeah. Then you'll probably need 21 lb/hr injectors.
Here's a nifty injector calculator, if you want to play around with some numbers: https://www.rcfuelinjection.com/technical Scroll down to the Fuel Injector Worksheet at the bottom.
The folks talking about lean/rich, pintle/disc, it's because they're trying to adapt the injector to the stock Fiero tune... If they get it close enough, then they can save the cost/time/headache of figuring how to modify the tune in the ECM.
In an ideal world, you select an injector to suit the engine (not the computer), and then you program the injector characteristics into the ECM.
For a 200 hp build, this sounds somewhat different from stock, so the engine builder should expect to modify the tune of your ECM.
Since the builder/tuner has to modify the tune for the modified engine's characteristics, it wouldn't be much more difficult to also adjust the tune for your injector characteristics, while he's in there.
Therefore, when you choose an injector, I would not add the constraint of matching the injector characteristics contained within the stock tune of the Fiero ECM.
[This message has been edited by pmbrunelle (edited 12-02-2020).]
I agree with the above. Your engine is producing almost 1.5x the power of the stock V6. So it's going to need a custom tune. You could have the tuner build the tune with emissions compliance in mind.
The engine will be making a little over 200 hp, according to the builders.
A lot of builders get their hopes hi because they are used to build Chevys and Fords V8s, not knowin the 60* V6 is a different specie. What's your set up? Cam, intake, exhaust, etc. Based on my experience I can give you and idea on what size injectors you may need.
I have been running my 3.4 conversion (In a 85) for 20 years...It has passed smog 8 times and I am using the original injectors because the 17 lb F-body injectors would not work with my computer- supposedly the 88 computer will run them.
The only problem I have is that at low throttle movements (Driving in 25 zones) it will jerk back and forth a bit...Driven hard it runs like a raped-ape. I now have an 88 computer but it has no cold idle- it runs at 1000 rpm cold or hot.....I will try swapping in those 17 lb injectors in the future
Thanks for the information... This is kind of what I expected. I have ordered a new set of 17 lb. injectors anyway, as I was not planning on using the old ones. I will see how it works out, once I get the vehicle back on the road.
------------------ 1988 Fiero, 1962 CJ-5 and more to come...
I agree with the above. Your engine is producing almost 1.5x the power of the stock V6. So it's going to need a custom tune. You could have the tuner build the tune with emissions compliance in mind.
Can you really do that in CA? Won't the smog test equipment know that the engine tune is not stock??
Not on OBD1 cars. They only hook OBD2 cars to the computer.
OB1 was up to 1996. Hot dog! Retaining the distributor of course, should ET1 Engineer also consider swapping in the ECM 7730 to accrue its several advantages?? Seems like a CA-friendly change since it is invisible and with OB1 they don't plug in.
ET1, here is one of the many 7730 threads if you get interested: 7730 ECM
I am getting conflicting answers as to which fuel injectors I should use in the new 3.4 engine I am installing in place of my 2.8. The 2.8 uses 15 lb./hr. injectors, but I have been told to use the 17 lb./hr. injectors in the 3.4. I was talking with West Coast Fiero today concerning flexplates, and was told that I might want to consider using 15 lb./hr. injectors because of the need to pass smog tests in the psychotic state of CA every two years.
Has anyone had any experience with this? I have ordered the larger injectors, but can change my order. I am not using the old injectors, obviously, so I will be getting new ones no matter what. I just don't want to buy two sets at 403.00 apiece...
Thanks.
I did my 3.4 swap 100 years ago, but if I remember correctly I was recommended Accel 17 lb pintle injectors. The 2.8 injectors weren’t sufficient, and (305?) injectors were once recommended but the car ran like s***. It ran great with the 17lb injectors.
OB1 was up to 1996. Hot dog! Retaining the distributor of course, should ET1 Engineer also consider swapping in the ECM 7730 to accrue its several advantages?? Seems like a CA-friendly change since it is invisible and with OB1 they don't plug in.
ET1, here is one of the many 7730 threads if you get interested: 7730 ECM
Depending on how thorough the smog check is, an aftermarket ECM might fail you for smog if something as simple as the check engine light doesn’t work. There’s also the measurement of what ends up coming out the tail pipe. A stock 3.4 with all the emissions stuff working (EGR system and all sensors) should easily pass smog. An aftermarket ECM, 200hp build and no check engine light will be a crap shoot.
As others have mentioned, you should expect to retune the ECM. You'll need to adjust the injector "offset" values to match the characteristics of your injectors. If those are set wrong the ECM will get confused trying to figure out the fuel trims and it may suffer the notorious hunting idle problem. My car is still a 2.8L but I believe the refurb injectors that a shop sent me several years ago came from a 1993-95 3.4L FBody (I didn't confirm with certainty). To make those injectors work properly the most important thing was to copy the injector offset tables that were in the stock ECM tune for those 3.4L cars. That fixed the idle and I think it was what also fixed a stumble coming off idle. The files for those cars were posted by somebody on another ECM tuning forum (maybe it was gearhead-efi?). After that you can start tweaking the BPC value to globally make it richer or leaner.
BTW on a side note, burning chips for the ECM also gives you the ability to tweak timing for an emissions test without it being detectable. They only check the base timing, not the advance added by the ECM.
quote
Originally posted by Notorio: OB1 was up to 1996. Hot dog! Retaining the distributor of course, should ET1 Engineer also consider swapping in the ECM 7730 to accrue its several advantages?? Seems like a CA-friendly change since it is invisible and with OB1 they don't plug in.
I recently left California, and I still have to pinch myself to realize that I don't have to worry about these nitpicky emissions inspections ever again.
But while I was there, I thought about doing a 7730 swap. If it's done correctly then the Check Engine light should still work so I don't think that's a problem. The only problem that I see with it is when the inspector checks your ignition timing. They will short the A-B terminals on the ALDL connector to bypass the ECM's timing advance, then go back to check the base timing against the 10BTDC spec. The 7730 requires a different procedure. On the 7730 you're supposed to unplug a connector, not short the A-B terminals. So it won't disable the ECM advance as expected when the inspector tries to check the timing, and you'll fail because of the extra advance. I'm guessing the CARB computer tells them about the A-B procedure so they'll expect it to be like that. I don't think there's any good way of telling the inspector about the EST wire without getting yourself into trouble for "tampering" with a 35 year old car.
Now you *could* make a test chip that runs 10BTDC at idle even with the EST connected, but that's an 8degree retard vs stock. That should get you past the timing check, but the "check engine" light won't be blinking as it normally does with A-B shorted. I don't know if the inspector would notice or care about that.
My plan was to build an adapter harness so I could easily swap back to the stock 7170 ECM for emissions test day. That's a little insane since the emissions are probably better with the 7730, but it's California. I never did the project, it's still on the "to-do" list. Now that I'm out I don't need to worry about testing anymore, but I think I'll still build an adapter harness to start with.
[This message has been edited by armos (edited 12-21-2020).]
I am a bit confused here. When I did my engine swap it was suggested to use a pintle type injector, yet some are saying to use the same unit that is found in the Camaro. At the time I did my swap it was suggested that I could use my stock 88 2.8l injectors. Looks like this information is wrong with the last couple of threads I have been reading.
Is there an advantage of the pintle injector one over the other?
The car seems to run ok, however I do keep getting a Code 32 (EGR) whenever I turn the AC on. This does not happen at any other time - new EGR, no vacuum leaks, etc, etc.
Any event, I am running the 3.4l HT crate engine using the 88 ECM, so would the GM part number: 17090849 injector work ok in my case? I know this is the same style as the Camaro one (not the pintle style).
[This message has been edited by Mickey_Moose (edited 01-24-2021).]
The common problem with the original 3.4 Rochester Multec disk type injectors is that the Fiero ECM can't efficiently operate them. Their pulse width is too long, causing a rich burn condition. I think maybe the 88 ECM has more ability over previous years. I've been told on several occasions that they worked fine when the owner had converted to the 1227730 ECM, however.
My 88 Formula is using stock Camaro 3.4 injectors and it runs perfect. But to re-iterate - in '88 they switched to different injectors so that's probably why. If you are having injector problems perhaps it's worth reflashing to an 88 bin file or just swapping in the whole 88 ECM? That's probably cheaper then a new set of injectors...
I did my 3.4 swap 100 years ago, but if I remember correctly I was recommended Accel 17 lb pintle injectors. The 2.8 injectors weren’t sufficient, and (305?) injectors were once recommended but the car ran like s***. It ran great with the 17lb injectors.
I am going to go with the 17 lb Accel injectors, since I have them already in hand. It sounds like this is all a crap shoot anyway. I will pass along anything I find out.
You could install an adjustable fuel pressure regulator, Aeromotive makes good ones. Turn your fuel pressure down before going for your emissions check. Has the benefit of helping you dial in your fueling if you aren't going to be tuning the computer. You will need to plug the return on the fuel line, or set it up to be dual feed as the aftermarket regulator will have the return line coming directly out of it.
edit to say I didn't see that you had left Cali but still would be a worthwhile mod even with an aftermarket ECU. The fuel pressures are rock solid and it is easily rebuildable for under $30.
[This message has been edited by zkhennings (edited 04-07-2021).]
In all reality the only real emissions equipment you need is the cat. I run a Holley sniper with no emission equipment except the cat and I not only have far more power but I also sail right thru emissions.
Fact is emission is ultimately a product of tune
If your system is metering truly proper air fuel and has a well controlled spark it will run fairly clean
With the cat working properly your emissions will be quite low
The egr system does very little to lower emission output and just dilutes the air fuel mixture with hot exhaust gasses 99% of which goes out the tailpipe any way.
It’s a very poor controler of emissions. And a complete waste of fuel as you just need to use more pedal to get going because of the contaminated charge going in the engine.
You can have your distributor set up to run thru the sniper system with a good CD box and the computer will also control your spark advance so well that alone cleans up a notable percentage of your emissions.
Use a factory looking air filter type assembly The non polished throttle body and make it look fairly stock. The sniper allows for a efficiency setting that’s quite fuel thrifty. Swap back to performance after the test. Takes less than two minutes.
Been thru twice now
No one said a word and I was burning clean with a significant boost in power. In fact it’s so clean I’m considering a mild cam upgrade.
Best 1000 bucks I ever spent.
[This message has been edited by Coolkoolpyle (edited 04-12-2021).]
... My plan was to build an adapter harness so I could easily swap back to the stock 7170 ECM for emissions test day. That's a little insane since the emissions are probably better with the 7730, but it's California. I never did the project, it's still on the "to-do" list. Now that I'm out I don't need to worry about testing anymore, but I think I'll still build an adapter harness to start with.
Please do let us know when you make the adapter harness and how it works out.
Retaining the distributor of course, should ET1 Engineer also consider swapping in the ECM 7730 to accrue its several advantages?? Seems like a CA-friendly change since it is invisible and with OB1 they don't plug in. 
