WHICH FUEL INJECTORS TO USE WITH A 2.8 TO 3.4 CONVERSION (Page 1/4)
eti engineer NOV 30, 01:04 PM
Gents,

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.
hnthomps NOV 30, 03:34 PM
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.

Nelson
eti engineer NOV 30, 04:00 PM
[QUOTE]Originally posted by hnthomps:

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.
cvxjet NOV 30, 06:10 PM
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
pmbrunelle NOV 30, 07:15 PM

quote
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).
http://www.fiero.nl/forum/F...L/142133-5.html#p198

[This message has been edited by pmbrunelle (edited 11-30-2020).]

jjd2296 NOV 30, 07:49 PM
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.
fierofool NOV 30, 08:12 PM
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.

Read my first couple of posts in this and then you can make your own determination of how you want to proceed. http://www.gafiero.org/bbs/index.php?topic=2080.0
Raydar NOV 30, 08:42 PM
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...
eti engineer DEC 01, 09:24 AM

quote
Originally posted by Raydar:

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...
Raydar DEC 01, 01:41 PM
.

[This message has been edited by Raydar (edited 12-01-2020).]