tequilaboy

I had the first chance to run my car with the 42s after my fuel rail o-ring fiasco. These are the so-called "009" injectors.

On a positive note, its idling fine with bpw down in the vicinity of 1 ms and below on the first shot at a tune for these injectors. This was a potential concern with the larger injectors. Its also running fine down as low as 0.75 ms with a little more rpm (1200-1300) where the voltage is up around 14 volts.

Of course, I've got some more tuning to do once the snow melts and I can actually drive, but the primary concern over how they would run at low bpws has been relieved. The IAC is occasionally hunting, but runs well once stabilized.

My "MAFless" open loop mixture is likely a bit off at this point under the current strange weather conditions (42 degrees and very humid due to all the melting snow) and changes to chip, fuel pressure and injectors at the same time introduce new sources of error.

I used the original low pw offsets in the tune and set the injector constants to 42.5 lb/hr. Fuel pressure is also back to stock at approx. 46 psi. Batch fire 165 ecm with $32B mask bin still set for double fire. Min pw is also set to 0 which was the stock setting from my original bin.

The original Lucas 23 lb/hr injectors at 54 psi would idle around 1.6 ms, so I knew the 42s would need to run down around 1 ms or less. As of now, I have no concerns in this regard.

STL94LT1

Just checked your profile. Why a 42# injector on your combination?

tequilaboy

The 42s were chosen to work with the blower and expected power at a reasonable 80% duty cycle. This is what the various injector sizing calcutalors recommend. Also the price was right, since there seem to be more 42s in circulation on the used market.

I know 36s would've been fine also, and may in fact be preferred for this application, but it now appears that the 42s will work fine and offer more room to grow.

STL94LT1

No, I wasn't saying you were running the wrong injector. Also didn't realize you were running a blower.

My 24's are maxed out on my car, and I have an extra set of SVO 42's. Just wondered if you were running 42's on a N/A engine, and if they might work on my car. I'll probably end up with the 30# SVO"s or 32# Racetronix.

tequilaboy

I've seen reports of problems at low bpws with the Ford/bosch pintle style 42 lb. injectors.

I know forum member anesthes has posted of his problems here and on thirdgen with idle issues below 1.3 ms.

I've also seen some similar reports elsewhere with these injectors. Apparently they can mis-fire or become erratic at low pw and are difficult to get the low pw offsets right without resulting in excess fueling.

BAM92

Best friend has a 408ci Mustang with AFR 205 heads and 600 lift cam and the 42's were too big for his motor. He lowered the compression (9/1) with Diamond pistons and put a Vortech blower (10#s) on and now they are perfect.

Johns87

STL94LT1,
Just Curious, what is your combination? I am building a 383 with Vortec heads and a higher-flowing TPI to go in My 87. I am trying to figure-out what injectors would be good for Me.
I don't mind PM's, I wasn't trying to hi-jack this thread.

You All Take Care and Be Safe, -John

tequilaboy

One thing I've overlooked in the first tune.

The injector pw correction vs battery voltage.

I can see now that I'm getting some big bpw changes as the battery voltage varies. My large alt. pulley and underdrive crank pulley are responsible for the voltage variation at idle.

Could be that this is causing some of my warm-up idle surge that wasn't present before along with a presumed to be slightly rich initial tune. I've seen reports of these injectors flowing above their rated values in the vicinity of 45-46 lb/hr.

Next step will be to reduce the battery voltage pw compensation proportional to the injector size ratio to see if it helps.

FD2BLK

I know the FMS 42's work fine with my combo. I had them on for a while when I suspected a problem with my 36's. Other then changing the injector constant I did'nt change a thing.

STL94LT1

Ported heads, 224/230 605/622 112 camshaft, full exhaust, stock CI LT1, and ~375 rwhp. I'll probably go with the Racetronix 32's.

DVNCI

My setup is almost identical to yours and I'm running the 30# SVO's. Car seems to be running well with em' and the base pulse width at idle is not TOO low.

As a side note, I ran some 42's for just a little while and the car ran fine. Though your pulse width at idle is a little too low for my comfort frankly, but it DID run fine.

2bar-c4

STL94LT1 you have an e-mail.

tequilaboy

The Slow idle surge that I had yesterday is now gone!

During warm-up, and periodically afterwards, I was getting a slow idle surge between about 700 and 1100 rpm with about a 2-3 second period. While the rpm surge was occurring, I was also getting some big voltage swings which was also impacting the injector bpw along with the changing rpm.

I made 2 changes. I increased the injector constants to 45 lb/hr to lean things out slightly. I also reduced the injector pw correction vs battery voltage as previously described.

Much improved.

Cold start, warm start, A/C off, A/C on sets right down to the commanded 900 rpm idle and remains steady. On average its idling around 1 ms BPW.

It still smells a bit rich, but that's pretty typical for my set-up.

tequilaboy

I had a chance to go for a test drive, tonight.

I started out with the injector constant set at 46 lb/hr. Once it got up to temp and into closed loop the blms were running a bit lean (ranging between 138 and 142 in cell 15). Leaner than I'd like to see.

I stopped to swap chips and went back to the 45 lb/hr constant. The BLMs in cell 15 dropped into the 132-134 range. Things were looking better.

Unfortunately, it started raining right after I swapped chips, so I didn't bother to evaluate the performance at WOT under boost on my cold bald tires.

I shouldn't have to worry about any top end lean out now with the 42s and 35-40% PE enrichment above 5200 rpm. That will have to wait for another good day.

Next round I'll try a 44 lb/hr injector constant. This should put the BLMs very close to 128 for cell 15 for future WOT testing.

tequilaboy

Made some WOT runs today with a 44 lb./hr injector constant in the bin. Still a little lean at cruise under todays 37 F weather. I need drop the injector constant some more to get the blms where I want them.

It also looks like I'm gonna need some more PE enrichment above 5200 rpm. Presently the rpm PE is set for 40% enrichment at 5200, 5600, 6000 and 6400 rpm which is resulting in a 9.06 Target AFR.

This extra rich target is intended to compensate for the roughly 40% extra airflow beyond what the MAF signal can indicate (255 gm/sec max) and should approximate a 12.0 target at 140% of max flow.

Since the PE setting is currently flat, as rpms increase, the bpw is actually slowly being reduced since the MAF signal is already maxed. However, the real airflow is still increasing due to the blower.

This is causing the narrow band O2 readings to begin fall below 900 mv above 5400 rpm or so. To keep up, the PE must get progressively richer as rpms continue to rise.

It appears that an 8 ms pulse or 80% duty cycle @ 6000 rpm will be just about right for these injectors, so they are a good fit for my application.

Currently the BPW is peaking at 7.90 ms at 5200 rpm, before it begins to decrease and start goin lean, so if I can get it to keep rising with rpm with an increasing PE vs rpm table, I should be all set.

95wht6spd

I use the Racetronix 42's and they are fine.

tequilaboy

Same injector.

Mine are also working fine, in case my point has been missed. They just need a little tuning, which is to be expected.

This thread was primarily intended to counter some of the warnings against using large injectors with a batch-fire ecm in double fire. They can and do work fine. So far, I've seen no issues that cannot be resolved via normal tuning methods, at least with these particular 42s.

Later sequential fire ecms should also be even more forgiving since the already small pw doesn't need to be split to double fire the injector and the pulse is delivered on time.