Bosch Fuel Injectors

I saw something about these on the SS Impala forum:

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I am curious about them.

Russ

Same here. Anyone use these?

It is worth moving away from the stock LT1 injectors as they are not ethanol resistant and will eventually degrade.  

That said, flow rate is only one of the three types of fuel injector characterization data you need.  You also need battery voltage compensation data, and short pulsewidth adders (which compensate for nonlinearities in injector flow at very short pulsewidths).  

If you just adjust flow rate for the new injectors, the engine will still make power and run good under load, but light load and idle behavior will likely be poor because those conditions are when the nonlinearities in actual fuel flow will show up.

IF you can get characterization data in the GM format and then make the appropriate adjustments in your PCM, great.   If you can get it in the Ford format and convert it (not trivial but doable), then just as well.  If no characterization data is available, then swapping in some other injectors will almost definitely result in a poorly driving car.

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Post the link to the ISSF post?

Once again I am overwhelmed by what I don't know.

It seems that ethanol is unhealthy for our cars. Why can't "Pro Choice" pertain to fuel?

Why not ask the seller for all of that data? He is advertising them as direct fit - physically they look like they fit, and then it's reasonable to expect that the he has those three pieces of data to make them work. And if he says "well they just swap in; the data is close enough," then ask him for three references from LT1 owners who have seen that proven in datalogs.

Good point- let's ask. I'm really only curious about stock replacement and not higher performance, so I'm not sure how these Bosch ones differ from the stockers.

The guy selling them got back to me, and he says they are intended for drop-in replacement with no computer tuning required. Hmm, I may get a set. I'd have to imagine after 20 years and 165k miles the originals may be a little "tired"

That may be true; ask him if he's actually seen the comparison data. I'm helping a friend with a rather high-power LT1 build and in the course of choosing injectors, we've discovered that even amongst injectors which look outwardly identical, the physical operating characteristics are vastly different.

Do yourself a favor and get some datalogs before and after the injector swap, with specific eye on the long term fuel trims under various operating conditions.  That will tell you how "drop-in" they are.

To be completely clear, I'm not saying that his claims are false; there ARE injectors out there that are relatively close to another injector in terms of operating characteristics; I'd just want a little proof.

I,m pretty sure that stock LT1 injectors are 22lb at 43-44 lbs fuel pressure,.

LT4's are 24lb,..

Also, how are you going to hold those injectors in place?  The chubby stock LT1 injectors physically cannot drop out of the fuel rail and I've seen far too many people get lazy with the retainer clips as a result.  If you start going 'off the reservation' on fuel injectors, this built-in safeguard is no longer in place.   I don't see any obvious method to keeping these injectors in place, so you'll need to figure out some system in order for this to happen.

BTW the Ebay cross-references 1997 Ford products as being the original applications for this. If you're going to go to newer injectors, why not MUCH newer injectors? That's only a couple of years newer; are you even sure THOSE injectors are ethanol-resistant?

Thanks to all. As usual I am learning a lot. My stock 1996 RMS still gets 27 mpg hwy with the original injectors and plug wires and I'm pretty sure the original opti at 176k miles.

Btw my mechanic says that when he cleans injectors he carefully runs water through them through the vacuum line from the brakes I think. He says that water de carbs great and doesn't harm the catalytic converters.

In that case I would not mess with injectors. 27mpg is plenty good for now, and if you have no misfiring, they are clearly working good.

For reference, as Nick indicated, ’92-’93 LT1’s had 22# injectors, 94’-‘96 had 24# Injectors and LT4’s were 28#. In '94-96 tunes, the stock injector flow rate is listed as 24.87 lb/hr.

27mpg is awesome! 24 is best I ever got from a LT-1.

Keep it inder 65 mph and use ethanol free gas in flat Indiana and it can happen!

The guy who was selling these injectors jacked the price WAY up right after I asked about them, so I passed on the Bosch ones. But I did come across a set of Standard ones which are drop-in for the Rochester ones (or maybe the OEM? I don't know for sure)

Anyway, the FSM is rather vague on replacement of the injectors. The Haynes book has some more detail. Doesn't seem too hard actually (famous last words!)

I do have an OBD1 cable and some software, I want to try and figure out how to track the fuel trim before and after the injector swap. I have a sneaking suspicion it may improve the exhaust smell from the car, which always seems to run on the rich side. Just a gut feeling, I have no real data to back that up.

rjathon wrote:

Keep it inder 65 mph and use ethanol free gas in flat Indiana and it can happen!

You almost sound serious...

Bosch Fuel Injector Update

A threat about broken exhaust manifold bolts led to the discovery of multiple loose bolts on my wagon. Re torquing the bolts led to the disappearance of my P1074 lean bank 2 code and my gas mileage really shot up. Now the wagon gets even better mileage than my sedan...I would post it but you wouldn't believe it anyway.

I never use much throttle so I don't know how the Bosch IIIs effect upper end performance but at the bottom end they appear to be significantly more efficient.

Sounds like a win-win.

rjathon wrote:

Btw my mechanic says that when he cleans injectors he carefully runs water through them through the vacuum line from the brakes I think. He says that water de carbs great and doesn't harm the catalytic converters.

somethings definitely not right there,..

the injectors are in the intake port,. its not s direct injection motor,.

water thru a vacuum line will clean carbon out of the combustion chamber, clean the exhaust port, exh valve,. spark plug etc,.

water makes steam steam will loosen carbon,.the chunks then pass out the exhaust,.

interesting thing tho,. catalytic converters don't lile big chunks of anything,. or steam,..

I got a tune from PCMforless and Keith factored in the Bosch IIIs, the 2.56 rear end, and the 735/25 R15 tires. The car runs great and gas mileage is amazing. I asked for a tune to maximize low rpm economy as I drive gently. He delivered magnificently.

I went with the Bosch's trying to eliminate the lean code. As it turned out the old injectors were fine. I deviated from stock out of ignorance and got lucky.

There is one anomaly though. The speedometer and gps jive well. The speedometer and HVAC speed reading (and OBD2 reading) are off by almost 15%. Before the PCM tune they were all in agreement.