welcome to the 150 BLM club.

 

I don't wanna be a member

 

Talked with Jon and gave him my info and he went back a got an OEM injector and matched it to a bigger injector. I installed them today and now have my MPGs back where they are supposed to be +- 1mpg. Did some datalogging and the BLMs are now between the 120's to 130's and sit close to 128+-4 most of the time. Gonna give it some time to re learn and see what happens. Everything seems to be in range now I will do another scan next week to double check. Thanks Jon now you have a solution for at least the 93's

 

Thanks for the update!!

 

Are you saying you installed bigger injectors to cure the problem?

What size did you move from/to?

 

From what John tells me yes I am sure he will chime in but here is my take. The ECM was trying to compensate for smaller injectors by upping the BLM and pulses making it think it was using more gas because of the constant thus lowering the MPG rating that was being calculated.Now with my new set the BLMs are around where they should be putting everything back to normal.I am not totally sure what all he did but it included modifing a 24lb injector to work like my OEM did on his flow bench. The 93 is a strange beast as far as ECM and LT1 batch fire vs 94-96 SFI. I guess I am another satisfied customer.

 

My '95 had about 11K miles on it. I liked the spray pattern of the III's so I installed them. Noticed the calculated drop in mileage as well. I was planning on data logging to see what the BLM's were. The engine didn't seem to be running richer at all. Exhaust smell wasn't strong (LT headers W/3" BB HF cats)

I've been watching for a solution to this. I wonder if Jon would send out an improved set in exchange, so the engine isn't left injector out until the turn-around.

 

I would do a scan first to get the data. If your BLM's are running 150ish it may be worth asking. See what happens ,and why you are not rich, is the short term (INT) can compensate for high BLMs and run just fine(i.e. not be rich). The problem I saw was at certain times my BLM would go to 160 and that is all she wrote they can't go higher to richen the system. That may cause the engine to go lean. The problem with High BLMs is your ECM calculated milage will be off at least that is what I figured. Your actual milage will probably be OK and close to what you ran before if you do the miles/gallons method just your display will be off. If you're running at 140ish or below I would not worry about it IMHO. In my case I was concerned about hitting that 160 wall.

 

i'm glad they worked so well. What we basically did was copy the flow from the oem to a Bosch 3 on the flow bench. The 93 Injector number according to the data that is out there says its a 20lb injector rated at 50psi.. I can tell you this, thats total BS.. The stock injector flows a tad over 24. The Bosch 3 24 is rated at 39 psi so that was too big. We took a Bosch 3 rated at 23+- and modified the discharge plate so it flowed identical side by side with the OEM at various pulse rates. So I guess we have the only correct replacement for the 93. All the other years we can use a off the shelf core that flows the same as OE. We will be putting up a listing for the 93 on its own as the injector from the 92 is too small and the 94-96 is a little too big.

 

on the 94-96 lt's we know our sets flow the same as the stock. The LT headers might have added enough hp plus the relocation of the o2's could effect it. Get a datalog and lets see.. I can always add a pound or 2 of flow for you. I have data log info from many 94 up lt's and they all looked good.. do it soon

 

The car is in storage. Won't see it again till April. As soon as it comes out of storage, it's getting a hotcam and computer sent off. I'll be getting with you at that point to see about injectors. Unless now would be a better time?

 

wait, put the cam in, data log it and we will probably up you to 26 lt4 injectors.. no charge don't worry

 

Hey Jon,
How was the ski trip?

Joel

 

GREAT but, I'm getting too old for 30 below wind chill and 1 wheel drive rented cars.. hey joel I got your injectors ready..

 

I had plans to see ya this week, looks like it might be next week now. But I am coming!
Thanks
Joel

 

You can read open/closed loop by putting a jumper across A and B pins on the ALDL connector while the engine is running. These are the same pins that cause the engine codes to flash when the engine is not running.

A fast flashing of the CEL (about twice a second) means open loop. Slower flashing (once a second) means closed loop.

 

I had my 88 road tuned last weekend. I installed 24 lb. Trickflow injectors a while ago. The Trickflows were a major improvement over the old style Accels. The Vette ran good but I thought it might be running a little rich.

The tuner is a C4 owner. I drove the Vette while the tuner logged all the information and made some changes. I was right, it was running rich. He put the laptop by the shifter so I could see the readings.

The software he was using showed the pulse rate, BLM and all that other stuff which I know nothing about. The display showed when it was running lean or rich. It was bouncing around between rich and lean. At WOT it was way too rich and then shoot down to lean on decel. At idle and low RPMs it would still bounce a little between lean and rich.

I had to drive at different RPMs around town while he dialed it all in. According to the tuner anytime you change to an injector that is not stock you should get a custom road tune. Not a mail order tune. He may be right.

I thought I could just install any 22 or 24 lb. injector and the ECM would compensate. I now think installing an injector designed for a different engine or a so-called universal injector does require a custom tune.

Any injector that fits may work but I doubt that you will see optimum performance and mileage without a good tune.

 

I had just the opposite effect running Bosch III 32# injectors in my 94. I was lean across the board, especially at idle. Running 43 psi and 32 injector constant I was dangerously lean. Finallly got it tuned in pretty well with 50 psi and a 30.6 injector constant. Also, the cars initial injector pulse to start is too rich, and will stumble at start especially if the car is warm. My stock minimum injector pulse width is 1.404, think it would help by dropping it to 1.05?

 

What would indicate that the ecm is trying to add fuel would be what you see the int. doing at that point (rpm vs load). If the Int. number is also high it will not be compenstaing anything. For the ecm to be able to compensate a 145blm at the given rpm vs load range, you would be seeing a low int. number (around 118 or so, assuming we are looking at a target of 128).
Michael, Do you have 'enrich vs start up' in your edit program, if so you can lower the target there which should help.
I believe the add-on/offsets may also need to be addressed as well as pw.

 

I've already reduced those values by 50% and it did help, especially on cold start-up. I can run the car, stop for a few minutes and it will fire right up. But, if I let it sit for a couple of hours it will load up at start.