First, engine is running better (see "Putting on Coil", and "irratic engine"). mileage on first tank of fuel avg 20.2mpg. Computer is saying 17-21 as I try various speeds and gears (LT1 6 speed now with about 80900miles). Checked again with previous owner and he installed new injectors, fuel pump. Put in Bosch series DES3 stock OEM I think the pressure is around 22 psi and a high volume Granetelli fuel pump. I think it is the 255LPH pump as it was over 200 either gallons as he stated but think he met liters, but still would be in the range of 120-130 gallons if it is liters. Anyway that pump lists a psi of 65psi. The stock fuel pressure regulator is 43psi and a stock fuel pump from Delphi is 27.6 gallons per hour and 50 psi. I'm wondering if the pump is too high of an output for the system or perhaps it has damaged the regulator and causing more fuel to the injectors. Should I replace the pump to stock and a new pressure regulator. No engine codes have shown up yet.

 

Jon Banner would know the exact answer to this question - I've seen it answered before and don't remember.

Get him on forums.corvetteforum.com . He is on the boards daily, and knows fuel flow tech. He's user 'FICInjectors', with stickies at the top of the C4/tech/perf section.

 

Here is Jon's profile: http://forums.corvetteforum.com/memb...injectors.html

 

I talked to Jon Banner from FIC Injectors and the problem is that for '93 there were two types of injectors and the replacement Bosch 3's in my car are the yellowish orange one's and what I need are the blue one's. Sometning about the ECM doesn't send the right signal to them. Maybe someone else can explain that better. I don't know all the facts about them, but he is sending me out the blue ones and I will send him back the others. He made a very good exchange for just the cost difference plus shipping.

Wish to thank those who made reccomendations. Will let you know if that solves the problem once I get them installed.

 

He knows his fuel tech. Seems to have good integrity too.

The 'signal' is pulsewidth. It's the duration of time that each injector opens up, and allows pressurized fuel to escape into the port for that cylinder. Each port has its own injector - Tuned Port Injection. LT1 is also a TPI engine. Your computer is sending a bad pulsewidth signal because it's getting a bad signal from some other sensor, which in turn is getting a bad signal from another sensor, and on and on...

A simple example is a bad coolant sensor (or a cut wire to the coolant sensor). If it reads 'cold', the computer sends extra fuel. A new sensor will not fix a cut wire either. A bad spark plug wire on a high energy ignition system will cause EMI - electro-magnetic radiation, and that will distort ALL solid state electronics. That's straight from the Chevy shop manual, and firsthand experience uh huh!!!

If you don't have enough fuel pressure, the fuel just drops out of the injector, instead of spraying under pressure. That's why fuel pressure is critical, and I keep telling you to measure it. It's as easy as putting a pump on a bicycle tire. Bad fuel atomization will make the O2's believe that NOT ENOUGH fuel is being delivered, when it is already getting TOO MUCH.

You also need to know how long the fuel pressure will hold static (motor off). The injector pintle, which reacts to the electronic signal, and lets fuel spray out, gets weak, and will let fuel get by when it isn't supposed to. This cause a rich burn, poor fuel economy, fouled cats, etc. You'll see black smoke at start-up too.

Putting different fuel components on, and having worn out components, that are not proper, cannot be compensated for by another part. You HAVE TO know basic specs, like fuel pressure...

 

On Sat. I put in new A/C fan switch which made the A/C clutch and fan work again as it had got hot a couple of weeks ago and the engine would keep shutting down. That was on another thread and code 42 was thrown again and a reply thought that probably the coil module went out. I repaced it this time with a better quality NAPA module and coil. I also relocated the module on the coil bracket and used another stud and mounted bracket away from the head more for more air circulation. Moved the heat sink towards the end of the bracket away from the coil and put a large nylon washer between the bracket and the heat sink, mounted module on the heat sink with the silicone dielectric grease from NAPA. Cleared the codes only the one. Now I also put on a new ambient outside temperature sensor as it reads about 40 degrees higher than the actual temp. But the new one has not taken care of that problem. I read that it needed a learn time in the book, but it did not work, need to trace wiring back on that to the ECM. When I picked up the car last year in SEP. he had that morning rechecked fuel pressure as he thought that was why it was not running smooth but the pressure was good and blamed it on a bad fuel filter. He had put in the injectors the month before. Once I get the correct injectors in I will check the pressure. I drove it yesterday and today to work and runs great other than fuel ecconomy was about 17-21 on the computer, will know more when I fill up again tomorrow.

Thanks.