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I have some leaking injectors that need replacing. I happen to have a new set of 440 cc injectors and adapters for my LT1 chevy SB that I don't have a use for. I believe the 3.0 uses 370 cc.
Will I run into issues if I use the chevy injectors with higher flow in the 3.0 and if so what kind of issues. Is the 3.0 ECU capable of adjusting for this higher flow, or will it run rich?
Has anyone used higher flow rates. The chevy does have a similar bore and displacement and this particular 3.0 runs slightly higher compression and more vacuum signal than the standard 3.0.
Any suggestions on this topic?
I'm pretty sure the ECU only activates the injectors longer or shorter periods of time, depending on the inputs from the the O2 sensors, and so forth. The thing is, the sensor inputs will tell the ECU it needs a certain time of activation for the injectors, but they'll let too much fuel in. So the ECU will cut them back, maybe too much, then back up to where they were, etc etc.
IOW: you'll be running to rich, and maybe too lean, in cycles.
I would stick to OEM. Get the ones that come out rebuilt/remanned, get new rubbers for them, and put them back in. Always get new rubbers when you remove/reinstall the injectors. I think there's 3 per injector, but it might be just 2. Like the crush washers for the fuel lines and so on, they made to be used once, only. That'd be your best choice. Again, all this is the personal opinion of a completely NON mechanic type, who's removed and reinstalled the injectors of a 1987 4Runner a grand total of 1, yes, count them ONE, times. Obviously well qualified to give an opinion, I know.
.... The thing is, the sensor inputs will tell the ECU it needs a certain time of activation for the injectors, but they'll let too much fuel in. So the ECU will cut them back, maybe too much, then back up to where they were, etc etc.
IOW: you'll be running to rich, and maybe too lean, in cycles....
I don't think it works that way. Once you get to closed-loop, The ECM will set the injector on-time based on what it sees from the O2 sensor. With higher-flow injectors, it will set the open time to a shorter value, until the O2 sensor is happy.
But there are (at least) two problems with this. First, the ECM is only going to accept a certain range (it will only make the open-time so short), and if it reaches the limit it will "throw up its hands" and call Code 26. I think pplusent is asking about that; how far is the ECM willing to accommodate high flow injectors. (I don't know.) Second, what happens before you get to closed-loop? The ECM relies on the VAF as a measure of air volume, then uses a look-up table to set the open-time, without the benefit of the O2 sensor. The look-up table is updated to match the real-world with long and short-term fuel trim. But fuel trim is only about 2 steps off center in each direction. That may leave you with a too-rich condition even when fuel trim is two-steps to lean, so that it will run so poorly in open-loop that it might not even start.
I don't know the answers to any of this. But given how little a reman OEM injector costs, I agree that it's probably not worth the exercise.
So as I expected these injectors may just be too much flow.
Anyone know the best injectors out there for the 3.0. How many holes best atomizes the fuel, 1, 2, 4, 12.
How good are the shops at re-manufacturing them. I have boxes of 1, 2, and 4 holed injectors, I just don't know how good they are.
Then again I an only guessing the originals are leaking.
My PCV valved failed and the crank case was put into an extreme vacuum the white smoke just billowed out the exhaust. I found it had burned 2 pints of oil in 1 mile.
I have gotten the crankcase back to normal now but it is still blowing a small amount if black smoke.
I have attached
some pic of the chambers that show some unusual wetting that i believe is fuel. I still am not sure what the malfunction did to the engine. The engine only ha 600 miles and ran good up until the pcv failed.
It ran for exactly one mile and used 2 pints of oil. I am running total seal rings, so the vacuum signal is higher than normal. and there is virtually no blow by. When the PCV was still connected I put my finger over the valve cover vent on the passenger side and and I could hardly get my finger off of it. There was a lot of vacuum in there. I don't know what exactly what effect it could have had on the engine. never came across this issue before, but I do think the injector seals were somehow effected. I had scoped the cylinders before this happened and the were perfect.
It seems to be running OK now but still a little black smoke when revved and the gas mileage has gone south. I was getting 18 mpg in the city, but now I am getting 10 mpg and when I start the car in the morning I can smell gas when I start it. Then the smell goes away. I think fuel is draining out of the injectors into the cylinders when sitting and the pic kind of confirms that.
When I say the PCV valve failed I mean it is stuck open, so with a high vacuum signal it will suck the oil out of the engine and right into the intake manifold which accounts for the billowing white smoke at idle when it failed.
The color of the valves I would indicate that the mixture may be running slightly lean yet it blows black smoke when I wing the throttle, meaning rich mixture.. The white smoke has stopped for the moment, but the valves should not be wetting like that. For now I am avoiding long periods of idling just in case it was something else.
No, not bad at all. I am a bit cautious to change them. The reason this is a new motor is that I was replacing the rear hoses and had to remove the plenum. There just happened to be a stray lock washer on the plenum somewhere and as my luck would have it the washer fell into the manifold without me seeing it. When I started the motor the valve chopped the washer in four peaces in a matter of 30 second run time. I removed the three pieces from the cylinder, but the fourth embedded itself into the squelch area and destroyed the head and piston.
I am trying to avoid replacing injectors and seals. Hoping something will get them to stop leaking. I am sure i will have to change them anyway.
07-05-2022, 12:14 AM
