How do you know it is running lean, exhaust pipe color ? Most of the vettes I have looked at seem to have black exhaust, to me that is rich. The chalk color indicates a nice clean burn. With the engine mods, higher compresion better flow you are most likely burning cleaner than most stock vettes. I would be real intrested in the milage you make on the open road.Read the plugs to be sure but I am betting you are ok.
I am getting a lean exhaust code. I can surely lower the fuel pressure. I dont want to do too much, because the guy that set it up was the guy that built the motor.
I have noticed that the car is running hot. Which I think leads to the car running lean. I am not sure what to cuase this, but it never ran this hot before. I saw the oil temp at 232 degrees today,and the water temp at 210. This is with Mobil 1 synthetic oil.
I have a 160 degree thermostat. It would run at about 210-212 on a hot day, and the coolant would stay in the mid to high 180's. Dont know to contribute this to the fact that the engine is new, so there is more friction because the motor is still really tight.
Your fuel pressure is too high, you are running too hot. The guy is wrong. D/C the battery for three min. Clear the codes don't worry about the relearn. I think you are running lean.
Find the cause, and forget about a bigger TB. FIX the LEAN condition before you mess with anything else. I believe a simple scan can give you the info you need. O2 sensor would be the first thing I would consider. But you need to see what your fuel tables are doing. Run too lean, die young.
WHen I told him this about running lean, he said that might just be a bogus reading because I removed the pipe from the exhaust manifold, to the intake manifold. We left the connector there, but it isn't connected to anything. I that that was the EGR temp sensor or something like that.
What do you guys recommend as far as a scanner goes? I find it hard to believe that the car is running lean, with the fuel pressure up that high. I had a theory, but it probably doesn't make sense. I think that with the fuel pressure so high, the computer has to cut the pulse width of each injector down so much to keep if from bieng rich. If that is the case, then perhaps the computer the computer not knowing is not allowing enough fuel. I will adjust it down, and see what happens. I need to get a scanner though, any suggestions?
I don't know if you've overlooked this, but did you replace the fuel filter? You may want to pull it anyway and give it the "blow-through" test. You can have fuel pressure that reads ok, but a clogged filter will affect the VOLUME of fuel delivered to the engine. Pressure in and of itself it meaningless without volume!
Put in simple terms: Pressure is nothing more than a measurement of restriction of a given fuel or fluid system. You need adequate fuel volume to feed an engine. Go back and check the basics first before throwing any more parts at it. Verify no clogged fuel filter. Verify no vacuum leaks. Verify proper airflow into the engine (air filter clear, intake tube SEALED to the MAF on the air cleaner side). If you're unsure, CHECK IT AGAIN. Don't get caught up in "I know it's right, so it can't be that" without going back to check. Lots of mechanics/techs/whatever fall into this trap (mostly due to ego), so it's possible it's simply something stupid like I've laid out here.
I changed the fuel filter, earlier this spring. Actually it probably only has 2000 miles on it. I will however replace it. Does any place sell a good AC DELCO replacement? I think the autozone one is Deutsch. I know with the older cars, I could always pull the fuel line, and crank the motor, and see how much fuel flows out into a coffee can. Is there any way to check how much volume I have.
Okay, I changed my Oxygen sensor, and also swapped out my fuel filter. My old filter was fine, I could blow through the end with ease. Once I got it off, I just said what the heck, and put the new one on.
I am going to drive it to work tomorrow, and see what happens. I had the ECM unplugged for about an hour while I did all this. I started it up, and it ran fine for 5 minutes or so with no light. We will see tomorrow.
Well I have put over 30 miles on the car today, to work, then school, then the the liscense branch. No light has come on yet, and the car runs good. It is still running hotter then I have seen before.
The low coolant light did come on today. The overflow is full, but I noticed something today. There is a tube that connects the expansion tank to the radiator. So when I pop the lid off of that expansion tank it should relieve some pressure, and I should see something in the tank. It doesn't. So now I am thinking that it might be low on coolant, and the rubber hose is plugged. I am going to take it off, and hook some air to it,and try to blow it free.
Could also be air bubbles in the radiator that are working their way out of the engine. Mine did that after the rebuild for a couple days. There's a sensor in the radiator right above where the overflow tank comes in; that's also supposedly problematic in 86's.
FWIW, coolant will only move into the expansion tank when it expands under heat. That's all.
[RICHR]
There is no difference, 12 volts, is 12 volts. If the ECM doesn't have a constant 12 volts then it will clear all of its codes. The one ECM hotwire is nice so you dont lose your radio presets and what not.
So the expansion tank will not supply the radiator any coolant. It was my understanding, that there is two levels on the dipstick. A cool and a high. So when the radiator is low will it not pull coolant out of the radiator??? I thought the level was a product of how the liquid expanded and contracted in the tank. When the level goes low, and the system is sealed I would think that the vacuum would pull fluid out through the hose of the expansion tank and into the radiator.
I thought the ECM power wire was there so that you didn't have to remove the negative terminal of the battery. If you disconnect the battery, you lose all info on the dash, and radio presets, which is a pain in the but. I wonder why it is there then?
The coolant will flow into and out of the tank, but the TANK is not under a vacuum or anything. There's a hole in the top of the cap on the expansion tank to let air in and out... I'm tired and may not have given a good explanation, but how I understand it is that the coolant gets sucked into and out of the radiator as it cools and heats but since it's always pushing against a liquid (the coolant in the tank) there's no need to keep the tank pressurized outside of the radiator and hoses.
[RICHR]
rrubel has it right. the coolant heats and expands forcing the axtra volume into the overflow tank. When cooland cools and contracts it creates a vaccum in the system and the coolant pulls back into the system. The overflow tank should always have some coolant in it. With the engine cool I would take the cap off and check the level it could easilly have had an air pocket in it and now be low.
What are your temps running? 42-44# FP is more than enough for your setup to start with. I'm running 44#'s with 30 lb. injectors. It's been dyno'd and I'm rich low and leaning out over 6 grand but OK.
I think you went with a 383. The only things different between your motor and mine is the injectors, the TB and the cam if I recall correctly.
Depending on what you have done to cool the motor, ie. water pump, radiator, thermostat, and I'm sure the heads, the car is going to run somewhat hotter.
Again, I caution you to make sure you are not lean.
Well the temps have come down. I have not seen the car about 200, in the last two days. Granted the temps are down about 20 or so degrees around here, but the coolant temps are lower. I am going to inspect the cooling system more this weekend.
I still have no engine light. Would the lean exhaust code come back on if I was in fact lean. It may be now that I could be rich. No codes, and the car kind of wants to load up, and idle ruff sometimes. I will play with the fuel pressure, but do not want to disturb anything as of now. I did pull the cap off, and had my brother rev it to 1500-2000, and was able to add half a gallon. I unpluged the over flow tube, so I will investigate things.
The computer would throw a code if I was lean right?
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