89 460 Running Lean
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89 460 Running Lean
I got my 460 running and it's running lean. I don't know why, the scanner will not tell me anything! The truck will run great as soon as i start it up and take it down the road. As soon as it get warmer it acts worse. When I take it farther down the road first and second gear is seams to run ok, when i get to 3rd it acts like it has no power. As soon as it gets to about 2500 rpm's it don't get enough fuel to run. Even after it has been ran up to temp I shut the truck off it turns over really hard and won't start till it's warm. the timing has been checked the plugs, fuel pressure and it has a new fuel pump. I unplugged the MAP sensor and it started running rich. Has anyone ever had this happen, I really need the help. This is a fresh motor and I don't want to blow it up. HELP!!!!
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well before I removed it from the parts truck, it did run, it had bent pushrods and the flywheel was missing some teeth, and really bad gas. I rebuilt the whole thing everything is new. and i used everthing out the parts to put into mine. I did a 302 to 460 conversion.
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i am using the 460 computer out of the parts truck and all sensors are working but the coolant temp sensor that runs the gauge because my gauge don't come up very far, but it seems to be circulating well. I am going to hook a manual guage up on my pillar pod with my oil pressure guage here in the next week. Also i used the 460 down pipes and converter for temporary hook up to get the truck running. But since last monday i thought my converter was plugged because my exhaust was glowing cherry red fromt he manifolds to the converter. so i rigged my flowmasters on the down pipes and that still didn't help. the 02 sensor should be working because the scanner didn't bring it up either. Heck it didn't even bring the Coolent sensor up so. I don't know. It's wierd.
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What fuel presure are you getting at the rail? You are using the injectors from the 460 right(blue), not the yellow ones from the 302? You may want to attach a fuel pressure gauge and monitor the pressure when driving.. a bad pump or clogged filter wil starve that motor pretty quickly.
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It has the injectors out of a 460(blue), fuel pressure is 40 Ibs, I know i could get a bad pump, but it's a brand new pump and sound strong and i just put a new fuel filter on. See I was just thinking that the MAP was stuck because it was sitting outside in the rain on the parts truck for a while. I can use the one from the 302(same part numbers) because we unplugged it and it starting running rich right away.
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Is that fuel presure with the vacuum attached or not? It should be about 32-35psi at idle with vacuum attached, and 42-45 with vacuum removed.. or when blipping the throttle.
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i don't know that, buddy of mine is a mechanic and he brought his tester over checked it idling and blipping the throttle. he said it was running about 40psi, we checked the book and that what it called for. So I don't know, he told me we was getting plenty of fuel.
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Alright. So what it sounds like is happening is it starts and runs fine when cold, but after a couple minutes it goes closed loop and leans out considerably. Is there an air pump on this motor? If so is it connected with some plumbing and vacuum actuated valves? Is the EGR present and connected? Is the motor a stock rebuild or is there a different cam in it?
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I hate to say it but I had the exact same problem with my '89 302 after I removed the air pump, the motor ran way too lean. I think there was always some air injected into the motor with the older system and the computer is calibrated to adjust for it. If it doesn't see that air it thinks it's rich and leans out the motor too much. I had to re-install the air pump and lines to get the 302 to run normally. You may be able to compensate by unplugging the intake air temp sensor, this will make it run open loop which will be a bit richer.. basically the way it does on a cold startup.
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