LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

running rich

Old May 1, 2010 | 11:00 PM
  #1  
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running rich

my lt1 is running so rich its dumping gas in the oil...for this reason i dont want to drive the car until i figure it out.. it has aeromotive AFPR accel 30lb injectors madz tune cc306 cam dont think i have a sticky injector fuel pressure is good around 38.5 at idle just wondering if you guys have any tips on trying to narrow this down possibly bad o2 sensors but there is no check engine light...idk at this point any help would be great thanks again guys.
Old May 1, 2010 | 11:14 PM
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how does it run, does it miss? lack of power?

does it run bad all the time, or just after it warms up?

also you need to scan it to see if it has any codes stored

did this just start on its own or did you do anything, modification or something

who tuned it, did it run ok after it was tuned
Old May 1, 2010 | 11:56 PM
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its a new build with only 2 miles on it because of the rich issue there are no codes or lights on madz28 did the tune its very powerfull runs good just to rich with black smoke and gas in oil is the main deal.... im lost here..
Old May 2, 2010 | 12:01 AM
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personally, the first thing i would do is call up madz28 and talk to him

almost sounds like he did not adjust for the 30# injectors
Old May 2, 2010 | 01:58 AM
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okay thanks
Old May 2, 2010 | 09:18 AM
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There are two very poor parts selections there - the Accel injectors and the Aeromotive AFPR. Both have been cited in numerous posts as causing problems with fuel delivery.

What is the fuel pressure without the AFPR vacuum compensation line connected? Have you checked that vacuum line for wet fuel?

You indicate "dont think i have a sticky injector fuel pressure is good around 38.5 ".... when you turn the key to "run" but do not start the engine, what is the fuel pressure, and how fast does it drop when the pump shuts off?

What did you do for O2 sensor extensions with the Hooker LT's? Homemade or purchased?

I'm also puzzled on how, in driving it only 2 miles with black smoke pouring out of it, you determined "its very powerfull runs good"? Seems like a contradiction.

Are you assuming there are no codes because the SES light is not on, or did you actually try and pull the codes? Not all codes turn on the SES light.

How did you adjust the valves? Any chance they are too tight, and blowing the air/fuel charge into the exhaust, unburned?
Old May 2, 2010 | 11:38 AM
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machine shop adjusted valves. there are only 2 miles on it but it has more run time then that, also it doesnt pour out black smoke but if you really step on the throttle you will get a little bit of black smoke ill have to get back to you on the fp with the the key switch on this is how i figured i didnt have a leaky injector, cause when the fuel pump stopped priming the line the fp didnt drop. I assumed that since the ses light wasnt on there are no codes also something else ill look into thanks for the tip. no fuel in vacuum line either. also bought o2 extensions.

Last edited by scottnorton; May 2, 2010 at 11:41 AM.
Old May 3, 2010 | 05:15 AM
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I suggest you check the plug wires again for accuracy. If you don't find anything there, pull an O2 connection and see how it runs. If it still runs crappy, pull the fuel rail and pressurize it.
Old May 3, 2010 | 09:37 AM
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i have the same exact issue and i have accell and aeromotive FPR. But one thing noone mentioned is BAD RINGS. You need to do a leak down test to rule that out. sounds like yur issue is much worse than mine i have no smoke at all and you have black smoke. not good at all. Mail order tunes suck bad, you caint even adjust anything there just going off of past experiances with simular combos. but every car acts diffrent and are not the same. Now someone mentioned that your tune may not be adjusted for your injectors, well i would rule that out since stock injectors are 24lbs hr and you have 30's so you would be running a little lean not rich if they were not set, unless they were set for bigger injectors witch would not make sence but i have seen it. Next thing is the leaking injector, i would not assume anything just by looking at pressure's and pressure drops. you reallyneed to pull the rail like said and check that way and garantee there not, if one or more is thats a big issue and could be yur problem. keep us posted on what you find
Old May 3, 2010 | 01:56 PM
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Originally Posted by 95z28onjuice
........Now someone mentioned that your tune may not be adjusted for your injectors, well i would rule that out since stock injectors are 24lbs hr and you have 30's so you would be running a little lean not rich if they were not set, unless they were set for bigger injectors witch would not make sence but i have seen it.
If the PCM has the flow constant set at 24#/HR (actually, stock programming is 24.9#/HR), and you installed 30#/HR injectors without changing the flow constant, the injectors would flow 25% excess fuel for every given pulse width = rich. An engine tuned to produce a PE mode A/F ratio of 13:1 with 24#/HR injectors would be running at 10.4:1 in PE mode with 30#/HR injectors.
Old May 22, 2010 | 02:18 PM
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okay sry it took so long to get back havent had time to mess with the car but when the lines prime the gauge on the fpr goes to 30psi then drops back to zero right away. i have the rail off with injecter with the fpr vacuum line off an engine running its got 43.5 psi fp. no fuel in the vacuum line. pulled the rail off and primed the lines a few times with injectors in the rail pressure drops right away. injectors not leaking. going to call madz28 an see if he tuned for 30lb injectors did a leak down test an came out good so any ideas would be great at this time i wanna figure this out before it trashes the engine. thanks guys

Last edited by scottnorton; May 22, 2010 at 02:28 PM.
Old May 22, 2010 | 09:31 PM
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well it looks like i may have found the problem would a backwards maf make the car run rich.
Old May 22, 2010 | 10:04 PM
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Originally Posted by scottnorton
well it looks like i may have found the problem would a backwards maf make the car run rich.
Flip it around and see what happens?
Old May 22, 2010 | 10:22 PM
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i did flip it around before i changed the oil and the dipstick doesnt smell like gas at all... just wondern from some of the seniors if that would cause the car to run rich.
Old May 24, 2010 | 09:47 PM
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anybody have this happen to them before

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