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Ecm retarding timing?

Old 02-05-2019, 09:19 PM
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Ecm retarding timing?

I have a 1991 camaro z28 tpi 5.7 fresh rebuild. Stock roller cam/lifters, New pistons (40 over), all new bearings and gaskets, AFPR 24 pound injectors,custom chip. It has a midrange noise like a lifter. Can a noisey lifter cause the knock sensor to freak out and retard the timing? I know the timing is adjusted right 6* BTDC with est unplugged. It pops out the ehaust like its low in time. Also fouls all 8 plugs.
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Old 02-06-2019, 09:57 AM
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Re: Ecm retarding timing?

Who did your tune?

Fouls them with what? Rich mix?
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Old 02-06-2019, 10:09 AM
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Re: Ecm retarding timing?

Originally Posted by Tootie Pang View Post
Who did your tune?

Fouls them with what? Rich mix?
Fouls them with gas not oil, very rich. The chip was a custom burn in my hometown by a engine builder and programmer and did fine for the past 25 years, I had the car running before I rebuilt the engine and it didnt run rich or foul the plugs( after sitting for 20 years). It had a bad miss which is why I rebuilt it ( 4 busted pistons). But another engine builder ( his every day job) had me to put the roller lifters in a c clamp and compress them and I have never heard of that before so I'm thinking that the knock sensor is picking it up and retarding the timing. Are you supposed to do that to the lifters? He is the kind of person to savatage somebody but I just want to be sure if it could be a lifter or not before I tear into the engine for the 5000 time... it's getting old lol, also it's not leaking injectors because I took them out cleaned them and ohmed them.

Last edited by HauntedZ28; 02-06-2019 at 10:15 AM.
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Old 02-07-2019, 11:21 AM
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Re: Ecm retarding timing?

Anybody?
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Old 02-07-2019, 11:28 AM
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Car: 1967 Camaro, 91 z28
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Re: Ecm retarding timing?

Who flow tested the injectors ? You might want to send them back to have the checked for leaking. I just helped a member tune his car and the injectors he had sat around for 6 months or so from his previous engine build and where exhibiting the same thing. Changed to Bosch 3s and set the offsets then tune.
Donít forget to change your oil before you do bearing damage.
how have you verified knock retard ? Scanner ? Timing light ?
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Old 02-07-2019, 11:36 AM
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Re: Ecm retarding timing?

I pulled
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Old 02-07-2019, 11:36 AM
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Re: Ecm retarding timing?

Originally Posted by HauntedZ28 View Post
I pulled
pulled what ?
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Old 02-07-2019, 11:55 AM
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Re: Ecm retarding timing?

Have you ever heard of putting the lifters in a c clamp and compressing them prior to installation, becuase I haven't and we have never done it before..
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Old 02-07-2019, 11:56 AM
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Re: Ecm retarding timing?

I was going to say that I pulled the rail and primed the system and injectors didnt leak
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Old 02-07-2019, 11:56 AM
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Re: Ecm retarding timing?

Never heard of that. I have always soaked them in oil prior to install to bleed the air out of them so they pump up fast. Loud valve train noise can cause knock retard. But I doubt it’s that bad to cause it run so rich. Have you disconnect the ks?
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Old 02-07-2019, 12:00 PM
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Re: Ecm retarding timing?

Could that have damaged them? And cause the noise, because it does not sound like a spark knock at all
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Old 02-07-2019, 12:39 PM
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Re: Ecm retarding timing?

I don’t think it would damage the lifter. Only if the clips come out of the inner part of the lifter.
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Old 02-07-2019, 04:06 PM
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Re: Ecm retarding timing?

what injectors are you running? Bosch-III's?
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