Holley HP MPFI Tuning Question - Team Camaro Tech
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post #1 of 9 (permalink) Old Apr 15th, 12, 08:25 AM Thread Starter
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Chuck
 
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Holley HP MPFI Tuning Question

Had the efi running for quite awhile now, and it runs good, but the only thing is that it runs really rough until the engine warms up. Once the engine warms up to around 180 it kicks in and runs perfect. Any ideas?
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post #2 of 9 (permalink) Old Apr 15th, 12, 09:16 AM
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Re: Holley HP MPFI Tuning Question

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Originally Posted by chuck0379 View Post
Had the efi running for quite awhile now, and it runs good, but the only thing is that it runs really rough until the engine warms up. Once the engine warms up to around 180 it kicks in and runs perfect. Any ideas?
what A/F are you running when cold versus warm? I usually shoot for about one point richer cold, and adjust from there; some like to be richer, and some don't need that much.

If your fuel map is set correctly when warm, and the A/F is being maintained with little correction hot, then you'll probably need to play with the corrections versus engine temp. In other words, richer when cold, leaning out as it warms up. There should be a separate table for temp correction to the A/F, not your base fuel map.

Also, idle rpm should be a bit higher when initially fired, tapering down as it comes up to temp. Maybe 100-150 rpm, sometimes more depending on what the engine likes, camshaft, etc.


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post #3 of 9 (permalink) Old Apr 15th, 12, 10:57 AM Thread Starter
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Re: Holley HP MPFI Tuning Question

Thanks for the info. I will have to take a look and mess with some of the settings. I'm pretty sure my A/F is at 14.0 from cold to warm. My first tune was good and ran good at cold, but must have done something to it when messing with it a few months ago. Thanks.
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post #4 of 9 (permalink) Old Apr 15th, 12, 11:06 AM
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Re: Holley HP MPFI Tuning Question

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Originally Posted by chuck0379 View Post
Thanks for the info. I will have to take a look and mess with some of the settings. I'm pretty sure my A/F is at 14.0 from cold to warm. My first tune was good and ran good at cold, but must have done something to it when messing with it a few months ago. Thanks.
The base A/F and fuel map will stay the same, if they are fine when warm. It's just the correction tables that you'll want to adjust. I don't know what they're called in Holleys system. Fast calls it coolant temp correction. Also, make sure in your config settings that the O2 doesn't become active until 140-150 degrees or so. Otherwise, if it's correcting when you first start it, it will try to keep it at 14.0 or whatever your base A/F table says, and you won't get the cold enrichment you need.


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post #5 of 9 (permalink) Old Apr 16th, 12, 05:14 AM Thread Starter
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Re: Holley HP MPFI Tuning Question

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Originally Posted by camcojb View Post
The base A/F and fuel map will stay the same, if they are fine when warm. It's just the correction tables that you'll want to adjust. I don't know what they're called in Holleys system. Fast calls it coolant temp correction. Also, make sure in your config settings that the O2 doesn't become active until 140-150 degrees or so. Otherwise, if it's correcting when you first start it, it will try to keep it at 14.0 or whatever your base A/F table says, and you won't get the cold enrichment you need.
Well, I ended up just doing a complete new tune, and it seems to be running a lot better. Have to do get some learning time in, but just a quick drive around the block was 10 times than better before. No sluggish acceleration or backfire. I messed around with the idel speed at cooler temps so it would be higher than when warm, and worked well. I'm going to have to look and see if my car giving false A/F reading at idle with my cam (253/260 @.050 -106 lsa). here is a screen shot of the air temp enrichment ATM:


This is from holley's custom cal for the 496 (650hp)
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post #6 of 9 (permalink) Old Apr 16th, 12, 07:55 AM
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Re: Holley HP MPFI Tuning Question

sounds like you're definitely heading in the right direction.


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post #7 of 9 (permalink) Old Apr 16th, 12, 06:05 PM
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Re: Holley HP MPFI Tuning Question

Chuck, how did you copy the screen and post it up? Thanks!

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post #8 of 9 (permalink) Old Apr 17th, 12, 04:25 AM Thread Starter
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Re: Holley HP MPFI Tuning Question

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Chuck, how did you copy the screen and post it up? Thanks!
Hi Sideways,
Hit the print screen button on the keypad, and go into paint and click paste, and that's it.
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post #9 of 9 (permalink) Old Apr 17th, 12, 07:41 PM
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Re: Holley HP MPFI Tuning Question

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Originally Posted by chuck0379 View Post
Hi Sideways,
Hit the print screen button on the keypad, and go into paint and click paste, and that's it.
Awesome thanks Chuck!!

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502 EFI/[224/228 HR]/T56/3.90
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