1990 EFI460? mods=poor idle

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Jun 7, 2006 | 03:58 PM

stngh8r

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From: Idabel, OK

1990 EFI460? mods=poor idle

<note: also posted in the computer section>

I have a 90 EFI460 E4OD. It has a K&N CAI and free flowing catback. Shortly after installing the K&N, I had the battery cable off and since then it has not wanted to idle properly. The two events were so close together, I am not sure which one to blame. Driving the truck is perfect and it runs like a dream, its just the idle quality that is shaky, especially before getting warmed up?

Are the speed density 460's very sensitive to mods? Do I need a chip or something just because of the CAI and Catback? If I later go with a cam/headers is the problem going to get worse?

Any help would be greatly appreciated.

thanks
eric <><

Jun 9, 2006 | 08:28 AM

smooth

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Well, the standard is yes, Speed Density does not like mods, however, in my opinion (with some experience attached) what you have done should not have caused your problem. Frederic is a good one for info on what you can get away with, and what you can't before you burn a chip, or change your computer system. If you search, there are many posts that contain his wisdom on this.

As an example, my SD 302 in my bronco was replaced with a remaned short block bored .40 over. I put on GT40P heads with 60cc combustion chambers.
1.84 in./1.46 in. valve diameters. A comp cam with 206/212 Duration at .050.
462/474 lift. 114 Degrees Lobe seperation. Ford Racing shorty headers, and a K & N FIPK filter and it still runs strong. Now, I'm sure Frederic can give some insight into why it still works, I can not as most of these numbers mean little me other then "better then stock." I do believe my cam selection was mild for the purpose of working within the parameters of the SD system.

Anyways, I hope you find the problem!

MoMo

Jun 10, 2006 | 09:47 PM

7DF250

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From: socal

I am in the middle of reading Frederic's posts, he could awnser your ?'s for sure! or try www.fordfuelinjection.com lots of tech reading there. After reading up it sounds to me like a sensor or something is happening other than the mods.

Jun 12, 2006 | 08:37 AM

stngh8r

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From: Idabel, OK

Thanks for the valuable information. I was myself thinking that the mods themselves were not too blame, but just wanted to throw the question out there to be sure. I read a post that is a few pages back about a guy with a motorhome that did not want to idle and it ended up being a MAP sensor. I may try and rule that out first.

Any other tips/experience will be appreciated. It never hurts to get more info on the board.

Jun 13, 2006 | 04:25 PM

stngh8r

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From: Idabel, OK

7DF250-Thank you for the fordfuelinjection.com link, it was very informative. Now that I have learned about a little thing called a IAB(idle air bypass) and its function to control engine idle, I think I will rule that out first. It seems that this little critter can obviously fail causing poor idle, but there is a possibility that a good cleaning of the part will take care of the problem.

link to the IAB description--> http://fordfuelinjection.com/index.php?p=39

Thanks
eric<><

Last edited by stngh8r; Jun 13, 2006 at 04:44 PM. Reason: add text

Jun 19, 2006 | 05:35 PM

stngh8r

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From: Idabel, OK

I tried the IAB cleaning and it did seem to help intially, but when i started it the next morning, it was the same ol same ol, rough idle and then dies. The hunt for the problem goes on.

Oct 1, 2006 | 01:24 AM

stngh8r

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From: Idabel, OK

update 9-30-06: I tried pulling the K&N FIPK off and putting the stock air box back on and presto, it idles just like before. I cannot believe that a K&N FIPK would add so much air that it would cause the engine to idle poorly, but that certainly seems to be the case. FYI-I have also cut out the silencers in the tubes, which has further enhanced the ability for more air to flow freely into the TB.

Eric