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Just Pluggin Along
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1,175 Posts
Discussion Starter · #1 ·
I just started the motor for the first time last weekend and again for a short time this evening. The sound is music to my ears, but there are a couple of things I am not sure of. I understand EFI basics, but the details I have trouble with.

According to my A/F gauge (and my eyes) my motor is running very rich. Is this something that the computer will compensate for eventually or do I need to adjust something?

The other thing is that the motor will not idle. I have to keep it about 1000RPM or above to stay running. If I let off the gas it goes lean and cuts off in no time. Suggestions?

Thanks for the help,

Cai

[ July 04, 2004, 04:04 PM: Message edited by: Lilnuke ]
 

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66 Posts
I've never seen a motor that could not be tamed.If everything is working right it should idle at first start.Thats the great thing about FI Turn the key and it idles.The majic box does all the thinking for you, It just needs to get the right info. Allways start with the basics.Fuel preasure,Timing, vacume leaks.Did you change injectors and or air meter? All sensors pluged in? Good luck! Robert. FFR 5086 arrived 3/06/04 Cart ride first time yesterday ;WHAT A BLAST!!!
 

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Charter Member
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2,135 Posts
I had similar problem with running rich and rough idle. I set the ISP voltage, changed o2 sensors and after about a thousand miles idle is fine, gas milage went from 12 to 17mpg. Not sure if the computer needed to learn e-cam or what but it is OK now. Never threw a code, very high hydro carbon reading (burned your eyes). Good luck!
 

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Just Pluggin Along
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1,175 Posts
Discussion Starter · #5 ·
All sensors are installed and hooked up, new O2 sensors. I need to set the timing, I dropped the distributor in at #1 TDC and let her rip. I will also check for vacuum leaks and computer codes.

I know that the EEC takes some time to "learn" the engine setup after being hooked back up to power. Anyone know how long this takes?

Thanks for the help,

Cai
 

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Premium Member
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7,237 Posts
the eec takes several start and warm-up cycles to fully learn the system. That said, it can only "trim" the factory tables so far. It might hunt around a bit after loss of power, but it's not like it'll be on it's face or run really bad.

You really need to get the timing set before you beat yourself up trying to figure out a problem that's not really a problem!
 

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Charter Member
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83 Posts
I had exactly the same problem building a motor for a buddy of mine. I have built many engines but was not familular with the EEC. Motor ran, but ran very rich. After contacting several experts they said to run a different computer. After getting three wrong ones, the forth did the trick. I don't have any numbers on hand to post for you, but it may give you some direction.
 

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FFCobra Fanatic
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2,266 Posts
Cai, you didn't mention the year/whether your engine is mass air or speed density.

Do you know the condition of the 02 sensors? It is a good idea to replace them if there is any question.

Does it idle OK after warming up? I have a donor build with a b-cam and it does not like to idle when cold if it has been sitting for a day or two but is fine for the day if I just give it a couple of minutes after initial startup for the day. Throttle Position Sensor voltage and all systems appear to be fine. I am told that this is not uncommon with some aftermarket cams. From what I understand there is a plate you can buy with an adjustment screw that lets you bleed air around the Idle Air Bypass valve which has been known to solve this particular issue.
 

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Junior Charter Member
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815 Posts
Matt, I have the exact same issue that you have described. Don't know what cam is in engine other than it is not stock. Guess I can say that it is comparable to a B cam.

Concerning the plate for the IAC- I have one, tried it, and couldn't get it to make any difference.

I guess I will just have to put up with it until I can drop in the FMS 392 crate that is on my Christmas wish list.
 

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Just Pluggin Along
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1,175 Posts
Discussion Starter · #12 ·
I have all of the vacuum lines in use or plugged/capped (I thought, have to check). I have power brake booster, charcoal canister, and the EGR in use. BTW, it is a 91 5.0 stock except a TF stage 1 cam.

After a while warming up, it seems to idle a little better. I am going to work on the timing first. Does anyone have a good number for intial timing for a 5.0? I have seen 10 degrees BTDC but I am not sure.

Cai
 

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Cai: 10 degrees is a great start You can fine tune after you get some time on the engine. Timing is one of the important things the computer looks at.It could be as much as 10 to 20 degrees off. Beg borrow or steal A light if you have to. Do not forget to unplug jumper just before module connecter. Get the timing set! Also Make sure egr is good and not giving you an internal leak. Good Luck Robert.
 

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Just Pluggin Along
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1,175 Posts
Discussion Starter · #15 ·
Thanks for everyone's input. I checked for vacuum leaks and could not find any. Went and got a timing light and put it to the engine. I was running about 0 degrees. Bumped it to 12 degrees BTDC and it idles great now, no matter what the temperature. That TF stage 1 cam sounds really good, nice and lopey.

Man does it get hot! I can already see why everyone puts insulation in this thing. A couple of trips around the block in the go-kart and I was ready to put it back in the garage for a bit.

On to the details...

Cai
 

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FFCobra Craftsman
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732 Posts
Try 14 degrees. Just something I read. It said start at 10 and try upping it till you get a knock. Then back it off one, usually at 14 degrees. Glen
 
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