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New 302 EFI install in my 65-idle problem

1

1965Mustang

Member
I can give all the specs for what I have but I just converted my 83, 306 (.40 over) to a 93 EFI. It will not idle correctly. Comp cam idles well @ 900 rpm. New everything including computer and all sensors. New tune by Roush Racing. Can set base idle @ 900 and works fine for a while then runs up to1900-2000 rpm. Just took out the new IAC and put another new one in. Switched computer to a new one. Checked all fittings and all seems fine. One other thing is when electric fan comes on rpm goes up even more even though it has nothing to do with the computer. Sometimes it will idle back to 900. No rhyme or reason. I am totally lost and Roush is more than willing to help but no real idea as to what the problem might be. Any advice? This is my first EFI install and know very little about them. Any help would be greatly appreciated. Any more info needed I will gladly supply. Thanks.
 
Does the Roush setup operate on the fox body Mustang computer setup or is it using an aftermarket system?


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What distributor are you running? I have had zero luck with both MSD and Mallory distributors with the Ford EFI computer. Bad idle was one of the symptoms.
 
Make sure you have a good strong battery. When the fans come on the voltage is probably dropping and it's slightly effecting the return voltage and the computer is making adjustments. Have you tied to adjust the TB blade? I'm thinking there should be "almost" no change in RPM at idle when you plug and unplug the IAC motor. I'd try that and report back. Also, take a vacuum gauge and see if the vacuum is stable, low or bouncing, this could indicate a leak or maybe the cam is too big. Do you have the cam specs?
 
Also look at your Mass Air Flow sensor... try clocking it at a different angles to see if it's picking up the air stream differently in different positions. I recently made a few adjustments on my intake tube and changed the MAF clocking and all went to heck... put it back closer to where I had it beofre and it is much better. Also is the air cleaner near the electric fan? I've heard folks comment that fan air can wash into the intake tube and cause trouble too. Try temporarily sheilding the fan are from the air intake filter if it's too close.
 
Al the above suggestions like ..
Computer setup ( ac or not , auto or man ) , voltage drop , air intake ,
and
Check your ground straps too , very important.
I don't know the exact words but don't you have an " electric idle valve " that regulates the idle ?
Those things can stuck sometimes and when you tap on them , idle can change to normal rpm.
Another taught , spray some brake cleaner where the intake meets the cilinder head and listen if the revs come up . is then a vac leak.
 
These guys are taking all my ideas. :thu I would also look to see if the spout plug that you disconnect near the distributor is plugged back in. That assumes you unplugged it when you set the timing. When I originally set up my car with EFI I hooked up the BAP sensor to a vacuum line which REALLY screwed with my idle.
 
"kb3" said:
What distributor are you running? I have had zero luck with both MSD and Mallory distributors with the Ford EFI computer. Bad idle was one of the symptoms.
MSD-Brand new. What are you running?
Click to expand...
 
"68EFIvert" said:
Does the Roush setup operate on the fox body Mustang computer setup or is it using an aftermarket system?

Not trying to be dumb, but I either do not know the answer or do not know what you are asking. My computer is aftermarket with a Painless harness. I have no idea what program Roush Racing is using but they are the Ford gurus. Please explain so I can answer you more intelligently. Sorry.


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Click to expand...
 
"67 evil eleanor" said:
Make sure you have a good strong battery. When the fans come on the voltage is probably dropping and it's slightly effecting the return voltage and the computer is making adjustments. Have you tied to adjust the TB blade? I'm thinking there should be "almost" no change in RPM at idle when you plug and unplug the IAC motor. I'd try that and report back. Also, take a vacuum gauge and see if the vacuum is stable, low or bouncing, this could indicate a leak or maybe the cam is too big. Do you have the cam specs?

Thanks. I will try that and let you know. Cam is a Comp-35-351-8, Extreme Energy. duration 270/276, 218/224 @ .050 lift. Valve lift .512/.512. 1.6 rockers, Trickflow heads 51400004, 61 cc chamber. Is that what you were asking? This is the set-up recommended by Summit when I originally put my stuff together.
Click to expand...
 
"stangg" said:
Also look at your Mass Air Flow sensor... try clocking it at a different angles to see if it's picking up the air stream differently in different positions. I recently made a few adjustments on my intake tube and changed the MAF clocking and all went to heck... put it back closer to where I had it beofre and it is much better. Also is the air cleaner near the electric fan? I've heard folks comment that fan air can wash into the intake tube and cause trouble too. Try temporarily sheilding the fan are from the air intake filter if it's too close.

Thanks for the suggestion. Intake is right beside the fan motor on the right side of the radiator. Only place I had room to put it.
Click to expand...
 
"68EFIvert" said:
These guys are taking all my ideas. :thu I would also look to see if the spout plug that you disconnect near the distributor is plugged back in. That assumes you unplugged it when you set the timing. When I originally set up my car with EFI I hooked up the BAP sensor to a vacuum line which REALLY screwed with my idle.

Thanks. good suggestions. Some more to try.
Click to expand...
 
"B67FSTB" said:
Al the above suggestions like ..
Computer setup ( ac or not , auto or man ) , voltage drop , air intake ,
and
Check your ground straps too , very important.
I don't know the exact words but don't you have an " electric idle valve " that regulates the idle ?
Those things can stuck sometimes and when you tap on them , idle can change to normal rpm.
Another taught , spray some brake cleaner where the intake meets the cilinder head and listen if the revs come up . is then a vac leak.

I actually ran 3 ground straps as I am also having a problem with my water temp gauge on my Dakota digital dash. Reads about 100 degree hot and I was hoping this was the problem with that..
Click to expand...
 
"1965Mustang" said:
"kb3" said:
What distributor are you running? I have had zero luck with both MSD and Mallory distributors with the Ford EFI computer. Bad idle was one of the symptoms.
MSD-Brand new. What are you running?
Click to expand...


I tried two MSD 8456 pro billets with the same results. The car would barely start, wouldn't idle and fell on its face about 2,500 RPMs. I tried a Mallory unit with the same results. So far the only distributor I can make work is an original 93 Ford unit, yes 20 years old and runs great. The only problem is that it looks bad! If you know someone with a stock distributor, you might give it a try. I thought I had a vacuum leak so I put a gauge on and checked that. Then I installed a fuel pressure gauge, kept trying things until i put the stock distributor in. Since then I have had no problems.

I assume you did the KOEO and KOER tests to see if you had any codes? If you need further info on those look at www.oldfuelinjection.com for answer, more specifically to http://oldfuelinjection.com/?p=23

Ken
Click to expand...
 
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