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ECU orange box

J

junkpile

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Can a failing ECU cause the Engine RPS to be higher than usual. I have a new firecore distributor as of last year, I have had nothing but excellent running. Saturday idle was higher than it was set for and the car just shut off at one point after i got it in the garage to check the trans fluid. I have had bad orange boxes in the past with it just shutting the car off but never a high idle RPM I usually idle in park at 1100 and in gear at 850 this time around it was 1500 in park, no changes to the carb or timing was made.
 
Never saw that usually less rpm, is it a real box or a knockoff? Have a pic of the actual box?
 
No, likely something else.
Do you have an automatic choke, electric?
Maybe the wire came off it then the choke won't open and you could be on the fast idle cam.
 
I have not checked for a vacuum leak although i did take the brake booster line of the tree on the intake. its back on but could be an issue. Electric choke, Wires are connected properly. Orange box is mopar performance model ( but thy have been crap lately).

I will have to see if that vacuum line is too loose to fit now, its was snug to put back on but then again you never know
 
08042013_CandO-91_zps6b840d2e.jpg
 
68Moparmaniac said:
Maybe some crap in the carb...
Click to expand...
Usually not gonna make it idle high.

orange box Is not the problem either.

check for vacuum leaks that PB line off will make it idle high. Also look at choke and fast idle cam or anything hanging up in linkage and throttle cable.
 
I have check this evening and no vacuum leak. I did not have any issue with the car the last time I drove it in late march. Right now in gear its running at 900 rpm but at idle in park it starts at 1100 but goes up to 1400, way to high and it causes diesling when I shut it off. Since it did not due this the last time i had it out or any time before I cant figure out what is going on. When I set the idle to be at 1100 in park the idle in drive is so low the car doesnt want to stay running. It likes between 850 and 950 at idle in gear.

440, 484/284, edelbrock 750
 
-maybe check the float levels of the carb... needle/seat going bad, letting extra gas thru?
-carb throttle linkage or butterflies hanging up, causing them to stay a little open?
-might still be a vacuum leak hiding somewhere, maybe on the carb near throttle shaft area. I know on Holley's the throttle bushings can go bad and pull extra air thru
-engine dieseling: seems like it's getting a little extra air (vacuum leak) or gas(bad float level?), and your 440 is using that to stay alive after you shut it off
 
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