Help! Idle is surging badly....tried replacing everything

wingnut1192000

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Nov 14, 2004
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Recently put in a new Ford 345 hp race engine with SVO aluminum heads. 70 mm throttle body, 75 mm MAF, 30lb injectors and Edlebrock RPM Jr. II upper and lower intakes, MSD distributor and coil. The car will not stay running...if I have anything electrical running including the headlights on the idle surges and then finally stalls. Even if I turn the steering wheel, it stalls. If I take off the fuel pressure regulator vacumn hose, it seems to run a little smoother but still feels like it will stall. There is a new BBK adjustable fuel regulator on the car. We have replaced just about everything we can think of at this point and to no avail.......any suggestions would be greatly appreciated!!
 
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2002BLGT

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Dec 18, 2003
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wingnut1192000 said:
Recently put in a new Ford 345 hp race engine with SVO aluminum heads. 70 mm throttle body, 75 mm MAF, 30lb injectors and Edlebrock RPM Jr. II upper and lower intakes, MSD distributor and coil. The car will not stay running...if I have anything electrical running including the headlights on the idle surges and then finally stalls. Even if I turn the steering wheel, it stalls. If I take off the fuel pressure regulator vacumn hose, it seems to run a little smoother but still feels like it will stall. There is a new BBK adjustable fuel regulator on the car. We have replaced just about everything we can think of at this point and to no avail.......any suggestions would be greatly appreciated!!

whats your FP at , try setting it 39 psi with vac off and plugged .....check timing , TPS voltage and all that stuff too
 

HISSIN50

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how is the IAC? it sounds like it is not accomodating extra load (PS, electrical loads, etc).
good luck.
 

HISSIN50

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i am SD and not well versed with MAF so take this as you will. have you tried introducing a small vac leak (remove a vac line on something unimportant) to see if it runs better?

does the TB butterfly have a small hole in it? tried a bypass plate?

good luck.
 

wingnut1192000

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Nov 14, 2004
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We did a vacumn test and nothing showed up, but it does seem like some kind of leak. We are going to try the hole in the butterfly and a bypass plate. Someone told us it might be a bad ground wire? Does this sound right?

Thanks for working through this with me! It's appreciated!
 

HISSIN50

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im sure a bad ground or electrical connection could cause problems but i cant think of one in particular to check.

have you pulled codes? if there is a horrible connection, the sensor should be out of range and a code tossed.

i still might try introducing a vac leak for a minute and see what happens. that might suggest if IAC and butterfly work is needed. it only takes about 2 seconds to undo a vac line. :)

good luck.
 

wingnut1192000

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Nov 14, 2004
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We did try removing a hose and it did improve so you might be on to something. Will try more tomorrow and let you know what happens. Thanks again for the help!
 

wingnut1192000

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Nov 14, 2004
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TPS voltage was 98. We replaced the IAC and TPS. My mechanic set the idle by computer. We ran a code analyzer on the car about an hour ago and got 33's which according to the book has something to do with the EGR valve. Please keep in mind that the mechanic we are using is a very good one, but does not specialize in high performance modifications. The idle has not been right since we put the motor in the car. It has gotten worse though as time goes on.
 

HISSIN50

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Nov 29, 1999
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i would add that some IAC's need to be installed upside down to function properly (it should say so in the instructions).

does the idle drop when you have it running (warm motor) and disconnect the ISC connector? if so, i would really hit that EGR. even if this does not happen, i would jump the code. if you are introducing EGR gasses at idle, the car will likely not idle or idle terribly.

good luck.

:OT: hey, Id, how ya been? :)
 
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