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

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wingnut1192000

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Nov 14, 2004

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#1

• Nov 14, 2004

• #1

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!!

 

2

2002BLGT

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Dec 18, 2003

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Bedford VA

Nov 14, 2004

#2

• Nov 14, 2004

• #2

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!!

Click to expand...

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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#3

• Nov 14, 2004

• #3

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

 

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wingnut1192000

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#4

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Fuel pressure is at 39. We have replaced IAC, cleaned the MAF and still surging...

 

HISSIN50

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#5

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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.

 

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wingnut1192000

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#6

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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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#7

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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.

 

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wingnut1192000

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#8

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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!

 

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Idwitheld-1`

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Nov 30, 2003

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Nov 14, 2004

#9

• Nov 14, 2004

• #9

How do you know the IAC is working? Have you measured a voltage at the IAC electrical plug?

How did you set the idle?

Any codes?

What is the TPS voltage at idle?

 

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wingnut1192000

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#10

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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 15, 2004

#11

• Nov 15, 2004

• #11

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?