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Username Post: Throttle sticking closed on idle Holley EFI        (Topic#345845)
hulsinc 
Forum Newbie
Posts: 89

Loc: Illinois
Reg: 04-02-10
07-05-17 07:32 PM - Post#2698897    

Just installed Sniper EFI and dual sync distributor on 62 Biscayne with 402 and strong cam. Having trouble with throttle sticking at low rpm when trying to accelerate from stop. Was told by Holley installer that it was a condition of trying to open throttle plates under engine vacuum. Turned the plate under gas pedal around to have smooth side against throttle pivot, oiled the pivot mechanism. Doesn't stick when engine not running. Can't drive it with 500 hp coming off a stop when the throttle suddenly opens. Any ideas to remedy this? tried adding springs for more resistance and didn't seem to help.



 




65_Impala 
Very Senior Member
Posts: 3805

Reg: 12-29-02
07-06-17 10:10 AM - Post#2698953    
    In response to hulsinc

Are the plates closing fully into the bore? Typically, throttle bodies have a stop that leaves the butterflies slightly open so they don't stick in the bore.



 
hulsinc 
Forum Newbie
Posts: 89

Loc: Illinois
Reg: 04-02-10
07-07-17 05:50 AM - Post#2699068    
    In response to 65_Impala

Many thanks for responding. The plates are cracked open just a bit. It does not stick when car is not running. Can't believe all Holley EFIs act like this. Would the big block 402 with strong cam create more vacuum than usual?



 
65_Impala 
Very Senior Member
Posts: 3805

Reg: 12-29-02
07-09-17 03:48 PM - Post#2699349    
    In response to hulsinc

Vacuum shouldn't be the issue or every car would have the same problem.

Is there an IAC on that throttle body? If there is and the counts are high at hot idle then open the blades more.

Have you watched the blades while manually working the throttle when running? Maybe the engine vibration is shifting the blades into a bind.



 
hulsinc 
Forum Newbie
Posts: 89

Loc: Illinois
Reg: 04-02-10
07-10-17 05:33 AM - Post#2699409    
    In response to 65_Impala

Thanks much for the response. Don't know on the IAC will have to check on that. haven't watched the blades while opening. I had the EFI tuned by a Holley installing dealer. This guy actually does R&D for Holley on EFI. Supposed to be the best. We discussed opening the blades further but would make idle faster and I didn't want that. It already idles at 900. I'll check on that IAC thing. Thanks again!



 
acardon 
Ultra Senior Member
Posts: 10801
acardon
Loc: DFW TEXAS
Reg: 03-25-05
07-10-17 05:49 PM - Post#2699516    
    In response to hulsinc

Opening the blades has nothing to do with idle. The IAC (idle control valve) controls idle. As long as the blades are in range of the IAC, the ECM controls idle speed.

Don
66 Corvair (driving)
57 2dr HT (driving)
56 2dr HT (waiting to be restored)


 
Rick_L 
Honored Member
Posts: 27156
Rick_L
Loc: Katy, Tx, USA
Reg: 07-06-00
07-10-17 07:27 PM - Post#2699540    
    In response to hulsinc

Holley had a problem on the new NHRA Pro Stock throttle body where it was difficult to open the throttle from idle because the throttle body blade against minimal vacuum because it was so big. This should not be a problem on other throttle bodies, especially a 4bbl progressive linkage deal like you have and even if so, you should be able to adjust the minimum air vs. the IAC to make it better, as already described.

If you are trying to open the throttle on a index racing deal with a throttle stop, there may be something to this.

The other deal they had with those huge P/S throttle bodies was that the airflow came on rather quickly when the blade was open only a small amount - so throttle linkage had to be modified to have not much opening vs. pedal travel at first. Again you shouldn't have that problem, at least not as pronounced.



 
hulsinc 
Forum Newbie
Posts: 89

Loc: Illinois
Reg: 04-02-10
07-13-17 09:17 AM - Post#2699939    
    In response to Rick_L

Big thanks to all who have thought about this and replied. I'm going have to study up on this opening the blades and IAC thing. Not a professional mechanic, but know enough to probably get myself in trouble with this EFI. It's definitely a huge problem. If I try to give it just a little throttle from standing still it goes all at once which throws my foot in it even more. With 500+ hp and 5 speed, it's not pretty. I look like I've never driven a stick shift before. Reminds me of teaching my girls how to drive. Is there a progressive linkage system available that has bigger leverage on start and less travel at WOT? Would more and heavier springs give me a little more control?



 
acardon 
Ultra Senior Member
Posts: 10801
acardon
Loc: DFW TEXAS
Reg: 03-25-05
07-13-17 11:20 AM - Post#2699952    
    In response to hulsinc

Can you post a picture of your throttle linkage. Can you ease into the throttle by operating the throttle body from under the hood, with and without the linkage hooked up?

Don
66 Corvair (driving)
57 2dr HT (driving)
56 2dr HT (waiting to be restored)


 
hulsinc 
Forum Newbie
Posts: 89

Loc: Illinois
Reg: 04-02-10
07-15-17 09:05 AM - Post#2700147    
    In response to acardon

Under the hood same results as with accelerator pedal. I'll see if I can get pic of linkage today.



 
hulsinc 
Forum Newbie
Posts: 89

Loc: Illinois
Reg: 04-02-10
07-22-17 03:54 AM - Post#2700894    
    In response to acardon

Worked a bit on EFI yesterday. Blades are cracked a bit but I don't think you could get a sliver of paper thru it. I opened the blades a quarter of a turn and it increased the idle by about 50 RPM. Tried to lower RPM with hand held controller by setting at 800 and it won't come down any. Runs at about 1000 RPM now. Wishing I'd kept my Edlebrock 750.



 
hulsinc 
Forum Newbie
Posts: 89

Loc: Illinois
Reg: 04-02-10
07-23-17 01:47 PM - Post#2701073    
    In response to hulsinc

Made a carb throttle extension bracket to give me a bit more leverage and that helped a bunch. Thought all along it was a set up issue, but after checking some of the Holley forums it's not a new issue. Problem solved and I want to give a big thanks to all who responded.



 




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