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Old 06-26-2013   #1
mgbrv8
 
Join Date: Jul 2009
Location: Texas
Posts: 790
Default strange surge

When coasting fron 30mph to around 5mph in neutral either with clutch in or out the engine surges until you slow to around 5mph and then it smooths out. Now i just replaced all the injectors with new delphis, rebuild the entire secondary vacum system, replaced the map sensor and anything else I could think of under the plenum. Now the car did this before I did all the work but it was more prone to dieing when it was surging and the surging was more erratic then. Dose anyone have any idea what it might be.

Here is the video of the surge

https://www.facebook.com/photo.php?v...42547347021421

And here are the pictures of all the work I have done so far

https://www.facebook.com/media/set/?...1&l=bf12a0aa41

Dave

Last edited by mgbrv8; 06-26-2013 at 11:20 PM.
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Old 06-26-2013   #2
mgbrv8
 
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Default Re: strange surge

I was thinking new O2 sensors maybe??

Dave
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Old 06-26-2013   #3
-=Jeff=-
 
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Default Re: strange surge

What PROM (MEMCAL) is in the the car?
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1990 Corvette ZR-1 #1051
Watson Headers (2" Primary) - Flowmaster Cats - Borla Catback
Late Model IH - Plenum
Coilovers - 4.10s
Shelby Series 1 - Wilwood Brakes
Custom Interior
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Old 06-27-2013   #4
mgbrv8
 
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Default Re: strange surge

What ever came from the factory.

Dave
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Old 06-27-2013   #5
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Default Re: strange surge

I think it was an issue in the OEM memcal and there was an updated MEMCAL to fix that specific issue
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1990 Corvette ZR-1 #1051
Watson Headers (2" Primary) - Flowmaster Cats - Borla Catback
Late Model IH - Plenum
Coilovers - 4.10s
Shelby Series 1 - Wilwood Brakes
Custom Interior
NCM Lifetime Member #978
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Old 06-27-2013   #6
Hammer
 
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Location: Ideho
Posts: 2,647
Talking Re: strange surge

It's not the chip. The engine would idle high for a bit and then settle down to normal, not surge like your's is doing. The later chip fixed that and Haibeck's chip does too. Call Corey or Marc and run it by them unless someone else has a fix, I don't.

TPS maybe??
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Old 06-27-2013   #7
scottfab
 
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Location: Portland Oregon metro area (Washington side)
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Default Re: strange surge

Surges? Try simple stuff first.
Clean the IAC and the pathway into and out of it on the TB.
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Vett owner since 1979._It's about the car and the people
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Old 06-27-2013   #8
mgbrv8
 
Join Date: Jul 2009
Location: Texas
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Default Re: strange surge

I dissasembled and cleaned the throttle body completely and the IAC. now I did order a new IAC and o2s it's on it's way we will see what that dose. Oh one thing this car has headers and O2 extensions


Dave

Quote:
Originally Posted by scottfab View Post
Surges? Try simple stuff first.
Clean the IAC and the pathway into and out of it on the TB.

Last edited by mgbrv8; 06-27-2013 at 01:44 AM.
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Old 06-27-2013   #9
tf95ZR1
 
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Location: Northridge, CA
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Default Re: strange surge

Quote:
Originally Posted by mgbrv8 View Post
I dissasembled and cleaned the throttle body completely
Dave
I remember reading that many people un-knowingly clean off some goop
from the throttle body butterfly shafts. This is supposed to be there (Dap?)
as a vacuum seal, else a leak.
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Old 06-27-2013   #10
-=Jeff=-
 
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Location: Bartlett, IL
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Default Re: strange surge

Quote:
Originally Posted by Hammer View Post
It's not the chip. The engine would idle high for a bit and then settle down to normal, not surge like your's is doing. The later chip fixed that and Haibeck's chip does too. Call Corey or Marc and run it by them unless someone else has a fix, I don't.

TPS maybe??


thanks I could not remember what issue the chip fixed.. that is why I stated I Think.. since I was not sure
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1990 Corvette ZR-1 #1051
Watson Headers (2" Primary) - Flowmaster Cats - Borla Catback
Late Model IH - Plenum
Coilovers - 4.10s
Shelby Series 1 - Wilwood Brakes
Custom Interior
NCM Lifetime Member #978
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