Slow speed surge
11-05-2005, 02:55 PM
#1
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Join Date: Nov 2005
Posts: 3
Slow speed surge
Ok I am new to the site and new to fuel injection camaros. I have an 89 IROC that starts bucking and surging at slow speeds and low RPM's usually under 2200 RPM's. You can power through the surging but it is getting frustrating dealing with it. I have a new mass air flow sensor in it, new o2 sensor, just had a new computer put in. Timing is right. Throttle position sensor is new and adjusted right. Have checked grounds and for vacuum leaks. Not sure where else to look. Thanks for any input or help.
11-05-2005, 05:22 PM
#2
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Join Date: Feb 2005
Location: Tampa, FL
Posts: 320
Re: Slow speed surge
Your idle air controller may be opening at an incorrect time. Also, if you have cruise control it could be coming on at an unwanted time.
If you are getting surge at closed throttle, that means that somehow the engine is getting air.
If you are getting surge at closed throttle, that means that somehow the engine is getting air.
Last edited by 91-Z28-L98; 11-05-2005 at 05:25 PM.
11-05-2005, 05:32 PM
#3
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Re: Slow speed surge
hmmm, the cruise control doesn't work, I will check the idle air control valve. Surge happens at part throttle, when trying to maintain a steady slow speed while driving. Thanks for the response
11-06-2005, 12:50 AM
#4
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Location: Tampa, FL
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Re: Slow speed surge
Well surging at part throttle could be other things as well. You seem to have all of the big sensors replaced already so I would look first at fuel pressure and injector status. Injectors can be tested by checking the resistance across them. I believe it should be around 17-18 ohms. If there is one that is significantly different than the others then you have a bad injector.
11-06-2005, 11:43 AM
#6
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Re: Slow speed surge
My 91 454SS tbi truck has/had the same problem. I changed a bunch of things with no improvements. Finally I installed 2 new injectors in the TBI and the surge went away or dropped off so much that it's not noticable any more and is much more drivable.
Idle was always smooth. Power under accelleration was good. It's just when I was at that cruise rpm and pushed the throttle ever so slightly that the hesitation could be felt. If it was a carb, I would have said it was an accellerator pump problem.
While testing I found the engine ran great while in open loop but as soon as it went into closed loop, the hesitation started.
Change the fuel injectors and let us know.
Idle was always smooth. Power under accelleration was good. It's just when I was at that cruise rpm and pushed the throttle ever so slightly that the hesitation could be felt. If it was a carb, I would have said it was an accellerator pump problem.
While testing I found the engine ran great while in open loop but as soon as it went into closed loop, the hesitation started.
Change the fuel injectors and let us know.
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