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| Vetron87 | erratic idle periodically | ||
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Elite Guru
 
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Noticed the last couple of nights I pull up to a stop light in the 87 its idles fine for the first 20 secs or so than the rpms drop to 500-600 in drive. This does not occur all the time. At high speeds 70-80 mph it seems to hesitate with a slight jerking motion. Surging again but not constant. IAC again? Removed precats and cats with corvette central system so clogged cats are not an issue.
New injectors from FIC, fuel pump, wires,plugs,dist and rotor. Replaced fuel filter last summer. |
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Posted on: 2010/7/22 18:22
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| WW7 | Re: erratic idle periodically | ||
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Check fuel pressure..WW
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Posted on: 2010/7/22 20:13
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| Matatk | Re: erratic idle periodically | ||
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How long ago did you replace the IAC? That sounds like a contender.
Also check for vacuum leaks. Matthew |
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Posted on: 2010/7/22 22:15
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2002 EBM convertible, Magnusson supercharger, cam, headers, etc. 1989 Corvette...RIP |
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| Vetron87 | Re: erratic idle periodically | ||
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Elite Guru
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Replaced IAC 2 summers ago and cleaned last year. Spent couple of hours since my post checking for vac leaks. Fuel pressure is 44 psi(adj unit) Holds pressure for 15mins. I'm starting to check ign. Dist rotor plugs wires are new. There are times it will hold idle in drive at a stop light. Next couple of stops later it begins to surge! I really have push hard on the brakes. Surge from 1400 down to 600 rpm. IAC according to Haynes adjustment is 1 1/8" from base of IAC to the tip of the pintel. I wonder if its the same condition at higher speeds holding 70 mph for 5mins acceleration at that point is hesitation. It drive me nuts! |
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Posted on: 2010/7/22 22:57
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| BrianCunningham | Re: erratic idle periodically | ||
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How's the shaft on the TB?
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Posted on: 2010/7/22 23:12
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Polo Green 95 LT1 6-spd http://mysite.verizon.net/vzevcp74/ 383 LT1/Vortech Supercharger/AFR heads/Rod end suspension/Penske-Hardbar dual rate coilovers/Wilwood 6pot brakes NCCC Governor: http://BayStateCorvetteClub.com |
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| Vetron87 | Re: erratic idle periodically | ||
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Elite Guru
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I justed checked it, seems like its Ok no movement of shaft and the throttle butterflies seem clean with no distortion. Brian the engine starts great and idles fine until it warms up. Then there are times it runs the fine all through the heat and cooling cycle. I replaced the ignition mode in the dist. three years ago to an Accel unit, as an upgrade. |
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Posted on: 2010/7/22 23:25
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Bone stock 87 conv. |
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| BrianCunningham | Re: erratic idle periodically | ||
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that makes me think either the o2 or the temp sensor. |
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Posted on: 2010/7/22 23:35
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Polo Green 95 LT1 6-spd http://mysite.verizon.net/vzevcp74/ 383 LT1/Vortech Supercharger/AFR heads/Rod end suspension/Penske-Hardbar dual rate coilovers/Wilwood 6pot brakes NCCC Governor: http://BayStateCorvetteClub.com |
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| Vetron87 | Re: erratic idle periodically | ||
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Elite Guru
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Replaced O2 sensor last fall with a Bosch unit. Temp sensor makes sense. I'll check the connector....seems fine. I keep a log on all my vehicles and I replaced the sensor when I replaced the water pump 3 years ago. Sensors can go bad anytime! Any thoughts. I bought my 87 new so I'm the only one that has worked on it. |
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Posted on: 2010/7/22 23:47
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Bone stock 87 conv. |
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| Tre57 | Re: erratic idle periodically | ||
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Senior Guru
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It appears that there are several of us on here with the same frustrating symptoms. I found a crack in my TB gasket and hope that had something to do with it. Haven't been able run it long enough to see if the problem is still there. If I had the money, I would buy new IAC, O2 sensor, vac hoses, injectors, EGR valve, FP regulator, etc., and replace them one at a time until I found the problem. My car is almost 18 years old with 125K and pretty much all original so it would need all these things soon anyway.
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Posted on: 2010/7/23 0:11
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| Vetron87 | Re: erratic idle periodically | ||
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Elite Guru
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These symptoms take all the fun out of a road trip! I have 32K on the 87. Honestly I had problems with the "surge" since early 1990 when it was off warranty. Vette Techs would tell me it's the nature of the beast! Since I have been a member of CG's the 87 has never run so well with their advice except for this surge now and then. |
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Posted on: 2010/7/23 0:31
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| Tre57 | Re: erratic idle periodically | ||
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Yes, the guys here have certainly helped me out a lot already. Sounds like those "Vette Techs" could learn a few things from these guys too. Here's to stompin' out this pesky surge gremlin!  |
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Posted on: 2010/7/23 5:39
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