Any ideas?
Thread Starter
Le Mans Master
Joined: Oct 2003
Posts: 6,130
Likes: 2
From: seattle WA
Any ideas?
87 auto, new plugs, cap,coil, new battery. Annoying miss between 1700-1800 RPMs, no codes.Same thing prior to above. I'll be checking Fuel pressure later today.No arcing in plug wires.Can't hear any vac leaks.Revs great-no stumble.
But I'm kinda wondering if my alternator could cause this-I'll have it checked later also. Idles very good, runs great except at this RPM range. Any ideas?
thanks in advance
But I'm kinda wondering if my alternator could cause this-I'll have it checked later also. Idles very good, runs great except at this RPM range. Any ideas?
thanks in advance
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
2027 Corvette vs The World: Every C8 vs Its Closest Competitor
Joe Kucinski
Thread Starter
Le Mans Master
Joined: Oct 2003
Posts: 6,130
Likes: 2
From: seattle WA
Took the ignition module in-ran through 10 cycles (hot) and that checked out good. Haven't done the EGR block off CFI suggested YET!
But I will. The reason I'm thinking alternator is-I had ran my battery way down-charged it enough to start (later charged it more) but the tach guage and the rest on that side were going crazy-after the longer charge it subsided-went to get something and asked them to check my alternator-they said OK-but the battery was way low-even after hours of charging-well replaced the battery-and guess what? the tach and guages on that side are still going nuts-until I rev the engine enough to reach 14 plus volts-then it stops. Think it could be the alternator?
gonna go out and do the EGR now-and see if the miss goes away or gets better-somehow me and my hrad head keeps saying ALTERNATOR.
But I will. The reason I'm thinking alternator is-I had ran my battery way down-charged it enough to start (later charged it more) but the tach guage and the rest on that side were going crazy-after the longer charge it subsided-went to get something and asked them to check my alternator-they said OK-but the battery was way low-even after hours of charging-well replaced the battery-and guess what? the tach and guages on that side are still going nuts-until I rev the engine enough to reach 14 plus volts-then it stops. Think it could be the alternator?
gonna go out and do the EGR now-and see if the miss goes away or gets better-somehow me and my hrad head keeps saying ALTERNATOR.
Thread Starter
Le Mans Master
Joined: Oct 2003
Posts: 6,130
Likes: 2
From: seattle WA
went to get the alternator checked-said come back in an hour. CFI-EFI,
I pulled the hose off the EGR, plugged it and went for a run-same thing-missing between 1700-1800, and the dash is still going bonkers.And that's why my hard head keeps saying alternator. Read the above post-can hardly wait to have that sucker checked. When a tune up doesn't get it and there ain't no codes-this sh*#t drives me bonkers.
I pulled the hose off the EGR, plugged it and went for a run-same thing-missing between 1700-1800, and the dash is still going bonkers.And that's why my hard head keeps saying alternator. Read the above post-can hardly wait to have that sucker checked. When a tune up doesn't get it and there ain't no codes-this sh*#t drives me bonkers.
Last edited by rick lambert; Mar 14, 2006 at 04:58 PM.
Race Director
Joined: Sep 2005
Posts: 13,269
Likes: 0
From: Sharpsburg Georgia
GA Events Coordinator
Rick, make sure they have a load tester, so they can do it on the car. some thing like a Snap-On avr tester, it will check the diodes also.
The reason i say this is that we have had several come into our shop with bad alternators, and the owners just would not listen to me, because autocrap or some other parts place has said there alternator was fine.
Greg N
The reason i say this is that we have had several come into our shop with bad alternators, and the owners just would not listen to me, because autocrap or some other parts place has said there alternator was fine.
Greg N
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Originally Posted by rick lambert
CFI-EFI,
I pulled the hose off the EGR, plugged it and went for a run-same thing-missing between 1700-1800, and the dash is still going bonkers.
I pulled the hose off the EGR, plugged it and went for a run-same thing-missing between 1700-1800, and the dash is still going bonkers.
RACE ON!!!
Thread Starter
Le Mans Master
Joined: Oct 2003
Posts: 6,130
Likes: 2
From: seattle WA
you're right-but I thought the dash light problem had gone away with #1 charging the old battery-it seemed to get better (almost gone) #2
when I asked them to check the alternator yesterday they said the battery was way to low? been on charger for hours prior to that-replaced the battery-dash lights got better-but still tweak! that combined with the miss keeps my one track mind going to alternator!
I'm glad you suggested the EGR though-cause that most likely eliminates it from the equasion. went back to have alternator checked-errrrrrrrrrrrr, there new equipment needs to have their battery charged 12-24 hrs. so back tomorrow. I'll keep u posted-and keep the
ideas comming-hard without codes to find these intermittent suckers-and I think I'm doing a systematic flow-been awhile since a tune-eliminated that-and some other diagnostics. Thanks.
when I asked them to check the alternator yesterday they said the battery was way to low? been on charger for hours prior to that-replaced the battery-dash lights got better-but still tweak! that combined with the miss keeps my one track mind going to alternator!
I'm glad you suggested the EGR though-cause that most likely eliminates it from the equasion.
went back to have alternator checked-errrrrrrrrrrrr, there new equipment needs to have their battery charged 12-24 hrs. so back tomorrow. I'll keep u posted-and keep the ideas comming-hard without codes to find these intermittent suckers-and I think I'm doing a systematic flow-been awhile since a tune-eliminated that-and some other diagnostics. Thanks.
Melting Slicks
Joined: Oct 2004
Posts: 2,510
Likes: 4
From: Austin Texas
Rick- I am not familiar with '87 distributer, but what controls your timing advance during acceleration? Do they still use the centrifugal weight advance system and vacumm advance????
anyway, i was thinking that maybe your advance weights could be sticking during the 1700-1800 RPM range until a higher RPM could break them free....
anyway, i was thinking that maybe your advance weights could be sticking during the 1700-1800 RPM range until a higher RPM could break them free....
Last edited by MikeC4; Mar 14, 2006 at 09:38 PM.
Racer
Joined: Feb 2006
Posts: 462
Likes: 0
From: green valley az
Miss or mrs?
Originally Posted by MikeC4
Rick- I am not familiar with '87 distributer, but what controls your timing advance during acceleration? Do they still use the spring and weight system and vacumm advance????
Thread Starter
Le Mans Master
Joined: Oct 2003
Posts: 6,130
Likes: 2
From: seattle WA
Maaaaaaaan, I love it-keep it comming Brothers 
MikeC4-no 
we're a little more advanced than that in our C4s-but honestly-thanks for asking We have what's called an Electronic spark control-controlled through the ECM, no vacumn advance and none of the old centrifugal weights-God-I loved thoughs.
Robert43- thanks for your input great info for others. I've basically tuned it-new plugs,cap, rotor,coil, had the ignition module
checked-and I checked the EGR per MY FRIEND CFI-EFI. I'm still leaning toward alternator-but-I'm hard headed.
MikeC4-no we're a little more advanced than that in our C4s-but honestly-thanks for asking We have what's called an Electronic spark control-controlled through the ECM, no vacumn advance and none of the old centrifugal weights-God-I loved thoughs.Robert43-
thanks for your input great info for others. I've basically tuned it-new plugs,cap, rotor,coil, had the ignition modulechecked-and I checked the EGR per MY FRIEND CFI-EFI. I'm still leaning toward alternator-but-I'm hard headed.
Last edited by rick lambert; Mar 14, 2006 at 10:18 PM.
Racer
Joined: Feb 2006
Posts: 462
Likes: 0
From: green valley az
Miss/
Originally Posted by rick lambert
Maaaaaaaan, I love it-keep it comming Brothers MikeC4-no we're a little more advanced than that in our C4s-but honestly-thanks for asking We have what's called an Electronic spark control-controlled through the ECM, no vacumn advance and none of the old centrifugal weights-God-I loved thoughs.
Robert43- thanks for your input great info for others. I've basically tuned it-new plugs,cap, rotor,coil, had the ignition module
checked-and I checked the EGR per MY FRIEND CFI-EFI. I'm still leaning toward alternator-but-I'm hard headed.
MikeC4-no we're a little more advanced than that in our C4s-but honestly-thanks for asking We have what's called an Electronic spark control-controlled through the ECM, no vacumn advance and none of the old centrifugal weights-God-I loved thoughs.Robert43-
thanks for your input great info for others. I've basically tuned it-new plugs,cap, rotor,coil, had the ignition modulechecked-and I checked the EGR per MY FRIEND CFI-EFI. I'm still leaning toward alternator-but-I'm hard headed.