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Discussion Starter #1
I'm a newbie to the "vette community" (bought my first C4 2 weeks ago so please be gentle with me:) Drove it back from Florida to the outer banks of NC with no problem whatsoever. Last night we took our manditory midnight cruise and noticed that everytime we hit 52 mph it started "sputtering" (REAL BAD). It has no problem from a full stop to 80/90+. Shifts, acceleration etc. Only happens at around 52 mph. Everything on her is stock (for now) and any suggestions / pointers would be appreciated.

m
 

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resident conservative
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Two things come to mind, one is the opti spark might be breaking up at that rpm and load, two could be the injectors them selfs could be going bad ,three is plug wires.
If you can get the engine scaned for any codes.
let us know what you find.
 

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Discussion Starter #4
Thanx Guys!
Tomorrow I will have a trusted mechanic take a look see. It does appear to have the original plugs and wires still installed (only 58k on the odometer) If in fact if all you mentioned is found to be the culprit, do you have any opinion what to upgrade them to?
(may as well do that now eh?)

Thanx for the quick replies too!
m
 

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Strange problem. Does'nt sound like plugs and wires, seems like they would give you a problem at any speed. Might be injectors.
If you need a trusted place to get them reconditioned, let me know. :)
 

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El Teafive
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xbroker said:
Thanx Guys!
Tomorrow I will have a trusted mechanic take a look see. It does appear to have the original plugs and wires still installed (only 58k on the odometer) If in fact if all you mentioned is found to be the culprit, do you have any opinion what to upgrade them to?
(may as well do that now eh?)

Thanx for the quick replies too!
m
I heard a lot of guys use Taylor Spiro Pro wire since they fit in the stock looms
 

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dont mean to hi jack this guys thread but i figured it would be better than posting a whole new topic, but i have an 85 and occasionally if i give it gas after idling in D for a while the car sputters and then takes off, its only after idling, what could this be, oh and its an automatic
 

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Discussion Starter #10
UPDATE on 52mph "sputter"

I wasn't able to get to my mechanic for his 2 cents. So I tried a can of injector cleaner. No noticable results from that yet since I've only burnt about a quarter tank of gas since I dumped it in.

What I did find however is that if I manually shift thru all the gears she runs fine then when I revert back to running in "D" with overdrive allowed to kick in ... THE SPUTTER RETURNS @ 52!!

Any light bulbs come on?, Bells go off? ..Should I try adding more Duct Tape? ;)

thanx,
m
 

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Re: UPDATE on 52mph "sputter"

xbroker said:
I wasn't able to get to my mechanic for his 2 cents. So I tried a can of injector cleaner. No noticable results from that yet since I've only burnt about a quarter tank of gas since I dumped it in.

What I did find however is that if I manually shift thru all the gears she runs fine then when I revert back to running in "D" with overdrive allowed to kick in ... THE SPUTTER RETURNS @ 52!!

Any light bulbs come on?, Bells go off? ..Should I try adding more Duct Tape? ;)

thanx,
m

Have heard that injector cleaner is a no no for our cars. Not sure how true it is, someone else may jump in with more info on that.

As far as the sputter happening only when the car is in drive and overdrive kicked in, does the sputter just happen when you reach 52 at a steady rate, are you accelerating at the time or what. Its possible that as you accelerate at 52, if your trans does'nt down shift your motor could bog down a little?? Don't know it thats any help to you, just not real clear on how and when the car is breaking down. :huh:
 

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resident conservative
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NEWS FLASH!!! I have the same problem ses light came on just as the sputter started and it a code 32 EGR circuit, so I am going to replace the EGR valve and control switch this should cure this problem.......I hope!
 

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The earlier Gm Multec injectors we known to develop a dead spot at certain pulse widths and RPMs. I've seen them just quit pulsing under certain conditions and work fine at others.
If you rule out the other things, you may want to be them flowed. And a good cleaning will usually improve the low end response and driveability on the LT1's.

Gordon
 

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resident conservative
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Switch said:
The earlier Gm Multec injectors we known to develop a dead spot at certain pulse widths and RPMs. I've seen them just quit pulsing under certain conditions and work fine at others.
If you rule out the other things, you may want to be them flowed. And a good cleaning will usually improve the low end response and driveability on the LT1's.

Gordon
Thanks for the info and I also bookmarked your site:cheers:
 

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Welcome to the forum.
Hope it works out to be an easy fix.
 

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Switch said:
The earlier Gm Multec injectors we known to develop a dead spot at certain pulse widths and RPMs. I've seen them just quit pulsing under certain conditions and work fine at others.
If you rule out the other things, you may want to be them flowed. And a good cleaning will usually improve the low end response and driveability on the LT1's.

Gordon
Exactly the problem I am having with my LT5 right now. I have a dead spot at 2200RPM. Have checked Coils and Replaced wires with no change. I have been told the same thing about the Multec injectors. So I am sure they are the problem. Went out and bought a fuel injector tester, so I will be pulling the fuel rail and testing all 16 injectors. What Fun.

That dead spot you are referring to at 52MPH is probably there at a certain RPM and just can't notice it in the lower gears. I can't notice the dead spot to well in 1st gear but can really tell in 6th gear (Tall gear 6th gear at 2200RPM=85mph). Hit the gas in that gear and you can really tell the dead spot (Freeway cruising gear).
 

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DC Crew
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RedRiderZR1 said:
Exactly the problem I am having with my LT5 right now. I have a dead spot at 2200RPM. Have checked Coils and Replaced wires with no change. I have been told the same thing about the Multec injectors. So I am sure they are the problem. Went out and bought a fuel injector tester, so I will be pulling the fuel rail and testing all 16 injectors. What Fun.

That dead spot you are referring to at 52MPH is probably there at a certain RPM and just can't notice it in the lower gears. I can't notice the dead spot to well in 1st gear but can really tell in 6th gear (Tall gear 6th gear at 2200RPM=85mph). Hit the gas in that gear and you can really tell the dead spot (Freeway cruising gear).
Boy, could I tell you about all the ZR1's I've heard of that have had injector problems.......
 

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Twice as many injectors... twice as many potential injector problems.
 

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Here is my question... When it sputters does the RPM's go up and down... Like, Does the tach go up then back down, or does the RPM's stay constant? If they are going up and down.. could be the trans slipping and gripping under load... just a guess.. it can be a pain in the ass to diagnose over the net... but what ever hints we can get can always help..
 
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