C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

9th injector problem

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Old Mar 8, 2012 | 11:08 PM
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Default 9th injector problem

I believe this is the 9th injector on l98. It's on the driver side runner. This must be a common problem because it is just a terrible design. My 9th injector sticks out at the bottom and causes a huge vacuum leak. My car will only run for like a minute. Has anyone else came up with a way to rig this?
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Old Mar 8, 2012 | 11:43 PM
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Originally Posted by lespaul4563
This must be a common problem
Not a common complaint on here

Originally Posted by lespaul4563
it is just a terrible design.?
A round item fits into a round hole

Originally Posted by lespaul4563
My 9th injector sticks out at the bottom and causes a huge vacuum leak.
Obviously your injector is not seated square into the bore it fits into
Remove and refit it

Last edited by vetteoz; Mar 8, 2012 at 11:45 PM.
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Old Mar 9, 2012 | 01:15 AM
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make sure its seated properly, make sure the flange that the bolt goes thru is flush with the mounting surface and not forced and make sure the o-ring is not damaged. When I swapped intakes , mine was not seated properly
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Old Mar 9, 2012 | 01:29 AM
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make sure its seated properly,...
Exactly, if not seated properly before you tighten the bolt you will bend the mounting flange causing a big-time vac leak.
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Old Mar 9, 2012 | 11:59 AM
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Where is the 9th injector located?? Is that some sort of Mod where you get a bit of extra boost when you need it......















sorry, I couldn't resist the temptation
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Old Mar 9, 2012 | 11:44 PM
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The cold start injector is the round white object under the PCV vacuum tube in the center of this picture:



The cold start injector only works while cranking. It is controlled by the cold start switch mounted on the front of the intake manifold under the throttle body. The cold start switch has a thermal timeout and will turn off the cold start injector after 8 seconds or if the coolant temperature is higher than 95 degrees.

Last edited by Cliff Harris; Mar 9, 2012 at 11:47 PM. Reason: Added description of cold start switch.
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Old Mar 10, 2012 | 12:44 AM
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Is that some sort of Mod where you get a bit of extra boost when you need it......
It was used to aid with cold starts on '85-'88 L98s; in '89 it was eliminated and the newer ECM just enriched the mix a bit on cold starts.
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Old Mar 10, 2012 | 05:21 AM
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i deleted it when i got my SuperRam, you can buy a delete plate for it and call it a day
The difference is not noticeable
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Old Mar 10, 2012 | 09:57 AM
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Originally Posted by Cliff Harris
The cold start injector is the round white object under the PCV vacuum tube in the center of this picture:.
Originally Posted by 65Z01
It was used to aid with cold starts on '85-'88 L98s; in '89 it was eliminated and the newer ECM just enriched the mix a bit on cold starts.
I learned something new today......

I was just joking at first, had no clue there was a 9th injector.
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Old Mar 10, 2012 | 10:41 AM
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I've read on here that you can plug the hole, switch to a later year ecm? and it actually runs better also, havent tried it ....yet, myself

Last edited by oldalaskaman; Mar 11, 2012 at 06:49 PM.
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Old Mar 11, 2012 | 06:42 PM
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Originally Posted by oldalaskaman
I've read on here that you can plug the hope, switch to a later year ecm?
and it actually runs better also,
CSI doesn't affect engine operation.
It is only activated when engine is cranking over and then it only operates if engine is below a specified temp to add extra fuel like a choke on a carb engine
You don't need to remove the injector to disable it; simply unplugging the elec connector it has same effect ;you can leave the injector in the hole as a plug

Only '85 has a ancient slow ECM
86-89 use the same '165 ECM

Last edited by rodj; Mar 11, 2012 at 07:16 PM.
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Old Mar 11, 2012 | 06:49 PM
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Originally Posted by rodj
CSI doesn't affect engine operation.
It is only activated when engine is cranking over and then it only operates if engine is below a specified temp to add extra fuel like a choke on a carb engine
You don't need to remove the injector to disable it; simply unplugging it has same effect ;you can leave the injector in the hole as a plug

Only '85 has a ancient slow ECM
86-89 use the same '165 ECM
excellent , many thanks
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