Author Topic: 87 V10 TBI - No check engine light & inconsistent idle  (Read 3795 times)

Offline buzzman351

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87 V10 TBI - No check engine light & inconsistent idle
« on: September 26, 2022, 05:40:51 AM »
I have been replacing components lately and have seen the posts on how to check for codes but i have no check engine light. i actually reached up behind the cluster and it feels that where the CEL should be is just a plug. any ideas?

Online bd

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Re: 87 V10 TBI - No check engine light & inconsistent idle
« Reply #1 on: September 26, 2022, 08:41:07 AM »
The bulb socket may not have good electrical connections with the PCB, the bulb could be burned out or simply missing. 
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline buzzman351

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Re: 87 V10 TBI - No check engine light & inconsistent idle
« Reply #2 on: September 30, 2022, 06:19:27 AM »
theres a plug in its place like it didnt come with one and i was reading a diagnostic page and the instructions had (for trucks with CEL)

Offline JohnnyPopper

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Re: 87 V10 TBI - No check engine light & inconsistent idle
« Reply #3 on: October 01, 2022, 11:32:30 AM »
What is the 'plug' that's in its place?
1957 Apache 3100 235 Inline 6, 3 on the tree
1973 C-20, 3+3 454 4BBL TH400  Water Injection
1978 K-10, 350 4BBL TH350 NP203 M.M. Part time Kit/Hubs
1980 C-10 under construction

Offline buzzman351

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Re: 87 V10 TBI - No check engine light & inconsistent idle
« Reply #4 on: October 11, 2022, 05:34:54 AM »
the CEL light port where the bulb should be is capped off. i havent found a wire that would hook to a bulb. ive also seen write ups saying CEL is not present on some vehicles. that being said is there a digital scan tool that i can purchase to read diagnostics. trying to stay under 200 bucks

Offline buzzman351

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Re: 87 V10 TBI - No check engine light & inconsistent idle
« Reply #5 on: October 11, 2022, 05:53:31 AM »
or is there anywhere i can tap in with a test light to get the flashing codes?

Online VileZambonie

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Re: 87 V10 TBI - No check engine light & inconsistent idle
« Reply #6 on: October 11, 2022, 05:48:45 PM »
There is no 87 K10 so are you sure your truck is an 87? Is it TBI?
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74 GMC, 75 K5, 84 GMC, 85 K20, 86 k20, 79 K10

Offline buzzman351

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Re: 87 V10 TBI - No check engine light & inconsistent idle
« Reply #7 on: October 12, 2022, 11:09:43 AM »
Ok 87 V10. Yeah I’m sure

Offline buzzman351

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Re: 87 V10 TBI - No check engine light & inconsistent idle
« Reply #8 on: October 12, 2022, 12:46:45 PM »
But a scan tool recommendation would be greatly appreciated

Online bd

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Re: 87 V10 TBI - No check engine light & inconsistent idle
« Reply #9 on: October 12, 2022, 02:01:26 PM »
Post a pic of the instrument panel from the driver's seat and a pic of the "plug" that fills the CEL hole.  Is there an ALDL connector mounted under the dash?
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline buzzman351

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Re: 87 V10 TBI - No check engine light & inconsistent idle
« Reply #10 on: October 16, 2022, 06:19:29 AM »
I have changed out the MAP, TPS, IAC, EGR solenoid and valve, CTS. probably missing something but this is a TBI off of a 94. i had to splice in a TPS harness. the wire colors were the same so i figured it was all good. i can set base idle to about 750 and it will run at that idle for a bit. the next day it will go back to being around 1000. i performed the idle procedure that i found in the forum. ive sprayed throttle body cleaner around all hoses and gaskets. i even set timing again. any help?

Offline JohnnyPopper

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Re: 87 V10 TBI - No check engine light & inconsistent idle
« Reply #11 on: October 16, 2022, 02:47:27 PM »
Have you looked for bad grounding wires?
1957 Apache 3100 235 Inline 6, 3 on the tree
1973 C-20, 3+3 454 4BBL TH400  Water Injection
1978 K-10, 350 4BBL TH350 NP203 M.M. Part time Kit/Hubs
1980 C-10 under construction

Offline buzzman351

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Re: 87 V10 TBI - No check engine light & inconsistent idle
« Reply #12 on: October 16, 2022, 03:11:59 PM »
I did clean up the grounds that are by the thermostat. 2 of them. What others should I look for

Offline JohnnyPopper

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Re: 87 V10 TBI - No check engine light & inconsistent idle
« Reply #13 on: October 16, 2022, 04:46:02 PM »
I've seen them on the firewall and passenger fender.
1957 Apache 3100 235 Inline 6, 3 on the tree
1973 C-20, 3+3 454 4BBL TH400  Water Injection
1978 K-10, 350 4BBL TH350 NP203 M.M. Part time Kit/Hubs
1980 C-10 under construction

Offline buzzman351

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Re: 87 V10 TBI - No check engine light & inconsistent idle
« Reply #14 on: October 16, 2022, 05:15:46 PM »
I’ll check those as well