HELP...1986 C20 5.7....smog removed,,,Check engine light???

[rfmaster]

Originally Posted by motornut

my 1985 sub intake

That's one Rochester 220 TBI!!!! How did it manage to get into your '85???? I always thought that TBI was introduced on '87 and later?!

//RF

[motornut]

i found it when i bought it about 9 years ago........same as my 87 4x4 sub.Anything i've ordered or done was based on my 87.Now i need to read the frame numbers but i don't know where to look,can't find that info yet.And if this engine can't be in an 85 then i should be able to remove the rest of the smog stuff ........explains why i was told the etest was based on an 87.......now exempt after 20 years

[rfmaster]

Originally Posted by motornut

i found it when i bought it about 9 years ago........same as my 87 4x4 sub.Anything i've ordered or done was based on my 87.Now i need to read the frame numbers but i don't know where to look,can't find that info yet.And if this engine can't be in an 85 then i should be able to remove the rest of the smog stuff ........explains why i was told the etest was based on an 87.......now exempt after 20 years

Looking at the photos it is clearly viable that you have centerbolt covers (post 86) , harness routing, bulkhead feed through grommet appear as factory like installation. I highly doubt that PO was this good to duplicate all these fine production line details. I hate to say but VIN swapping is more likely than not.

There should be A vin number stamped on frame (location - do not know)

//RF

[motornut]

wondering if these marks are norm,i can see writing says eng change 51?Can't remember if my blues had all of those,i know it had some.check out the 3rd seat hookup.

[72freak]

I was under my 86 the other day and saw some numbers stamped in the frame on the passengers side, rear, up near where the upper shock mount is. I was putting shocks on it when I noticed it. I did not compare them.....

Im sure a square body expert will chime in here soon and tell us where the frame VIN numbers are located

[motornut]

thanks i'll have peek there

[72freak]

Originally Posted by motornut

thanks i'll have peek there

Did you find anything?

I plugged the 2 prong back in and there seems to be no difference.....still no check engine light though.

[motornut]

nope cleaned and scraped /crud from behind the steering box to where it turns down, took a few picks,not seeing any numbers there,but a friend looked in asked if i had a fire?pointed above the booster to melted plastic holder,and harness going threw firewall.....not that i know of......

[72freak]

Ill get back under mine this week and find those numbers back by the shock mount and see if they match the VIN....

[motornut]

ok thanks

[motornut]

Stopped at a gm dealer told no vin corisponding number on the frame.Called last owner said he loved it, glad to hear it's still goin(i've owned bout 10 years).said he heard about the vin issue when getting it serviced,wrong parts were ordered,but he bought it Missasauga Ont ,from a guy from texas,will try to find out if he has other papers on it,but doubts it.

[motornut]

http://67-72chevytrucks.com/vboard/s...d.php?t=417457

[kristian_dancer]

Ihave been haveing exactly the same problem,

I have an 86 c20 dually converstion. Check enginelight would come on on when I went over 55 then off every time i turned ignition off.
Now it stays on.
I have no plug for code reading under dash.
No obvious smog equipment under the hood.
Trucks runs fine other than needing a break seal replacement on the dually rear end.
All I want to know is that im not killingthe truck and that the check engine light is not coming on for a good reason like trans temp or oil pump failure etc.

[clinebarger]

Originally Posted by kristian_dancer

Ihave been haveing exactly the same problem,

I have an 86 c20 dually converstion. Check enginelight would come on on when I went over 55 then off every time i turned ignition off.
Now it stays on.
I have no plug for code reading under dash.
No obvious smog equipment under the hood.
Trucks runs fine other than needing a break seal replacement on the dually rear end.
All I want to know is that im not killingthe truck and that the check engine light is not coming on for a good reason like trans temp or oil pump failure etc.

Did you see post #29? Do you have the "smog pump control module" on the firewall?