What is this part on the intake manifold??!

1987 GMC Jimmy said:

The diverter and pump are pretty much useless unless the truck has to be put on a sniffer or pass a visual inspection for registration. If you don’t have them, then you’re already ahead.

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cool yea no emission testing for me. so for the diverter and pump ports plug those also?

one more question while i am picking your brain. do i need to have the emissions deleted from the "PROM chip" i think its called?

I ordered the "Stage II 350 TBI" from west coast engines and they go through a company to get their chips burned. but they never called and talked to me about any specifics about my truck. they just sent me the chip in the mail and that was it.

1987 GMC Jimmy said:

The diverter and pump are pretty much useless unless the truck has to be put on a sniffer or pass a visual inspection for registration. If you don’t have them, then you’re already ahead.

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well i do not have to worry with emissions where i am at. only exhaust leaks will fail inspections. so for those ports do i plug those also?

also while i am picking your brain: i purchased an Engine from West Coast Engines and they have a company they use to burn "PROM" chips, I think thats what its called. the chip in the ECM... anyway, they never contacted me about any specifics on my truck and i didn't know if i do not have emissions if that needed to be burned into the chip so it doesn't throw a code... any insight on that would be great so i can get back with them and get the right chip for MY truck.

Yeah. That port is on the TBI itself. As far as your other question goes, that depends on what you’re looking to get rid of. You shouldn’t get codes for a deleted air injection system unless the truck’s running too rich because of something else and the lack of fresh air in the exhaust tips the scale for the O2 sensor, but you will get codes for a deleted EGR if it’s not programmed out of the PROM. You can delete the charcoal canister and PCV valve without ECM repercussions, but I would honestly keep everything besides the air injection on these. It’s not like the carbureted stuff from the 80s with fifty pounds of valves, switches, and hoses that do nothing. If you’re running no mods besides maybe headers, and you’re keeping the EGR valve, a stock PROM tune should be fine.

1987 GMC Jimmy said:

Yeah. That port is on the TBI itself. As far as your other question goes, that depends on what you’re looking to get rid of. You shouldn’t get codes for a deleted air injection system unless the truck’s running too rich because of something else and the lack of fresh air in the exhaust tips the scale for the O2 sensor, but you will get codes for a deleted EGR if it’s not programmed out of the PROM. You can delete the charcoal canister and PCV valve without ECM repercussions, but I would honestly keep everything besides the air injection on these. It’s not like the carbureted stuff from the 80s with fifty pounds of valves, switches, and hoses that do nothing. If you’re running no mods besides maybe headers, and you’re keeping the EGR valve, a stock PROM tune should be fine.

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okay sounds good. i will just keep everything i have all hooked up together and correctly, make sure to move EGR hose to the EGR solenoid. plug the port in the top of the intake thats not needed. Stock PROM tune will be good. (this is all a note to self so i don't forget) Thanks man i appreciate all the info!!

You’re welcome. Hope everything works out!

EGR solenoid at the bottom of the pic.

1987 GMC Jimmy said:

You must be registered for see images attach

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That's a very legit diagram there. Some may not be aware of what some of those parts are since we use WRONG terminology. The MAP sensor is the Manifold Absolute Pressure sensor. That's how we get by without having to tune for different elevations these days, that sensor takes care of that. Then the A.I.R is the Air Injection Reactor what we call the "Smog PUMP" when it really inject air instead of Pumps air, and the Diverter Valve, here listed as the AIR Control Valve. So if you understand all that, then you know it's a good diagram.

1987 GMC Jimmy said:

Plug it unless you want to run cruise, A/C with multiple settings, or a gauge.

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I deleted my EGR any my cruise still works.

But by saying A/C with multiple settings do you mean fan speeds or are you actually talking the difference between floor/vent/defrost/etc? That last part may explain a thing or two about my truck and why the air just comes out of everywhere. I thought the blend door was mechanical?

RecklessWOT said:

I deleted my EGR any my cruise still works.

But by saying A/C with multiple settings do you mean fan speeds or are you actually talking the difference between floor/vent/defrost/etc? That last part may explain a thing or two about my truck and why the air just comes out of everywhere. I thought the blend door was mechanical?

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When I said to plug it, I was referring to the port on the manifold. And yes, I’m talking about the different modes that you mentioned. Blend is mechanically controlled by a cable.

I have another question here fellas! Can I do without the o2 sensor? Or will that cause any issues with fuel regulation (fuel too rich or starving for fuel) the wire was cut previously but idk if it will throw a code or have fuel issues without it hooked up. Also was looking into some new headers and didn’t want to get a pair without the o2 port if I needed it..

Any recommendations for headers? Mine are old and rusted and I cleaned them up and painted and all but it’s only a matter of time before they burn up again..

You need the sensor. It’ll have a hard Code 13 if you don’t, and I’m sure it’ll default to a more liberal mixture. If the PO was lazy, which they often seem to be, the wire should be clipped somewhere where it won’t be hard to find or it maybe tucked just out of eyeshot. Worst case scenario, you run a totally new wire from the ECM or close to it. I’m sure you could also reverse trace it through the bulkhead if you had to. If you get to here and realize you need a pinout, post back that you’ve gotten to that point, and I’ll hook you up. I believe the O2 wire is purple. With the headers, you can have a bung for the sensor welded in or do it yourself. What I’d recommend is keeping the one wire sensor and installing it as close to the other side of the header flange as possible to avoid a Code 13. If you happen to have issues, which several people have mentioned that they haven’t, you can easily install a three wire sensor. I don’t know what headers to recommend. I’ve got a set of G Body headers that I’m gonna try on my Jimmy, but that doesn’t mean they’ll fit without a hitch. In fact, I’m expecting to collect my share of monkey wrenches along the way.

It's not important whatever it is, there's been a self tapper plugging my vacuum hose for years -and I just found out!