1987 Chevrolet 350 tbi high idle

[iamtherealJayy]

@Bextreme04 how do I set the mechanical advance to be at 0°? The guy didn’t move the distributor, as far as I know it should still be at the 8 btdc. I am going to proceed with checking it and report back.

 

[Bextreme04]

@Bextreme04 how do I set the mechanical advance to be at 0°? The guy didn’t move the distributor, as far as I know it should still be at the 8 btdc. I am going to proceed with checking it and report back.

Follow the timing set procedure that has been posted and is in the manual. If you don't unplug the tan wire at the connector you showed in your pic above then you are seeing the ECM controlled timing. That means the ECM gets a trigger signal and then makes its own adjustments before commanding the coil to fire. When you disconnect that tan wire, you are blocking the ECM from making any adjustments, so that you can see where the actual distributor is mechanically installed. It might not actually be in the wrong spot, but you will never know until you unplug the tan wire at that connector and verify it.

 

[Bextreme04]

@Bextreme04 how do I set the mechanical advance to be at 0°? The guy didn’t move the distributor, as far as I know it should still be at the 8 btdc. I am going to proceed with checking it and report back.

If the guy didn't unplug the tan wire, he(and you) have no idea where the timing actually is. You just know that the ECM has adjusted the timing to be at around 8 deg BTDC at idle. This could be because it is set to 30 deg BTDC mechanically and the ECM has pulled that much out because it is reading detonation.... you just don't know. I've heard of people really screwing it up because they are used to setting the timing mechanically and they dont unplug that connector. They have it running and the ECM adjusting and they just crank it around trying top get the timing light to move... but it doesn't. You are just artificially screwing up your available duration. The OBD2 vortec stuff requires the distributor to be within about 4 degrees or less of zero or it wont run at all(because there is a 1x cam position sensor in the distributor)

 

[Hugomartin]

My truck no longer bogs down in gear or at the unexpected stop light, Since I’ve turned up my idle screw

But unfortunately now I’m losing oil out of the dipstick and radiator is loosing coolant to the coolant reservoir !

 

[gmbellew]

there shouldn't be too many plugs not connected under the hood unless some stuff had been removed or added and then removed. there may be a fuel pump jumper hanging off the relay, a tach wire near the distributor. I can't think of anything else off the top of my head....

 

[iamtherealJayy]

There is a tach wire plug, I have it plugged and a tachometer installed on the truck.

 

[Snoots]

But unfortunately now I’m losing oil out of the dipstick and radiator is loosing coolant to the coolant reservoir !

Bad PCV or breather.

 

[Bextreme04]

But unfortunately now I’m losing oil out of the dipstick and radiator is loosing coolant to the coolant reservoir !

Bad PCV or breather.

or a blown headgasket... or broken rings.... or multiple issues.

 

[Bextreme04]

My truck no longer bogs down in gear or at the unexpected stop light, Since I’ve turned up my idle screw

But unfortunately now I’m losing oil out of the dipstick and radiator is loosing coolant to the coolant reservoir !

I'd run a compression test and change my intake manifold gaskets. Also change out the PCV valve as snoots suggests. Those are all cheap and easy things to do in a day or less. Low compression in one or more cylinders is going to tell you that you have a blown headgasket or broken rings that are pressurizing the engine. Coolant into the reservoir could be the headgasket or a bad radiator cap.

 

[iamtherealJayy]

Warmed truck up until thermostat opened, shut off truck. Unplugged est, started truck, timing was slightly off(can’t see the actual 0° need to clean it off and try again) rotating the distrivutor clockwise lowered the rpm, went until the line on harmonic balancer was at the beginning of the tab(assuming biggest V was 0 is now just past one V lower.) RPM’s got below 1000(roughly 900 tho) going to clean the tab and try again. Also going to replace throttle body base gasket. Found a leak of sorts behind throttle body, apparently throttle body cleaner isn’t as flammable as carb cleaner? But On back drivers side of throttle body spraying carb cleaner bogs down the engine.

 

[iamtherealJayy]

Did @Hugomartin ask a question on this forum? Or did he respond to the wrong one? I’m confused on how we’re talking about low compression now lol

 

[Bextreme04]

Did @Hugomartin ask a question on this forum? Or did he respond to the wrong one? I’m confused on how we’re talking about low compression now lol

I think he was having a similar problem to you and somewhere in this 16 page thread he hijacked it

Throttle body gasket leak will definitely cause a high idle. Clean the heck out of that tab and mark the 0 ref mark with a marker of some kind while the truck is off, it will help to identify the correct mark when things are spinning around. I would suggest wire brush and carb cleaner, then highlight the mark with a sharpie or paint marker

Change the gasket, unhook the battery to reset everything, and then check your idle.

Yes, throttle body cleaner is not carb cleaner. You should have been using carb cleaner or starting fluid to check for leaks... propane also works very well

 

[iamtherealJayy]

@Bextreme04 will definitely be replacing the gasket it can’t be too hard right? Three screws? I don’t have to unhook any lines will I? (Hard lines, I can unhook vacuum lines) I’ll clean up the tab tomorrow when it’s day time again, I tried to get a freeze photo of the flash of the timing light but it’s too dark my iPhone wouldn’t take the pictures right.

 

[iamtherealJayy]

Also the timing does advance with the est plugged in, the idle was approximately 300 rpm higher, started the truck after I’d adjusted timing and it was higher than without plugged in. Does that sound normal? I’m going to replace the gasket before I mess with timing anymore. Truck also still delayed to open thermostat according to gauge, gets to just above 210 before dropping off but I only let it open once

 

[Hugomartin]

Did @Hugomartin ask a question on this forum? Or did he respond to the wrong one? I’m confused on how we’re talking about low compression now lol

Lol yes it was a question and I got oil shooting out the dip stick and the coolant is filling in the radiator! He looks to have same issue lol. I must be losing compression? It drives good because I turned up my idle but losing fluids lol