'86 vacuum lines

[Escoces]

86' vacuum lines

Hi there, I'm new to this site. I have an 86' (original owner) that has had too many other people turn wrenches on it. I am now the only one wrenching. I have just put it back together after some head work. It runs good when warmed up but little or no cold idle. I cleaned everything (including IAC, plenum, runners) before I put it back together. I put all vacuum lines back where they were. Fixed one leaky connector.

I am not sure that the vacuum lines are routed correctly. Haynes, Chilton, etc. not specific about this. EGR valve seems to be Ok. I have researched enough to know that C4 EGR systems changed over the life of the C4 series. Mine has the EGR solenoid mounted to Therm. housing bracket with lines from under TB to solenoid, then from solenoid to EGR valve. Is this correct? If so, where is vacuum introduced within the TB to send it to the EGR valve for negitive backpressure? A diagram would be swell. Local Chevy dealer has none. Any help appreciated.

 

[JonM]

I don't know about an 88 but on my 84 the diagram for the vacuum hoses is on the radiator cowl.

 

[Escoces]

I don't have any diagrams anywhere under the hood. A result from an accident repair years ago.

 

[Ken]

I don't have that luxury either, due to similar circumstances.

Sure wish I did though; I can't find a decent vacuum routing schematic anywhere.

 

[Magmotor]

There are 5 different types of EGR valves: Pulse Width Modulated, Electronic, Digital and Backpressure...(positive and negative) Which kind do you have?

On a Negative backpressure system the pressure differental from the vacuum connection on top of the valve and the pressure at the "port intake" determinds which way the diaphram moves. To determind if you have a neg. sys there will be an "N" stamped into the part number on the valve itself. A "P" if it's positive.

 

[Magmotor]

Here is the diagram that goes with the emissions control label under the hood.

Hope this helps a little

 

[Escoces]

I've been online waiting and did not see anyone update this thread. Guess I don't know quite what operating procedure is here.

Thanks for the diagram! That is not my layout, with solenoid near Therm. housing, but the connections are the same and is as layed out in Haynes. At least now I know the lines are routed correctly.

I have SLP shorties so I can't get to the EGR to feel if it is moving Ok but seemed to when I had the manifold off. Can't even see the marking on top. Tell me. Where is the vacuum created? Should the solenoid pass air/vacuum when engine is cold with and without the key on?

 

[Ken]

I've been online waiting and did not see anyone update this thread. Guess I don't know quite what operating procedure is here.

Sometimes you just gotta hang in there for a while, until someone with knowledge of the system sees the question. You should receive plenty of replies, but it may take some time, especially on weekends for some reason. I guess maybe a lot of people log on while at work. :L

_ken

 

[Escoces]

Found that I have to keep hitting Refresh on my browser to see responses. Otherwise, it does not update automatically. Did the posted diagram help you any Ken?

 

[scorp508]

Found that I have to keep hitting Refresh on my browser to see responses. Otherwise, it does not update automatically.

Using MSIE?

Tools --> Internet Options --> Temporary Internet Files Settings --> Every Visit to the Page

 

[Escoces]

Yep. MSIE. Just changed per your que. Thanks.

 

[scorp508]

Good luck hope it works.

 

[Escoces]

Scorp508 - Do you know of any way to test an IAC?

 

[scorp508]

Scorp508 - Do you know of any way to test an IAC?

With or without a scanner?

 

[Escoces]

First, without. I don't have one. I can borrow one from my neighbor if I have to. Guess it beats paying $70 for a new one. Hate to replace parts if they don't need it.

 

[scorp508]

Yeah those foolish things are expensive. I forget the exact flowchart so I'll grab my service manual in the morning. Its out in the barn right now and its about 35* out there right now.

 

[Ken]

Did the posted diagram help you any Ken?

Any diagram helps me! :L

Seriously, yes it is very helpful, but what I'd really like to see is a diagram for the vacuum reservoir/heater controls. I'm trying to reconstruct my vacuum lines to my heater controls and cannot remember how the system was set up. I removed the cruise control, where in the book by the way, there is a diagram of a portion of the vacuum routing from the tank (reservoir) so the cruise is out of the picture and not needed, but I can't quite see the lines where the hit the check valve connection. That's the diagram I need to see.

I did get the routing correct for the charcoal cannister.

_ken

 

[scorp508]

Ken, here is the one outta my '87s book. I don't know if its different or not. I think I have the AC one in the book, I can snap a picture tomorrow.

 

[Mart]

Hey there, you wait long enough and someone will help out, I have an 86 and I am pretty sure the motor is original, can I help by taking a digital pic.

If so just let me know where.

Mart

PS. welcome to CAC, the best place to be if you own a vette.

 

[Escoces]

Thanks Mart. This place is pretty neat. Long story short. I am the car's only owner so I know pretty much what's been done because I paid for it. Lots of mods to the top end. Headers, heads, Custome .520 cam, Crane Golds, 52mm TB, and more. Local shop did it. The guy and I are no longer on good terms. He won't stand by latest changes. So, I had to have one of the Alum. heads repaired. I took it off, fixed it, put it back on. In doing so, now no cold idle. The guy has bad rep. around town. Now I am questioning everything he touched. The great diagram Scorp just put up is close to what I have except I do not have the "Y" out of the EGR solenoid spliting to canister and to TB IAC coolent plate. No "Y". Just single line to TB. Can you just look at yours and see if it "Y"s or is a single?