Component Identification

[KOPBET]

I was poking around under the right side fuel rail cover yesterday, just getting to know my LT1 friend. While standing next to the front right wheel looking at the right side of the intake, positioned about 1:00 o'clock from the oil filler cap I noticed what appears to be a vacuum solenoid with a BLUE electrical connector. This solenoid has a gozinda from what I believe is intake vacuum and a gozoutta to somewhere in front of the right side door (possibly the fuel vapor canister?). Anyway, what struck me as odd is that in the center of this same "solenoid" is another vacuum "port" with a right angled rubber vacuum hose that runs two inches toward the rear of the engine and just stops, no plug, no more hose, no connection to anything. Looking around I see nothing that is loose or disconnected that might mate with it. I did not start the engine to see if I had vacuum at this hose. Can someone please tell me what the purpose of this dangling vacuum line might be? :confused

Thanks,
KOPBET.

 

[KOPBET]

Well, if there are no takers, then can someone please look at their engine and see if theirs is constructed this way also?

I know I can't stump you guys this easily...

 

[Ken]

I don't know what it is with the responses lately; mine have gone unanswered, and sometimes unread, as well.

I am unable to answer your question simply because I know not the LT1.

Good luck.

_ken

 

[Rabbit]

I believe you are referring to the MAP sensor, Manifold Absolute Pressure Sensor. It's the only thing I can think of in that area. I keep my vette elsewhere or I would be happy to check. Will do so tomorrow if no else responds.

:gap

 

[dburgjohn]

The item you are looking at is called the Canister Purge Solenoid. It has a short hose that runs to the throttle body and a longer one that runs to the Fuel Vapor Canister which is sort of hidden in the bottom of the right side fender. Nothing hooks to the back side, just the two hoses and the electrical connection.

 

[KOPBET]

Ken , Rabbit - thanks for the replys.

Rabbit - The solenoid is external to the manifold and not connected to it. It is just lying there in close proximity.

dburgjohn - Thanks for the reply also, your response sounds like were on the right track. However my solenoid has three nipples. Not like in Total Recall though :eek. The third, or middle one, has no vacuum on it (at least at idle) and leads to nowhere.

 

[B17Crew]

KOPBET,

I have the same termination on the rubber tube you are referring to. I was so alarmed when I first noticed this, that I went to a dealer that has a large selection of C4’s for sale and asked if I could go out and look under several hoods of cars similar to mine. I figured if more than two were like that, I should be ok. Well, all cars matched mine, so no worries.

I then did a search on the internet of LT4 engines and found photos of the area in question and saw the same ending to the tube. Not being totally satisfied, I broke down and bought factory service manuals to check. It’s nice having the manuals to refer to for things like this, pricey as they are, they are a invaluable reference.

B17Crew

 

[KOPBET]

Thanks B17Crew.

If GM had plugged the end of the tube I wouldn't have given it another thought, but if I see something like this I can't blow it off or just let it die; kinda like what you went through. Being new to the LT1 and since the car was bought used I had to find out for sure. TGF the Corvette Action Center! I guess it's time to head off to Helm's for the manuals.

BTW, did the manual describe a purpose for this? My guess would be it is an atmospheric pressure reference point.

 

[B17Crew]

KOPBET,

I am at work at right now, but when I get home tonight, I’ll see what kind of info I can pull from the service manual.

B17Crew

 

[KOPBET]

 

[B17Crew]

Hey KOPBET,

Here’s what I was able to locate in the 1996 Y Platform Service Manual. I purchased the set (total of two books in the set) from Mid America for around $150.00. Here’s a link to their site.
http://www.madvet.com/

That tube comes off of the Evaporative Emissions Canister Purge Solenoid Valve. I am going to try to attache a photo I found in the internet of an LT4 Crate engine that clearly shows the tube. If it’s too large a photo or I can’t post it, sorry about that!

I am going to list what it says about related parts to this system. I’m on page 6-740 of Engine Controls-5.7

Evaporative Emission (EVAP) Pressure Control Valve
This System uses an in-line EVAP pressure control valve as a pressure relief valve. When vapor pressure in the tank exceeds approximately 5kPa (.7 psi) the diaphragm valve opens, allowing vapors to vent to the canister. A 1.14 mm (0.045 inch) orifice in the passage leading to the canister tube causes pressure to drop slowly, preventing the valve from oscillating (buzzing). When the tank pressure drops below 5 kPa (.7 psd), the valve closes causing vapors to be held in the fuel tank.

Results of Incorrect Operation
• Poor idle, stalling and poor driveability can be caused by the following:
-Inoperative purge solenoid valve
-Damaged canister
-Hoses split, cracked and , or not connected to the proper tubes

• Evidence of fuel loss or fuel vapor odor can be caused by:
-Liquid fuel leaking from fuel lines
-Cracked or damaged canister
-Inoperative canister control valve
-Vacuum hoses that are:
-disconnected
-Mis-routed
-Kinked
-Deteriorated or damaged vapor hoses

If the solenoid valve is open, or is not receiving power, the canister can purge to the intake manifold at the correct time. This can allow extra fuel during warm-up, which can cause rough or unstable idle.

EVAP Vacuum Switch
EVAP Purge Vacuum Switch
The EVAP Purge Vacuum Switch is used by the PCM to monitor EVAP canister purge solenoid operation and purge system integrity. The EVAP Purge vacuum Switch should be closed to ground with no vacuum present (0% EVAP Purge PWM). With EVAP Purge system flow should set a DTC P0441. A continuous purge condition with no purge commanded by the PCM should set a DTC P1441. Refer to Evaporative Emission (EVAP) Control System for a complete description of the EVAP system.

B17Crew

 

[Tanzanite3]

Holy Mackerel!!

That must be one hot engine... look at all the firewood in the engine bay!!

 

[froggy47]

I posted a picture of, what I think, is the same component on my LT4 engine. Check it out. Posted 4/9/03 c4 technical forum. Title "Ok to post picture....."

Moderator would not let me reattach it here.

 

[KOPBET]

B17 Crew - You are good.

Thanks a million for your explanation from the manual. I know that must have taken a lot of your time. I appreciate it. This helps.

:BOW

KOPBET.

 

[B17Crew]

Yep, that's the little bugger that has been driving us crazy.

When you first see the tube not attaching to anything, you think - now what the heck happened here, what's missing, where is this supposed to go? I thought for sure I was minus tubing. It just looks wrong, but that's the way GM designed it.

B17Crew

 

[B17Crew]

KOPBET,,

You are welcome!

I am glad to return the favor in this forum. I have had fellow Corvette owners/enthusiasts answer questions that I could not for the life of me figure out. This forum rocks!

B17Crew

 

[Ken]

I posted a picture ...
Moderator would not let me reattach it here.

I don't understand. :confused

 

[Wamp]

dreaded code

I came up with a check engine light last night, I pulled the code this AM and it is that P0441 (Evaporative Emmision control system incorrect purge flow) This is a generic code. Anyone else see this code come up before or have any insight on how to fix it?

I posted here because this thread talked about that code.

 

[froggy47]

Ken,

It was a picture of the "unplugged third nipple". I had posted the pic on another thread when I was puzzling out the same question & was trying to post it a second time on this one. The moderator message was probably generated by your software to prevent multiple postings of the same pic (takes up space?)

No problem, I'm still learning how the forum works.

Thanks!