testing the solenoid… looking at the assembly like this The upper two connections are for the vacuum sensor and the lower two are to drive the solenoid.
first I removed the short hose from the solenoid to the vacuum sensor then pried the vacuum sensor and the connection block out of the bracket. if you remove the solenoid from the bracket, be careful not to break off the fitting pointing sideways
removed two screws that hold the connection block and vacuum sensor together. Now you can see what is left of a 20 year old foam filter.
I used a $3.00 meter from harbor freight for the testing, so any meter can do this… Check the vacuum sensor without vacuum. It should be an open circuit, or infinite resistance.
on the 3 sensors that I tested, they all showed continuity around 5” of mercury vacuum
then I tested for continuity in the windings of the solenoid. ** the readings were all over the place. From very high resistance to almost no resistance. This would back up pauls statement,
quote
Originally posted by Paul Prince: I had a bad weather-pak pin (corroded) in the connector to the solenoid.......Paul
[This message has been edited by buddycraigg (edited 01-16-2004).]
ahhhh, The heart of the solenoid. A hollow metal tube with a copper wire coiled around it.
this is the solenoid disassembled. From left to right. Vacuum port Spring Block off plate Metal tube and windings Sealing O-ring Sheet metal cover
I applied 12vdc to the solenoid and it was able to “suck” the block off plate from my finger into the hole to seal up the hollow tube that runs through the center of the solenoid .
[This message has been edited by buddycraigg (edited 01-16-2004).]
From what I can tell this is how the system is suppose to work.
The best way I can describe it, is that it’s a controlled vacuum leak.
The vacuum circuit for the EGR starts at the throttle body. It is ported so there really isn’t any real vacuum until the throttle is about 1/3 open.
Next it runs though the one of the hard plastic lines that are known for breaking. If you have a line that only has one or two breaks you can splice the line back together with a short piece of hose. If it’s too bad you can buy a complete set made of steel from http://www.rodneydickman.com/
Now we get to the single port on the front of the solenoid. And from there it get’s interesting.
EGR is NOT working. Fresh air is being pulled from the air filter through the metal tube bolted to the firewall, through the center of the solenoid, all the way to the throttle body. The spring holds the block off disk against the tube in the solenoid, but it is very weak and the suction can overcome it.
EGR is working. The solenoid is energized and the block off disk is held firmly to the tube in the solenoid. Now vacuum is going to the double port on the solenoid. There is a brass filter in this port, probably to slow the flow of air. Vacuum is supplied to the EGR to open it AND to the vacuum sensor. The vacuum sensor tells the computer that the EGR is open (or at least it’s suppose to be) A small amount of air leaks past the vacuum port head through a groove at the base.
EGR is turning off Now is when it gets really busy. This is why the solenoid is designed the way it is, the vacuum ports cant just be blocked because the EGR would hold the vacuum and stay open. Once the solenoid is deactivated the only thing holding the blocking disk against the tube is the spring pressure. The vacuum that is in EGR diaphragm and going to the throttle body is now able to pull the disk away from the tube. The EGR is able to close and then fresh air continues to flow to the throttle body.
[This message has been edited by buddycraigg (edited 03-28-2004).]
There is a short hose that connects the side port and the line going to the vacuum sensor. This hose isn’t made of normal vacuum line and rots out badly.
The fresh air port on the back of the solenoid is suppose to have a hose that goes to this metal line on the firewall.
If you ever wondered why they didn’t simply remove the large pipe that use to go to the valve cover when they did the recall, that’s because it's attached to the small line. big pipe with GREEN arrows. small pipe with RED arrows
And finally the small line connected to the air cleaner.
The hard plastic lines connected to the solenoid.
[This message has been edited by buddycraigg (edited 02-05-2004).]
testing the whole system Everything that I have see claims that the code 32 is set if one of two things happen.
You DO NOT have enough vacuum at the vacuum sensor when the computer wants the EGR open Or You DO have too much vacuum at the vacuum sensor when the computer wants the EGR to be closed.
** Please note, although I cannot find anything in books nor have I ever experienced it myself. There are too many people that claim they also had a code 32 when they had a leak in the EGR system itself whether it be a bad gasket where the EGR is mounted to the exhaust or a cracked tube. Since I cannot prove or disprove this situation I will not cover it.
So your first question is do you have vacuum when you should? This one is the most common and most time consuming to diagnose.
The check engine light will come on mostly at cruising speed on the highway or with very mild driving after the engine is at normal operating temperature. That means the computer is NOT seeing the sensor close when it should. The possible causes seem almost endless.
1 The solenoid is bad, check for an open circuit in the windings. Of course a short in the winding would cause a problem by not creating a strong enough magnetic field to pull the block off disk to seal the tube. But since I was unable to get a steady reading of the ohms on a working solenoid we�ll just have to hope it�s working.
2 The solenoid is not pulling the block off disk in to place when it is energized. This one is not easy to check. Just because the block off disk is against the tube, there is still a slight air bleed built in to the side of the port. You cannot pull a constant vacuum at the front of the solenoid even when it is energized. The vacuum will bleed off slower than when the solenoid is off, but it still bleeds off. The difference is less than a second.
1 and 2 can be tested with out a meter or a vacuum gauge. With the engine running and the connector unplugged, apply 12 volts to the solenoid pins, open the throttle part way, the EGR diaphragm will pull in.
3 The vacuum sensor is not closing when vacuum is applied to it. check it with a vacuum pump and a meter.
4 The vacuum signal is not getting to the sensor. A blockage or leak between the throttle body and the solenoid, or that little hose in the pic with the quarter.
5 Leak in the EGR diaphragm
6 ECM or wiring problem.
(if you do not have some of the tools I used everything can be substituted with stuff you have laying around. Vacuum pump = rubber hose connected to a non-ported vacuum line on a running engine. Meter for testing continuity = flashlight battery, flashlight bulb, and some jumper wires. ** be careful using the flashlight battery, even at 1.5 volts you can damage some things 12 vdc power supply = car battery and jumper wires.)
[This message has been edited by buddycraigg (edited 10-02-2011).]
Anybody that will take this amount of time to help explain a very basic, vital piece of the fiero engine electronics deserves quite a hardy vote of thanks. Keep it up please, you are laying this out very well.
Great Job A++ in my experience the most common cause of failure of the solenoid is water from the deck lid in rain or carwash and /or coolant spills. I highly reccomend coating the solenoid especially where the wires enter with liquid tape, the more the better. Works for me
thanks jazz, you being "the picture guy", thats a big compliment.
i've already got dibs on the pickup coil replacement, and plan on redoing my Gen I headlight rebuild.
if you wanna get to it before i do, i would really like to see a write up on the 4 freaking different temp sensors, where they go, what they look like and what each one controls.
[This message has been edited by buddycraigg (edited 01-17-2004).]
You get a big + from me. guess what I have the solenoid off my fiero lying in the floor for two days trying to figure out how it works you sure came to my rescue. THANKS Don
This article is GREAT, and may have just helped me pass emissions (I'll find out tomorrow) Seems the vaccum source line and the EGR line were switched, the sensor got vaccum, but the egr didn't!
One thing I didn't see you answer (and I'll look thru again to be sure), is the vaccum source the bottom fitting on the solenoid? That's how I swapped it and I'm now pulling 2" of vaccum to the egr on revs. (that should be enough, right?
Again, great post! Wish I could give you yet another positive! (already had you rated + for another great post).
Originally posted by Banner: One thing I didn't see you answer, is the vaccum source the bottom fitting on the solenoid? That's how I swapped it and I'm now pulling 2" of vaccum to the egr on revs.
thanks, if this pic doesn't answer the question, then i'm not really sure what you are asking.
Gotta say you just saved me hours of time, I have a code 32 on my car and was planning on getting around to solving it, but I did not plan on dissasembling the entire system like you did. With all the info you supplied you just turned what is usually a week project for some to get rid of that code, in to a couple of hours of a few simple test that you outlined very well, A+ from me on all that time and research. Thank you for saveing me a lot of possible headachs.
I'm following the procedure in the Shop Manual to check Code 32. With the key in the on position and attempting to add vacuum to the manifold side. It doesn't hold a vacuum. Should it be holding a vacuum.
I'm following the procedure in the Shop Manual to check Code 32. With the key in the on position and attempting to add vacuum to the manifold side. It doesn't hold a vacuum. Should it be holding a vacuum.
Thanks
Sorry I didn’t see your post. I’m sending you a PM to get you back to this thread.
From my experiments, the “vac from engine” port will not hold vacuum unless the solenoid is energized. Because it is sucking air from the air filter all the way through that thin metal tube on the firewall.
And even when the solenoid is energized, there is still a slow leak down in the vacuum, through a slit in the side of the vacuum port and possibly through the vacuum sensor itself.
The only thing in the system that will hold vacuum indefinitely is the EGR valve when connected directly to a vacuum pump.
Buddycraigg, Excellent write up! Thanks for taking the time.
quote
Originally posted by WHT 88 Fiero GT:
I'm following the procedure in the Shop Manual to check Code 32. With the key in the on position and attempting to add vacuum to the manifold side. It doesn't hold a vacuum. Should it be holding a vacuum.
Thanks
In order to do this, you need to have the diagnostic pins on the ALDL shorted. (Same as for pulling codes.) In that configuration, the EGR solenoid is always turned on.
Also... Check for vacuum leaks. I replaced a solenoid once, because all the lines looked good, but weren't. That was an expensive and frustrating mistake. Pay particular attention to the rubber ends, where they connect to the various devices, and where the hard tubing plugs in.
The vacuum source for the EGR is a tube that comes out of the bottom of the TB. It's the one nearest the back of the car.
------------------ Raydar 88 3.4 coupe........... Coming soon... 88 Formula, presently under the knife.
Now I think I understand why the EGR would start working if I partially restricted the fresh air tube. I just isn't working quite the way it's supposed to. Outstanding writeup. Thanks.
Dave
[This message has been edited by 2farnorth (edited 05-14-2004).]
Great stuff......My hat goes off to you for an excellent write-up and time involved. I for one and I'm sure as many other Fiero owners have suffered from the dreaded Code32. Again, thanks.
Buddycraigg You are one talented individual dedicated to solving Fiero problems. Everything from steering wheel covers to rocker switches, now the EGR Solenoid. My hat is off to you, and the obvious + to follow. Jim
Awesome thread. I've had this code on and off basically since I got my car years ago. Have swapped out 3 EGR sol and all the same(used). I have been meaning to tackle this but never get around to it, now I will Cheers!
this just in... i cannot prove or disprove this, but i had someone email me claiming that he/she had an intermittent code 32 that he/she couldn't fix.
Replaced the ECM coolant temp sensor and the problem has been gone for 2 weeks.
I spoke to this person at wheatstock and he said the code 32 has not come back. and he is positive it was the temp sensor. he mentioned something about it being talked about in a manual somewhere and i will searchin All Data for something in writing.
