Yes, that little looped vacuum line can be a hard to find cause. My first 85 threw a trouble code within 10 miles of the seller's house. At the time I knew nothing about Fieros and bought a Haynes manual before I got home. That was in the days before Pennocks and I was on a newsgroup called AltAutosFiero. Someone suggested looking at that line. The little soft rubber connector had rotted, becoming porous, and the tube had a tiny crack in it. Replaced the whole thing with a piece of vinyl tubing from my daughter's fish tank supplies. No more problem.
While corrosion on copper windings is common defect, a sticking spring/block-off plate is also common, and of course a break in the tiny vacuum line to sensor is popular.
I assumed easy fixes like the vacuum line would be repaired rather than replacing the $$$ part.
So I bought one. The cover pops off of the solenoid. The cover holds some potted circuitry. The two outside pins pass through that circuitry and onto the solenoid itself.
So
For this two work the connector would at least have to be rewired to put the solenoid wires on the two outside wires.
In the potted circuitry is a flyback diode.
There is no plumbing for the switch. No vacuum line that runs to a switch.
Thus this solenoid can not work as a 2.8 Fiero solenoid. Not unless the switch is plumbed in and wired in.
So I bought one. The cover pops off of the solenoid. The cover holds some potted circuitry. The two outside pins pass through that circuitry and onto the solenoid itself.
So
For this two work the connector would at least have to be rewired to put the solenoid wires on the two outside wires.
In the potted circuitry is a flyback diode.
There is no plumbing for the switch. No vacuum line that runs to a switch.
Thus this solenoid can not work as a 2.8 Fiero solenoid. Not unless the switch is plumbed in and wired in.
Are you talking about the open closed switch to tell the ECU if the solenoid has opened or closed? The newer solenoid should be using a simple open closed based on position to detect that unlike the over complicated way the old solenoid used to do it. This means the center pins should open and close depending on the state of the solenoid just like the old solenoid would on pressure changes. The type of switch should not matter as long as the ecu is getting the proper feedback when it opens and closes. Unfortunately you will no longer throw a code unless the unit fails vs you would throw one with a big enough vacuum leak.
Again, it can't be a pressure/ vacuum switch without being connected to a pressure/ vacuum line.
You really don't need the switch. Easy fix. Just connect the ECM lead that normally goes to Pin C the vacuum switch to ground. You may need a pull up resistor but that will shut off the code. The EGR solenoid will still function perfectly (it only needs two wires) as long as it receives the PWM signal from the ECM.
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The vacuum lines are set up similar to our stock solenoid. The two nipples are connected to the intake/throttle body and the EGR valve. Our solenoid uses a supply line coming from the air filter canister. This solenoid has an internal filter under what looks like a large knob, seen on the opposite end from the two vacuum ports. The port skywurz highlights doesn't appear to connect to anything in the second image. I don't know what year and model phonedawgz specified for the solenoid, but it has the same number as the one I have for an 86 and 87 Grand National Turbo.
It will still be a bit before I'm able to install and test. Surgery coming up Tuesday.
[This message has been edited by fierofool (edited 08-08-2021).]
While I don't hold the GM engineers in too high of esteem (they did leave the temp gauge/temp light miswired for 5 years), I do believe they put the vacuum switch in there for a reason. That being there are two times the switch would read open that might be important. The first is at idle/near idle when the ported vacuum is yet to produce vacuum. The second would be during failure of the solenoid. For the ECM to think the system is applying vacuum and the EGR valve is open, that would also mean the ECM is advancing the timing when it should not. And this could lead to detonation and piston failure. I don't think hotwiring the EGR vacuum switch in a closed position is a good idea.
While I don't hold the GM engineers in too high of esteem (they did leave the temp gauge/temp light miswired for 5 years), I do believe they put the vacuum switch in there for a reason. That being there are two times the switch would read open that might be important. The first is at idle/near idle when the ported vacuum is yet to produce vacuum. The second would be during failure of the solenoid. For the ECM to think the system is applying vacuum and the EGR valve is open, that would also mean the ECM is advancing the timing when it should not. And this could lead to detonation and piston failure. I don't think hotwiring the EGR vacuum switch in a closed position is a good idea.
Based on the picture above....it looks like you don't even need the connector. Just use the old connector but run some wires to the new solenoid? The Solenoid in my was wrecked...rusted solid.
[This message has been edited by Forrest (edited 08-31-2021).]
From looking at what phonedawgs took apart and the original wiring id say with the wires of the plug facing you and the clip for the plug on top you would go from Solenoid, Solenoid, Sensor, Sensor ----> to Solenoid, Sensor, Sensor, Solenoid. but that's a guess. We are also speculating that the conductivity on the center sensor pins changes depending on the level of vacuum as to tell the ECU the EGR is switching. There is a lot of unknowns
I found an alternative to pigtail PT1136 which is $40 This $6 one fits perfectly.... 64021 Alternator Plug Connector Fits Delco / GM CS130D, AD230, AD237 & AD244 https://www.ebay.com/itm/384408710501
I went ahead and broke it down all the way. The solenoid is virtually the same. No reason this solenoid cannot be modified to work with the existing sensor. Just need a T in the vacuum line from what I can tell. New on top old on bottom.
[This message has been edited by Forrest (edited 02-15-2022).]
I am going to swing by Oriellys after work and see if I can pick up some vacuum lines and Ts.
Plan is: Cut the existing long since rusted solid Solenoid off the original plug/sensor assembly Run the wires through the two holes where the posts plug in to the S10 Solenoid (Need to be drilled out a bit) and solder them in place Reassemble the solenoid part of the new S10 EGR. The plug and electronics are not needed....seems they are incompatible.
Remove the rubber piece off of the vacuum lines Patch the larger line with a piece of tubing into the solenoid Put a T into the smaller line and plug one end into the solenoid...the other into the sensor
Whatever it ends up being I am sure it will be ugly....for a lot of us though we just want it to work.
It's good to know that EGR codes are set at highway speeds. Every once in a while, my check engine light will come on, but it is usually after I have been driving on the freeway and it's always the same code, the one most common to the Fiero, the EGR problem. I was wondering why. When I drive around town, no light, but hit the freeway and it comes on every once in a while. This explains why... Thanks...
quote
Originally posted by fierofool:
Just in my initial appraisal, I think the replacement could be bolted to the original bracket with its existing bolt. It's pretty much confgured for connections like our original, so nothing should be seriously out of place.
For a check engine light at testing, try a similar tactic my father in law used when he was trading for a new truck. His old car had a bad transmission that would only slip once it got warmed up really good. He parked it on the street near the dealership on the night before. Next day his son took him down and he drove the car into the dealership. Their test drive was uneventful and he made the trade for the new truck.
Just clear the ECM before driving into the test center since EGR codes aren't set except during highway driving speeds.
This is what I put together so far. One thing I noticed is since I installed this the alarm triggers more frequently (Not just a highway speeds). My EGR valve does not hold vacuum so my thinking is that with a working solenoid/sensor this is triggering the alarm. I never even checked it before. After I replace the egr valve I imagine the alarm will clear. Once I see that I will clean up the installation. If we can narrow this down to just replacing the solenoid we may be able to find a cheaper donor part. I think I spent $80 on mine....kinda a lot just to tear it apart for the solenoid. If there is any interest Ill write up a full how to thread. I tested the solenoid both ways so polarity does not seem to matter.
[This message has been edited by Forrest (edited 02-20-2022).]
Good work so far! Im still wondering what the other 2 wires on the replacement assembly do. Im still holding out hope for a simpler solution. I can see the 2 holes the removing of the new solenoid sending unit left where the power posts passed through. Was their a 3rd hole somewhere in the body? Here perhaps? I was expecting to see a molded air passage in the solenoid body that passed to the sending unit.
[This message has been edited by skywurz (edited 02-20-2022).]
Did this on a customer car not mine years back. Misplaced the notes and my 60* V6 that has a good solenoid has been in mothballs for quite a while. The pin outs on the Fiero EGR solenoid are : A. Ignition 12V B PWM ground signal supplied by the ECM C. vacuum switch signal that sets the trouble code D. Ground Is that what you have found? They should be exactly the same on the later GM EGR solenoids. Just got to find the S-10 pin diagram and confirm. BTW, are you ready to try the conversion? I understand that California will not allow it.
Hey, Dennis. Were you able to confirm the pinout on the '88 V6 S-10 EGR solenoid is the same as the pinout on the V6 Fiero?
Since the vacuum switch on these seems to last (I had two solenoids with good switches, but bad windings), I went looking for the cheapest EGR solenoid I could find. Found one used in several Mazda vehicles and bought it new for $9. It has two ports - one to vacuum, and the other to EGR. I just put a T connection in the line to EGR and piped it to the EGR solenoid vacuum switch we have, then soldered the two wires to it. I've only done about 50 miles of varied driving since, but no code 32 yet.
Since the vacuum switch on these seems to last (I had two solenoids with good switches, but bad windings), I went looking for the cheapest EGR solenoid I could find. Found one used in several Mazda vehicles and bought it new for $9. It has two ports - one to vacuum, and the other to EGR. I just put a T connection in the line to EGR and piped it to the EGR solenoid vacuum switch we have, then soldered the two wires to it. I've only done about 50 miles of varied driving since, but no code 32 yet.
that's fairly exciting. Let us know exactly which solenoid it was, and how things have progressed with more driving.
that's fairly exciting. Let us know exactly which solenoid it was, and how things have progressed with more driving.
Falls under these part numbers: 911-707, 226874, EVS189, KL0118741, FS0518741, Kl01-18-741, Kl0118741, K5T49051, 911707, K5T49099, K5T49091
I don't really have any idea if it's working or not, since I didn't get code 32 very often before anyways - so I don't want to give false hope. Just offering this up as another idea for a potentially cheap ghetto solution.
Since the vacuum switch on these seems to last (I had two solenoids with good switches, but bad windings), I went looking for the cheapest EGR solenoid I could find. Found one used in several Mazda vehicles and bought it new for $9. It has two ports - one to vacuum, and the other to EGR. I just put a T connection in the line to EGR and piped it to the EGR solenoid vacuum switch we have, then soldered the two wires to it. I've only done about 50 miles of varied driving since, but no code 32 yet.
Thanks for posting this. If you can remember I'd love to hear an update in a few months.
Again, it can't be a pressure/ vacuum switch without being connected to a pressure/ vacuum line.
