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As you may or may not be aware, you can not obtain new OEM EGR solenoids for our TPI cars. This became pertinent to me as I failed CA smog with high NOx.
When I failed smog I tore into my EGR system to discover the solenoid virtually falling apart. The hard line had also seen better days. That would explain some occasional light-throttle stalls I had seen.
Bad TPI EGR Solenoid
I decided to just replace anything and everything EGR related so I did not have to worry.
There have been several posts about using VS25 solenoids to replace TPI ones, but there wasn't anything to help with visualization that I saw.. so I took pictures and documented the process.
Parts Required
(1) Standard Motor Products VS25 EGR Solenoid
(1) Painless Performance 70402 Weatherpack Connectors 2-Wire Kit
(1) 92-97 LT1 Camaro/Firebird/Corvette EGR Solenoid Wiring Harness Connector Plug
(1) Dorman Hard Emissions Tubing 47418
(3) L Vacuum Connectors
(1) Strait Vacuum Connector
While I was in there I also replaced the EGR Valve and EGR Temperature Switch...
(1) ACDelco EGR Sensor Switch 212-336 (Since it is for a Corvette, I had to lengthen the wire. I found a NOS one and I'm sure there's a vette guy shaking his fist at me)
(1) ACDelco EGR Valve and Gasket 214-5538
To remove the old solenoid, you have to find it first. It's hidden way under the ignition coil, left-side of the engine bay, back by the distributor. It's actually mounted with the 2 bolts holding the coil mount. Simply (hah) un-bolt the 2 coil mount bolts.
Disconnect the EGR solenoid wiring and 2 vacuum lines. Remove Solenoid. Reattach ignition coil mount with the 2 bolts.
Now, you could mount the new one there, but I did not want to try to wrestle with trying to run vacuum hose down there. Instead I decided to mount it on the fuel rail with the fuel rail bolt.
To do so, I had to modify the VS25 solenoid mount a tad. First I tapped out the bolt that is in the mount. I just laid it over a socket and tapped it out with a small hammer. I enlarged the hole to accommodate the fuel rail bolt. I bent off the small protrusions on the mount as well.
VS25 EGR Solenoid mounted to the TPI fuel rail
After that, I made an adapter for the old EGR solenoid connector to connect it to the new solenoid. Wire orientation does not matter. Plug and play, no messing up your harness.
TPI EGR Solenoid to LT1 style adapter
Then it was a matter of connecting the vacuum lines. The shiny nipple on the solenoid goes to the vacuum source (throttle body,) while the black plastic nipple goes to the EGR valve itself. Here's the routing I ended up with.
VS25 EGR Vacuum Diagram
After that I buttoned everything back up. It looks pretty decent, plus it won't be such a chore to change if it ever needs swapped again.
VS25 EGR Solenoid final installation
Hitting smog again tomorrow, so I'll post up results. The car ran fine and threw no codes, so fingers crossed!
Thanks for the great info and part numbers. Ill definitely be keeping up with how your smog goes. Also from california and i plan to restore evry part i can once i do my engine swap to keep up on emissions here in CA.
Update: The EGR setup I posted does indeed work. Verified with a vacuum gauge off a T at the EGR valve.
I did fail smog again, but just found my timing was set to 10 BTDC (after testing the EGR stuff 100 times over.) That'll cause high NOx for sure. Going in for a retest as soon as tomorrow.
Unfortunately not, but it did cut NOx in half to 950ish. EGR and solenoid working good. Clear of obstructions, so I'm going to give the EGR system a clean bill of health right now.
That being said I datalogged my car and my BLMs are not looking too awesome. 108 at idle, definitely under 128 moderate cruise. It's obviously rich and I wonder if the computer is correcting on the lean side? (I say that because NOx is usually a sign of hot combustion temps which can be caused by lean conditions. As if you don't know that though heh)
New plugs, NTK o2 sensor tomorrow. Datalog and tuning thereafter.
Has it always run rich since the injectors have been swapped out ?
stock tune ?
Iirc your engine is pretty stock with truck tbi heads.
Probably.
Stock tune, truck heads heads and cam. Either Delphi flow more than 22lb at stock pressure or my head's and cam are weak enough that 22lb is rich. If I had an AFPR and the state allowed it I could just drop pressure a tad probably.
A afpr can only drop to stock 3 bar. I can’t imagine why it’s rich stock engine. You might have to tune for the injectors. If you can’t find the offsets you can adjust the maf tables. https://www.thirdgen.org/forums/atta...air-flow-tuned
High HC at idle ?
You need a tune. I put in Bosch D3's and an AFPR on a bone stock, refreshed 89 LB9, set it all up and it was terrible. Got a tune and wow. The 19lb D3's were more like 24lb. Engine feels great now and passed smog with flying colors.
You need a tune. I put in Bosch D3's and an AFPR on a bone stock, refreshed 89 LB9, set it all up and it was terrible. Got a tune and wow. The 19lb D3's were more like 24lb. Engine feels great now and passed smog with flying colors.
where did you get the offset information?
was the constant injector flow changed or just offsets ?
A afpr can only drop to stock 3 bar. I can’t imagine why it’s rich stock engine. You might have to tune for the injectors. If you can’t find the offsets you can adjust the maf tables. https://www.thirdgen.org/forums/atta...air-flow-tuned
High HC at idle ?
Sadly they do not test at idle so no idea if HC is high then. It's within limits at 15/25mph.
That link is awesome.
Slapping in the fresh o2 sensor and plugs in tomorrow. I have a PROM that has the injector constant changed from 22lb to 23lb, gonna datalog after and go from there.
where did you get the offset information?
was the constant injector flow changed or just offsets ?
Man you got me, I don't about all that stuff. I worked with Scott. He said these act like 24 lb injectors. He backed off the richness incrementally. Took 7 iterations.
I’m curious how one #hr constant will effect blm. I always set the injector flow rate and make adjustments to the maf tables for rich or lean conditions.
19s flowing like 24s makes my eyes water just thinking about it. Pretty gassy
Last edited by Tuned Performance; 02-14-2019 at 05:32 PM.
I’m curious how one #hr constant will effect blm. I always set the injector flow rate and make adjustments to the maf tables for rich or lean conditions.
19s flowing like 24s makes my eyes water just thinking about it. Pretty gassy
I'll follow up with some comparative BLM readings (similar load/gear/speed/rpm)
Some tunes $6e mask. I’m not sure what the broadcast codes are but I know the vette arap has lean cruise mode enabled. You said your cruising is 128. This might change when you install the 23#hr tune. You should see leaner than 128 cruising.
If you decide to tune out the rich condition buy a moates.net burn 2. Depending on your memcals if they have been fitted with the newer sst eeproms you can use a hdr1 and flash directly. If you choose to go the diy way send me a pm I’d be happy to look at your datalogs and revise your tunes.
Last edited by Tuned Performance; 02-14-2019 at 06:44 PM.
Unless they were specifically looking to be a jerk, I doubt any tech would ever fail you for that. Most of them don't even know where to look for it, especially if you have the plenum extension on there.
I’m curious how one #hr constant will effect blm. I always set the injector flow rate and make adjustments to the maf tables for rich or lean conditions.
19s flowing like 24s makes my eyes water just thinking about it. Pretty gassy
LOL. I didn't ask for much info but what he said he was doing was backing off the injectors and then he was going to hit the MAF tables. But on the last one, he said we got it. I don't know if he needed to mess with the MAF tables.
These are old cars, and some smog techs probably don't even know what they're looking at anymore.
Yeah, they were trying to unhook a hose for the vac advance to check timing on my TPI last time I had it at a smog station... ended up unplugging the EGR somehow.
And thanks for the part numbers to get a new EGR solenoid in one of these. I happened to have a Corvette one laying around and stuck that in place of my old dead one, but the vette one is a bit crusty looking too so I've been looking for a new one.
As you may or may not be aware, you can not obtain new OEM EGR solenoids for our TPI cars. This became pertinent to me as I failed CA smog with high NOx.
When I failed smog I tore into my EGR system to discover the solenoid virtually falling apart. The hard line had also seen better days. That would explain some occasional light-throttle stalls I had seen.
Bad TPI EGR Solenoid
I decided to just replace anything and everything EGR related so I did not have to worry.
There have been several posts about using VS25 solenoids to replace TPI ones, but there wasn't anything to help with visualization that I saw.. so I took pictures and documented the process.
Parts Required
(1) Standard Motor Products VS25 EGR Solenoid
(1) Painless Performance 70402 Weatherpack Connectors 2-Wire Kit
(1) 92-97 LT1 Camaro/Firebird/Corvette EGR Solenoid Wiring Harness Connector Plug
(1) Dorman Hard Emissions Tubing 47418
(3) L Vacuum Connectors
(1) Strait Vacuum Connector
While I was in there I also replaced the EGR Valve and EGR Temperature Switch...
(1) ACDelco EGR Sensor Switch 212-336 (Since it is for a Corvette, I had to lengthen the wire. I found a NOS one and I'm sure there's a vette guy shaking his fist at me)
(1) ACDelco EGR Valve and Gasket 214-5538
To remove the old solenoid, you have to find it first. It's hidden way under the ignition coil, left-side of the engine bay, back by the distributor. It's actually mounted with the 2 bolts holding the coil mount. Simply (hah) un-bolt the 2 coil mount bolts.
Disconnect the EGR solenoid wiring and 2 vacuum lines. Remove Solenoid. Reattach ignition coil mount with the 2 bolts.
Now, you could mount the new one there, but I did not want to try to wrestle with trying to run vacuum hose down there. Instead I decided to mount it on the fuel rail with the fuel rail bolt.
To do so, I had to modify the VS25 solenoid mount a tad. First I tapped out the bolt that is in the mount. I just laid it over a socket and tapped it out with a small hammer. I enlarged the hole to accommodate the fuel rail bolt. I bent off the small protrusions on the mount as well.
VS25 EGR Solenoid mounted to the TPI fuel rail
After that, I made an adapter for the old EGR solenoid connector to connect it to the new solenoid. Wire orientation does not matter. Plug and play, no messing up your harness.
TPI EGR Solenoid to LT1 style adapter
Then it was a matter of connecting the vacuum lines. The shiny nipple on the solenoid goes to the vacuum source (throttle body,) while the black plastic nipple goes to the EGR valve itself. Here's the routing I ended up with.
VS25 EGR Vacuum Diagram
After that I buttoned everything back up. It looks pretty decent, plus it won't be such a chore to change if it ever needs swapped again.
VS25 EGR Solenoid final installation
Hitting smog again tomorrow, so I'll post up results. The car ran fine and threw no codes, so fingers crossed!
im going to try this. THERE ARE 4 parts on solenoid.
(Blue)FIRST- I understand pigtail to solonoid
(Green)SECOND- metal nipple connects to vacuum line to TB
***Here is where I’m mixed up. ***. There are 2 black plastic nipples on solenoid right?
(RED) goes to EGR valve
what is the second black plastic nipple for?( that should be next the RED wire in your color coded diagram.??
please help
LAST you said we need the adapter to not mess up the harness. The male clip from the wire coming from my harness is ruined. I’m savvy enough to solder and replace male connection that connects to Adapter you said which connects to solenoid. But I don’t now what that piece is called?
i failed smog and mechanic is charging me through the roof to fix this.
Last edited by Dramirezav2016; 03-15-2019 at 02:03 AM.
There is usually foam over it, but it's open air vent.
Thank you so much. I get it now.
have two more questions.
1.Painless Performance 70402 Weatherpack - is this used for the EGR tempature switch?
2.LT1 Camaro/Firebird/Corvette EGR Solenoid Wiring Harness Connector Plug- is a adapter that works by connecting male end of adapter to solenoid and connection from harness plugs into female end of adapter BUT MY MALE END FROM HARNESS NEED TO BE REPLACED so I can plug into female end of adapter.
WHAT WOULD A REPLACMENT PART FOR THIS BE CALLED?
Thank you so much. I get it now.
have two more questions.
1.Painless Performance 70402 Weatherpack - is this used for the EGR tempature switch?
2.LT1 Camaro/Firebird/Corvette EGR Solenoid Wiring Harness Connector Plug- is a adapter that works by connecting male end of adapter to solenoid and connection from harness plugs into female end of adapter BUT MY MALE END FROM HARNESS NEED TO BE REPLACED so I can plug into female end of adapter.
WHAT WOULD A REPLACMENT PART FOR THIS BE CALLED?
The two connector packs are to make an adapter pigtail for the EGR solenoid, not the temp switch, so it will plug into the standard plug.
If your existing old-style male EGR solenoid connector is messed up, do not worry, the painless 70402 kit includes both sides of the plug. Simply replace your existing plug with the one included in the kit, and make the adapter like I posted above (old-style connector type female to new connector type male)
Just want to add that I installed this solenoid on my TPI car today and it's working nicely so far. While bench testing the solenoid, I found that the polarity didn't matter but it does have a + molded into the case, and that it is normally open. I went with an ACDelco 214-357. I picked up a pigtail (PT2830) for it and just spliced it into my harness rather than making an adapter.
Just want to add that I installed this solenoid on my TPI car today and it's working nicely so far. While bench testing the solenoid, I found that the polarity didn't matter but it does have a + molded into the case, and that it is normally open. I went with an ACDelco 214-357. I picked up a pigtail (PT2830) for it and just spliced it into my harness rather than making an adapter.
So all you did was splice in the new connector and install new vacuum hoses?
So all you did was splice in the new connector and install new vacuum hoses?
Nice! I'll need to look into this
If you do not even want to go to the trouble of splicing wires the ones for TPI Corvettes work as well and plug right in, just a bit tight but I did mine a few summers back and no problems. The only issue is the same with the other solenoid is mounting it but you just have to get a little creative. I also second the idea of changing the vacuum lines, mine were pretty beat, and that will help vacuum but be gentle, the plastic bits are weak.
If you do not even want to go to the trouble of splicing wires the ones for TPI Corvettes work as well and plug right in, just a bit tight but I did mine a few summers back and no problems. The only issue is the same with the other solenoid is mounting it but you just have to get a little creative. I also second the idea of changing the vacuum lines, mine were pretty beat, and that will help vacuum but be gentle, the plastic bits are weak.
So they still make for the TPI Vettes but not us??
Sure do, eBay has them or the specialty Corvette parts places and you get the "Corvette Tax" with it but not terrible. I just remembered a member recently may have said they finally reproduced the EGR solenoid for us but you will have to look at maybe Classic Industries or Ecklers but the EGR temp sensor you will have to look Corvette...I found this all out when I rebuilt my entire EGR system basically to cure that annoying code 32 two summers back.
Sure do, eBay has them or the specialty Corvette parts places and you get the "Corvette Tax" with it but not terrible. I just remembered a member recently may have said they finally reproduced the EGR solenoid for us but you will have to look at maybe Classic Industries or Ecklers but the EGR temp sensor you will have to look Corvette...I found this all out when I rebuilt my entire EGR system basically to cure that annoying code 32 two summers back.
I don't see why GM didn't just use the same parts / sensors for the F0bodies and the Corvette! Its more less all the same!
I agree they largely are the same, but the Vette guys are known to spend more $$$ so they will reproduce more obscure parts for them IMO. That EGR temp sensor is identical except the plug wire is way longer for the F bodies ( just have to splice into the old one if replacing). Also I forget to mention the solenoid thtanner used is probably 50% less expensive that the Vette one as well. I used the other because I hate messing with wiring.
I agree they largely are the same, but the Vette guys are known to spend more $$$ so they will reproduce more obscure parts for them IMO. That EGR temp sensor is identical except the plug wire is way longer for the F bodies ( just have to splice into the old one if replacing). Also I forget to mention the solenoid thtanner used is probably 50% less expensive that the Vette one as well. I used the other because I hate messing with wiring.
Same here. i'm mixed on that myself. mine is still good for now and relatively low mileage...but it looks hella crusty down there by the ignition coil.... but I don't want to spend the money excessively....but don't want it to break!
Might be replacing the original injectors though so MAYBE I'll just change it all at once and take care of it all! MAYBE hahahah
If you change the injectors that is the time to replace or delete EGR, its cake with the runners and fuel rail out of the way, less so with just the plenum and TB removed. I replaced my FPR diaphragm and injectors and the next year I was in there for EGR stuff and wished I would've killed 2 birds with 1 stone.
If you aren't throwing that code 32 or annoyed by CELs then if ain't broke don't fix it lol.
If you change the injectors that is the time to replace or delete EGR, its cake with the runners and fuel rail out of the way, less so with just the plenum and TB removed. I replaced my FPR diaphragm and injectors and the next year I was in there for EGR stuff and wished I would've killed 2 birds with 1 stone.
If you aren't throwing that code 32 or annoyed by CELs then if ain't broke don't fix it lol.
DEF gonna do EGR / FPR if I end up doing injectors.......that does not look fun to have to go back and redo.
I can see myself updating the solenoid and then posting "Replaced EGR solenoid....HELP!! WHAT DID I DO WRONG??!!"
I've been chasing a lousy idle / stalling on my all stock 1989 for years. Just found the EGR solenoid crumbling apart.
So from reading this, I buy the Corvette solenoid? I'm not modding, I'm not slicing up wiring harnesses. I just want a stock replacement. Does the corvette solenoid have the same vacuum and electrical connector, then I'll fab a mount ?
I have the top opened up now. Injector rail off. so now is the time.
Last edited by Eightyninef; 02-13-2022 at 05:16 PM.
I've been chasing a lousy idle / stalling on my all stock 1989 for years. Just found the EGR solenoid crumbling apart.
So from reading this, I buy the Corvette solenoid? I'm not modding, I'm not slicing up wiring harnesses. I just want a stock replacement. Does the corvette solenoid have the same vacuum and electrical connector, then I'll fab a mount ?
I have the top opened up now. Injector rail off. so now is the time.
Yes the Corvette one will work and plugs in with no wiring modification, the plug is a little tight for some reason, but worked good on my car when I ran EGR. The vacuum ports are the same, only difference other than mounting is the electrical connector faces the opposite direction as stock IIRC. Should not make a huge difference. To be sure I would compare them on like Zip Corvettes site.
Weird thing, no codes. But this idle problem is ridiculous at this point. Off idle car runs amazing. Corvette solenoid valve is on order. Top of motor is opened up. Waiting on parts.
I hope this Corvette part works out, because I am not hacking up my wiring harness. I will let you know for sure. Hopefully there is enough slack in the connector harness to have it come in from the other side.
Weird thing, no codes. But this idle problem is ridiculous at this point. Off idle car runs amazing. Corvette solenoid valve is on order. Top of motor is opened up. Waiting on parts.
I hope this Corvette part works out, because I am not hacking up my wiring harness. I will let you know for sure. Hopefully there is enough slack in the connector harness to have it come in from the other side.
No codes is par for the course with these cars lol How does the EGR look? No vacuum leaks? On my 88’ GTA it was not an issue with wire slack. The only thing I will say is I replaced the broken or brittle plastic vacuum lines with new rubber ones when I did this and it was much easier to mount. If you are crafty you might be able to get it the new one mounted in the factory bracket but I wound be careful of the plastic.
Also AC Delco 214-5538 EGR valve is a good fit if you have the need/provision for the EGR temp sensor(which is the typical cause of code 32 if so equipped but not all had them). I ran it for awhile and had no issues but I did not like it was made in China. It fits a lot better than many aftermarket ones and no worry about plenum clearance.
Yes the Corvette one will work and plugs in with no wiring modification, the plug is a little tight for some reason, but worked good on my car when I ran EGR. The vacuum ports are the same, only difference other than mounting is the electrical connector faces the opposite direction as stock IIRC. Should not make a huge difference. To be sure I would compare them on like Zip Corvettes site.
I'm playing with the Corvette solenoid now. There is literally no slack in the wiring harness what -so- ever on my 89. and the mounting plate is only designed for the thermostat housing. So I need to extend the wiring harness no matter what. Weather it's extended for the VS-25 above, or extended for the Corvette solenoid, I guess it doesn't matter. I am considering moving it to the Corvette location, front of the motor. Either way, it's a custom job, and relocation.
Not even sure this is my problem, as my old solenoid has 20 ohms across the electronic coil.
So it's a success. I now have the C4 EGR solenoid on the thermostat housing. Took a bit of wiring and vacuum, but no codes. Still have a slightly lousy idle, but no more stalling.
Last edited by Eightyninef; 03-26-2022 at 08:48 PM.
01-21-2019, 11:29 PM
