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Hey guys, I was the guy who connected a Costco battery backwards and brought a ton of laughter to this forum a while ago.
The saga continues. The truck has a rough idle. I poked around for a while, cleaned IAB and EGR, and eventually found out that there's a vacuum at the EGR at idle. Traced the vacuum lines to the valve control solenoid, took it out, took it apart, measure the resistance between the two terminals (43 ohms), but couldn't figure out why it stays open no matter what I do - put 12V on it, or disconnect the electrical connector - the vacuum is always passed to the EGR.
Worse yet, I exhausted every part store and online resource and couldn't find a replacement vacuum control solenoid. Timbersteel posted the same problem back in 2013. I'm reaching out to this mighty forum for help.
BTW I've order a new TPS, MAP and EGR position sensor, but I really don't think they are the problem.
The solenoid appears to be available on line. In the meantime unplug the vacuum line from the EGR valve and cap it the vacuum line, that should cure the rough idle problem.
There Timbersteel showed two pictures, and the one with a longer arm is the only one that supposedly fit the 87-91 5.8L trucks. I don't know for sure whether the Standard Motor Products VS77, the one with the shorter arm, with work on the 5.8L engine, but all online sites say it doesn't.
The long snout in those pics looks like an extension, that is where the electrical plugs in so maybe it's an adapter. I have never seen one of these with an adapter like that so I can't say for sure why it would be needed, the solenoid itself looks the same.
Here's a question, does the solenoid in your truck now have a long snout? I suspect it doesn't.
Yes the one I have does have a long snout. And it is a detachable extension. I hesitate to just buy a short snout one just to try it out because no one seems to believe it will work. The difference, if any, has to be in the electrical circuit.
Will the electrical connector plug into your solenoid without the "adapter"? Have you got a multimeter? It would be interesting to see if the 'adapter" is anything special, like does it contain any circuitry(a diode) or does it reverse polarity. Or is it just a straight through connector?
Do they do a tailpipe smog test or a test similar to a dyno where the engine is under load and the wheels turning? If just a tailpipe, putting a BB into the vacuum connector before the EGR controller to keep it from opening will work.
You shouldn't set a light, The EGR is not doing anything when idling or during a snap test anyway..
Good point. I will find out tomorrow morning whether it's a straight through or reversed polarity. Easy to find out if there is a diode too. Will also take a closer look at the connector.
If all there is is a reversed polarity adapter, crossing the two wires would be an easy mod. Will post some pics if I get around to it.
The long snout version costs $80+ and simply isn't available anywhere. The short snout version can be had for less than $30.
Originally Posted by Conanski
Will the electrical connector plug into your solenoid without the "adapter"? Have you got a multimeter? It would be interesting to see if the 'adapter" is anything special, like does it contain any circuitry(a diode) or does it reverse polarity. Or is it just a straight through connector?
Last edited by supernova1987a; 03-15-2017 at 10:41 PM.
Reason: Adding a point
Actually I don't know. I believe it's the dyno type of smog. Haven't done a smog for older cars for a while.
Originally Posted by yardbird
Do they do a tailpipe smog test or a test similar to a dyno where the engine is under load and the wheels turning? If just a tailpipe, putting a BB into the vacuum connector before the EGR controller to keep it from opening will work.
You shouldn't set a light, The EGR is not doing anything when idling or during a snap test anyway..
If it's not going to be smog tested, just plug the line and let it go.
@yardbird - Every gas engine 1976 and newer gets a smog test here in The Peoples Republic Of Kalifornistan except brand new vehicles that get an exemption for the first few biannual inspections. Also, no "Snap Test" here; that would be so easy to get around. The trick is, will your chosen smog technician test it right? The test equipment is not infallible and it's only as good as the input from the tech and the d00d that wrote the database in the machine.
Federal emissions trucks over 8500 gvw are supposed to be administered a two speed static test, idle and 2500 rpm. One tech here tried the rollers with my truck, failing it for high overall emissions. When I got it to my regular tech for repairs, he passed it with flying colors on a two speed idle test, doing no repairs beforehand.
Trucks under 8500 get the roller test in most cases. No EGR flow would cause high NOX, failing the truck so you just can't plug the line with a BB and go. Those days in Kalifornistan have been over for decades. I should point out there are some counties that do not smog test, only because there's fewer people in that county than what lives on my block here in Freakmont. People do register their trucks in those counties to get around the smog testing. Just sayin'.
I would lean toward checking that extension and if it is just an extension, order the more common solenoid. It doesn't seem plausible there is no solenoid available.
Last edited by raystankewitz; 03-16-2017 at 09:47 AM.
Reason: Added some information
Just finished my multimeter inspection of the solenoid. Findings:
1. There doesn't seem to have any diode in the circuit. Resistance is the same no matter how you measure.
2. The extension is there for a silly reason. There is a 14 ohm resistance at one terminal, the other arm is a straight passthrough.
The solenoid body itself has a resistance of roughly 57 ohms with either polarity. See attached photo.
Be mindful this is a broken one. A good one may be different.
I decided to go ahead and get a VS77 and test it out anyway. Will post resistance numbers here. If the connectors works with the VS77 "short snout", and the resistance is also around 57 ohms, then attaching the old extension to the VS77 will probably solve the problem.
@yardbird - Every gas engine 1976 and newer gets a smog test here in The Peoples Republic Of Kalifornistan except brand new vehicles that get an exemption for the first few biannual inspections. Also, no "Snap Test" here; that would be so easy to get around. The trick is, will your chosen smog technician test it right? The test equipment is not infallible and it's only as good as the input from the tech and the d00d that wrote the database in the machine.
Federal emissions trucks over 8500 gvw are supposed to be administered a two speed static test, idle and 2500 rpm. One tech here tried the rollers with my truck, failing it for high overall emissions. When I got it to my regular tech for repairs, he passed it with flying colors on a two speed idle test, doing no repairs beforehand.
Trucks under 8500 get the roller test in most cases. No EGR flow would cause high NOX, failing the truck so you just can't plug the line with a BB and go. Those days in Kalifornistan have been over for decades. I should point out there are some counties that do not smog test, only because there's fewer people in that county than what lives on my block here in Freakmont. People do register their trucks in those counties to get around the smog testing. Just sayin'.
I would lean toward checking that extension and if it is just an extension, order the more common solenoid. It doesn't seem plausible there is no solenoid available.
Thank you. You answered a question that I didn't know the answer to, specifically the roller test. In a situation like that, the EGR would need to work.
Between these type test for older vehicles, and the lack or replacement parts, this country is doing everything it can to get rid of older vehicles.
Getting rid of good older vehicles was almost totally what "Cash for Clunkers" was all about. I had my dealers license when that crap came about. Most of the cars traded in were older cars and suvs with lower miles and in good shape. The people that owned these types of vehicles usually had the money to keep them up, and only traded because the allowed trade in was much more than the blue book trade value, and the owners could afford a new car,
The really worn out high mileage cars wern't traded because the owners of those vehicles did not have the money to trade, if they had a job at all during that time.
I talked to a general manager at a dealership, and looked over his lot full of "clunkers". There were many olders cars and trucks with less than 100k in great shape, while all that was available at the auctions was worn out junk in the lower price range.
Want to know why used cars are so expensive now? You can thank "Cash for Clunkers". That fiasco changed the shape of how, who, and how much used cars are sold for for many years yet to come.
03-15-2017, 04:03 PM
