my 93 SHO has cel on after diving for a few min?

[pawpaw]

Originally Posted by tylerdahl

ok no dry rot on vacuum hoses, but i am concerned should they always be under vacuum?
they seem to stay under vacuum.

will check vsv connectors tomorrow and update you on that information!

The line TO the EGR valve diaphragm should Not have vacuum on it at idle, or when the engine is cold. If the EGR line has vacuum to it All the time, suspect the Vacuum Switching Valve. So turn the engine off, pull the vacuum line off the EGR & you should Not be able to blow back through it if the VSV is properly closing & sealing. If you can blow back through it, its bad & must be replaced.

The other line going into the VSV Will have vacuum to it when the engine is running & this is as it should be, as under computer electrical command, the VSV's job is to switch this vacuum on & off to the EGR valve to cause it to open & close.

[ISHOU]

I had this code once. Research showed it was some clogged passages. These passages can be easily reached by removing the throttle body. The passages are just past where the throttle body and intake connect-on the bottem of the intake. Take a stiff wire and and carb cleaner and clean the carbon that has collected. Should cure your problem.

[tylerdahl]

ok located the passages and cleaned them, still got problem, taking vacuum hose off egr and blowing back through it, the air goes right through like an open straw! with car off.

going take vsv off and replace it, tomorrow will update you on my results.

[pawpaw]

Originally Posted by tylerdahl

ok located the passages and cleaned them, still got problem, taking vacuum hose off egr and blowing back through it, the air goes right through like an open straw! with car off.

going take vsv off and replace it, tomorrow will update you on my results.

OK, good feedback. With the vintage of this ride, it was probably a good idea to tidy up the tubing of any carbon deposits, as that is a common failure mode & you might have more than one problem.

Good trouble shooting on the VSV blow back test & with the result you got, its earned a spot high up on your suspect list. Will be interesting to hear what you find on your removal inspection.

Even though you don't have a trouble code for it, you could still have a problem with the PFE/DPFE sensor, or its EGR or vacuum lines/connections, but if the VSV is bad & the blow back test result makes it sound like it is, you'll want to put it right first, to complete your EGR system trouble shoot.

[tylerdahl]

ok result i changed the VSV and cleared the computer, no CEL for a few days, today on way home from work, CEL comes on, stopped hooked up my jumper, ran tests, 332 is all i got, checked VSV working properly now, went directly to AutoZone and got vacuum hoses, changed all in AutoZone parking lot, reset computer, mile down the road CEL again??? all is working, VSV is replaced, hoses replaced??? any clue? i think i need to backtrack a bit and look some more!

[pawpaw]

Originally Posted by tylerdahl

ok result i changed the VSV and cleared the computer, no CEL for a few days, today on way home from work, CEL comes on, stopped hooked up my jumper, ran tests, 332 is all i got, checked VSV working properly now, went directly to AutoZone and got vacuum hoses, changed all in AutoZone parking lot, reset computer, mile down the road CEL again??? all is working, VSV is replaced, hoses replaced??? any clue? i think i need to backtrack a bit and look some more!

OK, it sounds like the replacement VSV is working. So when you had the EGR valve off did you remember to look in below it, to check the PFE/DPFE feedback orifice below the EGR valve, to make sure it wasn't clogged with carbon???? The PFE/DPFE exhaust gas feedback hose, connects below the orifice & you need to have the EGR valve off, to look in to see if its clear.

If all is ok there, then move on to checking out the PFE/DPFE sensor & if its ok, checking to see if the computer is sending the VSV a command to open & apply vacuum to open the EGR valve.

[tylerdahl]

ok not the pipe below the egr valve! but i do not know how to test if the computer is sending anything, and my local AutoZone says they cannot scan the computer this car is too old, local body shop told me not to bother with the egr system? he said that the car is running and looked at the egr valve and system and said it is working properly, don't worry and put a piece of tape over cel? this is going to be a SHOW car, so it must be perfect!

[pawpaw]

Originally Posted by tylerdahl

ok not the pipe below the egr valve! but i do not know how to test if the computer is sending anything, and my local AutoZone says they cannot scan the computer this car is too old, local body shop told me not to bother with the egr system? he said that the car is running and looked at the egr valve and system and said it is working properly, don't worry and put a piece of tape over cel? this is going to be a SHOW car, so it must be perfect!

Well one way to test the EGR & VSV to see if the VSV is getting a computer voltage command to open, is to fully warm the engine, open the throttle & let it snap closed, while watching to see if the EGR valve pintle moves.

If it doesnt move, disconnect the vacuum line between the EGR valve diaphragm & the VSV Output port to the EGR valve, where ever it's easiest to access.

Then with the engine fully warmed up, connect your vacuum gauge to the Output VSV port, or disconnected EGR diaphragm vacuum line, or put your finger over the port or the disconnected vacuum line at the EGR diaphragm & open the throttle to rev the engine & when you let the throttle snap closed, you should measure or feel vacuum at the VSV Output port, or disconnected vacuum line to the EGR valve diaphragm, if the VSV is working & recieving an electrical signal from the computer to open & apply vacuum to the EGR diaphragm.

If you Don't feel vacuum on the VSV Output port, or vacuum line to the EGR diaphragm when the throttle snaps closed, then suspect the new VSV, or that it isn't getting an electrical signal from the computer to open & apply vacuum to the EGR valve, OR, maybe the vacuum line between the intake manafold & Input side of the VSV has a problem.

If you come to suspect the computer isn't sending an electrical signal to the VSV to open, back probe the VSV electrical connector to see if the signal is there. If not there, then back up to the computer firewall electrical connector & back probe there. If you don't have a pinout of the computer firewall connector, look for the same color code/stripe wire thats on the VSV electrical connector. If no signal at the firewall connector, suspect the computer VSV driver has gone belly up.

Again, if all that checks out, look/inspect to make sure that the small feedback differential pressure port/aperature, inside & below the EGR valve, is clear of carbon deposits. If its clogged up, it'll not be able to apply EGR feedback & that'll corrupt the PFE/DPFE sensor feedback pressure measurement across the feedback aperature/port, that the PFE/DPFE sensor measures & the electrical signal it generates & sends to the computer will be corrupt, so the computer will get confused about what to tell the VSV to do, to control the EGR valve, all a really vicious circle.

[tylerdahl]

ok getting suction but only after i let the throttle down it gets suction like a second after throttle reaches idle?? uncle says sending late???

[pawpaw]

I'm not clear on Where you have idle suction???? We aren't to have vacuum to/at the EGR valve diaphragm at idle.