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1994 4runner 3.0L 3VZE engine code 71 throttle port E no vacuum at 3500 RPM
Hi,
I am inquiring on an issue I ran into on 3vze 1994 toyota 4runner 3.0l engine. The vehicles check engine light is on. I ran test and pulled code 71. This refers to EGR system malfunction. I did multiple checks, suck air on the EGR and verified engine bogging and wants to die, checked vacuum at the q port of egr modulator. no vacuum. I then checked vacuum from the 3 ports at the throttle body. P E R. R had vacuum on my gauge when reving engine up, P had vacuum when reving engine up also, but port E from the throttle body to port P on the egr modulator had no vaccum? I verified at the throttle body port again to make sure and still no vacuum out throttle body metal line? my thoughts is to replace the throttle body??? anyone got any feedback on this? vehicle symptoms are idle drops and gets rough when braking or when throttle is slightly pushed??? help thank you
Ah, the infamous invisible question! So you're not sure YotaTech is right for you, and you're cutting-and-pasting your question all over the internet. I don't know why, but when you cut-and-paste here the font color is sometimes wacky, including black-on-black. So "edit" your post, highlight all the text, select "color" (underscored "A") and select "Automatic":
Don't pick any other color, unless you have a good reason.
Yes, you need vacuum all-the-time on port E. Here's the manual page: http://web.archive.org/web/201204061...77exhaustg.pdf If you're sure you're missing vacuum, before I invested in a new throttle body I'd try: blowing on the port with compressed air, and if that doesn't work, carefully sliding a fine wire through the port.
If you're not sure you're missing vacuum (you've got a gauge, so I'll trust your measurements, but ...) don't forget that it's the temp sensor that triggers the CEL. Checking the temp sensor itself is pretty easy: http://web.archive.org/web/201003261...00egrgaste.pdf
When I do my annual tune up of my 87's, I take a can of carb cleaner, and stick the little red tube into those ports on the TB, on my 4Runner, and give a short squirt. Makes sure they're nice and clean. If it come's down to it, yes, a thin wire through the port will open it up, but it would still need a shot of cleaner. IMHO.
That carbon that clogs them is actually soft stuff, and when you push a wire through, it can easily close down again. That's why I use the carb cleaner. It removes the carbon, not just punch a hole in it, if that makes sense. Important to hold the throttle plate open, with a rag in the inlet to absorb the cleaner and carbon it removes. Otherwise, you get a layer of ick on the bottom of the TB, and it can prevent the proper closing of the throttle plate.
All just my opinions, for whatever they're worth.
Pat☺
thank you for that intro to this forum. I have since edited my post. I hope people can read this now. Thank you for helping and responding. If I recall right, I believe I should only read vacuum when revving up the engine 3,500 but no vacuum on idle? I have a vacuum gauge tester and yes I hooked it up to port P and R on modulator coming form throttle body. I verify vacuum on R port when revving engine, but no vacuum on P port. I have also tried cleaning that port. I have sprayed carb cleaner with throttle body in open position and I have also tried blowing compressed air in the throttle body port. No luck. I can try the the wire in the port. I will also run a ohm reading on the temp sensor to rule that out. thank you for responding and I appreciate the help.
When I do my annual tune up of my 87's, I take a can of carb cleaner, and stick the little red tube into those ports on the TB, on my 4Runner, and give a short squirt. Makes sure they're nice and clean. If it come's down to it, yes, a thin wire through the port will open it up, but it would still need a shot of cleaner. IMHO.
That carbon that clogs them is actually soft stuff, and when you push a wire through, it can easily close down again. That's why I use the carb cleaner. It removes the carbon, not just punch a hole in it, if that makes sense. Important to hold the throttle plate open, with a rag in the inlet to absorb the cleaner and carbon it removes. Otherwise, you get a layer of ick on the bottom of the TB, and it can prevent the proper closing of the throttle plate.
All just my opinions, for whatever they're worth.
Pat☺
thank you for responding. I have already tried spraying carb cleaner in the port. I will try the wire method next. thank you for helping.
Ah, the infamous invisible question! So you're not sure YotaTech is right for you, and you're cutting-and-pasting your question all over the internet. I don't know why, but when you cut-and-paste here the font color is sometimes wacky, including black-on-black. So "edit" your post, highlight all the text, select "color" (underscored "A") and select "Automatic":
Don't pick any other color, unless you have a good reason.
Yes, you need vacuum all-the-time on port E. Here's the manual page: http://web.archive.org/web/201204061...77exhaustg.pdf If you're sure you're missing vacuum, before I invested in a new throttle body I'd try: blowing on the port with compressed air, and if that doesn't work, carefully sliding a fine wire through the port.
If you're not sure you're missing vacuum (you've got a gauge, so I'll trust your measurements, but ...) don't forget that it's the temp sensor that triggers the CEL. Checking the temp sensor itself is pretty easy: http://web.archive.org/web/201003261...00egrgaste.pdf
thank you for that intro to this forum. I have since edited my post. I hope people can read this now. Thank you for helping and responding. If I recall right, I believe I should only read vacuum when revving up the engine 3,500 but no vacuum on idle? I have a vacuum gauge tester and yes I hooked it up to port P and R on modulator coming form throttle body. I verify vacuum on R port when revving engine, but no vacuum on P port. I have also tried cleaning that port. I have sprayed carb cleaner with throttle body in open position and I have also tried blowing compressed air in the throttle body port. No luck. I can try the the wire in the port. I will also run a ohm reading on the temp sensor to rule that out. thank you for responding and I appreciate the help. all ports have vacuum above idle
here is the link that elaborates more on this http://www.ncttora.com/fsm/1993/engine/93throttle.pdf
update. I have taken the throttle body up and cleaned the ports. several of the ports were restricted. I needed to use my pick first and then a small wire to punch through all that gunk. I was able to free up all vacuum ports. I reinstalled the throttle body, and now am getting a fluctuation in RPMs when I first step on the gas paddle. I also notice that the car feels like it will die but then engine kicks back on type of deal. when revving above 2,000 RPMs seems like the issue isnt there. Mostly happens just above idle. I was wondering if it had to do with TPS sensor? I ran the check from the FSM manual and couldnt get it to go to infinite when using .031 or .80mm in filler gauge test. All other test on TPS sensor measurements were within specs except for the one I mentioned. I read that there could be a problem with the IAC in the throttle body? anyone ran in to this issue b4? please help. thank you in advance
06-20-2021, 12:59 PM
