Throwing code 71.

Replaced:

EGR-Factory OEM
Vacuum Modulator-Factory OEM
Coolant temperature sensor-Factory OEM
Tested the EGR VSV as the manual states. Clicks open/close and blocks air as the manual states.
Checked all hose routing.
Checked all hoses for leaks. Put an UNLIT MAPP gas torch at all hoses, ends, EGR, and connections related to such while the truck is idling. No change in behavior to indicated a leak anywhere.

1994 PU 4x4 with MT.

Code 71 tortures me in my sleep.

ThePlumber

 

It's pissed me off to the point of draining the coolant and flooring it.

ThePlumber

 

so it runs fine. but throws a egr code?

Throw a 1k resister in the egr temp sensor wiring clip. problem solved

 

2 things:

1) What about temperature increases that could cause premature failure of the head gaskets (replaced-no problems for thousands of miles).

2) Why is the m'fer on???

Thanks.

ThePlumber.

 

The EGR still works but the sender just thinks its working perfect all the time... so.

I have no idea!

 

Thanks. Might have to "resistorize" it.

ThePlumber.

 

No problem.
I mean I figure, if the EGR is all new and working perfect, then just fool the sensor into thinking (well knowing!) that the egr is working fine.

Most trucks dont even have that sensor, mine doesnt!

 

yup. yup.
passage through the head is likely blocked. passage blocked= little-to-no exhaust gas flow so EGR temp sensor doesn't get heated up as much as it should hence the code.
Unless you're a contortionist, you're not going to get the PAIR and coolant pipes as well as the plate off the back of the head as well to clean it up. A stiff, yet flexible pipe cleaner might work though, passed through the EGR valve's passage in to the head.

 

I cleaned the EGR passageways before I installed the EGR. I'm willing to do it again if necessary.

The EGR & metal piping DOES get hot.

Thanks for all replies.

ThePlumber.

 

Might be that the sender is either bad or out of spec. I imagine the Factory Service Manual has a test procedure for that sender.

 

Update. I found one of the hoses off at the EGR VSV. Don't know how, but it had to be my fault completely.

Put it on, removed battery cable to reset codes, (Couldn't get the EFI fuse out), drove about 100 miles both highway and city traffic. Four separate stops to pick things up.

Got my paperclip out, NO CODES STORED.

Still doesn't run very well though. I get the "Porky Pig" at various unpredictable points of acceleration. vrooooOOO-duh-t-duh-duh-OOOM...

ThePlumber.