EGR related issues

[joemag7]

I have read through the other EGR related posts, but none seemed to match mine.
My '97 4cyl. Ranger is due for registration and my 'engine light' is reading an EGR problem.
I did the difficult task of replacing the EGR valve, but all the while noticing the EGR has no electrical connectors(just a single vacuum line), so of course how could it be affecting the on board computer.
Well sure enough; after replacing the EGR valve the 'engine light' came on again.

Any of you guys dealt with EGR issues before?
Can anyone reccommend what other components to look at?

Thanks
Joe

 

[kimcrwbr1]

Did you erase the memory and reset the computer. Try that and see if the CEL light clears. Turn the ignition off when it starts flashing codes then disconnect the battery for 1/2 an hour. Then run it for about 20 minutes at medium speeds and while it is still hot run the codes again.

 

[kimcrwbr1]

If your using a jumper wire to pull the codes disconnect the jumper when it starts flashing codes then disconnect the batt.

 

[BRUTUS_T_HOG]

the egr system is simple. check the vacuum lines to the control solenoid and then from the solenoid to the intake manifold. if these are leaking the egr won't work

more than likely is that the DPFE sensor or its hoses are bad... let me guess insufficient flow code? you should first start by checking for cracked hoses going to the DPFE sensor, it mounts above the exhaust manifold and has hoses coming off the EGR tube.

if the hoses are ok you'll need to monitor voltage out of the sensor while you manually open the EGR valve.. should have 1volt or less when EGR is off and 4-5Volts with the EGR valve fully open. the most common problem with this sensor is that it gets stuck and doesn't change voltage

clear codes if you havn't already by disconnecting the battery. there is no jumper wire on a 97'

 

[adsm08]

The EGR valve itself is vacuum operated. There are several ways that EGR codes can be set. Most of them relate to the DPFE sensor. Rather than monitoring the valve itself directly there is what Ford calls a Differential (or Delta) Pressure Feedback Exhaust Recirculation Gas sensor (or DPFE for short). Basically it is a pair of pressure sensors that straddles a restriction in the EGR tube and watches for changes in the relationship of the pressure on each side.

If your code was P0401 Ford has a TSB out about not even diagnosing that code but just replacing the DPFE. The down-stream side of the sensor being plugged from the yuck in the exhaust is the cause of that code almost 99% of the time. Also, if you didn't clear your codes, the light will stay on for about 40 drive cycles (not key cycles like the EEC IV system) and it can take weeks of months of normal driving to complete one drive cycle. I even saw one once, new car, 1 year old, came in and failed the emissions test because the lady only ever drove in stop and go traffic and it hadn't even completed it's first full drive cycle yet.

If you got a P0401 go buy a DPFE and I'll let you know how to put it in, really easy. Either way, go buy an el-cheapo code reader if you don't have one already, and clear your codes.

 

[joemag7]

Thanks for everyones inputs above; each post speaks volumes.
The DP sensor sounds highly likely, depending on price I think I will just replace it,
thanks for that info ADSM.
I don't personally have a trouble code puller, but rather two different places that read the code told me the EGR is the issue.
My boss at work has an OBDII reader and is supposed to bring it with him tomorrow. And then I'll check if it's the specific PO401 code.

Beside that; do the codes have to be cleared manually? What I mean is I thought removing the battery cable while working under the hood clears the codes automatically?

 

[adsm08]

Disconnecting the battery will clear the codes, if it's left off long enough. A code reader is a far more effective and efficient way to clear the code. It also won't wipe out the rest of the memory like unhooking the battery will.

 

[joemag7]

So I to looking at the different components mentioned above last weekend and came across a pair of vacuum lines running close to the exhaust head that were melted just enough to not allow any air through.
Went to the parts store and bought a foot 1/4" ID tubing, cut out the bad part, sleeved it with the new tubing and rerouted the lines. Drove it for a week for the CPU to finish its test and got my registration done yesterday

Thanks Everyone
Joe

 

[BRUTUS_T_HOG]

thanks for posting a fix