a couple days ago i posted about my problems with my new code reader, well it still doesnt work so i broke out the old beeper reader. i got code 128-map vaccume hose loose or damaged, i visualy inspected it and seemed good so i put a little bit of vassalene on it and put it back on and i still am getting the code for it, shoud i just replace it? 542 and 546- furl pump circut open and circut relay problem. the fuel pump has a toggle switch hooked up to it to break the circut,,, could this cause the code? code 121-tps voltage to high or low, 327&328-egr to low, 624 epc circut failure, are codes i have no clue how to fix. just repace the sensors???? any help would be aperciated.

 

You can measure the MAP sensor with a meter that has a frequency setting. I use a small handheld vacuum/gauge to apply vacuum to it. Saves a lot guesswork.

Yes, the toggle switch can and probably is triggering the fuel pump codes.

Code 121 can be caused by a "noisy" TPS sensor. Noisy meaning the internal wiper is dirty which then causes the signal output to vary. The same thing can happen if the connectors are corroded. Use a meter to verify the root cause, TPS or connectors.

Code 624 indicates a problem with the EPC driver circuit or solenoid in the transmission solenoid pack. Before going too far I will once again suggest you pull the connector to the solenoid pack to inspect/clean as necessary.

Codes 327/328 are EGR related. These can be caused by a faulty EVP sensor, the one on top of the EGR valve, a collapsed EGR valve diaphragm or spring. Once again, get that meter out to verify what the signal values are. This set of codes is difficult to diagnose because the EGR diaphragm/spring preloads the EVP sensor when properly installed so it is a process of elimination.

 

ok i will get a multimeter and see what i can find out. thanks

 

how much vacuum do i apply to the map sensor?
and what readings am i to get with the multimeter for the egr?

 

and what wires do i touch on the egr to get the reading?

 

MAP Sensor info: Ford Fuel Injection » Manifold Absolute Pressure Sensor (MAP)

EVP info: Ford Fuel Injection » EGR Valve Position sensor (EVP)

 

i went to the auto parts store and they didnt have a vacuum pump, so i sprayed starting fluid around the vacuum line and no change in idle is that a accurate method of checking for leaks?

 

I have similar codes on my 95 F-250 Thanks for the thread... Im reading with you.

I have code 327 also and the reader made reference to PFE also. any enlightenment on this ?

 

In my opinion, no that is not a valid test on these EFI engines. Others will argue for and against it. It should be used in combination of somehow qualifying if the entire vacuum circuit is operating correctly. It can be effective for finding leaks in the upper intake/gaskets area.

The metal vacuum reservoirs are well known to rust out and cause vacuum leaks. There is another small plastic reservoir on the side of the blower/evaporator case than can lead to a vacuum leak in the HVAC circuits. My '92 F350 has a third reservoir hidden behind the driver side headlight. I put my finger through it when I was tracing down the vacuum lines for the cruise control ('92 uses the older style vacuum operated cruise).

 

Your truck is most likely using the EVP style feedback just like the one in this thread. Before chainging any parts measure the EVP signal. I posted a link in a previous reply.

 

would the egr ,tps or map sensor cause a looping idle then stahl once and a while?

 

My money would be on a dirty/faulty IAC.

 

when working on my truck yesterday i found a broken vacuum line so i replaced it and in the process i un-pluged a vacuum line in the throttle body (pass side) and the truck idled just fine would that be the line for the iac? if so how do i disassembel and clean it? also my pcv needs replaced is their a way to do that without removeing the throttle body/intake assembley off?

 

The IAC is electronic controlled. Ryan has a writeup of it's operation here:Ford Fuel Injection » Idle Air Bypass (IAB)

It is located on the driver side of the throttle body. Here is a cleaning procedure from another forum: IAC Cleaning - FSB Forums

The PCV is located on the passenger side valve cover next to the firewall. It is not easy to get to. I find it easier to remove the upper intake to remove and inspect it. There is also a rubber hose and grommet in the valve cover than can crack with age. Very difficult to get a good look at those without removing the upper intake as well.

 

i tested the iac as ryan said to when i un-pluged it no change in the idle, if i read right it is not functioning properly correct? would that throw the other codes i have because of them all being air/fuel related? this truck is just nickel and dimming me , it has a pretty bad oil leak from the rear main i think i cant tell where it is coming from yet, i just found a radiator leak and with all the other problems i am having i am about ready to just drive it off a cliff!!!!!!!