Should the Map BP signal wire 2.5 volts I get 4.2 volts, to battery ground should be? I cut the wire from the eec and still got 4.2 volts. So it must be correct. I read your old post that said you replaced one that has 2.5 and the new one had 2.5 also was that on your 87 f150 4.9?

Map plugged in a got 1 volt from Map bp sig to VREF. SIG RTN to Map bp I got 4 volts. If i get a code 22 Map out of range is there anyway that it could not be the Map thats the problem? I know it could be the wiring or the vacuum also. Thanks Mike 87 f150 4.9

 

The voltage you are getting on the MAP signal wire is too high in my opinion. The map sensor on my truck ('87, but it's a 302) reads 2.5V on the signal wire, when backprobing the connector with the MAP sensor plugged in. It should be a frequency varying MAP sensor, meaning the voltage would stay at approximately 2.5V regardless of what signal the MAP sensor was sending out. I would focus on trying to figure out why you have 4V on the MAP signal wire (you said you had this, even with the sensor unplugged, right?). Check for continuity between VREF and the MAP signal wire.

 

If you disconnect the MAP, and probe the wire coming from the computer, you may well see 4 volts as a normal thing. The analog buffering circuitry inside the computer may pull the line up. If you want to investigate for the possibility of short circuits, you need to use something like a 1K ohm resistor from Radio Shack between the MAP wire and ground, in order to load the circuit and eliminate the effect of the pull-up in the computer. Now probe between the MAP wire and ground. If the voltage is still 4 volts, you have a short. But I bet it will drop to near zero volts.

A working MAP produces a variable frequency square wave, swinging from SIGRTN to VREF. Many voltmeters set on DC will average the high and the low and produce "2.5 volts". But this is not a guarantee that all voltmeters will respond to the signals in this way.

I agree with EPNCSU2006 that your MAP signal sounds suspect. And you are getting a code 22 as best I can tell. I'd recommend the following:

1) Set your meter to "AC volts" (not the "DC volts you've been using) and measure between the MAP signal and ground again (with everything connected). This should read 4 volts, more or less. If it reads 0 volts, your MAP output is not switching.

2) You said you cut the MAP signal wire. What you might try is connecting the MAP sensor, and probing the MAP side of the cut signal wire. This should provide power (VREF) and ground (SIGRTN) to the MAP sensor, yet isolate the MAP sensor from the harness. Probe the MAP signal on the sensor side of the break in the wire with your meter set to AC volts and DC volts. You should see 4 volts on AC volts if the sensor is working, and will likely (though no guarantee) see 2.5 volts on DC volts.

3) Disconnect the MAP sensor from the harness. Run a KOEO test. Do you get the same codes as with the MAP connected? Or do you get a different code? This may help isolate a MAP problem from a harness wiring problem.

4) Attempt to start the vehicle with the MAP disconnected. Maybe the computer will substitute a default for an obviously dead MAP and allow the engine to sort-of run. Or maybe not. But it is worth a (brief) try.

 

1) Set your meter to "AC volts" (not the "DC volts you've been using) and measure between the MAP signal and ground again (with everything connected). This should read 4 volts, more or less. If it reads 0 volts, your MAP output is not switching.

#1 I got 9 AC volts on the Map ( plugged in) at Map BP Signal wire to battery ground.

2) You said you cut the MAP signal wire. What you might try is connecting the MAP sensor, and probing the MAP side of the cut signal wire. This should provide power (VREF) and ground (SIGRTN) to the MAP sensor, yet isolate the MAP sensor from the harness. Probe the MAP signal on the sensor side of the break in the wire with your meter set to AC volts and DC volts. You should see 4 volts on AC volts if the sensor is working, and will likely (though no guarantee) see 2.5 volts on DC volts.

#2 I got 12 DC volts from VREF to SIG RTN with Map bp signal cut at the EEC. Map was plugged in. Was that what you wanted?

#2 I got 5 AC volts from VREF to sig rtn with Map bp signal cut at EEC. Map was plugged in.


3) Disconnect the MAP sensor from the harness. Run a KOEO test. Do you get the same codes as with the MAP connected? Or do you get a different code? This may help isolate a MAP problem from a harness wiring problem.

#3 Unhooked ground on battery for 10 minutes. KOEO codes the same. but CM codes I got 11 11. Then tried to start, ( only ran for 3 secs ) and got the same CM codes as before 22 22.


4) Attempt to start the vehicle with the MAP disconnected. Maybe the computer will substitute a default for an obviously dead MAP and allow the engine to sort-of run. Or maybe not. But it is worth a (brief) try.[/QUOTE]
#4 Tried and it did not start.

 

With the Map sensor plugged in <!-- / message -->I checked the VREF to the MAP signal wire and i got one Volt.

 

It is frustrating to do this over the internet. The measurments you took weren't quite what I was looking for, and the values you measured seem odd.

Vref and sigrtn are DC signals provided by the PCM. The voltage from VREF to SIGRTN with the PCM connected to both should be 4 to 6 volts DC. 12 volts makes no sense and is a bad thing. Check VREF to battery ground. Should be 4 to 6 volts.

There should be no (0) AC voltage between Vref and sigrtn. 5 volts makes no sense. Are you sure you've got the right wires? Just to check out the meter, try measuring AC volts between VREF and battery ground, and battery pos to battery ground. All these should be zero.

The voltage from VREF to battery ground should also be 4 to 6 volts DC. The voltage from SIGRTN to battery ground should be 0 to 1 volt DC.

The MAP output is provided by the MAP sensor. This should be about 4 volts AC relative to SIGRTN. What I wanted to see with VREF and SIGRTN connected from the PCM to the MAP, with the MAP output disconnected from the PCM. Probing the MAP sensor side of the break should give the 4 volts AC. Probling the PCM side of the break should give 0 to 1 volts AC. Splicing the wires back together should not change the output of the MAP -- should still be 4 to 6 volts AC.

I'm going off to deer hunting camp tomorrow and will be without Internet service for awhile. Perhaps in the interim you could scrounge a junkyard MAP sensor. Your tests prove that the MAP you have looks like an open circuit -- computer responds the same with the MAP connected as disconnected.

 

oops so sorry it was #2 I got 5 DC volts from VREF to SIG RTN with Map bp signal cut at the EEC. Map was plugged in. Was that what you wanted?

#2 I got 12 AC volts from VREF to sig rtn with Map bp signal cut at EEC. Map was plugged in. Sorry!

I found a parts store that will let me return a new map sensor if it is not bad.

 

I need to correct an earlier post. When I said I was looking for 4 volts AC, it should be more like 2 volts AC.

The normal MAP output is a variable frequency square wave switching from 0.5 to 4.5 volts. The output should be measured between the MAP signal wire and SIGRTN. Many DC voltmeters will read this as "2.5 volts".

An AC voltmeter should read about 2.0 volts. Not the 4.0 volts I mentioned earlier. An AC voltmeter should reject the DC component, and measure the difference between the peak and average voltage, which in this case is about 2.0 volts.

I am glad to hear that VREF to SIGRTN is the 5.0 volts that it should be.

12 AC volts from VREF to SIGRTN suggests that your voltmeter has some noise issue or you are using the wrong scale etc. I could believe 0.12 volts as the noise component on VREF, but 12 volts is way too much.

Again, we are looking for AC volts from the MAP signal to SIGRTN.

But even the Dali design diagnostic charts say that the best way to check out the MAP sensor is to swap it for another one. If you have a place that will take back the MAP sensor, by all means give it a shot. You should at least be able to get rid of code 22, and maybe even get the truck started. Good luck!

 

I replaced the Map with a new one. Added new spark plugs. no start on fuel. I added started fluid and it run on just that, for ten secs. each time. I'll switch fuel tanks and try again. I rechecked the codes two times and I get KOEO 21 and 24 and CM 11 You said not to worry about 21 and 24, with no start and its 20 deg. now. Code 22 (map) is gone now! I must no have to much fuel pressure I can smell the fuel on the spark plugs. Thanks

 

THANKS GUYS!!! After engine was hot, DONT KNOW IF IT MATTERS. I reinstalled the old map and it started RIGHT UP. Why did I get the code 22 then??? Should i keep the new Map? It seems that the front intank fuel pump may have a problem sometimes it stutters, and it runs a little loader then the rear one. Ran rear tank for half hour no strutters. I will try codes while its running just to see if anything comes up.

 

Another success story. Glad you got it running. How long has the truck not been running? I think I might run the front tank awhile with some fresh fuel and see if the stutter won't go away. I don't remember if you said you changed the fuel filter or not?? Have you tried to crank the truck with the new MAP? The MAP on mine is Original from the day I bought the truck new and still working, so today it will quit since I said that. If you need the cash worse than the MAP, I would take it back. You could always buy it again. Too many questions for this early, sorry.



guzzler96

 

I think I might run the front tank awhile with some fresh fuel and see if the stutter won't go away. I don't remember if you said you changed the fuel filter or not??

Two motorcraft filters and the fuel in both tanks are two months old. Added water remover and fuel injection cleaner.


Have you tried to crank the truck with the new MAP?

Both work but the old one throws a 22 code. very odd

The MAP on mine is Original from the day I bought the truck new and still working, so today it will quit since I said that.

I can sell you one for cheap. LOL

If you need the cash worse than the MAP, I would take it back. You could always buy it again.

May will buy a salvage one and hold on to the new one for 30 days

Too many questions for this early, sorry.

Morning SUCK!! LOL



guzzler96[/QUOTE]

 

Yesterday only had codes 21 and 24 when no start. I was told thats ok when cold.
Today while running i get koeo codes

31 EVP
1
12 ISC
41 RUNNING Lean
33 EGR
13 ISC
77 GOOSE THROTTLE..... DIDN'T DO
52 tURN WHEEL.... DIDN'T DO
CODES REPEAT 12 TO 52

ENGINE Hot not running CODES I GOT TODAY

11
11
1
22 Map sensor replaced with new one and cleared code yesterday
51 ECT
87 FUEL PUMP .... i have two fuel tanks
33 EGR
CODES REPEAT 22 TO 33

Engine misses for a half a sec on low idle about every 3 to 5 minutes while in the driveway. Don't know about on the road yet. wONT STALL IF I GOOSE THROTTLE. DO I NEED TO REMOVE the BATTERY GROUND after installing the new map sensor? Do all these codes make sense sense i didn't get them yesterday??

 

Yeah, they seem to. I have a Code 33 going right now. The 33 is apparently telling me the PCM was expecting the EGR to open and it didn't or has insufficient flow. I am trying to check it out now, but have to work on it on weekends.

Code 31 - Is the valve position sensor (EVP) with the EGR. Is yours mounted on top of the EGR with an electrical plug on it?

Code 77 - Goose Test. If you had a reader with a display, during the process of reading my Autoxray prompts me to depress and release the throttle all the way to the floor. I assume for WOT. I wouldn't be too concerned about that one.

Code 52 - Power steering pressure switch. Again, my reader prompts me to turn the wheel all the way to the right and then back to center. I wouldn't be too concerned about that one.

Code 12 - Cannot control high rpm during high rpm test. May be IAC related. What is condition of the Idle Air Control valve?? New or Old?? May need cleaning. Don't clean the electrical part just the valve body.

Code 13 - Cannot control Low rpm during Low rpm test. Also IAC related.

Code 41 - O2 sensor lean. May be related to EGR probs.

Don't know if any of this helps, but maybe it will. I for one will be glad when fefarms gets back from killing Bambi's so we can get help with these codes. There killers. EPNCSU2006 is not bad with this stuff either.



guzzler96

 

The (engine running) codes stayed the same after unhooking the battery. I redid the KOEO (not running) codes and got 21,24,21,24,1,11,11. so that looks good I think.

CODE 51, I Checked the ECT sensor today on my 1000 ohms setting. I got 6 which I think is 60 ohms, with engine was warm, not running. I got 2.5 volts at the plug end ( unpluged and pluged ) between the two wires. When the engine was cold I got 60 ohms which is 600 ohms. The manual says cold should be 58,000 to 40,000 ohms and hot should be 3,000 to 1,840 ohms. 5 volts between the two wires. Is the ect ok?