I've got a 2000 Ranger XLT 2.5L which gives teh PO340 code on a regular basis. I recently aquired the truck so I've not much knowledge on its service history etc. I've replaced the Camshaft Sensor twice to no avail. What is weird is that when the temperature drops below a certain level, (like it did this week dropping 30 degrees in one night) it strightens up performance wise. What it does when it is not performing correctly: Idle races after coming to a stop and letting off accelerator, idles very roughly sometimes dying, falls flat on its face when accelerating slowly sometimes, when decelerating it chugs violently then I hear a rapid clicking sound coming from outside the firewall and lastly driving around town it's getting about 13 mpg.

If anyone has any ideas what to check next I'd be grateful. I've pulled the harness connectors off, cleaned them, the hook up to the computer, I found that someone had taped off the two wires that go to the sensor, so this had been a problem with the previous owner.

Thanks

 

P-0340 is "CMP sensor CIRCUIT fault."
Dont know about yours, but the wiring diagrams for other Fords that I have looked at show the CMP receives 12 volts from the ignition switch.

Take a look at the read first sticky at the top of the forum & see if theres anything about testing the CMP circuit.

If theres nothing there enter the info for your truck at www.autozone.com & you should be able to pull up the online wiring diagram for your ignition system. Then test to see if the CMP is receiving voltage.

 

Thanks 87 XLT, I haven't looked at that wiring diagram yet, I will in a bit. I did find a very knowledgable fellow working at Autozone though. He'd worked as a mechanic etc, he told me that the Crankshaft Sensor was also on that circuit bank, that it could possibly be the culprit. I went ahead and replaced it. It mostly has ran 'correctly' since then, although it did give signs of its old behavior this morning...I'm going to take that old sensors in for testing on their meters and keep investigating that particular circuit.

Thanks for the input, very useful.

 

hmm, try and find out the past service records of your ranger. Thats a tough question cant help ya right now

 

With no input from the CMP, I would guess that the PCM fires the injectors in limp mode, more or less at the right time. Seems that would give you a rich or lean code also, bur I would'nt think it would cause the high idle.

Rockledge mentioned a TSB on the throttle position sensor on this engine causing high idle, but I dont have the details. Maybe he will see this post & have more details on that.

The crank sensor times ignition & the CMP times the injectors so it doesnt seem that there would be any connection between the 2, but if it runs better with the new CKP.....

Keep us posted on what you find & good luck with it.

 

Cheech5o I just aquired the XLT a couple months ago, I don't know who owned previously, neither does the person in my family who had bought it from a dealer...I suppose if I asked enough questions I might find something there but I'm not so confident.

87 XLT, thanks for the input on the purpose of the crank sensor and the camshaft sensor, I'm out of town so I haven't checked the wiring diagram so far, before I left I had changed the crank sensor which helped tremendously. Yesterday it acted crazy again for a bit, so I changed the fuel filter which I normally would have but this computer thing which I'm new to got me off guard. The filter was filthy. Now it even has more pep when accelerating. I'm not sure yet about whether I've cured the check engine signals yet.

Thanks for the info and ideas, I'll give more of a report when I have time to check the wiring diagram.

Also before when performance was very unpredictable it felt like to me that the timing was way off, in it would feel on an old purely mechanical engine, when the advance was malfunctioning or it was too retarded, something like that. So 87 XLT if the crank sensor was faulty does it have its own code number? Am I confuse on this one?

 

Well I don't seem to find an actual diagram on the autozone site. I'll keep looking. The 2.5L is continuing to run oddly, as described above but lots less violently, on a much smaller scale, I reset the MIL light then after two starts it is on again. I'll get the codes tomorrow if possible. Meantime I'm predicting the same problem is occuring PO340. So 87XLT if you have any more suggestions on how I find the 'circuit' diagram etc I'm all ears.

Thanks

I guess I should say the racing idle is mostly gone, now it is small surging and occasionally dying at idle, previous problems but smaller. And I've replaced the throttle postion sensor as it was coded a few weeks ago.

I'm wondering if the camshaft sensor controls the fuel timing then a disruption in the fuel distribution might affect this also..?

 

Best bet for wiring diagrams is the Ford "vacuum & electrical troubleshooting manual" which will have diagrams for all the circuits on your truck including the CMP circuit.

I have these for my Taurus & Ranger. Very handy for fixing electrical problems. It's amazing how a quick look at a GOOD wiring diagram is sometimes all it takes to figure out an electrical problem.

If you still get the P-0340 theres apparently a wiring problem in that circuit.

 

87 XLT, I got another code reading today, as per usual a PO340 and this time also a PO453. I've been suspecting something is up with the evap system but haven't looked that close into it. In fact the last couple times I went to one Autozone I swore I read over the should '1 out of 2' then the fellow told me, 'Nope, only one code'. Today I went to a different one. I replaced the gas cap for good measure, but still after driving no pressure in the tank when I release the cap. Tomorrow I'll take down the spare tire and check the evap canister. It makes sense to me maybe a restricted line from evap to engine? Or leak?

Would you conjecture that this could set off the camshaft sensor as a result?

The sensor is reading too high for the current operation.

Thanks.

Yeah you are right about the wiring diagram book I intend to purchase one at some point.

 

Theres no connection between the 2 codes.

I dont think the EVAP code would effect running, but could be wrong on that

Seems to me theres been some posts about rust causing problems with whatever is mounted on top of the gas tank for the EVAP system.

 

Well as per usual yesterday I was coming south on a long trip, the atmospheric temperature dropped...maybe it is connected but the MIL light went off on its own while highway driving. Hmm.



Before that happened I was planning next to take the tank completely off and out, I was able to put it on the lift I couldn't take the tank off then but did see signs of moisture...tel-tale signs anyway...dark spots on the frame cross members...more later when I have time to remove the tank and check out all the connections etc.


Thanks 87XLT.

 

Well since the temperature went up today it again chugs violently, MIL came on etc. I'm pulling the tank.

 

Pressurized the tank fill hose just to check it, no leaks. No signs of an obvious leak on top of tank.

Running extremely bad again, after running great all of the last 8 days.

???

Do you know anything about the sensor on the little vacum unit that mounts on the drivers side wheel well, the hose from the purge canister connects to it then it goes to the intake. There is sensor on that, being I don't have anything but a Chilton I'm not knowing myself what it is. There is a green cap on the side as if one could take that off and perform some test or other. I inspected the canister itself a few days ago not finding anything that looked suspect...so I'm not sure what to do next.

 

HX33 DTC P0453: CHECK FOR HIGH FTP SENSOR VOLTAGE
Note: FTP sensor input with no pressure/vacuum on the fuel tank (fuel filler cap open or not open to atmosphere) is 2.37 to 2.97 volts.

Connect scan tool.
Key on, engine off.
Access FTP V PID.
If FTP V PID is not present on the scan tool, measure voltage between FTP and SIG RTN circuits at the PCM harness connector with PCM connected.
Is measured voltage or FTP V PID reading greater than 4.50 volts?
Yes No
KEY OFF. GO to HX34 . The fault that produced DTC P0453 is intermittent. GO to Z1 .

HX34 CHECK FTP CIRCUIT FOR SHORT TO POWER
Disconnect FTP sensor.
Key on, engine off.
Measure voltage between FTP circuit at the FTP sensor harness connector and battery negative post.
Is the voltage greater than 10.5 volts?
Yes No
KEY OFF. The FTP is indicating a short to VPWR. GO to HX35 . KEY OFF. GO to HX36 .

HX35 CHECK FTP CIRCUIT FOR SHORT TO VPWR IN HARNESS
Note: Refer to the PCM connector pin numbers in the beginning of this pinpoint test.

Disconnect PCM.
Key on, engine off.
Measure the voltage between FTP circuit at the PCM harness connector and battery negative post.
Is voltage greater than 10.5 volts?
Yes No
REPAIR short circuit. REPLACE PCM. (REFER to Section 2 , Flash EEPROM.)

HX36 CHECK OPPOSITE INDUCED LOW FTP SIGNAL
Connect a jumper wire between SIG RTN and FTP circuits at the FTP sensor harness connector.
Key on, engine off.
If a scan tool communication concern exists, turn the key off, remove jumper immediately and GO to HX41 .
Access FTP V PID.
If FTP V PID is not present on the scan tool, measure voltage between FTP and SIG RTN circuits at the PCM harness connector with PCM connected.
Is measured voltage or FTP V PID reading less than 0.10 volt?
Yes No
REMOVE jumper. GO to HX37 . Unable to induce opposite signal. KEY OFF. GO to HX39 .

HX37 CHECK FOR IN RANGE VOLTAGE BETWEEN VREF AND SIG RTN CIRCUITS AT FTP SENSOR
Key on, engine off.
Measure voltage between VREF and SIG RTN circuits at the FTP sensor vehicle harness connector.
Is voltage between 4.0 and 6.0 volts?
Yes No
KEY OFF. GO to HX38 . VREF voltage is out of range. GO to C1 .

HX38 CHECK FTP CIRCUIT FOR SHORT TO VREF IN SENSOR OR HARNESS
Note: Refer to the PCM connector pin numbers in the beginning of this pinpoint test.

Disconnect PCM.
Measure resistance between FTP and VREF circuits at the PCM harness connector. (For LS6/LS8 measure to both VREF pins.)
Is the resistance greater than 10,000 ohms?
Yes No
REPLACE FTP sensor. REFER to Evaporative Emissions, Section 303-13 in the Workshop Manual for component removal and installation. RESTORE vehicle. FOLLOW the Vehicle Preparation for Monitor Repair Verification Drive Cycle and COMPLETE an Evaporative Emission Leak Check Monitor Repair Verification Drive Cycle (REFER to Section 2, Drive Cycles ). REPAIR short circuit.

HX39 CHECK FTP CIRCUIT FOR OPEN IN HARNESS
Note: Refer to the PCM connector pin numbers in the beginning of this pinpoint test.

Disconnect PCM.
Measure resistance of FTP circuit between PCM harness connector pin and FTP sensor harness connector.
Is resistance less than 5.0 ohms?
Yes No
GO to HX40 . REPAIR open circuit.

HX40 CHECK FOR OPEN SIG RTN CIRCUIT BETWEEN PCM AND FTP SENSOR
Measure resistance of SIG RTN circuit between PCM harness connector pin and FTP sensor harness connector.
Is resistance less than 5.0 ohms?
Yes No
GO to HX41 . REPAIR open circuit.

HX41 CHECK FTP CIRCUIT FOR SHORT TO VREF IN PCM
PCM disconnected.
Measure resistance between FTP and VREF circuits at the PCM harness connector. (For LS6/LS8 measure to both VREF pins.)
Is the resistance greater than 10,000?
Yes No
REPLACE PCM (refer to Section 2, Flash Electrically Erasable Programmable Read Only Memory (EEPROM) ). REPAIR short circuit.

 

Ken I really appreciate your post about the PO453 code, but maybe since I replaced the gas cap or checked an tightened the fill hose that particular code went away. But the performance is worsening. The persistent code is PO340 the camshaft sensor code. I was thinking of handing the truck over to a mechanic that was recommended to me. I ran into him today not at the garage, he recommended that I purchase a 'proper' new sensor instead of the one I bought at autozone for $19, I bought one from ford for $111. No difference. I replaced the pigtail to it also. No difference, as far as the 'left bank circuit' In the chilton manual I have it shows a simple single wire in to sensor and single wire out to pcm. I don't know what else to check on that 'circuit'. Without the Helm manual which I haven't purchased. When I installed the new pigtail I simply used the voltmeter to each wire seperately, at idle they both read 5.72 volts. When I revved the engine the voltage went all over (lower) the scale.

Would you maybe have the kind of detailed check list for the PO340 that you did for the PO453?

Thanks for the information and ideas. I am grateful for any direction.