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2008 F-150, 5.4L 3v, no start, no spark, no pulse; but cranks over. Constant power confirmed at injector pigtail and coil pack. Fuses check out and nolno codes. This leads me to believe, that the crank sensor is the culprit. However, testing terminals at the pigtail, revealed a positive value on either side??? 2.5v & 1.5v... Now I'm confused.lol....
Last edited by Steve Hutchinson; Sep 14, 2020 at 05:35 PM.
Reason: Adding information
How do you know no spark-exactly.do you have a tester. How about fuel pressure ,you need to check your fpdm on rear axle . Common problem. Does your tach move when cranking . Do you have torque pro ? 5$ app ,android phone cheap blue tooth reader amazon .Does it try to fire if you shoot some fuel into intake or starting fluid.
You need spark, fuel and air at the right time . Or at least close to get a cough even if its timing . My bet is fuel loss .
Torque pro will tell fuel pressure. .Check fpdm for corrosion . No fuel no boom .
How do you know no spark-exactly.do you have a tester. How about fuel pressure ,you need to check your fpdm on rear axle . Common problem. Does your tach move when cranking . Do you have torque pro ? 5$ app ,android phone cheap blue tooth reader amazon .Does it try to fire if you shoot some fuel into intake or starting fluid.
You need spark, fuel and air at the right time . Or at least close to get a cough even if its timing . My bet is fuel loss .
Torque pro will tell fuel pressure. .Check fpdm for corrosion . No fuel no boom .
Yup, inline spark tester. I can hear the fuel module driver ( it was replaced about 2 yrs ago w/ the stand off kit. Tach does not move while cranking. App reads fuel pressure is good. Spraying starter fluid won't do anything, if there's no spark. Niode light doesn't show pulse. I just did a timing job, two weeks ago and it's been running fine. There's also a new manifold intake, that was installed last week and MAF sensor yesterday. Lol. She's been relentless this past month..🙄 Tried unplugging the MAF and still no start. Did I mention that it's not throwing any codes? Inertia switch wasn't activated and fuses test good...
When cranking does the tach move at all? If not replace the crank sensor, or at least check that the wiring to it is good.
RELAY 203! FFS. It didn't even cross my mind, because it cranked over. Unplugging the CPS didn't throw a code, so I began going through the fuse panel layout, in the owners' manual and out of desperation, swapped the relays; boom she's ALIVE!! But there's a misfire or something, because she's shaking.
***Shake is gone. I forgot to plug in #5 coil pack lol..
Unplugging the CPS doesn’t throw a code.
If the PCM doesn’t see a CPS signal, it
doesn’t think you are cranking it, even though
you are. AND, it doesn’t know enough to turn
the fuel pump back on, or fire the coils or
injectors.
Unplugging the CPS doesn’t throw a code.
If the PCM doesn’t see a CPS signal, it
doesn’t think you are cranking it, even though
you are. AND, it doesn’t know enough to turn
the fuel pump back on, or fire the coils or
injectors.
The fact it didn't provoke a DTC, for the CPS, it was evident that there was no communication; that's why I'm glad it was the relay and not ECU.... Thanks for taking the time to add your thoughts. 👍
Went riding yesterday, first around the block and then expanding out more and more, to the point that I felt confident that I could make a run to the dump; about 10km round trip. Just as I got to the scale, there was a hesitation. Made it home and was idling, while retrieving live data, which took about 5 min and the truck died. Now back to no start, the relay swap didn't work (lol) and I'm amazed it didn't throw a code... I need a master mechanic to chime in on this, please! Both cats were same temp, trims were within range. Could it be an intermittent fault of the CPS?
So, when the truck died, were there any codes?
Any freeze frame data?
Does the tach move when cranking with no start?
Does the CEL turn off while cranking with no start?
Tach doesn't move while cranking, CEL stays on and FF would be almost nothing, because it was cleared before the test drive. I replaced the CPS today, with no luck, tried starting it with the MAF unplugged, still nothing and removed all three connections to the ECU, cleaned and blown with compressor air; still nothing. There's a clicking coming from the passenger side fuse panel though. Recruited the wife to crank it over, so I could isolate which relay was the culprit; it seemed to be the starter solenoid relay. Swapping out each relay didn't yield any success. They all tested good. The only thing I have maybe overlooked us the IMRC controller that came with the used intake manifold; but could that cause no spark or injector pulse?
Try inspecting cable under engine to cps it frequently gets damaged or bad plug/wires may be going to ground.You could also have tone ring damage behind timing cover if broken guides have chewed it up .
I assume you got a new relay for 203.
You don't get spark now? again. The irmc just fools with air turbulence in intake manifold -nothing to do with spark. But the wires going thru that area get tangled in irmc linkage if routed wrong -which is common on intake work.
Tone ring sends pulse thru cps to Pcm it then sends ground pulse to cops .Tone ring has aluminum fingers that stick out and broken guides fall on them acting like a grinder.
If your tach is not moving during crank thats a fail sign of the crank sensor system .
I just re read your post and you did a timing job -sometimes the tone ring is put on backwards ,it is stamped front towards radiator. Sometimes it will run intermittently or not at all . We spotted one that way from pictures op sent when he finished. His did not run at all. I can't find my file on it with pics of the correct way . The teeth face towards the radiator .
Actually it did work. When you swapped the relay the engine fired right up. To me it seems the issue could be with the relay socket, contacts, or solder joints. If you remove and reinstall the relay again will the engine start and run decent?
Try inspecting cable under engine to cps it frequently gets damaged or bad plug/wires may be going to ground.You could also have tone ring damage behind timing cover if broken guides have chewed it up .
I assume you got a new relay for 203.
You don't get spark now? again. The irmc just fools with air turbulence in intake manifold -nothing to do with spark. But the wires going thru that area get tangled in irmc linkage if routed wrong -which is common on intake work.
Tone ring sends pulse thru cps to Pcm it then sends ground pulse to cops .Tone ring has aluminum fingers that stick out and broken guides fall on them acting like a grinder.
If your tach is not moving during crank thats a fail sign of the crank sensor system .
I just re read your post and you did a timing job -sometimes the tone ring is put on backwards ,it is stamped front towards radiator. Sometimes it will run intermittently or not at all . We spotted one that way from pictures op sent when he finished. His did not run at all. I can't find my file on it with pics of the correct way . The teeth face towards the radiator .
Funny you mention the ground(s), I was out checking and cleaning them all morning. I'm almost 100% I put the tone ring in properly, but I can put a meter on the sensor, while she cranks, to verify. Checking the harness is my next step.
The CEL flashes now, while cranking over and the relay "clack" is louder, I'm gonna try that route again. I even had my stethoscope on to check them, yesterday. 🙄
I was referring to a temporary grd short of cps cable possibly disabling it. Your symptoms does lead some of us to question your relay connection socket on the relay 203.Do you think there may be a problem on that power board/socket that is intermittent.
We only mentioned the tone ring to rule it out.
