anyone make a good pip sensor
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Mountain Pass
Joined: Mar 2024
Posts: 114
Likes: 3
anyone make a good pip sensor
1987 f150 5.0
I've gone through 4 or 5 pip sensors 3 in the last month or 2.
I was chasing a low rpm miss for a long time, finally turned out to be a bad pip. bought a new distributor it ran great for a few weeks. It started cutting out for split seconds going down the road, then wouldn't idle for nothing. of coarse I figured idle air controller is going out, which it may still be. then the pip outright died.
put in a brand new pip sensor today bad missing, and wild tach fluctuations sometimes when setting the timing it was all over the place. new sensor is bad out of the box.
Is there any brand of pip sensor for these trucks that's not bad out of the box and is actually reliable.
I've gone through 4 or 5 pip sensors 3 in the last month or 2.
I was chasing a low rpm miss for a long time, finally turned out to be a bad pip. bought a new distributor it ran great for a few weeks. It started cutting out for split seconds going down the road, then wouldn't idle for nothing. of coarse I figured idle air controller is going out, which it may still be. then the pip outright died.
put in a brand new pip sensor today bad missing, and wild tach fluctuations sometimes when setting the timing it was all over the place. new sensor is bad out of the box.
Is there any brand of pip sensor for these trucks that's not bad out of the box and is actually reliable.
Hotshot
Joined: Jul 2020
Posts: 10,565
Likes: 2,674
From: Near Salt Lake City
Are you sure the processor is not the fault?
Check the capacitors inside the ECU of your 1987
Pip sensors (stators) do not control ignition timing, the processor does
Unplugging the spout connector takes the processor out of the timing equation
That does NOT mean it will run well with the spout disconnected if the caps are leaking or exploded
Check the capacitors inside the ECU of your 1987
Pip sensors (stators) do not control ignition timing, the processor does
Unplugging the spout connector takes the processor out of the timing equation
That does NOT mean it will run well with the spout disconnected if the caps are leaking or exploded
Thread Starter
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Mountain Pass
Joined: Mar 2024
Posts: 114
Likes: 3
I've had a couple of bad ecms fail and do some weird stuff. I've got two ecms I have tried them both, doesn't change anything. I blamed the low rpm miss on the ecm, it wasn't the problem before. So now I've got 2 good ecms. I've got something else going on to, but it's had to figure out when it won't half way run right.
Weird thing is it got a bit better after driving a few miles. Even with the spout unplugged the timing jumps around quite a bit.
Weird thing is it got a bit better after driving a few miles. Even with the spout unplugged the timing jumps around quite a bit.
Hotshot
Joined: Jul 2020
Posts: 10,565
Likes: 2,674
From: Near Salt Lake City
The bushings in your distributor may be getting worn and can no longer hold a dwell setting?
Having a spare processor is good, but both may be no good, and have failing injector drivers et, al.
The caps in the processor are just one thing you can inspect visually
87 4.9 is old enough to have bank fire
means bank A and bank B will fire 3 injectors each
I think I would have Noid lights wired into three injectors and watch them for about an hour while having a beer or a few cocktails
Having a spare processor is good, but both may be no good, and have failing injector drivers et, al.
The caps in the processor are just one thing you can inspect visually
87 4.9 is old enough to have bank fire
means bank A and bank B will fire 3 injectors each
I think I would have Noid lights wired into three injectors and watch them for about an hour while having a beer or a few cocktails
Hotshot
Joined: Jun 2015
Posts: 12,885
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I suppose it could still be bad. So much new stuff is bad out of the box.
Tuned
Joined: Apr 2023
Posts: 468
Likes: 67
From: Near SLC Utah
The 87 F-150 should have the TFI module, I would check that out, be weary of the replacement ones. This can cause a whole assortment of problems, but one of these can be a jumping tach.
It sounds like the timing chain could be worn out causing the rough engine running and jumping ignition timing, especially after replacing the distributor. How many miles does the truck have on it? The chain could also be warming up and expanding as you drive tightening up the slack.
I would also check all electrical connections to and from the distributor.
How are you verifying that the PIP is actually dead? The best way to do this is with an oscilloscope.
+1 on the EEC capacitors.
It sounds like the timing chain could be worn out causing the rough engine running and jumping ignition timing, especially after replacing the distributor. How many miles does the truck have on it? The chain could also be warming up and expanding as you drive tightening up the slack.
I would also check all electrical connections to and from the distributor.
How are you verifying that the PIP is actually dead? The best way to do this is with an oscilloscope.
+1 on the EEC capacitors.
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Mountain Pass
Joined: Mar 2024
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The timing chain has no more than 15,000 miles on it I replaced the chain and rolled in main and rod bearings about a year ago. It's a high milage engine causes that wasn't the first chain ever put in it. I'm thinking about 248,000.
As far as how I know there dead, I try a known good module. I have a few spares, if it doesn't change anything I look at the pip a couple just out right died and stoped making a signal at all. The ones that just acted weird, a new one fixed the problem or just acted significantly different and another new one fixed it. It is worth noting I've been through all the wiring more than once, and I do have the icm relocated.
As far as how I know there dead, I try a known good module. I have a few spares, if it doesn't change anything I look at the pip a couple just out right died and stoped making a signal at all. The ones that just acted weird, a new one fixed the problem or just acted significantly different and another new one fixed it. It is worth noting I've been through all the wiring more than once, and I do have the icm relocated.
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Mountain Pass
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The couple that have had tach fluctuations weren't small fluctuations. Locked up in 3rd it was bouncing 300 or more rpm with out any change in speed. And would miss when the tach dropped. Or it completely loose spark for small fractions of a second, the tach just go straight to 0 then come back. That stuff does happen most at lower rpm.
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Tuned
Joined: Apr 2023
Posts: 468
Likes: 67
From: Near SLC Utah
Who makes the modules? 9/10 times if they are not motorcraft they are garbage right out of the gate. The symptoms sure sound like a module is dying. Did you use dielectric grease or heat sink compound on the back of the module.
I went though 5+ modules when I had to fight the infamous TFI-4 system. Only thing that cured it was a new old stock motorcraft TFI and some thermal paste.
I should have clarified, how are you measuring the PIP signal? A MM or a DMM are ok, but an o-scope is really the best tool for the job. This will show you exactly when the PIP has an issue, or if the module has an issue. I got mine on amazon for about $100.
I would also do some resistance measurements on the ignition coil, and the wires.
Another thing, some of the distributor gears are cast, and some are not. I had to swap over my gear because it will eat the camshaft gear. Just something else to think about.
I went though 5+ modules when I had to fight the infamous TFI-4 system. Only thing that cured it was a new old stock motorcraft TFI and some thermal paste.
I should have clarified, how are you measuring the PIP signal? A MM or a DMM are ok, but an o-scope is really the best tool for the job. This will show you exactly when the PIP has an issue, or if the module has an issue. I got mine on amazon for about $100.
I would also do some resistance measurements on the ignition coil, and the wires.
Another thing, some of the distributor gears are cast, and some are not. I had to swap over my gear because it will eat the camshaft gear. Just something else to think about.
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Mountain Pass
Joined: Mar 2024
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I don't have a good way to measure the signal. As much as I would use it I have trouble justifying an osciloscope. I just know if all else is good and changing the module doesn't work, the pip is about all it can be and it has been the problem all but once. I only had one module go bad on its own. The other was killed when a pip went out, it was a new motocraft module I put on to rule out the module.
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Mountain Pass
Joined: Mar 2024
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I will see what it does if I unplug the spout tomorrw. A previous one run good with out the spout and missed a low rpm with it in, it was the pip. The replacement ran great for a few weeks and then started cutting out, and then just out right died. The new one acts different from the last one
Tuned
Joined: Apr 2023
Posts: 468
Likes: 67
From: Near SLC Utah
You can also use a multimeter just measure the pip output to ground and it should be between 3-8.5v AC, although this will just verify the presence of the signal, not actually tell you whats going on.
I got all of these values from the haynes manual and have verified they are accurate.
Even if the signal voltage is present you don't know the actual signal in relation to the rotor vanes and the crankshaft position. So it won't tell you if the PIP is sending out inconsistent signals relative to the crankshaft position, thus causing an erratic timing issue.
I got all of these values from the haynes manual and have verified they are accurate.
Even if the signal voltage is present you don't know the actual signal in relation to the rotor vanes and the crankshaft position. So it won't tell you if the PIP is sending out inconsistent signals relative to the crankshaft position, thus causing an erratic timing issue.
Tuned
Joined: Apr 2023
Posts: 468
Likes: 67
From: Near SLC Utah
Also are you getting any ignition related codes?
If it runs good without the spout, then the spout signal is probably to blame. The TFI during engine starting makes it own timing commands based off of the PIP signal, and ignores the timing commands from the EEC. After the engine starts it uses the timing commands from the EEC, unless the SPOUT connector is unplugged. You can also verify this signal is present with a multi meter, it should measure from 3.0-8.5v AC. Even if this signal is present it can be feeding in bad timing commands.
Another issue is there is a shielding wire that runs around the wires to and from the TFI module, this can rub through the insulation of the wires and cause a short. Although if you have been through the wiring then it may not be the case. Another thing you can check, there is a 22k ohm resistor that goes to the tach and the eec to determine engine speed, this could also be to blame.
If it runs good without the spout, then the spout signal is probably to blame. The TFI during engine starting makes it own timing commands based off of the PIP signal, and ignores the timing commands from the EEC. After the engine starts it uses the timing commands from the EEC, unless the SPOUT connector is unplugged. You can also verify this signal is present with a multi meter, it should measure from 3.0-8.5v AC. Even if this signal is present it can be feeding in bad timing commands.
Another issue is there is a shielding wire that runs around the wires to and from the TFI module, this can rub through the insulation of the wires and cause a short. Although if you have been through the wiring then it may not be the case. Another thing you can check, there is a 22k ohm resistor that goes to the tach and the eec to determine engine speed, this could also be to blame.