HEI COP 4.6L Ford LTC What gap shoud I use to test spark?

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  #1  
Old 10-08-14, 09:58 AM
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HEI COP 4.6L Ford LTC What gap shoud I use to test spark?

2005 Lincoln Town Car 4.6L engine having Coil On Plug (COP) ignition

I'm getting misfire codes on the entire right (passenger) bank. The entire list of codes minus pending duplicates):
------
PO102 problem with the Mass Air Flow (MAF) sensor or circuit. A more technical description would be that the MAF circuit had lower than expected voltage (air flow).
PO174 an oxygen sensor in bank 2 detected a lean condition (too much oxygen in the exhaust)

PO351 an open or a short is detected in the driver circuit for coil number 1
PO352 an open or a short is detected in the driver circuit for coil number 2
PO353 an open or a short is detected in the driver circuit for coil number 3
PO354 an open or a short is detected in the driver circuit for coil number 4

P2106 Ford - Throttle Actuator Control System - Forced Limited Power P2106 Ford Throttle Actuator Control System - Forced Limited Power OBDII Engine Light Trouble Code | Engine-Codes.com
P2195 Lack of HO2S-11 Switch Sensor Indicates Lean
-----
I have another thread if you want some history.
At this point I'm determining the cause of the failing-to-fire on the right bank cylinders. I've determined the always-hot wire to the plug COP is indeed hot, and the other wire is getting an AC (grounding & un-grounding) to the + battery.
Thus, my next test is to see if the COPs themselves are good or bad, and I need to test for spark. I don't have a scope nor a timing light, so I tried to locally buy a tester for HEI ignition which is recommended.But I couldn't find one and was only able to get one with an adjustable gap.
It seems I should be able to use this tester if a set the gap properly. The engine require a gap of .054 to .056 inches, but that's in the combustion chamber.
What gap should I set this tester for to test COP HEI spark?
 
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  #2  
Old 10-08-14, 12:09 PM
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Welcome to the forums Nehmo,

I'm not knowledgeable with that HEI ignition of yours (or much of anything else for that matter). However, I would test the gap at .054-.056 and then maybe a bit narrower and then a hair wider than those figures (a slightly narrower gap might be used to simulate and "in cylinder" condition w/ a proper fuel/air ratio).

Anyway, you probably already know this but, you might want to double check the grounds on those circuits and particularly the eng. grounds (there's usually more than 2 of these main grounds on modern engines).

Hopefully someone with more knowledge on this engine/HEI system will chime in shortly.

Good luck!
 
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Old 10-08-14, 01:48 PM
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I think that at this point you should ignore all codes other than the PO351 - PO354. Once you figure that out, I would reset the ECM and see which codes recur.

You "could" take the air cleaner apart and spray some MAF sensor cleaner on the sensor, but don't touch it. A can of cleaner is cheap and could/should be done anyway every time you change the oil or check the air cleaner.

My Ford truck doesn't have COP, but here is what the manual suggests for engines that do. If you don't have a good digital electrical tester, get one.

8). With the ignition off, disconnect the electrical connector(s) from each coil assembly. Connect an ohmmeter across the coil primary terminal (+) and the negative terminal (-). The resistance should be as listed, if not replace the coil.

Primary resistance: 0.55 ohms

9). Remove the COP assembly from the cylinder head. Connect an ohmmeter between the secondary terminals (the one that fits over the spark plug). The resistance should be as listed.

Secondary resistance:: 5,500 ohms



If they all check out, I would head to a junk yard and try a different ECM.
 
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Old 10-08-14, 07:46 PM
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how does it seem to run? but gap should be tested at double spec.
 
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Old 10-09-14, 02:19 AM
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So far, the results are depressing. I only checked one failing cylinder's COP (#2), by using the adjustable gap tester, and simply using the regular gap of an installed plug, I got a good spark.

Regarding testing the resistance of the windings in the COP, I believe the "primary" isn't directly accessible because the internal COP wiring diagram I saw shows the wires going in to go to the base circuit of a transistor. But I tested the COP anyway and I got readings roughly like the ones you, XSleeper, reported.

I agree in that the first order of business is to address the misfire problem. The other things certainly can wait, and I'm not sure they even affect driveability.
 
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Old 10-09-14, 06:18 AM
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Here are a couple illustrations (copywrite Haynes North America Inc) that might clear things up.

Primary... disconnect the "electrical connector" to the COP and test the terminals that the electrical connector would fit over.

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Secondary... remove the COP and test resistance between secondary terminals.

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Old 10-09-14, 06:30 AM
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"If they all check out, I would head to a junk yard and try a different ECM."

Not necessarily, I have had to replace all the coils in my 5.4 twice now and BOTH times I did the testing called for and every one of the coils passed the tests. By replacing all of them I fixed the miss/rough run issue. Now I have 16 used coils and still have no idea which of them is weak or bad.
 
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Old 10-09-14, 06:37 AM
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If the COP is removed for testing, prior to reinstalling the COP into the cylinder head, coat the entire interior of the assembly with silicone dielectric compound.
 
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Old 10-09-14, 09:40 AM
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[ATTACH=CONFIG]39709[/ATTACH]
This pic is from the Chilton Library which I got via using my county library's access (using my library card # over the web) . As you can see, according to the pic, the "primary" circuit is for the base of the transistor. And since the COP doesn't have an obvious ground connection, it would be hard to directly access the windings of the transformer. However, I'm not certain this diagram is correct. In most other representations (including the other wiring diagram in Chilton), the 2 pins of the COP go directly to a primary winding.
The secondary windings are problematic too. I really don't understand what that guy is hooking up to in the bottom Haynes pic. One wire of the secondary is obviously the plug wire, which is a short spring in this case. The other must be the ground.
In any case, I'll go test again. This time I'm going to switch around the COPs from the good cylinders to the bad and then get OBD codes.
The truth is out there.
 
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  #10  
Old 10-09-14, 03:00 PM
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I just swapped one of the COPs from a non-functioning cylinder with one from a functioning cylinder. There was no change in either test: testing for engine sound change by disconnecting a COP electrical connector - the COP in the previously bad cylinder now functioned in the previously good cylinder; testing via the code reader, there was no change in the OBD codes - no new pending code. Good cylinders remained good, and bad ones remained bad.
Thus, the COPs (probably all, but definitely the one swapped) are OK. It's something else. I suppose the next test is a compression and vacuum test. (I don't have those testers yet.) But actually, I thought the codes displayed showed something wrong in the COP circuit. That doesn't seem to be the case.

Oh, yeah. Thanks for the help, gang. I mean it.
 
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Old 10-09-14, 03:24 PM
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You do know that you have to clear the stored codes to see if you've made any real changes, right? And codes often don't show up until the ECM has fully performed all it's testing... after you've driven X amount of miles in all types of driving conditions. So just swapping the COP and starting the car and letting it idle won't necessarily prove anything.

If you haven't already, I would clear the codes, and see which ones (if any) recur immediately. That would be a clue to a starting point in diagnosing any potential code problems. If the codes have "never" been cleared you could have 10 years worth of code data there. Codes don't disappear when you fix the problem, you have to clear the codes from the computer. Not sure how much of that you already know...

Compression and vacuum tests are meaningless if you really have an ignition problem.
 
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Old 10-11-14, 12:11 PM
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As I mentioned before, this is the first time I've used a On Board Diagnostic code reader.. Although the current system, OBD II, was mandatory for vehicles made in the US in 1996, I didn't get acquainted until now because I, being of the used car class, had always dealt with older vehicles. But I'm learning now.

Thank you XSleeper.

I didn't realize you needed to clear codes before getting a good new reading. Apparently, a condition noted by the reader is "pending" until after existing for a pre-set number of drive cycles, then it matures into a "code". Different conditions and models of vehicles have different pre-set numbers of cycles.
Anyway, I erased the existing codes. I played around with the connector on COP #2. I cleaned the MAF sensor. I then started the engine, and read the codes. Now I'm getting 3 pending codes:

PO102 pending - problem with the Mass Air Flow (MAF) sensor or circuit.
PO315 pending - an open or a short is detected in the driver circuit for coil #1
PO106 pending - MAP/Barometric Pressure Circuit Range/Performance Problem

I also bought a vacuum gauge and tested the intake manifold vacuum. It seemed steady enough at 14 inches Hg. This is perhaps a bit lower than the suggested 15-22, but I'm not sure one inch is significant.

I also squirted starter fluid all over the place to try to find a vacuum leak. I didn't find anything.

I'm going to play around with the engine some. I'll concentrate on COP #1 to see if there is a signal (on & off ground), a good + battery connection, and I'll test for spark.

I'll re-tighten the intake manifold bolts. As some of you know, I just replaced that. I'm sure I torqued the bolts properly, 19 Ft-Lbs (26 N-m), but who knows? I'll re-torque them.

I welcome suggestions. Basically, it idles bad and doesn't have power. I think it's missing, but I'll double check that.
 
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Old 10-11-14, 12:30 PM
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Ok thats what I wondered. if you unplug a cop (or anything else) while the engine is running its going to record a code.
 
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Old 10-11-14, 12:38 PM
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The vacuum is pretty low. Hose leaks can sometimes be hard to locate. I would retest coil 1, primary and secondary, with the ohmmeter.

MAF code is most important thing that controls the engine performance so you might clean it again and reset codes. Reset them as often as you like but realize that the car will have to reset its drive cycle to give you a complete idea of any major code problems.
 
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Old 10-13-14, 09:34 AM
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I disconnected & reconnected a bunch of stuff, and I erased the codes again. Now, I get, with a warmed-up engine (the last reading was from a cold engine), 16 inches Hg vacuum, which is in range. And I get no codes. However, the idle is still rough, and if I put it in gear, and I press on the accelerator pedal, the engine will die. If I accelerate while under no load (gear-shift in Park), the engine revs up.
I'm not sure what my next step is. Ideas?
 
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Old 10-13-14, 10:24 AM
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When you clear codes you need to drive the vehicle through a wide range of conditions over a period of time before the PCM has completed all of its tests... which means actually taking the vehicle on a test drive, not necessarily just starting it at idle.

Can't really give you much advice... maybe someone else has some ideas. Even though the vacuum is within range it seems low to me.

When you look at your OBD-II scanner "live data", what are your bank1 and bank2 fuel trims at idle?
 
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Old 10-13-14, 11:03 AM
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I went the economy route with the scanner, PocketScan Code Reader CP9125, and it doesn't display live codes.
I'm worried about taking it for a spin. I barely can make it out of the yard, and towing it back is going to be another problem.
If someone told me a car was dying under load, I would suspect a fuel delivery problem, but in this car, I just replaced the fuel pump and filter. (A bad new pump? I suppose I could check the pressure.)
Searching on the subject found people suggesting a blocked catalytic converter. I just don't believe that one. I suppose I could remove the O2 sensor to test it.
I haven't done a compression test yet either. I'd have to buy/borrow a tester for that.
But really, I'm at a loss for now, but there must be an answer.
 
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Old 10-13-14, 11:24 AM
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Well, one thing you probably have the tools to check is the MAF sensor voltage.

Not sure if your connector is the same as mine but it has 4 terminals. b+, PCM power ground, SIG (+) and GND (-). With key on, engine off, disconnect the electrical connector and probe the terminals on the harness side. There should be 12V present when you probe between B+ and ground.

Then reconnect the connector and backprobe the MAF SIG (+) and GND (-) terminals. (Backprobing is when you stab a t-pin or wire... or a straightened paperclip works well... next to the wire you want to probe, but into the back side of the terminal so that it makes contact with the wire without damaging it). Be sure your backprobed wires don't touch each other! A pair of small alligator clips will help hold your probes, if needed. Start the engine and check the voltage. It should be 0.2 V to 1.5 V at idle. If you manually operate the throttle from the engine compartment, the signal voltage should increase to about 2V as more air passes by the MAF sensor.

If anything there doesn't check out, I'd wonder about the MAF sensor itself. Like I mentioned, its pretty important and if it's screwed up it would royally screw up the way the engine responds to the snap of the throttle. When you snap the throttle the MAF should be immediately telling the PCM that it needs more fuel.

One other thing you might check if you can... while you have the vacuum gauge attached... (you are checking it directly off the intake manifold, right?) disconnect some of the main vacuum hoses that originate from the intake manifold... (vacuum will drop) and then quickly plug them with your finger. (vacuum should return back to the same reading. If it somehow goes up 1 lb or so... it might be a clue to a vacuum leak) If you have a brake booster, that would be a good one to eliminate. If a brake booster is leaking vacuum that would be hard to detect, and your foot would be on the brake when you put the car into gear. Just a thought.
 
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Old 10-13-14, 07:05 PM
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sorry dude but 16 inches of vacuum on this eninge is bad news. i would bet your chain has jumped time on that bank. you should get 20-22 at 700 rpm.
 
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Old 10-14-14, 06:56 AM
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I'm worried about taking it for a spin. I barely can make it out of the yard, and towing it back is going to be another problem.
I wouldn't drive it with the way it's running. Doing so can ruin the catalytic converter(S).
 
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Old 10-14-14, 05:22 PM
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I'd wonder about the MAF sensor itself.
I don't have a compression tester handy, but it's beginning to look like one's needed. I'm not sure, though. I don't think I'm getting the tailpipe smoke characteristic of bad rings.

The place where I'm attaching the vacuum gauge hose is where the power brake normally attaches, so the PB system is not even attached while I'm checking engine vacuum.

I'm investigating the (MAF) mass air flow sensor. .
Maybe I can test it.

easyautodiagnostics.com seems convinced Ford uses the hot wire MAF (although the 4.6L engine isn't listed there). I do have 6 wires and the circuit diagram agrees. I suspect the Powertrain Control Module (PCM) supplies a 5+ reference on one of the wires. I already cleaned it once. I'm did that again for GPs. Now I'll try to test it electrically.
I use a sewing needle to probe the wires. The damage is limited.
The GY gray and the GY/RD gray/red look like the temperature sensor.
So far, I've determined I'm getting a good 12+ at the RD (red) wire. Big deal.
The BK/WT black/white should be ground.
I wonder what MAF RIN means on the schematic? Mass Air Flow Reference In? If so, maybe that should be 5V.
 
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Old 10-14-14, 07:24 PM
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thats maf RTN, return signal. should be around 1v at idle. the maf is 5v
 
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Old 10-19-14, 02:00 PM
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I was able to find a few places
How to Test the Ford Mass Air Flow (MAF) Sensor, test 4
2vid vid Ford MAF Sensor Testing, Ground & Signal
MAF Sensor & Wiring Diagrams that seemingly explained how to test a Mass Air Flow MAF sensor, even a Ford one, but I didn't find instructions on my specific one [ATTACH=CONFIG]40323[/ATTACH]
According to troubleshootmyvehicle, for a 1999 Ford 4.6L (mine is a 2005 4.6L),[ATTACH=CONFIG]40334[/ATTACH]
Tan/light blue - MAF ground (labeled MAFRT, return, apparently, on wire diagram)
Light blue/red - MAF signal (labeled MAF on wire diagram)

I conducted the tests insofar as I understood them.
The hot red test good.
The BL/WT is a good ground.
The TN/LBlu is also a good ground as it should be. There are 2 grounds here.
Now the LB/RD, labeled MAF signal (and just MAF on the wire diagram) is 1.2 V at idle and when the engine is revved up (don't have RPM meter), I get maybe 2.6 V. This an increase alright, and the increase is repeatable, but is that enough? The last vid linked to above says a small increase is correct. (In that example it goes from 1V to 1.8V.) But I had the impression that the voltage increase should be more. IDK.
I'm beginning to think I need to look elsewhere for the source of the problem. I suppose the fuel rail pressure temperature sensor is next. Suggestions?
 
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  #24  
Old 10-19-14, 07:41 PM
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The MAF sounds like it checks out as ok. As iceman said it could be timing. Your fuel pressure is probably not the issue since it idles and runs well at higher rpms. Without having more to go on its pretty hard to say what to check. We can't hear it run or smell the exhaust or any of that.
 
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Old 10-20-14, 12:33 PM
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[QUOTE XSleeper]The MAF sounds like it checks out as ok...could be timing...Without having more to go on its pretty hard[/QUOTE]

My best info on the MAF is http://www.motor.com/magazine/pdfs/072006_04.pdf which doesn't give actual test procedures but explains theory somewhat. Sam Bell, the author, says misdiagnosis is common because, for one thing, the MAF sensor can fail in both directions:
"The foremost clue
that the fault lies with the MAF sensor
itself will be excessive fuel trim correc-
tions, usually negative at idle, more or
less normal in midrange operation and
positive under high load conditions"

"Why is this a hard diagnosis? Conta-
minated MAF sensors often
overreport
airflow at idle (re-
sulting in a rich condition and
negative fuel trim corrections)
while
underreporting
airflow
under load (resulting in a lean
condition and positive fuel
trim corrections)."

I don't suspect valve timing because the engine is a single overhead cam, and a timing belt slip would affect all cylinders, and the engine doesn't sound anything like others I've dealt with having that problem.

The hesitancy I have of dismissing the MAF sensor as faulty (despite apparently passing the voltage test) is that the symptoms are similar to what other people reported when that was the problem. The main issue is
Lack of power.
In idle, I can gun the engine, and it revs up. But when I try driving with just a bit of load, negotiating up a 3 inch brick in the drive path, the engine will die.
Now here's another clue: When the engine is cold, it starts with fairly easily. But once it warms up, it is difficult or not possible to start.

Sam Bell emphasizes two precautions prior to a good MAF test, check for vacuum leaks, and make sure the PCV valve is good.

Shaking the PCV valve gives me a good rattle. That's the only way I know to test those things - other than a replacement.

The exhaust looks normal. Both pipes seem produce about the same looking smoke too.
 
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Old 10-20-14, 07:14 PM
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i am still with the timing, the maf will affect all cylinders not just one bank. as it measures air for the engine as a whole. you said your vacuum was at 16 in of vacuum. thats low. its very possible and i have seen it where the "chain" jumps time on one cam affecting only one bank. Name:  th.jpg
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Size:  14.2 KB there is two chains on this engine making it very possible.
 
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Old 10-21-14, 12:12 AM
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You're right, iceman681, although I've been working on this 4.6L (which is a V) for weeks, somehow, when I was writing the post, I had a different engine in mind, a totally different one.
 
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Old 10-22-14, 09:15 AM
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I realize you can check for a timing chain jump by removing the timing cover (and everything atop), and inspecting the marks. [ATTACH=CONFIG]40508[/ATTACH]This Autozone guide seems right. But is there any way without going through all that?
 
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Old 10-22-14, 08:10 PM
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there are ways to put the crank at tdc but none i know of with out taking the valve covers off to know about the cams.
 
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Old 10-22-14, 09:07 PM
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Ok, so for the sake of argument, I'm going to ignore the low vacuum for a moment, and let's assume that many of the codes you mentioned in your very first post were caused because of unplugging components while the engine was running.

The code that stands out to me as being a primary suspect that might cause the engine to die when you put it in gear would be the P2106 since that's basically saying the engine is in limp mode, it will be rough running.

But since you have cleared the codes, no codes have recurred? I would start it up and try and at least take it around the block. Until the PCM relearns fuel ratios and such, its going to be a little rough running either way.
 
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Old 10-23-14, 05:39 PM
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[QUOTE iceman681]there are ways to put the crank at tdc but none i know of with out taking the valve covers off to know about the cams.[/QUOTE]

I'm sure I could find Top Dead Center TDC on a cylinder by using a plastic straw inserted into the spark plug hole and then rotating the crankshaft slowly while watching the straw rise to its maximum. And with the valve cover off, I could estimate the cam (for a particular valve) position. But I wouldn't be able to read position well enough to detect a one cog jump in a chain.

I suspect, if one bank of the engine has jumped valve timing, doing a cylinder compression check would show a different result from one bank compared to the other. In the timing-jumped bank, the valves wouldn't be in proper synchronization with the crankshaft. I'm not sure if a one cog jump is detectable via this method, though. But the test wouldn't hurt, and I can get a compression tester for under $50 USD. (And yes, I could borrow with deposit too, I know.)

[QUOTE XSleeper]...no codes have recurred? I would start it up and try and at least take it around the block.[/QUOTE]

Previously I cleared the codes, and then after experimentally running the engine a bit, I got 2 pending codes:
pending PO183 - Ford - Engine Fuel Temperature Sensor 'A' Circuit High Input

pending PO193 - Ford- Fuel Rail Pressure Sensor Circuit High Input

I cleared the codes again. Now after starting once, I get one pending code:
pending P0106 MAP/Barometric Pressure Circuit Range/Performance Problem

The engine doesn't have a MAP; it uses a MAF sensor.
 
  #32  
Old 10-23-14, 08:16 PM
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i would say with a compression tester you can be 90% sure if cam has jumped on one bank. my thoughts are that if one side is off bad enough to cause all these running issues then the compression has to be way lower. i would almost bet if the timing is off you will see at least 40 psi difference.
 
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