Ignition timing all over the place

ttocs

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electronics can play a LOT of silly little games. All it takes is for a clip to break on a harness and suddenly it is not as tight and resistance creeps in and slowly things go awry. It may sound stupid and make you feel stupid right up till you find the problem but don't be afradi to give all the electrical components technical taps. Start the car and just start with your finger tips tapping, work up to the knuckles knocking and don't be afraid to give it a half descent knock as any electrical piece should be able to take this. Look for any changes in how the car sounds or runs while you do this and if it acts differently when you knock on a certain place take a closer look. Next get stupid with your harnesses and give every electrical harness you can see a good push/pull/tug and again see if you notice it runs any different.

Technical taps actually goes all the way back to the vac tube days, and they work.
 

96blak54

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Hell, ive seen tictoc vid of a mechanic describing an ignition problem on a brand new chevy truck that couldnt be figured out. Turns out the computer harness connector had oil in it. He discovered the oil psi sensor broke and was sending oil into the computer signal wire up to the computer
 

RAU03MACH

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I agree!

This may boil down to simple figgiting with mechanical components to find problems.
If he had a star tester he would pin point it
Just by doing the wiggle test
Also I would check the main harness plug and the eec plug to make sure it's not grounding out or shorting out on other wires and body
 

ttocs

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true story - Probably my 2nd month in electronics tech school we were building a circuit in a lab when the kid behind me told the prof that his signal generator wasn't working. Mr Birch was a Big guy and didn't get out of his chair unless he had too so he asked about some of the settings and such to diagnose they had it set up correctly. As he started to get up from behind me I heard two "WACK"'s that I knew was the sound of him smacking it with an open palm before he announced "oh fixed it". Mr Birch got excited to the point of telling us if we were sleeping to wake up, this is important... I was sure he was going to lecture us about not hitting school equipment or something and instead took the opportunity to explain to use the magic of the technical tap.
 

shovel

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The engine in my 94 had its timing all over the place when I first got it running, pretty quickly isolated it as a sloppy timing chain assembly. New timing assembly solved it lickety split.
 

SlowRider

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Any update on your car?

I still have not checked the MAF sensor (can the engine run with a bad MAF?). Meanwhile I discovered that my radiator, water pump and timing chain cover were leaking from their respective gaskets and not holding pressure. So I replaced radiator, water pump and the gaskets. I am not sure if pockets of overheating can cause detonation/pinging. So far I have checked all the grounds, PCM for corrosion/ground, checked plugs/wires, replaced IAC, distributor cap, ignition coil, ICM, HB. I am running 14 degrees BTDC ignition time and with 87 gas it pings under load in any gear. With 93 gas it generally does not ping except when I floor the gas pedal in 5th.
In conclusion the problem is not solved while with 93 the car is drivable. I don't think the problem is from ignition system (I am not sure if I should check the distributor pickup coil). Also, I will change the timing to 10d BTDC and see if the pinging changes with 87/93. I notice that the voltage needle shakes very slightly only while idling. I have checked the alternator and it is fine. Battery is practically new. I don't know if the shaky needle is related to pinging. I do smell unburnt gas while idling. Will leaky fuel injectors cause pinging? Any other thoughts/suggestions?
I have bought a factory troubleshooting manual ($$$), but the sheer size of that thing is quite repulsive...
 

Maximum95

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Wow, quite a bit of work lately! I feel you. There's always something owning older cars!

A couple things...

Yes, I would absolutely suggest returning the base timing to 10° BTDC, as suggested by the underhood sticker.

Besides that, I still have to wonder if the MAF is the culprit. Take a look at this TSB, it will give you a little more insight on MAF function. Our cars are included in the effected models.

 
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The engine in my 94 had its timing all over the place when I first got it running, pretty quickly isolated it as a sloppy timing chain assembly. New timing assembly solved it lickety split.
I mentioned the stretched timing chain as well a year ago in March. Considering the engine has 170.000 miles on it and is cheap to replace the chain with a good cloyes TC, it is cheap insurance, easy to change and it marks off one possible issue of the problem.
 

SlowRider

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Besides that, I still have to wonder if the MAF is the culprit. Take a look at this TSB, it will give you a little more insight on MAF function. Our cars are included in the effected models.


The TSB describes the problem exactly. I did clean the MAF or are they talking about a contamination that can not be cleaned with MAF cleaner?
Anyway, how do I look at Long Term Fuel Trim?
Maximum95, I really appreciate you pointing me to the TSB. I was considering to make my peace with this problem...
 

Maximum95

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The TSB describes the problem exactly. I did clean the MAF or are they talking about a contamination that can not be cleaned with MAF cleaner?
Anyway, how do I look at Long Term Fuel Trim?
Maximum95, I really appreciate you pointing me to the TSB. I was considering to make my peace with this problem...

Absolutely! It would be great to see this issue resolved once and for all.

Yes, you cleaned the MAF correctly, but if the MAF is faulty it may be beyond cleaning.

As far as checking LTFT, I believe you would need a scanner capable of connecting to a Ford OBD-I system. I'm not even sure how to read LTFT on one, since I've only ever done it on an OBD-II system. I wish I could help you more there.

According to the TSB, if you unplug the MAF the car runs in a failsafe mode. Have you tried driving the car with the MAF unplugged? I want to say I forgot to plug in the MAF on my car once and it was able to drive. I'd say give that a shot.
 

SlowRider

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I forgot to ask, is the check engine light on?
No, it is not. I have scanned the PCM multiple time with my OBD I scan tool. But I have not seen any LTFT function in the manual. I need to check. I will run it with the MAF unplugged and see if it does any better.
Also, as far as I know distributor pickup coil is the only other sensor that can contribute to the timing/pinging issue. Worst case I will replace both MAF and the pickup.
 

Maximum95

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The only time I've seen a bad PIP, it caused a no start. With no PIP signal, the ignition will not spark and the injectors will not pulse. I do not think a problem with the PIP would cause the issue you're describing.
 

SlowRider

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I changed the ignition time to 10 deg BTDC and it drives perfectly fine with 93 gas in it. The pinging under load is gone completely. However, during idle it still shakes a little. It feels like momentarily the engine is losing RPM slightly causing the voltage needle to shake a little but it does not cause any noticeable drop in RPM. Also, exhaust smells of unburnt fuel. The can has been having this issue since I got it couple of years ago.

According to the TSB, if you unplug the MAF the car runs in a failsafe mode. Have you tried driving the car with the MAF unplugged? I want to say I forgot to plug in the MAF on my car once and it was able to drive. I'd say give that a shot.

I read that the air fuel ratio is calculated based on MAF and ACT sensor. So I first disconnected the ACT with the MAF connected. The check engine light came on and the car cranked but as it tried to settle down to the idling RPM it died every time I cranked it. Next, I disconnected both the MAF and ACT. The check engine light came on the car was able to settle to the idling RPM and honestly if felt very similar (if not same) as the normal condition with little shake as I mentioned above. I was revving it up with no problem but did not drive it with the MAF and ACT disconnected. I have ordered new MAF and ACT sensor. I will replace them and drive with 87 gas in it. My hope is this will fix the pinging and shake at idling.
 

duh09

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I changed the ignition time to 10 deg BTDC and it drives perfectly fine with 93 gas in it. The pinging under load is gone completely. However, during idle it still shakes a little. It feels like momentarily the engine is losing RPM slightly causing the voltage needle to shake a little but it does not cause any noticeable drop in RPM. Also, exhaust smells of unburnt fuel. The can has been having this issue since I got it couple of years ago.



I read that the air fuel ratio is calculated based on MAF and ACT sensor. So I first disconnected the ACT with the MAF connected. The check engine light came on and the car cranked but as it tried to settle down to the idling RPM it died every time I cranked it. Next, I disconnected both the MAF and ACT. The check engine light came on the car was able to settle to the idling RPM and honestly if felt very similar (if not same) as the normal condition with little shake as I mentioned above. I was revving it up with no problem but did not drive it with the MAF and ACT disconnected. I have ordered new MAF and ACT sensor. I will replace them and drive with 87 gas in it. My hope is this will fix the pinging and shake at idling.

I think it's been asked but going to ask again, what kind of shape is the balancer in? Any possibility that it's slipped and your timing marks are off? Possibly starting to come apart - leading to vibrations?
 

SlowRider

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The HB was changed recently. The old one was also not is bad shape but I changed it anyway.

Gotcha. Yes, good idea. I'm curious to see what the new MAF does.

Well, the new MAF and ACT did absolutely nothing...

If it is not air or ignition then it must be fuel. The fuel pump was changed recently as well. Fuel pressure is fine also. I think it may be the injector(s). I may end up changing all the sensors in this car and hopefully the last one will fix it...
 

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