Ignition timing all over the place

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Just from things I have seen over the years, My guess without being with the car would be Wiring, ECU, or the timing chain just strait wore out AKA stretched. When the chain is stretched you can see timing jumping around due to spring pressure on the camshaft putting tension on the upper sprocket and causing the chain to tighten and loosen. Basically, it's snatching the shit out of the chain.
 

SlowRider

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Just from things I have seen over the years, My guess without being with the car would be Wiring, ECU, or the timing chain just strait wore out AKA stretched. When the chain is stretched you can see timing jumping around due to spring pressure on the camshaft putting tension on the upper sprocket and causing the chain to tighten and loosen. Basically, it's snatching the shit out of the chain.
It's interesting that you mentioned wiring. I have noticed that the voltage needle shakes tiny bit while idling in general and sometimes it shakes a lot. I do not know if/how that is related to the unstable timing. This is with or without the spout connector in. How do I start diagnosing that?
About the timing chain, the car is bone stock with only 24k miles on it with absolutely nothing done on it but regular oil change. I'll look at the timing chain as the last resort. But it definitely can cause such issue, I agree.
 

95opal

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Well, with the spout connector in the PCM should not advance ignition time when the engine is at normal operating temperature and idling. But that is not what is happening with this vehicle.The timing should be just the timing I set at the distributor. instead its jumping around like crazy which is causing the engine to shake while idling. Today I checked the #1 cylinder TDC with HB and distributor alignment as they should be according to the guideline. Actually even with the spout connector out, #1 cylinder spark timing is off sometimes but it is mostly stable at the set timing. In fact it is more stable with some dielectric grease on the distributor cap and rotor connectors. This makes me wonder if the it is because the cap and rotor is not making good contact sometimes and the PCM is trying to correct it making it have even more unstable timing. I checked and the ICM ground is good. I am planning on checking the connections at PCM end as well. Meanwhile I will order new cap and rotor.

The only situation that you will see a rock steady timing is with the spout out. The minute you put the spout back in the PCM will start adjusting even at idle this is why you pull the spout to time the car. Impossible to do with the spout in as it will be constantly moving according to the PCM.
 

ttocs

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I have to agree with opal. I would need to pull up an old data log to show how my holley ecu adjusts timing but at no point short of me telling it to stay at a set timing so I can check it does it stay at any set timing position for long at all. If there are other problems its reading that would explain even more why its all over the place.
 

Ronnied

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Ok before I get a TON of crap, I looked, may have overlooked but I did. Here goes...I need a tuner , I have looked online but feel at this point it would be more beneficial to ask people in the groups and base off of there experience. Please someone direct me. Also one other thing. Cat delete or not? Not an issue in our state and I was looking at replacing from headers back.
 

ttocs

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Ok before I get a TON of crap, I looked, may have overlooked but I did. Here goes...I need a tuner , I have looked online but feel at this point it would be more beneficial to ask people in the groups and base off of there experience. Please someone direct me. Also one other thing. Cat delete or not? Not an issue in our state and I was looking at replacing from headers back.
If you can find a tuner to take your car with the problems at hand it will only get tuned after they diagnose and fix the problems. They hate when they book an appt only to find out that there is some minor problem that keeps them from doing what they have planned. You could check locally and see if any of your local guys are good with 94/95 computers but there are a lot that reject them outright and recommend a stand alone system to replace it.
 

TrickVert

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@Ronnied - If you post your location in your profile, folks might be better able to help with tuner recommendations. As ttocs mentioned, some tuners can't/won't tune with the 94/95 computer, and will tell you you need an A9L swap. If that's the case, find a different one. (And yes, have everything else sorted out before engaging one, or at minimum, tell them about any issues in the initial conversation.)

As for the cats, there's no reason to delete them unless you're trying to eek out every bit of oomph from a high-performance, eleventy-billion-horsepower build. The losses are negligible, and smelling like exhaust after every drive simply wasn't worth it to me. (Does sound nice, though, if you like things louder.)
 

Ronnied

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@Ronnied - If you post your location in your profile, folks might be better able to help with tuner recommendations. As ttocs mentioned, some tuners can't/won't tune with the 94/95 computer, and will tell you you need an A9L swap. If that's the case, find a different one. (And yes, have everything else sorted out before engaging one, or at minimum, tell them about any issues in the initial conversation.)

As for the cats, there's no reason to delete them unless you're trying to eek out every bit of oomph from a high-performance, eleventy-billion-horsepower build. The losses are negligible, and smelling like exhaust after every drive simply wasn't worth it to me. (Does sound nice, though, if you like things louder.)
Thanks for the input. Still learning as I go
I do the research and repost properly as well.
 
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Everybody starts somewhere. :)
No doubt!!!!! I started getting into mechanics heavily in the early 90s. I was lucky to have grown up around drag cars, dirt cars, and pretty much anything that had an engine. One thing that doesn't change in the car game you never stop learning new things EVER. An old man once told me if you don't break or misdiagnose something every once in a while you're not learning!!! You'll not see me judge an up-and-comer hell, not even a 50-year veteran.
 

SlowRider

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I am back to this thread as I continued diagnosing the timing/pinging issue with no success. I have checked all the grounds, PCM, replaced all the ignition components but still the car pings/knocks. However, I have noticed a few things about this issue.
First, jerking of the voltage needle is related to the engine vibrating/jerking during idling. This additional vibration is periodic and in addition to the normal vibration from the engine. I believe somehow there is a misfire although it passes cylinder balance test. This happens with or without the spout connected but more with the spout connected and I believe is causing the timing to be erratic under timing light. Also, the excess vibration goes away at higher rpm.
Second, it seems that this problem is temperature dependent. It pinged a lot during summer (80-90F) under any sort of acceleration with the spout connected. So I took the spout connector out during the summer which makes it ping less and keeps the car drivable. However, as the temperature dropped (50-60F) in last couple of weeks it pings much less even with the spout connector in. Also, pinging/knocking is virtually absent when I drive the car first time in the morning with cold engine. As the engine warms up the pinging/knocking comes back.
During the KOEO test the only code shows up is 564 which is cooling fan circuit related (although the fan runs in low and high speeds during the test) and nothing else. KOER test pass successfully.
I am looking for a powertrain control/emission diagnostic manual for OBD 1 to be able to diagnose this correctly.
It makes me wonder if EGR could be the culprit. Any suggestions/inputs will be much appreciated.
 

Maximum95

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I've done some reading on the subject in the past. There are some major differences between the Fox and SN EEC strategy. The Fox EEC had two timing tables. One for part throttle, and one for WOT. However, (from what I understand) the CBAZA strategy used in the '94-'95 cars has a much wider range of ignition advance capabilities. The MAF reading is used to calculate "load". Once "load" is calculated, the EEC uses it to determine the ignition advance. If I find the source material again, I'll post it here.

That being said, I have to wonder if the MAF has a problem. I read that you cleaned it, but perhaps it needs to be replaced. It is a near 30-year-old sensitive electronic part. Might be a route to explore.
 

TrickVert

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@SlowRider - This may sound like a stupid question, but when you reinstalled the dizzy and wires, is it possible you got a set of wires mixed up? Also, did you make sure that the wrong wires don't run parallel? Spark can jump from one wire to another causing all sorts of headaches.

EDIT: Here are a diagram and photo showing the correct way to avoid crossing spark.

Screenshot_20190505-211339.png

Screenshot_20190325-224536.png

On the same topic, are you using conductive wire separators?
 
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SlowRider

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That being said, I have to wonder if the MAF has a problem. I read that you cleaned it, but perhaps it needs to be replaced. It is a near 30-year-old sensitive electronic part. Might be a route to explore.
I will look at the MAF as well. Is there a way to check MAF without swapping with a known good one? (In this case I have to by one...)
 

Maximum95

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I will look at the MAF as well. Is there a way to check MAF without swapping with a known good one? (In this case I have to by one...)

Here's a quick write up that I found. Maybe go through these steps. Should at least give you an idea if the MAF is working correctly.

 

96blak54

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Simply unplug the maf sensor ,then run the car. If its better, you found the culprit.

Be sure the components in the distributor are good and tight. Try gently by hand to twist and move whatever is inside the distributor just to ensure nothing is loose and playing games with you
 

SlowRider

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Simply unplug the maf sensor ,then run the car. If its better, you found the culprit.

Be sure the components in the distributor are good and tight. Try gently by hand to twist and move whatever is inside the distributor just to ensure nothing is loose and playing games with you
At this point it does seem like something is playing games with me...
 

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