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post head rebuild indications of something not quite right; black, sooty spark plugs, poor mpg
Topic Started: Jul 17 2012, 07:39 PM (2,186 Views)
jaevans
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I hate trying to decypher nested quotes.
Edited by jaevans, Jul 20 2012, 07:06 PM.
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jaevans
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Bad Bent
Jul 20 2012, 02:18 PM
jaevans
Jul 18 2012, 08:43 PM
blue rhino
Jul 17 2012, 09:01 PM
Is the check engine light on? Theres a difference between black sooty plugs and oil fouled plugs. Black sooty plugs usually indicate a rich running condition.
No check engine light but I am not sure it is even functioning.
The check engine light will come on as you start the engine. The second key position: right after "accessories." :-/
Well, the check engine light "will" come on in the accessories position of the ignition switch "if" there is a bulb and it is wired and the wiring is good. I'm not seeing the light light in the accessories position so I need to fix that to get data.
Edited by jaevans, Jul 20 2012, 04:31 PM.
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jaevans
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Update - I pulled the instrument cluster to check the MIL (CEL) light. The far right bulb compartment had spots for two bulbs (are they both CEL positions?) with only one bulb in one slot and it was bad. I located two good bulbs and populated both slots. Now, at the accessory position of the ignition switch, I get a steady CEL. :banana

Jumpering the diagnostic position in the junction box and turning to accessory displays one code - DTC 46. Keep in mind this is a 90 body with 94 engine and upgraded emissions (re: 6E2-A2 in the FSM), wiring harness, and I assume ECM, etc. According to the FSM, DTC 46 indicates an issue with the Idle Speed Control (ISC) motor circuit, so I will be following next the troubleshooting chart for it next. I did notice something odd while driving yesterday. While at a light early in the morning and 10 miles of driving, the idle would cycle form 1500 up to 2000 and then repeat every couple of seconds. On the trip home, it went away. Also, today after topping the tank off, the metro was hard to start while warm, but I had put the timing back to 0 degrees TDC. I may back off that and see if there is a difference. I may also reset the ECM and see if DTC 46 goes away, suspecting it is an indication of trouble starting when warm.

Data is good, though I'm not sure if this has anything to do with poor mpg. :hmm
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Bad Bent
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Facetious Educated Donkey

Zero (0) TDC ignition timing is one reason for poor performance and fuel mileage.

I don't see an OBD code 46 in my 1991 FSM or the Check Engine Light Guide. My 1996 FSM has a 6E2-A2 section but OBDII codes.

However there may be a vacuum leak in the ISC circuit causing the 1500-2000 rpm swing. Usually a high base rpm is where the previous owner adjusted the Idle Stop Screw or something they shouldn't have. :shake
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jaevans
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Jul 23 2012, 01:38 PM
Zero (0) TDC ignition timing is one reason for poor performance and fuel mileage.
I don't see an OBD code 46 <snip>
However there may be a vacuum leak in the ISC circuit causing the 1500-2000 rpm swing. Usually a high base rpm is where the previous owner adjusted the Idle Stop Screw or something they shouldn't have. :shake
Hey, Bad, how goes it?

DTC-46 is for the upgraded emissions available beginning in the 94 model (Frankie has a 90 body with a 94 engine with the upgraded emissions - and the cluster, wiring harness, ECM, etc that goes with it). Not sure when the OBDII stuff came out in the Metros. I don't think the idle stop screw was tweaked on this - I only occasionally get the hi rpm swing, otherwise it is around 900 and my tach dial could be off - I know my gas needle certainly reads a smidgen low. It is just noticeable when I see that hi swing. I do plan to check and replace vacuum hoses - it is on my list. Oh, and I'm off of 0 degrees TDC now, probably around 5 degrees advanced. 0 TDC was not the only reason for poor mpg, but I wanted to try that setting as that is where the PO had it. I was getting 45 mpg consistently before.

Thanks for the pointers.
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Bad Bent
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Facetious Educated Donkey

I'm doing OK, thanks for asking.

"0 TDC was not the only reason for poor mpg, but I wanted to try that setting as that is where the PO had it. I was getting 45 mpg consistently before." Well, I know one tooth is 18 deg. of rotation. Have you gone back and checked the timing belt? Maybe the PO had the belt off one tooth and so 0 would/could be advanced. :dunno Has your setting at 5 deg. BTDC rotated the distributor really close to the end of the adjusting slot/firewall?
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jaevans
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Jul 24 2012, 12:44 PM
Well, I know one tooth is 18 deg. of rotation. Have you gone back and checked the timing belt? Maybe the PO had the belt off one tooth and so 0 would/could be advanced. :dunno Has your setting at 5 deg. BTDC rotated the distributor really close to the end of the adjusting slot/firewall?
Well, progress of a sort tonight. I decided to test the coolant temp sensor on the input and was able to see a varying resistance as the engine warmed up - I think it was probably at air temp here which was 90 degrees F and the resistance started out at about 950 ohms and dropped from there down to about 450 ohms or so at normal operating temp - this with the harness connector off so I was just measuring sensor resistance. It did seem to give me some weird readings in the middle at times - it would read as open or infinite resistance but that could be due to vibrations of a flaky alligator clip connection to the connector housing pins. I also got a definite CEL when the connector was off and afterwards a read of the DTC showed a 14.

Anyway, when I connected it back up, the idle changed - it dropped significantly to the point where I couldn't even keep it idling and the engine ran somewhat rougher (I could get this to repeat by removing the connector and reconnecting). When I attempted to put a load on the engine (simply backing out of the garage) the rpm's would drop to almost nothing and there was no power at all, to the point where I had to nurse it to get it back into the garage. No power whatsoever and running rougher. But, no more black sooty carbon on the spark plugs, so I am onto the rich fuel issue.

So, I agree - I need to go back and check my timing (I'll leave the cover off until I get it going right this time) and see if that makes a difference, though 5 degrees BTDC wasn't close to the end before. I didn't check timing because I had to nurse the throttle just to keep it near idle speed.

I cleared the DTC's from the ECM and will see if anymore accumulate. I had just the 46 prior which may or may not have been an issue. I will also check my wiring to the coolant temp connector and and if I can locate a new temp sensor, I'll install that as well. Hopefully, I can pop the pins on the harness connector and extend the wires some to reduce stress on the wire and connector.

I seem to recall there are supposed to be 35 teeth? between timing marks when cam and drive sprockets are at 3 PM, correct? Regardless of the number, I recall having difficulty counting teeth. Do I want the teeth count on the belt for those teeth between teeth on the sprockets? I thought I had set it correctly by the marks (versus teeth count) and 2-3 rotations of the belt resulted in the marks still lining up. Anyway, I'll try that again.

Thanks,
John
Edited by jaevans, Jul 24 2012, 09:32 PM.
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Bad Bent
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Facetious Educated Donkey

I didn't do the teeth count. I did have the valve springs move the cam a little and throw it off one tooth. If you have eliminated all other factors then try changing the setting one tooth. Advance it one tooth and test drive it. I know it is a long process if you put the belt back on and test drive but it's worth it to eliminate this problem. Adn do it regardless of the marks.
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Woodie
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No point in counting the teeth, there's nothing you could do about it anyway. Number of teeth between the two sprockets is determined by how far apart the sprockets are. The only way that could change is by adding or removing metal to make the engine taller or shorter.

Put a drinking straw down the #1 plug hole and turn the engine over until it's at the absolute highest point. Check your timing mark to make sure it points to 0°, this verifies that the crankshaft key has not sheared. Then check the cam sprocket mark to ensure that it lines up with the V in the valve cover flange. This checks the timing belt timing. Then, if your ignition timing is set to 5°, the distributor should be about in the middle of the slot.
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jaevans
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Quick question. I just want to verify that everything is lined up as it should be before I go one tooth fore and aft. First, when I look through the oil port on the top right of the cam cover, I see a cam that seems to be pointing back toward the firewall. Is that correct?

Also, the drive sprocket is aligned correctly for TDC as verified through the spark plug hole of cylinder one via a straw. However, I notice that the alignment mark on the pulley is NOT aligned with the key on the pulley. It is somewhat behind actual TDC. Is that normal ? I ended up marking actual TDC so I can get a visual when I adjust the timing belt. I'll post pix in a bit. Taking a break before I try to move a tooth each way.

Thanks,
John
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jaevans
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Photos as promised.

Crank sprocket at TDC.
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Cam sprokcet aligned with cover.
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Cam view.
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Crank sprocket with added mark aligned with key.
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I'll take a shot later on with the original pulley mark (solid with etched line) and the mark I added to indicate how the sprocket/pulley should be aligned for TDC (dotted line).

John

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jaevans
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crank sprockets marked lined up. The dotted line is right in line with the key on the pulley and the tick mark on the crank sprocket.
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cam sprocket lined up on the mark. At this setting, I get no power, I can't rev past about 4k rpms, the distributor is centered in the range, and it won't hold idle.
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cam sprocket at plus one tooth. At this setting, I get no power, idle is fair, it revs up to a decent amount, and the distributor is set max to the firewall.
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cam sprocket at minus one tooth. At this setting, I get no power, poor idle, it revs up and gives a throaty sound, and the distributor is mid-range.
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cam sprocket at plus two teeth. At this setting, I get poor idle, a very throaty sound, and the distributor is set to mid range.
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In all these, if I disconnect the coolant temp sensor at the input, I seem to get a lot more power and the idle is more normal. I think before I proceed I need to replace the sensor and see if it yields different results. Your thoughts?

Thanks - John

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jaevans
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I am so red-faced. :banghead You can't tell in the previous photos, but the hose to the MAP sensor was kinked and cut off. I am certain I kinked it when pulling the manifold up and out of the way to do the head gasket replacement and didn't check for nice smooth curves after putting it back together. Anyway, I unkinked it and now the timing works, right on the alignment as recommended, there is power to the engine, no black, sooty spark plugs, the engine sounds like it did before, drives like it did before, and hopefully, the mpg will be back where it should be.

Current photo:
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Here's the photo where it is kinked, though you can't see the kink from this view:
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Now I can get back to fixing the little things while driving it, then the 93 XFi will come in for a rebuild.

Sorry for the confusion, misdirection, and craziness. You guys have been helpful and gracious in trying to save me from myself.

John
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