Can someone help read these spark plugs for me?
04-02-2010, 07:21 PM
#1
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Can someone help read these spark plugs for me? From my experience with carbed engines, these look a little lean but I know FI can go tighter tolerances and be safe but I just can't tell.
I hope these pictures are sufficient, thanks very much.
Brady
I hope these pictures are sufficient, thanks very much.
Brady
04-02-2010, 08:42 PM
#2
Well, how many miles? what plug is it? LT1? I'm guessing? I see champion but I don't know anyone that still runs those. It looks as if the heat range is off by a bit. The only way to tell if it is lean is to acually run a 2nd or 3rd gear pull and shut it off after the pull. Google how to read spark plugs. I found several great articles about what everything means. Don't look at the ceramic color, it has nothing to do with reading them if you didn't do a load run. If you look at the ground strap this is what I think tells you the heat range. Yours look to have the color blend way down almost to the threads and it should be just up after the bend on the top side somewhere.
04-02-2010, 09:12 PM
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Sorry, should have given more info.
'94 TA. About 1500 miles on the plugs.
I'm having am issue of the car "resisting" throttle as I apply it. It feels like a cylinder drops in and out after half throttle (or knock retard). I'm going to check fpr and injectors as soon as I can. It just dawned on me that it could be fuel starvation issues.
'94 TA. About 1500 miles on the plugs.
I'm having am issue of the car "resisting" throttle as I apply it. It feels like a cylinder drops in and out after half throttle (or knock retard). I'm going to check fpr and injectors as soon as I can. It just dawned on me that it could be fuel starvation issues.
04-02-2010, 10:35 PM
#5
It could be starvation so throw a gage on it and test it at idle with vac line on, record the reading. Now with the car at idle pull the vac line and record that reading. If it looks ok say between 42 to 49 with the vac line off then drive it with the vac line on and watch the gage. Under throttle the negitive vac in the manifold will drop and cause the pressure to raise (just like pulling the vac line. If you get on it and see it raise pressure and then fall while under still under full load you have a supply problem at the regulator, pump or fuel filter. The tests with pulling the vac line will tell you if the regulator is working properly. This is the easiest way to eliminate these parts. Then it is off to the injectors and sensors.
04-02-2010, 10:39 PM
#6
By the way what is the plug number? There are multiple plugs that will fit these engines but getting one with the right heat range is critical to not cause an extra hot combustion chamber. To hot can cause all kinds of problems and damage. To hot of a plug can cause preignition and force the pcm to retard the timing causeing loss of power. The pcm adjusts for this but not enough to save wear on valves, pistons, ect.
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04-03-2010, 02:16 AM
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It could be starvation so throw a gage on it and test it at idle with vac line on, record the reading. Now with the car at idle pull the vac line and record that reading. If it looks ok say between 42 to 49 with the vac line off then drive it with the vac line on and watch the gage. Under throttle the negitive vac in the manifold will drop and cause the pressure to raise (just like pulling the vac line. If you get on it and see it raise pressure and then fall while under still under full load you have a supply problem at the regulator, pump or fuel filter. The tests with pulling the vac line will tell you if the regulator is working properly. This is the easiest way to eliminate these parts. Then it is off to the injectors and sensors.
I think I'm following what you're saying in order to test the FPR, but I'm not positive.. (maybe it's the cap'n and coke.
was a good night at the club). I'll read this again in the morning and do my best to follow what you're saying but if you can elaborate just a bit, I'd appreciate it.Let'sRun. Gapped at .050
Wicked. Yeah, shitty pic, sorry. When you say, "Cut the plug", what do you mean?
I tossed the plugs so I can't get a better pic of the electrode.
I'm going to go back to the shop tomorrow (later today) and I'll try to wrap my head around how to test the FPR and see if I can't get some good readings on that.
Thanks very much for all the help and suggestions so far.
-brady
04-03-2010, 07:50 AM
#9
Its going to be very difficult to read these with this picture. You need to get close up of one plug and cut the threads off of it or a magnifying light to see down at the bottom.
It does look like your timing mark is way too far around the bend on the strap though.
It does look like your timing mark is way too far around the bend on the strap though.
04-03-2010, 08:46 AM
#10
If there is a possible problem don't throw them away next time. What everyone wants to see is a very detailed pic of the top of the plug to see the ground strap and a couple of pics from the side view to see the other side of the ground strap and electrode tip and under side of the ground strap. In the future always keep your plugs untill the next change for referance. Or at least untill you know they are fine. To be honest when you pull them they should look like they have been barley used if your runing a stock engine, and only slightley more wear if it's modded.
To test the Fuel pressure & regulator. The vac line is on the regulator at the back of the fuel rail. When I say record the reading I mean write it down. DON'T try to remember. You test it with the vac line connected to the regulator and with out to make sure the regulator changes pressures. Pulling the vac line shows what would happen if you where running WOT.
To test the Fuel pressure & regulator. The vac line is on the regulator at the back of the fuel rail. When I say record the reading I mean write it down. DON'T try to remember. You test it with the vac line connected to the regulator and with out to make sure the regulator changes pressures. Pulling the vac line shows what would happen if you where running WOT.
04-03-2010, 08:16 PM
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I didn't get a chance to test it today... will try tomorrow, but was revisiting this info and wanted to make sure... and I KNOW this should be blatantly obvious to me, but I'm exhausted.....
When I pull the vacuum line to simulate WOT, I should see an increase in pressure, right?
What should it jump to?
When I pull the vacuum line to simulate WOT, I should see an increase in pressure, right?
What should it jump to?
04-04-2010, 12:48 PM
#15
Another thing to look for when you do this is make sure no fuel comes out of the regulator housing. Sometimes when they go bad they will leak through the diaphram in the regulator. Then when you remove the vac line, fuel will come out of that port on the regulator.
04-05-2010, 01:04 AM
#19
It looks good. Those numbers are very close to mine. Regulator is working and the pump is ok at idel. feed the gage up through the hood and take it for a drive and watch the pressures as you stand on it. Take a spotter with you to read the gage. do a 2nd or 3rd gear pull to the read line and make sure it doesn't fall off from what it is as soon as you crack it wide open. after that you can eliminate the fule pump and filter all together. What plugs did you put in that thing anyway?
04-05-2010, 02:06 AM
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Autolite platinum xp105.
I may have effed myself. The counter jockey told me to gap at .050 and I picked up a disc shaped gapper. I don't know if the plugs came pregapped to lt1 specs or not but they all seemed to be at about .040 and I loosened them (gently) to what I thought was .050 according to the pretty inaccurate gap tool. I'm kicking myself now wondering if
A: I shouldn't have messed with platinum plugs in general
B: I may have overgapped any of them causing my miss issue..
Freakin 6 bucks a plug and 2 hours of burning my hands... I guess I'll pick up a set of recommended plugs and hope they're correctly gapped....
I'm just trying to eliminate all possible causes of this damned miss.
Jaycen, thanks very much for your time and letting me pick your brain.
I may have effed myself. The counter jockey told me to gap at .050 and I picked up a disc shaped gapper. I don't know if the plugs came pregapped to lt1 specs or not but they all seemed to be at about .040 and I loosened them (gently) to what I thought was .050 according to the pretty inaccurate gap tool. I'm kicking myself now wondering if
A: I shouldn't have messed with platinum plugs in general
B: I may have overgapped any of them causing my miss issue..
Freakin 6 bucks a plug and 2 hours of burning my hands... I guess I'll pick up a set of recommended plugs and hope they're correctly gapped....
I'm just trying to eliminate all possible causes of this damned miss.
Jaycen, thanks very much for your time and letting me pick your brain.