93 S10 Blazer Spark and spark plug question

[shanes76]

my brothers blazer has the vortec and had a miss, we took out the plugs and looked at them, one side of the plug looks clean and the other side is a dark rusty color, like only half of the plug is firing or something, the rusty color doesnt go all the way around the electrode- just half and then the rest looks like a new plug, we put the plugs back in and pulled the coil wire off the distributor and checked spark, it was a bright orange/ whitish looking- and a few of the plug boots were deteriorated in which they are not old, maybe a month. it only has the miss at idle or stopped at a light - it doesnt miss going down the road from what we can tell. Is this a weak coil? Why would it only do it while it was idling and not going down the road? Any help would be appreciated

[MT-2500]

Originally Posted by shanes76

my brothers blazer has the vortec and had a miss, we took out the plugs and looked at them, one side of the plug looks clean and the other side is a dark rusty color, like only half of the plug is firing or something, the rusty color doesnt go all the way around the electrode- just half and then the rest looks like a new plug, we put the plugs back in and pulled the coil wire off the distributor and checked spark, it was a bright orange/ whitish looking- and a few of the plug boots were deteriorated in which they are not old, maybe a month. it only has the miss at idle or stopped at a light - it doesnt miss going down the road from what we can tell. Is this a weak coil? Why would it only do it while it was idling and not going down the road? Any help would be appreciated

Good AC Delco plugs?

Can you feel what cylinder is missing?

[shanes76]

yes good ac plugs, its like a random misfire and i got orange spark from the coil

[MT-2500]

Originally Posted by shanes76

yes good ac plugs, its like a random misfire and i got orange spark from the coil

Test fuel pressure for up to par.
Post back pressure readings.
How far will the spark jump?

Check cap and rotor real close.
And dist shaft bbushings.

What is the vacuum reading at idle and at 2K rpm?
Have you checked for carbon under EGR Valve plunger?

How is the base timing?
Any check engine lights or codes?

[shanes76]

no engine codes, havent got fuel pressure checked yet, not sure about the timing, gonna buy a timing light and pressure guage tommaro, what should I look for on the cap and rotor? The cap and rotor wasnt changed when the plugs and wires were. How do I check distubtor shaft bushings?

[Schrade]

Originally Posted by shanes76

my brothers blazer has the vortec and had a miss, we took out the plugs and looked at them, one side of the plug looks clean and the other side is a dark rusty color, like only half of the plug is firing or something, the rusty color doesnt go all the way around the electrode- just half and then the rest looks like a new plug, we put the plugs back in and pulled the coil wire off the distributor and checked spark, it was a bright orange/ whitish looking- and a few of the plug boots were deteriorated in which they are not old, maybe a month. it only has the miss at idle or stopped at a light - it doesnt miss going down the road from what we can tell. Is this a weak coil? Why would it only do it while it was idling and not going down the road? Any help would be appreciated

Betcha' it IS doing it at higher RPMs. You just cannot notice it. Same as a vacuum leak - at idle, a vacuum leak will make the motor lope idle - up and down RPMs, but cruising, you notice nothing...

A bad coil will NOT make the same plug misfire repeatedly. It MIGHT make several plugs misfire occasionally.

Raise the hood, in TOTAL darkness, and look for arcing (you WON'T notice it with light). Use a spray bottle and spray near the lines.

Misrouted wires can cause arcing. This arcing emits EMI - electromagentic interference - same as a nuke - and can cause false codes on some sensors, including ABS modules. Ask me how I know about it, and where I read it one day in the vette factory shop manual YUP UH HUH

Another post to bookmark!!!

[shanes76]

I didnt post this in my last reply, sorry MT, but I took off the coil wire from the dist. and put a screwdriver in it and laid it on the plenium, and the spark would go about an inch but the color concerned me, but it did make a loud snap while cranking. I did some searching and found some pics of plugs, how they should look and everything, from what I can tell from that it looks like his plugs are splash fouled, which his nut kit did leak and he replaced that, then put new plugs in, and I read that splash fouling happens when the deposits are broke loose from the piston and foul out the plugs, have you ever heard of this? I checked the spark at the plugs and it was orange also. If you give it a little gas(very little) the miss isnt really noticable. When using the spray bottle with water do I spray te spark plug wires? I can rent a vacum guage from Autozone, but where do I hook it up at? And also he dont have a tach so I wouldnt really know when I was checking at 2000rpms. Thanx for the help

[MT-2500]

Originally Posted by shanes76

I didnt post this in my last reply, sorry MT, but I took off the coil wire from the dist. and put a screwdriver in it and laid it on the plenium, and the spark would go about an inch but the color concerned me, but it did make a loud snap while cranking. I did some searching and found some pics of plugs, how they should look and everything, from what I can tell from that it looks like his plugs are splash fouled, which his nut kit did leak and he replaced that, then put new plugs in, and I read that splash fouling happens when the deposits are broke loose from the piston and foul out the plugs, have you ever heard of this? I checked the spark at the plugs and it was orange also. If you give it a little gas(very little) the miss isnt really noticable. When using the spray bottle with water do I spray te spark plug wires? I can rent a vacum guage from Autozone, but where do I hook it up at? And also he dont have a tach so I wouldnt really know when I was checking at 2000rpms. Thanx for the help

You are welcome.
A vacuum gauge is cheap.
One of the cheapest and best testers for the money and tell you many things.
Will show late timing and egr valve and plugged exhaust and valve problems.
Most are under 10$
They can hooked to any engine intake vacuum source.
If no tack just check at idle and then speed the engine up some and test.
On coil test a 1/2 should be good.
But always check coil cold and hot.

Around your year a I have found a lot of dist with a worn shaft bushing.
That cause misfire and also check cap and rotor real close.
If the dist shaft moves sides ways when pushing the rotor sideways the shaft bushing is bad and also look for the shaft stater rotor teeth catching on pickup coil.
Look cap over for carbon tracking and cracks and rotor for burn marks and check the end pointer good.

[shanes76]

hey MT, I went to harbor freight on thursday and bought the fuel injection tester and timing light, I just havent had time to do them yet. Do you have a part number for the vacum guage or where I can get one for around 10 bucks? I just found out he put a new fuel pump in not long ago and he said it came from Autozone but doesnt know what kind it was. He said it was around 80.00 for it though. When you first start his blazer it dont have a miss, idles good then after a few minutes it starts, its kinda weird, well Im not even sure it is a miss actually, if you put your foot on the throttle lightly it idles pretty smooth. But I want to check his timing and fuel pressure do you know what his specs should be on it? Thanx in advance

[MT-2500]

Originally Posted by shanes76

hey MT, I went to harbor freight on thursday and bought the fuel injection tester and timing light, I just havent had time to do them yet. Do you have a part number for the vacum guage or where I can get one for around 10 bucks? I just found out he put a new fuel pump in not long ago and he said it came from Autozone but doesnt know what kind it was. He said it was around 80.00 for it though. When you first start his blazer it dont have a miss, idles good then after a few minutes it starts, its kinda weird, well Im not even sure it is a miss actually, if you put your foot on the throttle lightly it idles pretty smooth. But I want to check his timing and fuel pressure do you know what his specs should be on it? Thanx in advance

Check your local parts places for a vacuum gauge.

4.3 code w Non turbo specs.
Ac delco plugs CR43TS at .045 gap.

Fuel pressure is 55/61 lbs.

Timing specs is 0 degrees TDC with EST tan /black wire disconnected at hot idle.

Check and clear codes after checking timing.

POST BACK ANY CODES AND VACUMN AND FUEL PRESSURE READINGS.

[Leeann94astro]

$80 pump = the cheap stuff. They are often bad off the shelf...and usually die within the warranty period.

[shanes76]

is there a difference in checking my base timing at cold idle and at hot idle? DO I just let it warm up to operating temp?

[MT-2500]

Originally Posted by shanes76

is there a difference in checking my base timing at cold idle and at hot idle? DO I just let it warm up to operating temp?

Get it up to operating tempt but make sure you pull est base time wire to open circuit.