Misfire issues perhaps more?? (1 Viewer)

[2001LC]

Possibly, a stop leak had been added to coolant system.
I'd visual inspection head gasket. With a flashlight. 98-05, we can get our eyes on 95% (100% of outer, and 90% of inner area under intake manifold). With a borescope we can inspect 100% of head gasket in all years. Also, look at all points of possible coolant leak, for signs coolant.

When we get a P0300 misfire DTC. We typically go to the cylinder it points to. P0303 is cylinder #3, which is the easiest to work with.

First, we swap coils, with say #1. If DTC does not move to #1, indicating a bad coil. But remains at cylinder first indicated by DTC.

We then, pull spark plug. Inspect spark plug. If looks good. We then check for spark.

Spark good. We then check compression. Since spark plug, is out.

Compression good.

We then check fuel injector (FI).
Easy first FI test. With engine idling. Pull wire housing block, from FI. RPMs should drop. No RPM change, fuel injector is not delivering fuel.

Most times, when we find "fuel injector is not delivering fuel". It's a dead fuel injector.

Next, easy FI test, is resistance. If FI fails this, I replacing the FI.

But it can be short in wires to injector, or even issue with ECM not giving signal to FI.
We start by visually inspecting wire housing block and wires from FI all the way to firewall. All good.
We then check wire from ECM to FI. We need to get behind glove box for this.
Next we test ECM.

 

[Gonefly470]

Possibly, a stop leak had been added to coolant system.
I'd visual inspection head gasket. With a flashlight. 98-05, we can get our eyes on 95% (100% of outer, and 90% of inner area under intake manifold). With a borescope we can inspect 100% of head gasket in all years. Also, look at all points of possible coolant leak, for signs coolant.

When we get a P0300 misfire DTC. We typically go to the cylinder it points to. P0303 is cylinder #3, which is the easiest to work with.

First, we swap coils, with say #1. If DTC does not move to #1, indicating a bad coil. But remains at cylinder first indicated by DTC.

We then, pull spark plug. Inspect spark plug. If looks good. We then check for spark.
View attachment 3886335

Spark good. We then check compression. Since spark is plug out.

Compression good.

We then check fuel injector (FI).
Easy first FI test. With engine idling. Pull wire housing block, from FI. RPMs should drop. No RPM change, fuel injector is not delivering fuel.

Most times, when we find "fuel injector is not delivering fuel". It's a dead fuel injector.

Next, easy FI test, is resistance. If FI fails this, I replacing the FI.
View attachment 3886348

But it can be short in wires to injector, or even issue with ECM not giving signal to FI.
We start by visually inspecting wire housing block and wires from FI all the way to firewall. All good.
We then check wire from ECM to FI. We need to get behind glove box for this.
Next we test ECM.

Thanks for the write up. I know there want any stop leak added since I had all that work done and provided the oem coolant and gallons of distilled water. Nothing else has gone into it.

Regarding the head gasket. What are the best locations to be able to see it. I havnt had any coolant loss over the last two years. Again. I have only driven it about 1,000 miles.

As per the resistance. I unplugged just the #3 FI and got about 16ohms. I checked #5 and also got 16 ohms.

I am yet to pull the spark plug because I don't have a torque wrench.

 

[Gonefly470]

The thing is it drove just fine in January. The last time I drove it. It sat on a battery tender since then and when a attempted to start it a week ago....after doing the heater tees. I got these codes.

Again, first it was a flashing p0301. I cleared it did a restart. Again p0301.

I drove it about 7 miles. Flashing CEL would turn off for a while then on again. Would have hesitation when accelerating. When I would apply full power CEL would turn off. I got codes p0300 p0303 p0304.

When arriving back home. At red light and idle, very noticeable vibrations.

When I got home. Cleared the codes. Turned off then on after a short while. CEL turns on immediately with VSC lights. Now only P0303 code after multiple obd2 code clearing.

I repalced all the coild with rock auto densos. Still getting p0303

Smell a lot of fuel on start ups. When i clear CEL and blip the throttle no light. As soon as throttle drops to idle. CEL illuminates

 

[Gonefly470]

Anyone have experience with SMP injectors?

 

[2001LC]

Thanks for the write up. I know there want any stop leak added since I had all that work done and provided the oem coolant and gallons of distilled water. Nothing else has gone into it.

Are you the first owner!

Regarding the head gasket. What are the best locations to be able to see it. I havnt had any coolant loss over the last two years. Again. I have only driven it about 1,000 miles.

With mirror.
Also from below, shields off.
Between intake manifold plumes
Or
Borescope, directional.

As per the resistance. I unplugged just the #3 FI and got about 16ohms. I checked #5 and also got 16 ohms.

If good multiment and at 68F. That's to much resistance. Since both, read 16 ohms, likely their both fine.

I am yet to pull the spark plug because I don't have a torque wrench.

Your parts store, may lend TQ wrench and compression gauge.

Consider, picking up combustion gas tester. To test coolant.

Make sure to check A/T fluid. ATF flows through bottom of radiator on way to cooler. Leaks have been known to happen.

 

[Gonefly470]

Just pulled my #3 spark plug.
Thoughts on Findings?

 

[Gonefly470]

Just pulled my #3 spark plug. This is after 2 years and 1,000 miles after install. Thoughts on findings?

 

[TahoeZ]

Looks like the plug was loose and wasn't sealing properly.

 

[AARONTLC]

There shouldn’t be any oil on your plugs. Looks like time for valve cover gaskets and spark plug tube seals.

 

[Gonefly470]

There shouldn’t be any oil on your plugs. Looks like time for valve cover gaskets and spark plug tube seals.

There shouldn’t be any oil on your plugs. Looks like time for valve cover gaskets and spark plug tube seals.

Those were repalced under 1k miles ago. Tube seals as well....

 

[Gonefly470]

Looks like the plug was loose and wasn't sealing properly.

Maybe backing out? Looks like my guy added anti seize to the threads. Unfortunately I dropped the coil bolt. Removed the underbody trays and no dice. Can't seam to locate it. Maybe went into one of the holes of the subframe or control arms.

 

[2001LC]

Just pulled my #3 spark plug. This is after 2 years and 1,000 miles after install. Thoughts on findings?View attachment 3888488View attachment 3888489View attachment 3888490View attachment 3888491View attachment 3888492

Is there any oil on top tube seal?
Was spark plug tight (could you tighten more)?
Is the spark plug electroid (tip of plug) oily?
Did you get spark, during sprak test?
What was compression? (Throttle body open, fuel pump disconnected, 250RPM)
How did head gasket look?

Bad coil may have resulted in fouling spark plugs. Try cleaning with gasoline, do above test. Then, if you get spark and compression.
After engine at op temp. Try driving at ~2,700 RPM 3 min, then ~3,500 RPM 5 min, then 4,500 RPM for 7 minutes.
BTW: You can use engine cover bolt to secure coil, for now.

 

[AARONTLC]

Maybe backing out? Looks like my guy added anti seize to the threads. Unfortunately I dropped the coil bolt. Removed the underbody trays and no dice. Can't seam to locate it. Maybe went into one of the holes of the subframe or control arms.

It happens. Hopefully it didn’t drop into the cavity of a pulley or between belt and pulley where it will rattle or lock up. @2001LC has you squared away with where to go next.

 

[Gonefly470]

Is there any oil on top tube seal?
Was spark plug tight (could you tighten more)?
Is the spark plug electroid (tip of plug) oily?
Did you get spark, during sprak test?
What was compression? (Throttle body open, fuel pump disconnected, 250RPM)
How did head gasket look?

Bad coil may have resulted in fouling spark plugs. Try cleaning with gasoline, do above test. Then, if you get spark and compression.
After engine at op temp. Try driving at ~2,700 RPM 3 min, then ~3,500 RPM 5 min, then 4,500 RPM for 7 minutes.
BTW: You can use engine cover bolt to secure coil, for now.

Is there any oil on top tube seal?
Was spark plug tight (could you tighten more)?
Is the spark plug electroid (tip of plug) oily?
Did you get spark, during sprak test?
What was compression? (Throttle body open, fuel pump disconnected, 250RPM)
How did head gasket look?

Bad coil may have resulted in fouling spark plugs. Try cleaning with gasoline, do above test. Then, if you get spark and compression.
After engine at op temp. Try driving at ~2,700 RPM 3 min, then ~3,500 RPM 5 min, then 4,500 RPM for 7 minutes.
BTW: You can use engine cover bolt to secure coil, for now.

1.No oil on top of tube seal. The oil you see on the picture is dry and sticky. Not wet.
2.Spark plug could be tightened a bit more. But since I don't have a torque (on order) I didn't want to turn more. But definitely not tight to the right.
3. Electrode dry and in perfect condition
4. Didn't do spark test. But I did pull harness while engine running. Didn't feel much of a rpm drop. Check engine light never came on again after I plugged it in. Not until restart.
5. No compression test
Head gasket looks intact. No anomalies with the coolant or overheating.

 

[2001LC]

1.No oil on top of tube seal. The oil you see on the picture is dry and sticky. Not wet.
2.Spark plug could be tightened a bit more. But since I don't have a torque (on order) I didn't want to turn more. But definitely not tight to the right.
3. Electrode dry and in perfect condition

When we've a loose spark plug. Combustion gasses can pass its threads. More so, during engine warm up. The dry and sticky oil, is likely byproduct of combustion gasses.

4. Didn't do spark test.

Checking for spark while spark plug out. Is an, important and easy step. Which I post picture from FSM above, of the steps on how to.
Finding issue of misfire. Is most often, a processes of elimination. You've not eliminated spark. Which can be dead: spark plug, bad coil, short in wires to coil, contact between coil & spark plug, signal/power to coil.

But I did pull harness while engine running. Didn't feel much of a rpm drop. Check engine light never came on again after I plugged it in. Not until restart.

When pulling (disconnecting) fuel injector harness (wire housing block), while engine running. "Feel" is not very reliable. "Look" to see RPM change.

You can have someone watch RPM gauge, in combination meter (dash). But I find watching RPM in tech stream, much better than watching dash gauge. Since the drop is minor, dash RPM needle won't move much. Best is, to see actually digital reading of RPM. Say 773 RPM drops to 720 RPM.

I use my smartphone and with OBDII wireless connection device. These sell for from $20 to $200.
Read out of date points, I picked on my smartphone.

5. No compression test

This was another important step, and so easy while spark plug out. Without compression, we'll not have combustion. We may have spark and correct fuel/Air mix. But we'll still not have combustion.

I just had a case P0303 (#3 misfire):

• Spark present.
• Compression okay.
• No RPM change when fuel injector disconnected.

Misfire due to dead fuel injector. Issue corrected.

We just had a case in mud. Where a misfire DTC, was reported in one cylinder.

• Spark was present.
• No RPM drop when fuel injector disconnected. Assumptions at that point, failure of fuel injector to delivery fuel. But lacked all clues needed.
• Compression test. No compression in misfire cylinder.

Misfire, due to no compression in cylinder.

Head gasket looks intact. No anomalies with the coolant or overheating.

Great news.

I've seen more than one with floaters in coolant system. Most, I found stop leak had been added. Some, I had no idea as why (where leak was). In a few, I found signs head gasket leak.

Sometimes when a stop leak added or a coolant or additive, not compatible with our coolant added. We get unintended issues. One is hose/cap to reservoir gets clogged.

 

[Gonefly470]

When we've a loose spark plug. Combustion gasses can pass its threads. More so, during engine warm up. The dry and sticky oil, is likely byproduct of combustion gasses.

Checking for spark while spark plug out. Is an, important and easy step. Which I post picture from FSM above, of the steps on how to.
Finding issue of misfire. Is most often, a processes of elimination. You've not eliminated spark. Which can be dead: spark plug, bad coil, short in wires to coil, contact between coil & spark plug, signal/power to coil.


When pulling (disconnecting) fuel injector harness (wire housing block), while engine running. "Feel" is not very reliable. "Look" to see RPM change.

You can have someone watch RPM gauge, in combination meter (dash). But I find watching RPM in tech stream, much better than watching dash gauge. Since the drop is minor, dash RPM needle won't move much. Best is, to see actually digital reading of RPM. Say 773 RPM drops to 720 RPM.

I use my smartphone and with OBDII wireless connection device. These sell for from $20 to $200.
Read out of date points, I picked on my smartphone.

View attachment 3889171





This was another important step, and so easy while spark plug out. Without compression, we'll not have combustion. We may have spark and correct fuel/Air mix. But we'll still not have combustion.

I just had a case P0303 (#3 misfire):

• Spark present.
• Compression okay.
• No RPM change when fuel injector disconnected.

Misfire due to dead fuel injector. Issue corrected.

We just had a case in mud. Where a misfire DTC, was reported in one cylinder.

• Spark was present.
• No RPM drop when fuel injector disconnected. Assumptions at that point, failure of fuel injector to delivery fuel. But lacked all clues needed.
• Compression test. No compression in misfire cylinder.

Misfire, due to no compression in cylinder.


Great news.

I've seen more than one with floaters in coolant system. Most, I found stop leak had been added. Some, I had no idea as why (where leak was). In a few, I found signs head gasket leak.
View attachment 3889186
View attachment 3889185
View attachment 3889184

Sometimes when a stop leak added or a coolant or additive, not compatible with our coolant added. We get unintended issues. One is hose/cap to reservoir gets clogged.
View attachment 3889191View attachment 3889190

Thanks for all the info! What's the best way to ground the spark plug?

 

[2001LC]

Warning:
While spark plug out and cranking engine. If fuel injector working and power to it and fuel pump. Fuel vapor can blowout spark plug and ignite from spark.
I cut power to fuel pump, so no fuel to engine (engine will not start).

We've a few ways to cut fuel delivery:

• Remove FOB, from IG key housing. FOB houses immobilizer (cuts off power to fuel pump) chip. Security light keeps blinking, when IG key in IG SW. (engine will not start)
• Pull fuse (98-02 EFI fuse IIRC). Cut power to fuel pump. (engine will not start)
• Disconnect wire housing block (98-07) underbody, below DS rear door, near frame rail. (engine will not start)
• Pull wire from fuel injector, of cylinder(s) spark plug removed from. (Engine "may" still start and run.)

Ground the spark plug:
You'll see the engine hoist hook close to, #3 cyl. By touching metal of spark plug to metal hook, it will be grounded. Have plug in coil and wire on coil. Just hold plastic of coil, to insulate your hand from shock.

You can compare spark, to another cylinder, like #1.

 

[Gonefly470]

When replacing the spark plugs. Should I use anti seize on them? Or just install directly?

 

[TahoeZ]

You'll get mixed opinions on that topic. Personally, I use a tiny tiny dab of anti-seize. Don't goop a bunch on and you'll be OK.

 

[2001LC]

No anti-seize (AS).

I'm using 18ft-lbf torque on spark plugs. If threads lubed with AS. I'd actually be, between 27 & 36ft-lbf at 18ft-lbf. A safe torque may then be 10ft-lbf. Which we already have walk out issues at the FSM of 13ft-lbf.

If spark plugs walk out. The combustion gasses well mix with AS in threads and cook. This will stop the walking out as the mix hardens. But will make plugs extremely hard to remove. If not removed soon. Just to break free, they'll be very very hard to turn. Most can't even get them out.