MY turn for car trouble...again

L

logres

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Symptoms: Missing at idle and low rpms. Drop in low end power.

Observations: Driver side copper plugs looked like they had 50k miles on them - rounded terminal and gap at around 0.080". Passenger plugs looked like they had the real 10k miles on them. Also, driver side IMRC seemed to be sticking. While driving, what appears to be a vacuum leak is heard from the engine - pfft pfft pfft pfft pfft - at the same frequency as the vibration - rpm dependant.

Testing

1. Did seafoam in intake and B-12 in tank - no change.
2. Replaced all plugs - slightly better, but still a problem.
3. Swapped out Demon coil packs with new unit from Autozone - no change.
4. Vacuum testing on all lines going to IMRCs passed.
5. Replaced driver side IMRC - no change.
6. Replaced cracked EGR tube, pressure sensor, and EGR valve - no change.

Previously replaced parts:

IAC - 20k miles
EGR - 100 miles
IMRC (driver) 100 miles
plugs - 100 miles
Coil packs - 20k miles

I finally waved the white flag and took it to the dealer. They found that my NOLOGY wires were arcing through. They isolated the arcing to the #2 piston, so they must have actually found something. They wanted over $500 for replacement, I said no-way, paid the $105 and left. I can replace the Nology wires for free through the lifetime warranty. I'm a bit dissappointed that these supposedly invincible wires did indeed fail. They lasted a mere 30k miles. If not for the warranty, I would have to say that the minimal increase in power is not worth it. Anyway, I'll get them swapped out and see if that fixes the miss and vacuum leak sound.

If anybody has thoughts, I'm listening.
 
A lot of these high performance wires have issues.

I know jesse had to track down some issues also and he paid like $90 for 1 wire to be shipped!! ugh!!

When my gen 2 was missing due to a faulty coil boot, it sounded like a vacuum leak also very wierd...

So that should probably take care of your problem.
 
The plugs match the symptom.

I'm puzzled why just one bank though. I can see one cylinder, or all cylinders... but 4 cylinders on one side? Weird.

The only things I can see common would be an intake leak on that side or a bad O2 sensor on that side. Either one causing a lean condition leading to pre-combustion causing detonation and plug wear.

Another wild guess would be maybe the knock sensor on that side not working? :rolleyes:
 
driller said:
The plugs match the symptom.

I'm puzzled why just one bank though. I can see one cylinder, or all cylinders... but 4 cylinders on one side? Weird.

The only things I can see common would be an intake leak on that side or a bad O2 sensor on that side. Either one causing a lean condition leading to pre-combustion causing detonation and plug wear.

Another wild guess would be maybe the knock sensor on that side not working? :rolleyes:
Click to expand...

What testing can be done for the intake/head leak and O2/knock sensors? Should I just replace the knock sensor anyway? Is it expensive and/or hard to replace?

Nology has been very cooperative. Since I have the receipt, I can send the wires to them for free testing and replacement. The guy I spoke with said these wires with the deep sockets (4.6 DOHC) have been known to arc through the plastic tube piece that goes through the heads. I'm impressed when someone admits fault like that. Anyway, we'll see.
 
I forget the price but the knock sensors are not expensive. The only way to get to the knock sensor is to remove the intake! :eek:

There are two knock sensors, one for each side. They are located in the valley on the block beneath the intake. When I swapped intakes, I replaced both for prosperity. ;)

A bad O2 should throw a code - but if you have a chip, I don't think you'll see it?

At our dealer, they use a smoke machine to look for intake leaks. At our shop, they use starting fluid (I do not recommend that). I have used propane back in the day. Usually a vacuum test will help diagnose if you have a leak, then it's trying to locate it that's the hard part. For vacuum lines, I find it easier to isolate the line(s) and use a vacuum pump.
 
driller said:
I forget the price but the knock sensors are not expensive. The only way to get to the knock sensor is to remove the intake! :eek:

There are two knock sensors, one for each side. They are located in the valley on the block beneath the intake. When I swapped intakes, I replaced both for prosperity. ;)

A bad O2 should throw a code - but if you have a chip, I don't think you'll see it?

At our dealer, they use a smoke machine to look for intake leaks. At our shop, they use starting fluid (I do not recommend that). I have used propane back in the day. Usually a vacuum test will help diagnose if you have a leak, then it's trying to locate it that's the hard part. For vacuum lines, I find it easier to isolate the line(s) and use a vacuum pump.
Click to expand...

I'll pray it's not a knock sensor then.

I used to have a chip, but then went with Lonnie's Xcal 2 and reflashed the ECM. I'm not getting any codes or CE light.

Would it be logical to assume that if a bank of plugs are wearing way too fast and you hear an rpm dependant leak, that the only conclusion is an intake leak? If so, I'll just start on popping off the intake then.

Can we rule out a leaking head gasket?
 
If you weren't in the land of the smog militia I would liberate those cats to be sure one of them isn't failed.
 
logres said:
By failed, do you mean clogged?
Click to expand...

I suppose that's a possibility. You could have an exhaust gasket leak exasperated by a clogged cat on that side. The pft pft could be the exhaust leaking rather than an intake leak.

I wouldn't pull anything without pin pointing the leak. If it's audible it should be discoverable. Feel around the outside of the drivers side head (what you can) and see if you can feel the exhaust leaking. When my gaskets developed a leak it was barely audible at first but eventually worsened to the point you could tell what it was.

If the intake is leaking, it may actually be more difficult to tell. I would try a vacuum test and see if the vacuum is low enough to suspect an intake leak or try spraying some carb cleaner around the intake seams at the IMRC and head on the offending side.
 
Nology called and confirmed my address to send updated/repaired/new plug wires. So far, they are being very easy to work with. I'll report back on what I actually get in the mail.
 
Looks like they replaced all of the boots and plug tubes. After installation, the engine ran much better. No miss, no vibration, and low end power has returned. Still have the vacuum leak sound though...and looks like one of my HID ballasts died. Cheap chinese crap.

Now the local mechanic said he did a smoke test and found no vacuum leaks. Should I still take it to the dealer for more thorough testing (if it exists)?
 
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