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Discussion Starter #1
Ok... having a few odd symptoms, and trying to track down what is going on. Maybe you guys have seen these things before and have some ideas.

Here's the background on the problems, listed in chronological order of appearance:

0. Car Specifications
  • 1999 Mercury Cougar V6
  • 5spd Manual
  • Modifications listed in signature
  • 125,000km [78,000mi]

1. Intermittent Clunk on Accel
  • Changed both roll restrictors under the car with SVT units + inserts
  • Clunk still present
  • Investigated upper mounts (only visual inspection with no removal) and can't _see_ anything wrong
  • Manually operating TB plate to rev engine shows no rocking motion at all
  • When starting from a stop, there feels like no power till clunk, then goes.
  • Could be my perception, but after some clunks, the car feels like a rocket, and after others, like a dud
  • Had place that changes my oil double-check my work. They said the bottom mounts were totally solid, and their brief investigation didn't show anything.

2. Coolant light
  • Was coming on sporadically, I thought when I parked on slopes
  • Figured it was time for a coolant flush anyway, so did that, and coolant light still on
  • Had coolant topped right up to MAX line, and maybe a millimeter or two over, still on intermittent.
  • No overheating or coolant circulation problems that I can detect thus far.

3. "Chunky" accel towards secondaries opening (900 to 3400 RPM)
  • This is a weird one... feels like not all cylinders are firing down low.
  • Pretty mild problem, not severe like fuel delivery cut-out due to fuel-pump problem.
  • Probably intermittent as well. Maybe temperature dependent, but can't see a pattern yet.
  • At point in accel, it suddenly goes perfectly smooth
  • Not too much power during "chunky" accel, but pulls really smooth and hard from 3000+
  • Part throttle may be smoother, possibly even faster accell, then full throttle down low.

4. CELs
  • Had a couple of codes. Scanned them, got P0402 EGR Flo Exces Flow Excessive Detected and P0340 Camshaft Position Sensor A
  • Reset the codes, they have not returned.

5. Airbag light
  • Saw this flash for the first time just recently.
  • This happened as it started to get really cold out here (-20 C / 0 F)
  • Restarted car, and no problem. Haven't seen it since.

6. Needle Sweeps
  • When I start the car cold, like in the morning, or after work, the speedo and tach sweep smoothly to max vals then back
  • If I start it warm, they do not do this.
  • Just started happening very recently

Tests
-Cleaned battery up a while ago, some new corrosion has formed in past month on positive terminal.
-Coolant light after warm start not on (I think)
-Voltage checks OK on batt when cold or when running.
-Alternator recently replaced due to batt light coming on at high RPMs. Replacement was off a 2000 Cougar with 50,000km on it.
-No batt light coming on ever after replacement, and headlights and guages have expected brightness.
-Checked the plugs, they look good (as far as I know. See pics below).


Theories
I'm thinking that the clunk is unrelated, but I have no idea what is causing it. It's not reproducible without load (i.e. when I'm manually operating the TB) so can't really watch what's happening. Ignoring the clunk, I'm wondering if the battery is dying and causing the other symptoms. This is the stock battery -- it has never been changed. I'm thinking that maybe the coolant sensor is very sensitive to low voltage, and maybe the airbag light too. When starting cold, the lack of power in the batt is causing the needle sweeps, random CELs (maybe), and maybe ignition issues. I'm wondering if the chunky accel could be due to the battery having very little amperage or voltage, and the spark plugs aren't getting strong enough juice to ignite the mixture well. As the RPMs rise, the alternator generates enough to compensate for this, and the power smooths out instantaneously past a certain point. This is NOT the fuel pump issue. I've had that, and this is different. Power is still linear, and revs still increase, but it feels... uneven until a certain point.

Other than this... no ideas! Thought maybe my plugs were worn, and thus it took a lot of power to get a good spark (NGK Iridiums I put in in the spring, ~25,000km+ on them). Check the pics below for the front-bank plugs. Someone correct me if I'm wrong, but they look textbook perfect.

Anyone seen these problems before? Is this just a bad battery acting up and causing all of this?

Thanks,

Massiv.

Cylinder 4





Cylinder 5




Cylinder 6



 

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I have the problem with low-rpm acceleration, worse when cold. My next target is a bad or clogged fuel injector.

I will be running a pure solvent cleaning directly thru the fuel rail next weekend, and failing that, I'll be replacing the injectors.

The "clunk" you describe could be a pop back thru the intake. That's what mine does. The fouled plugs are an indicator of a lean condition, consistent with a pop thru the intake.
 

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Discussion Starter #3
Yeah... I'm thinking worse when cold as well. Tonight, it is only about -4 C out, and I can't BELIEVE how hard the car was pulling. Thing was a rocket. Two days ago, the low RPM issue seemed worse, and it was -20 C. Not sure about high speeds at that temp, as I haven't had a clear road (traffic) to drive fast on for about two weeks until tonight.

What's up with the pop back through the intake? I wonder if that might be it. What causes that?

Thanks,

Massiv.

EDIT: Am running a "premium" injector cleaner via gas-tank method. A thought I too had, about injectors pissing into the cylinder at low fuel pressure (i.e. low RPM), versus high pressure pulses at higher RPM causing them to spray/mist better.... Will report back after this tank is done. (Seemed pretty good tonight, and I'm nearing the end of this cycle with this stuff, so maybe that's it, and it's working?) Also, Here's an interesting link on reading plugs.
 

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Not too sure of your problem but i must ask you. What kind of digital camera is that and how many megapixels is it. I've never seen such sharp pictures from a digital cam. Not trying to change the sub. or anything. You can pm me if you like. Thanks
 

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2. The coolant light is a PITA and is overly sensitive. This is normal. Either top off or cut and splice the sensor wires.

4. My airbag light sometimes flashes when it's very cold or wet out. Normal as well.
 

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Discussion Starter #6
Zeteckat --> It's a Canon Powershot S400. It's a 4.0MP. The first 9 little shots were done at lowest sharpness, and lowest resolution (640x480). That last one was done at the full 4MP, and cropped.

About that clunk, forgot to mention that when it happens, I hear it clearly, and I feel it through the gas pedal!? Kind of weird.

ignernt --> Seems like a lot of things with these cars are "normal". I remember when I first got it, I had this huge list that I went to the dealership with... most of those items were normal too! :D

Massiv.
 

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Pop thru the intake is caused by too much air and not enough gas in the cylinder.

At low RPM's, when you open the throttle, the injectors must deliver a long, heavy charge of fuel to compensate for the increased air intake. Carbureted engines had an "accelerator pump" specifically for this purpose. A clogged or malfunctioning injector will not do this, and the cylinder(s), starved for fuel, detonate early (while the intake valves are still open) - hence the POP! back through the intake At higher RPM's, the pistons are moving so fast that the injectors are spraying VERY short bursts into the cylinder, and the fuel delivery problem isn't as noticeable, since the engine isn't on the verge of stalling. You may probably still have pinging at higher RPM's though, as the cylinder is still running lean - just not AS lean...
 

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Discussion Starter #8
Very very interesting thought. That would actually make sense on a few different levels!! :
  • The "clunk" has become more frequent over time [continued buildup in injectors or other area of fuel-delivery path]
  • I think the pics I posted show a "normal" condition, with the possible exception of little deposits, and on the rim of the plug casing (where the threads end). According to NGK's site, if that looks like "pizza" instead of smooth, that can be a sign of detonation.
  • Detonation, and the computer retarding timing on its presence, could explain why the car sometimes pulls hard, and sometimes seems sluggish.
  • Last night, I said the car was pulling really hard. Today, in high-torque, low RPM situation in higher gears (3rd, 4th), the car didn't accel as roughly as I recalled. In fact, it seemed pretty smooth. Note, that at the start of this tank, I dumped in some sort of "premium" fuel system cleaner. I had done the regular $2 STP bottle thing, which did nothing. This is supposed to be guaranteed to have 5 x the power of those or something. Maybe it really has cleaned it up.
  • The fuel-system additive may also be responsible for some of the deposits that dot the plugs.

I guess now that this tank of gas is almost done, I'll fill again, and observe the car's behaviour with respect to the clunk and chunky accel feeling. If it is present still, but somewhat diminished, I'll run another can of that cleaner. If totally gone, them I'm laughing. If nothing has really changed, and the better behaviour is just the result of variability within this problem, then it's square one. (or have a shop actually test the injectors one by one).

Thanks!

Massiv.
 

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Discussion Starter #9
Two more thoughts...

Pop through the intake would be consistent with feeling that clunk through the gas pedal. A sudden pressure change in the intake tract (especially when the pressure is suddenly backwards), could definitely cause the TB plate to move one way or another suddenly, transmitting this back through the cable to the pedal. <u>Very</u> interesting.

What solvent will you use to try and clean the injectors, and what is the procedure for hooking it right up to the fuel rail? Is this a "motorvac" or "terraclean" type of procedure?

Thanks,

Massiv.
 

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My dad is a service tech, and has a ton of hardware for crap like that. He has an aerosol solvent can that hooks up to the schrader valve on your fuel rail. You pull the fuel pump relay, and start and run the car strictly on the solvent.

It has been known to cure a number of ills...I'll post back next weekend on what happens - we're doing it to my car on Saturday.
 

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Discussion Starter #11
Bennet... That sounds good. Btw, if you need new injectors, BAT has a deal on them right now. $19/ea for 17lbs injectors. Check Here.

Massiv.
 

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Hey Massiv.. I have NGK Iridiums as well.. did you gap them to our specs... or did you leave them the way they came in the package?

One more thing... dont know if you know this but... what happens if gap is too small? Goods bads?
or... if gap is too big.... goods/bads?


Thanks....

anyone else help me on this? HOW THE HELL DO YOU GET THE VACUUME LINES OFF THE UIM? PICTS? I tried and failed miserably!
 

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Originally posted by: VanCityKitty
HOW THE HELL DO YOU GET THE VACUUME LINES OFF THE UIM? PICTS? I tried and failed miserably!
The holes where the lines go into the manifold are lined with a plastic sleeve. Take a small screwdriver, and press in on the sleeve only (I press in on the sleeve at the 6-o'clock position - that's the only spot that works for me). As you press in on the sleeve, pull out on the line, and it will slide out pretty easily. There's about 2 inches of line inside the manifold.
 

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Discussion Starter #14
VanCityKitty:

The NGK Iridiums are indicated as *** DO NOT GAP *** in the catalog. :biggrin: So no... I didn't gap them. The NGK specifies the correct NGK Iridium model with the correct gap for our application. I believe that the reason is because iridium is very brittle, and you could crack the iridium electrode if you try and gap them.

Massiv.
 

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coo coo.. yeah.. I didnt gap mine either but do you know what the NGK gaping was? I want to see if the gaping is the same from when I first installed them. BTW, how do you like the plugs? I have read alot of controversy on these vs double tipped platinum. Personally I felt like there were a few more ponies under the hood.. but maybe it was the neat packaging hahahaha. :goofy:
 

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Discussion Starter #16
I recall that the gap specifications are on NGK's site for the Iridums. I have also read the controversy, and I also agree with you that there were a few more ponies under the hood after I put these in. That, and I can afford to change my plus more frequently if they wear out quicker than double plats. Plats are for durability, not performance, in all of my experience. Besides... look at my plugs... I don't see any wear on the electrode or the ground strap... a few deposits, but no wear yet, and I drive hard <u>all</u> the time.

Massiv.

P.S. On StangNet, they put denso iridums into one of their project cars (might've been Project Bullit), and did dyno 2 more hp, back to back, averaged.
 

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thanks I'll look it up tonight sometime. I see what you mean by your picts. After running my NGKs over the summer they looked exactly like yours, the iridium tip was clean and the same height as from when I put them in. I'm going to clean the plug and check the gaping over the weekend, but its more of an excuse to check on the condition of the plugs :biggrin:
 

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Discussion Starter #18
Hey Bennet...

What happened with your motor cleaning exercises today? Btw, I have a NEW theory on what's going on with the rough running! Here it is...

The reason low RPM accelleration is rough is two fold. I think one part is the buildup in the intake system/combustion chambers/clogged injectors... but I think there's another reason as well. I thought about this today because I noticed that the colder it is, the worse this problem gets.

My thought is that when you have a shortram, the engine is seeing drastically different temperatures in air coming in at different times. I can see this, because I recently hooked up an OBD-2 scanner while idling, and was surprised that when it was -15 C outside, the OBD-2 scanner said the Intake Air Temperature was 72 F, or 21 C. That's a huge dif!

So, my thought is, when you're stopped, or idling at a light, the air under the hood is being heated rather quickly, and the intake tract is being filled with very warm air, but not for long enough to change the IAT's average reading that significantly. Then you start rolling, and the engine takes a big gulp of hot air, when it was used to cold air. The "rough" accel is the engine choking that down, probably with a bit of detonation, until airflow under the hood cools, and you start getting the good stuff again as you roll.

I'm picking up a CAI very soon, and my theory is that when I install it, I will notice much of the rough running improve. I will probably also do a Motorvac or Terraclean process to clean out the whole intake system and fuel injectors. It will be interesting to see which fixes it, or at least which reduces the problem more. I will post the results here.

Massiv.
 

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keep me posted... your theory sounds solid. I have a short ram as well, and I have thought of this too but didnt get back to it. :hitit:
 

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Discussion Starter #20
Ok... new theory. I've had multiple CEL's that are IACOE --> Idle Air Control Valve Overspeed Error... meaning, it's flowing too much. Actually, my idle is higher too. I think it's sticking, and gunked up, and letting too much air in, leaning me out, and causing detonation. That AND the shortram, intake tract, combustion chambers, etc.... (Have I covered every possibility yet?).

As soon as the freakin' temperature raises a bit here (Thursday or Fri it says it'll be zero, which is NICE for a change), I'll pull the IACV and clean the sucka out. If I still get the CEL, I'll replace it. In the meantime, the Cold Air Intake will be on the way. Probably also MSDS headers, and nicely worked over heads... those should hopefully fix something, and no doubt cause other problems! :)

Massiv.

P.S. Still waiting for an update from Bennet on how his fuel-line salvo went this weekend.
 
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