Coil Pack Giving Up?

[DrumrBoy]

I think my coil pack is giving up, but before I change it I'll ask for others' experience.

Symptom is a breaking up at lower rpm under load. Feels like fuel/spark cut off...stumbling until the rpms get up to 4000 and higher, then it catches just fine.

If i"m easy on the throttle at lower rpms its fine, I can nail it above 3500 or so and its all good, but mash it when the rpms are lower, no dice.

Plugs are good.

Plug end and coil end of wires seem nicely connected (checked 'em all)

Wires look perfect, no observable blemishes


Anybody else experience this?

Happened on the track last weekend, 75 and sunny....not too hot not too cold.

 

[dave6666]

Fuel pressure? Fuel filter?

 

[99 R/T 10]

Have new plug wires? I had a set two years old and they looked great too, but they weren't

Is it the cam sensor that triggers the coil pack? That's what come to me if I was going to start looking at it. It's pretty rare for the coil packs to go bad. Not saying they don't. It is an easy replacement though. If it doesn't fix the problem, just means you'll have an extra coil pack for later down the road.

 

[plumcrazy]

im thinking cam or crank sensor too

 

[dave6666]

Isn't the crank sensor just for TDC and when you start it up?

 

[DrumrBoy]

Fuel pressure? Fuel filter?

God ideas, but I checked that....fuel pressure is good and I replaced the filter last year - so filter is probably not the problem (though I haven't taken it out to check...its a PITA). Plugs look fine too, no sign of lean.

Surprisingly the plugs are not wet either....probably because once it sparks and runs well, it burns up any wetness there might have been.

 

[DrumrBoy]

Have new plug wires? I had a set two years old and they looked great too, but they weren't

Is it the cam sensor that triggers the coil pack? That's what come to me if I was going to start looking at it. It's pretty rare for the coil packs to go bad. Not saying they don't. It is an easy replacement though. If it doesn't fix the problem, just means you'll have an extra coil pack for later down the road.

I can try different wires....probably a good thing to do to eliminate the possibility of a frailty that isn't visible.

Regarding the cam sensor.....I'm not familiar with the failure modes of that device, but if the sensor is a binary thing.....sensing or not sensing.....then why would the amount of load make the spark problem happen or not happen. Not challenging the idea, just don't understand it.

 

[bmw2nv2000]

I think I am experiencing the same thing.

 

[George Farris]

Had same issue on my 2002 GTS - changed wires - that was it.

The wires were less than 2 years old and had less than 8K miles on them.

 

[DrumrBoy]

Doh! that was supposed to be "good" ideas, though Dave is somewhat of a Viper-knowledge diety anyhow.....didn't want any Sunday morning blasphemin' going on!

God ideas, but I checked that....fuel pressure is good and I replaced the filter last year - so filter is probably not the problem (though I haven't taken it out to check...its a PITA). Plugs look fine too, no sign of lean.

Surprisingly the plugs are not wet either....probably because once it sparks and runs well, it burns up any wetness there might have been.

 

[99 R/T 10]

I can try different wires....probably a good thing to do to eliminate the possibility of a frailty that isn't visible.

I will say it first, get a set of ab's wires (home)!

Regarding the cam sensor.....I'm not familiar with the failure modes of that device, but if the sensor is a binary thing.....sensing or not sensing.....then why would the amount of load make the spark problem happen or not happen. Not challenging the idea, just don't understand it.

Me either, I was just thinking out loud, but I believe it or the crank sensor si used to fire the plugs in the proper sequence and if they have an intermit failure, then it could be the problem. Either way, I would start with the wires, then call Chuck Tator, the real expert in these matters

 

[RTED]

I had what sounds like the same symptoms on my Gen I last year. The throttle bodies were slightly out of sink. I was heading down the same path considering new plug wires, coil packs, etc. I was surprised when the problem went away and did not return all year following synch of the throttle bodies. Worth a try!

 

[DrumrBoy]

I'll definitely try the wires first and will check the TBs.....will report on what the heck it turns out to be when I find out.

Thanks for the input and suggestions.

 

[Sweet Ride]

Check the throttle position sensor.

I doubt it's the cam sensor as you would likely notice a failure across the entire rev range and it would more than likely throw a check engine light or code as well.

 

[dave6666]

Paint your hood vents white. I've seen simpler miracles.

 

[Sweet Ride]

I'll definitely try the wires first and will check the TBs.....will report on what the heck it turns out to be when I find out.

Thanks for the input and suggestions.

Any updates?

Did you check the MAP as well?

 

[Joseph Dell]

Let's not forget that the car has an AEM on it. There may be info in the data-log that will help you figure out the problem. It isn't the crank position sensor or the cam position sensor most likely. coil packs are easy to test, so you can get /borrow a replacement set. we've been talking about wires on that beast for quite some time... now's the time! and maybe plugs if you haven't done them since you last raced...

damn, i just noticed this thread is months old. Bob - give us an update!

 

[DrumrBoy]

It went on the dyno (Ed did the look-see) and the fuel maps were off....A/F curve not nice and flat. He asked whether I had changed the program, nope. He wondered whether you changed the fuel maps and I told him nope, just the idle portion which I think you and he discussed (or at least he saw in the program and credited you with a "that's actually a good trick for managing idle" comment).

For the past two months, the shop has been way slow, changed the steering rack, replaced the control arms because I melted my grease boots over the balljoints, aligned it and then, stupid stupid me, I said - paint the fascia since Scott the knucklehead curbed it. The paint job was the kiss of death.....ain't seen my car's "face" in a month.....seems like every frikkin Accord that crashes in the rain gets in line ahead of me.

Enough complaining.....

The only thing I can think of is that something changed when you and I did the exchange of the Performance PCM. I can't really see how that could change any settings in the AEM, but your idea of checking the data in the AEM is a wise one.

Ed can re-load the original tune and check it on the dyno next week (so I'm told). If I still miss, then can substitute coil packs, check all connections (for the fifth time!) and replace the wires.

I'm hping to not get kicked out of the VCA for not having the car for too long....what's the limit, 3 months?

 

[Bob D]

I had a 4000 rpm breakup issue that I couldn't figure out even logging the AEM. One day when testing it broke up and just went dead. I had no cam sensor signal and removed the sensor and found the end had been knocked off by the cam sprocket. The cam bolt was loose enough to make the sprocket wobble. I hope that's not your problem because it's a pain to get to.

Woops, after rereading your post I see you have a low rpm/ load problem.

 

[DrumrBoy]

Bob, thanks for that tip. I'll check that too if review of the logging doesn't answer the question. I'll post the result (and hopefully the fix) as soon as I get the data. Its just taking forever.....

 

[Red Shift]

Hey Drumr,

I just got this low load/RPM cut out on Sunday for the 1st time. I did change my spark plugs last week, but that's the only work I've done lately other than tuning my VEC. It felt like the entire fuel or ignition system shut off for ~.2 seconds as I was at a lower RPM and adjusted to about 50% throttle. I got it twice from leaving a stop light and giving a bit more gas and once on a country road when accelerating some. Is this the same you've noticed? I'm interested to hear what you find and I'll keep you updated too.

 

[Catwood]

Check the throttle position sensor.

I doubt it's the cam sensor as you would likely notice a failure across the entire rev range and it would more than likely throw a check engine light or code as well.

It won't always through a code as I've recently learned. They can start partial failing under hot it would appear.

A&C has some recent experience with an intermittant failure that seemed to be heat related.

 

[bluesrt]

 

[Red Shift]

It won't always through a code as I've recently learned. They can start partial failing under hot it would appear.

A&C has some recent experience with an intermittant failure that seemed to be heat related.

How do you check the TPS? I read the output on mine a few weeks back with an OBDII reader and everything seemed fine (Somewhere around 20% @ idle and ~80% @ WOT - the butterflies open all the way). I was checking out an idle/low RPM flat spot at the time.

 

[RedSrt007]

Ive got a basically new set of coil packs (both) that I took off my car (9k miles) that I thought was bad...turned out to be the VEC, I will sell them if you need a set.

 

[DrumrBoy]

Waiting on a new set of O2 sensors as the last step in the process of eliminating variables. The AEM program shouldn't change so if its getting all the right signals, it must be spark.

I'll post results when we figure this out.

 

[Red Shift]

Ive got a basically new set of coil packs (both) that I took off my car (9k miles) that I thought was bad...turned out to be the VEC, I will sell them if you need a set.

What failed with the VEC? I'm thinking my VEC is having problems. While logging 3rd gear pulls the MAP signal will sometimes completely drop off for a short time, just a spike on the graph to 0. This also drops the water/**** signal because boost pressure is a trigger for it. Did you ever see this when you tuned the car? (Carlo's car)

 

[RedSrt007]

What failed with the VEC? I'm thinking my VEC is having problems. While logging 3rd gear pulls the MAP signal will sometimes completely drop off for a short time, just a spike on the graph to 0. This also drops the water/**** signal because boost pressure is a trigger for it. Did you ever see this when you tuned the car? (Carlo's car)

No, never saw this when it was finalized, I would check the vec....For mine, the harness prong "legs" were bent to far open, causing non-contact issues. Some tweezers fixed her right up. As for the W/M, Log the PWM and the A/F's, also log the internal map of the vec (don't worry about the stock map).

-Red

 

[Dom426h]

I'll post results when we figure this out.

any progress?

 

[DrumrBoy]

Dom,

Good timing on the prompt!

I have been on the road for a month doing different track events (with another car) and just recently got back to this one this past weekend.

Changed the wires though they were all decent looking and noticed that the rear most drivers side wire looked dodgey, not terrible, but bent funny and not entirely round. The wires were relatively new and stock mopar (which I wouldn't recommend after seeing how it bent).

I also noticed that some of the wires pulled off the coilpack easily while others seemed more firmly attached. When I checked 'em before, I took them all off and put 'em back on, I thought carefully, so either I didn't get them on perfectly or they loosened up. If all the loose ones were bad connections, I don't think the car would run at all so that might not be the issue.

Though I'd normally attribute this to my sloppiness, when I took them off the first time, they were the same way....some looser than others. Possibly the boot or the inside fitting being different from wire to wire? What I wish i had done but didn't is make a note of the wires that seemed loose to see if it was the same ones both times....but I didn't. Duh.

Installed Taylors and it seems like the problem has gone away. So it was either the dodgey wire or the looseness at the coil pack. I'll drive it around a while and then takle the wires off at the coil pack to see if some of the Taylors are as loose as the stockers were......if they are then it was the dosgey wire. If not, then I'll never know.

Morale of the story, "even if you visually inspect the wires carefully, take them all off at
both ends to be frikkin' sure!"

Now if I can get the AEM to idle, I'll be all set.