[D Britt]

The following is my situation and problem. Any thoughts or comments from those more knowledgeable would be greatly appreciated:

Car: 2006 Elise
Miles: 11,300 (7,000 from prior owner, the rest are weekend, no-track miles)


While bedding in new front brake pads (accelerating and braking repeatedly), MIL came on. Bought scan tool, which returned 1301 and 1302 codes. Checked cams and no premature wear or rocker problems. Cleared the codes and car ran fine for next two trips. Last Saturday, drove car for about an hour and let it idle for about 20 minutes while I hooked it up to the scan tool. There were no codes and the car idled fine the whole time.

Started car the next day and let it idle for about 5 minutes while I checked the tires other odds and ends. Just as I was going to get in, car started idling roughly, went into limp mode, and then died. Codes were 1301, 1302 and cylinders #2 & #4 misfire. Cleared the codes and restarted. Idled fine for about 5 minutes and then started idling roughly. It seemed to "snap out of it" briefly when I hit the accelerator, but then went back to idling roughly. It then went into limp mode again and stalled. Codes were the same thing (same cylinder misfires). Bought new spark plugs and installed (coil packs looked fine). Cleared codes and went for about a 30 minute drive. No codes, no rough idling at any stop lights. Returned home and let it idle in the garage. After about 3 minutes, it went through the same cycle (rough idling, MIL, limp mode, stall). Codes were again #2 and #4 misfire.

I can't figure it out and I don't have much hair left to pull out. The car ran perfectly on the road. I even hit the 2nd cam 3 times and it behaved perfectly. It's like it has forgotten how to idle after a couple minutes. I unhooked the battery last night and will re-attach today in the vain hope it will "clear" the ECU and perhaps fix the situation. Could it just be a bad tank of gas?

 

[charliex]

its misfiring, 1302 says its misfiring badly.

could be all sorts of things, engine issues, bad gas, bad injector, fuel supply pressure/filter etc, voltage supply problems, dirty maf, dirty TB the list goes on.

disconnecting the battery doesn't clear the ecu.

 

[D Britt]

Yikes. What is so perplexing to me is that it runs fine on the road. I probably would have never noticed the problem if I hadn't let it idle for several minutes before and after driving. Wouldn't the problems you mentioned manifest themselves at all times, and not just during idle?

 

[charliex]

depends what it is, it could be possible for air leak to cause it to misfire and that won't affect it as much off idle, however if its misfiring badly enough to throw a 1302 then its got to be a decently big issue.

but i'd also say its not always easy to determine if the cars running ok at higher speeds, its not always obvious, it could be having issues.

the idle is pretty sensitive, so it'll pick up problems there more easily, say if there is a slight injector issue, but say it was a badly gapped plug it'll affect the power overall but you might not notice it.

the alternator could be not putting out enough juice, loose connection, bad battery too.

unfortunately its a fairly endless list.

 

[andykeck]

I had a similar sounding problem that turned out to be the coil packs arcing to the valve cover.

 

[tesprit]

I had a similar sounding problem that turned out to be the coil packs arcing to the valve cover.

+1, but mine misfired more when the engine was under load. It is easy to check though, just pull out the coils and look for corrosion deposits and/or oil and carbon deposits on the insulators.

 

[charliex]

those deposits appear on nearly every car i've looked at.

 

[D Britt]

CharlieX, you may have hit on to something when you say "voltage supply problems". I bought a new Optima red top battery in December when the stock battery went flat and could not be revived. Foolishly, I hooked a $200 battery up to a $25 Black & Decker battery maintainer. I put it on a timer so it only charged at night. A couple days before all this happened, I went in the garage and there was an audible electric crackling sound coming from the battery! I immediately unhooked the charger and started the engine for just a few seconds. The car ran fine and the crackling noise stopped. The next trip after that is when the idle problems occurred. Obviously, I haven't used the charger since. Any chance I damaged the battery with the charger and that has somehow caused my idle problems?

Many thanks for your time and thoughts.

 

[charliex]

i'd say its a definite possibility, it could have damaged the electrical system too, since the car is running ok, then its probably not a blown fuse, but i'd double check just in case.

 

[D Britt]

I would never have thought of that. I'll check the fuses tonight and probably pick up a new battery as well and see if that works. I'd gladly pay $200 for a new battery than $2,000+ for engine work.

 

[shay2nak]

doesn't a dirty MAF throw a code, too?

 

[charliex]

nope.

 

[kverges]

FWIW, once in a blue moon my trubo car throws a 1301. Par for the course, as the MAF is re-mounted in a larger diameter intake tube to keep it from maxing out and it also has no vane to smooth airflow, so at idle MAF can be erratic and the car just does not idle very smoothly, so the idle misfires are real.

Here is the interesting part. The 1301 codes have gotten less and less frequent, so the computer is learning something (fuel trims never change appreciably). Then I had a code a few months ago and coudl not clear it as I left my computer at my track house, and the MIL went out after a few drive cycles.

So it could really be a bad batch of gas in your case and, unless it becomes consistent, I'd not worry about it since the car seems to drive fine in all other respects.

 

[D Britt]

Well, I just checked the fuses in the engine bay and all of them are okay. I also installed a new Optima red top. Just idled the car for about 15 minutes and got several 1301 codes. Although there were no 1302 codes and no specific cylinder misfire codes, I still don't think I've found the cause of the problem. Looks like a 4-hour trip to the dealer is in order. Now I just got to figure out how to explain to the wife that my "toy" has crapped out on me after only 11,300 miles. I'll never hear the end of this one.

At any rate, thanks for all your input guys.

EDIT: Restarted again. 1301 code in first couple minutes of idle. then none for 15 minutes. Drove for 20 minutes with laptop hooked up to OBD. No codes. Back in garage, a few 1301 codes at first, but none for next 20 minutes. Idles much smoother than before. Pretty sure it was a bad tank of gas.

 

[charliex]

it certainly could be, or a combination of both. the cracking of the battery might have reset the adaptions in the ecu and it just needed time to reset.

 

[D Britt]

If I'm ever in Vegas, you'll have to let me buy you lunch and pick your brain for awhile.

 

[charliex]

Anytime