Random cylinder balance SEFI test failures. What can cause this?

[shojuan]

Brazing my EGR pipe got rid of a bunch of my codes (33, 41, 91. still get a code 25 sometimes)and did a great deal to restore the idle. However I'm still getting random cylinder failures during the cylinder balance SEFI test. Sometimes I just get one cylinder. Sometimes I get 2, 3, or 4 cylinders showing as bad. The wires and plugs are 4000 miles old. No oil in plug tubes (got new seals in there).

Strangely enough the car had no problems getting up to 115 mph last night. Since I fixed the leaky EGR tube I get 11 every time during KOEO, and sometimes code 25 during KOER. Got a code 12 once last night too, but the car seemed to idle fine.

What things should I be looking at?

Rick

<small>[ December 02, 2002, 07:22 PM: Message edited by: shojuan ]</small>

 

[luigisho]

I'm having a hard time finding the info. at ALLDATA. Usually its in there but can be very hard to find if you don't have the exact cross reference terminology. Try cross posting to the Techsho list on Topica.

 

[DougLee25]

You could possibly have an intermittent fuel injector problem. I have seen sometimes when the cylinder balance will be fine, then run it again, and a bad cylinder shows up. Turned out the be a faulty injector.

Doug

 

[SLOSHO89]

Hey rick,

How big was the hole in the EGR tube? Glad that that was part of the problem...at least that part is fixed. Is it still back firing? Is the idle good, or is it just better?

Efren

 

[shojuan]

SLOSHO89:
Hey rick,

How big was the hole in the EGR tube? Glad that that was part of the problem...at least that part is fixed. Is it still back firing? Is the idle good, or is it just better?

Efren

There were two nasty cracks on the short flex portion of the tube. The cracks went almost all the way around the circumference. I bought some brass rod for a buck and a cylinder of MAPP gas and brazed it up with two ugly beads o' brass. I would have been better off buying a piece of flex copper pipe (the stuff used for water heaters) for a couple bucks, cutting a length to match the EGR steel flex portion, cut out the steel flex portion and braze the copper piece in there. That would have been much neater and probably a lot quicker (plumber's rule of thumb which I ignored yesterday: Cut out the old rotten stuff and sweat in new good stuff. Don't try to repair the old rotten stuff.) No more stink in the engine compartment! A lot less stink out the tail pipe! Thanks for helping out on Friday, Efren! thumbs_u

The car seems to idle fine now, but the wife said it sputtered and "popped" when starting up this morning then drove fine. When she came home from work it again sputtered and "popped" during startup. Then I took the car and it sputtered and backfired a bit then drove fine. A few hours later the same thing. I think this means the CID might be crapping out so I'll get a new one later this week.

Maybe my plugs got a bit fouled while the car was running like crap? With the big air leak from the EGR the O2 sensors would read lean so the computer richens the mixture to compensate. Maybe this fouled the plugs a bit?

Rick

 

[SLOSHO89]

"Maybe my plugs got a bit fouled while the car was running like crap? With the big air leak from the EGR the O2 sensors would read lean so the computer richens the mixture to compensate. Maybe this fouled the plugs a bit?"

I'm Glad I was of help!! It wouldn't hurt to take the spark plugs out, clean them with some fine sandpaper and re-check the gap.

Efren

 

[luigisho]

Are you sure there's no vacuum leak still? Timing, spark, and vacuum leak problems can all appear similar. Just something to recheck.

 

[shojuan]

luigisho:
Are you sure there's no vacuum leak still? Timing, spark, and vacuum leak problems can all appear similar. Just something to recheck.

I'm pretty sure there's no vacuum leak still. But I'll double check, may as well. Keep the ideas coming, anyone.

Rick