abrupt CEL after tune up?

[1990LTD]

Motorcraft cap/rotor/plugs and Ford Racing wires went on today..car runs great, but very randomly (it might happen twice in two minutes or once then nothing for half an hour) my CEL will flash its ugly face on my dashboard. Accompanying this is a noticeable drop in power, but as quickly as it comes, it is gone again. It never lasts more than two to three seconds.



Any idea what's up? Checked and rechecked all of the points and connections before even firing it up and everything is snug. Plugs are all gapped identically. Could it just be burning up any unburnt funk that is in there from the previously misfiring cylinder(s)? I really have no idea.






Would a line coming off of the smog pump being broken have anything to do with this? Line was extremely brittle and broke, so both ends got capped for the time being until I cut its life support (AKA belt) tomorrow. What say you?

[1990LTD]

..I forgot to mention I checked the firing order like three times. Idles just fine unless that engine light shows up and it misses. Like I said, it goes away very quickly but I want to make sure it doesn't come back a while. 15426378, right?

[gadget73]

Check it for codes, the computer will tell you where to start looking. Could be a lot of things, but my bet is on EGR related problems. Need the code to figure out where to start tho.

[1990LTD]

thanks gadget73. Is the EGR system really complex? As in, if it's a problem in there, would I have to replace a whole whack of parts before the problem is remedied?

[1990LTD]

Actually the codes might tell me where it is in there...d'oh.

[1990LTD]

Does anyone think it could have something to do with that busted line coming off of the smog pump? As far as I could tell, it was just blowing warm air out..

[gadget73]

all told there are 3 parts in the EGR system, and they're actually not that difficult to check. EGR vacuum regulator solenoid, egr valve, and egr position sensor. A vacuum leak in the tubes will cause egr problems too, so it may be as simple as a leak at that rubber connector thing.

[1990LTD]

At idle when it does the CEL thing, it sounds like it almost stalls and the revs drop by about 200rpm, then it revs (surges higher than idle by a bit, then back down) back up. This morning when I used my automatic starter from the house, it DID stall. BAH!

What's a good normal idle speed in these boats? Idle set too low? D'ya think having the plugs gapped too wide or too thin could do this? Just random guesses since I don't know much of anything about cars other than what you guys tell me.

I'm taking it to the garage in the morning to have them hook it up to their fancy-pants computer to see what codes are going on. Is there a list anywhere of trouble codes and what they mean? Can I get the thing tested to see if there's a vac leak anywhere that might be causing it, or would that be the kind of thing that the scanner would tell them?

Again, sorry for all of these ridiculous n00b questions, but - I didn't disconnect the battery after taking the AC/smog belt off so could it be a possibility that sensors need to re-learn things after those pumps are taken out of commission? Probably a stupid question..

[1990LTD]

bah, just now i turned it over a couple of times, start, rev up high like it normally does, then back down...and down...and stall. if i give it gas as soon as the CEL lights up and it starts to dip, the revs stay high enough for it not to stall wtfffffff

[gadget73]

sounds like you may have knocked a vacuum line off. Those are vac leak symptoms.

[1990LTD]

I like the sounds of that. Time to learn about vac lines and just how fucking many we have under the hood

[Smokestacklightnin]

Check vacuum lines and look around for damaged wires to sensors. Without checking for codes It really could be anything. Dont think it would be smog pump related unless its the vacuum lines associated with it. I removed all that long ago, and actually improved performance.

[1990LTD]

I have no idea where to start looking for leaks, I wouldn't know a vac line from a conga line.

[gadget73]

With the exception of the windshield washer hose, any rubber hoses under the hood are most likely a vacuum line. The plastic ones are vacuum lines too. Just look for anything thats cracked, broken, or not connected to something.

[1990LTD]

Some rubber lines look like they're starting to crack around bends, but none are actually cracked through..just on the surface as far as I can tell.