Check engine light wierdness, need help

[Whisky]

Ok here's the deal. Every once in a while I get a check engine light, but it doesn't come on and stay on, it flashes. At idle it will go 3 seconds on, 3 seconds off over and over. If I rev it to 2000, it does the same thing, but faster, up to 3000, same thing but even faster, at 4000 it starts to skip a flash every now and then.

It doesn't do it all the time, just a couple of times a week. The problem is that it has now done it every time I have taken it for smog. All three times!

Nissan says there is nothing wrong, but offered to sell me a new ECU for 1200. Gee, thanks

Any help would be appreciated.

The car is an early 1995 OBDI

[Drift For Food]

The check engine light comes on...and the dealer said there's nothing wrong?

Error codes:
http://www.troublecodes.net/Nissan/9....shtml#95240sx

It's not the old fashoned check it yourself type. You need a diagnostic tool to read the code. Oh how I long for the days of my old GM where a paper clip and a list of codes would tell me all I needed.

Find a place that checks them for free, like AutoZone. They'll give you the code and tell you what it is, and it won't cost you a dime. Then go from there. It might be your oxygen sensor or your ecu. Find out what it is first.

[Whisky]

Actually, it is the old check it yourself type, you just have to turn a screw on the side of the ECU to change modes. It currently flashes 55, which means everything is fine (no codes stored). Actually, it almost acts like its stuck in its mode II diagnostic mode, but its not, and its intermittent.

I know EXACTLY what you mean about the paperclip in the old GMs. I had an 88 Iroc 5.7 and I had so many damn sensor problems I used to carry a paperclip in the center console so I could check codes anytime anywhere. Piece of garbage car, but hey, it was cool when I was 16 (and still the current bodystyle at the time, how sad).

Anyway, I still can't smog my Nissan because of some phantom problem, so this isn't proving to be much easier than the old GM was...

[Drift For Food]

Hmm, it's odd that it would light up the check engine light but not store an error code.

Have you checked out any Nissan forums? If you can find a good, large Nissan forum or a forum devoted to your car, you might find some helpful people that know what's going on.

[Whisky]

Thanks guys, got it figured out. Apparently the mode select switch was screwed-up and it was stuck in diag mode. I turned it back and forth a few times and now it works normally. Diag mode works fine, as does mode I, so the car is smogged and ready for a turbo now, heh.

[teamINERTIA]

next time anyone isnt able to pass smog because of a check engine light do what i do just pull the check engine light bulb it works fine when your in a pinch.

[Crabapple]

next time anyone isnt able to pass smog because of a check engine light do what i do just pull the check engine light bulb it works fine when your in a pinch.

lmao man great idea.

[Whisky]

It's not that simple. When you first turn your key to "ON" your dash lights, including, your CEL, light up for a second or so. Thats a called a "bulb check" and its meant to allow the driver to ensure that all of his warning lamps are functional. Smog shops use this "bulb-check" to prevent you from pulling the bulb if your car has a problem.

Sorry, no dice at any competent smog shop.