# Check Engine Light MAYHEM



## fetalslap87 (Apr 19, 2010)

Hey everyone! How's it going?

My issue is that my check engine light has been on for a while and I was getting bad gas mileage. I replaced the O2 sensor and that didn't change anything. I did the self diagnosis and found out it was the E.G.R. valve. So I pulled the valve out and gave it a good cleaning and put back on the car. my check engine light when off within a minute of the test drive. About an hour later all of a sudden there was a slight loss in power during acceleration. It only lasted until about 3500rpms. Then the check engine light came back on. Now if I'm sitting at a red light, the check engine light comes on. Once I'm out of first gear it turns off then comes back on and goes off when I'm not accelerating. I went through and checked everything to make sure I didn't leave something unplugged or disconnected and nothing was. I haven't done the self diagnosis yet but I wanted to get some input on the situation. Any insight will help. Thanks for taking the time to read and reply.


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## jdg (Aug 27, 2009)

Whatever you do... Don't make any mention of what kind of car/engine this is happening on. Don't mention anything about modifications done to the engine. Don't do anything. Troubleshooting and diagnosing a problem is so much easier if we just guess in the blind.


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## fetalslap87 (Apr 19, 2010)

Well..... I assumed that posting in the *B13 91-94 chassis 1991-1994 Sentra and 1991-1993 NX* sub forum would pretty much make it as obvious as possible. Seeing as how you are a "Nissan Fanatic" I assumed you would know that USDM Sentra for those years only had the GA16DE and the SR20DE. In fact those 2 motors were your only option until model year 2000 when they upgraded to the GA18DE, SR20DE, and QR25DE. Seeing as how the Sentra SE-Rs are few and far between and I made no mention of it being an SE-R (which I am sure anyone with a 91-94 SE-R would brag about as much as possible), I figured that it was pretty obvious that it was a GA16DE. As for mods, all that is done to the car is a SRI (short ram intake in case you were unsure as to what SRI stood for) which was installed months before my CEL (check engine light) lit up. I was raised with manners and one thing I was taught was that if you don't have anything nice to say don't say anything at all. A simple "Hey could we have a little more details please so we can better assist you?" would have been just fine. It's posts like yours that give forums a bad name. I do not believe I need or would like your advice on the matter since you were not even sure what kind of car I was talking about even though I posted in the *B13 91-94 chassis 1991-1994 Sentra and 1991-1993 NX* forum. But thanks any way buddy.


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## jdg (Aug 27, 2009)

But you said none of that in the first place...so...waaaaaaaaaaahhhhh. Could assume a whole lot from a whole lot of nothing ya know. "Nissan Fanatic"? The tag under the name? Don't know where that comes from. Then again, I can diagnose 99% of my own problems, 'cause I know what I've got under the hood, on the trunk lid, etc. Ever heard of paragraph breaks? Or run on sentences?
But, you're right.
Try this. As far as the diagnosis goes... I'm assuming you did the 'turn the dial on the back the ECU' type that kicks out codes on the Check Engine Light? Did you make sure you put the ECU back into 'normal' mode?
You said the CEL now comes on while accelerating and goes off while NOT accelerating.
Well, that light may or may not have something to do with the ECU still being in a diagnostic mode, and it just might have something to do with a rich and/or lean trending mixture as determined by the ECU.
Just might...I guess you'll never know.


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## fetalslap87 (Apr 19, 2010)

the problem has been known and solved. like i said i wanted some input on the situation. so not only just a nissan master tech but an english teacher as well. i didnt know they bred the incest so well up there in hick ass north dakota. i hope you think of this thread when you're banging your sister later. maybe thats why youre such a negative person, cause you cant do any better. once again thanks for all your insight. im gonna go back to using the sr20forums cause the people on that forum are smug assholes that think they know everything about anything, enjoy yourself dude, im sure you are the only one who does.


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## jdg (Aug 27, 2009)

HA HA HA!! !! ROFLMAO!! Amazing!
That's a good one! You come up with all of that yourself? Congratulations are in order. Such grammatical prowess is surely to be rewarded.
Now then, how did you solve the "problem"?


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## chrismariscal (Jan 10, 2011)

Hey jdgrotte, my car is having the same issue! 
Since fetalslap87 didn't reply i thought maybe i could ask you. 
I have a 94 Sentra XE, GA16DE engine. It feels as if the acceleration is really delayed, and the check engine light keeps coming on then off, on then off. Like Fetalspap69 or whatever said, most of the time it seems to go off when i get into 3rd gear or so. 
Any suggestions? And what is the ECU? 
Thank you!!


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## jdg (Aug 27, 2009)

For starters, you can download the FSM...
Aside from that, what have you tried so far?


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## chrismariscal (Jan 10, 2011)

Well i should have mentioned that, im sorry. 
in the past two weeks i have: 
new cap + rotor
new NGK iridium ix plugs
new Bosch wire set 
new timing chain tensioner
new valve cover gasket set, and spark plug gaskets 
new thermostat and gasket
new oil pan gasket
new oxygen sensor 
new fuel pump 
new starter
new fuel filter
new air filter 
new gas cap 
flushed power steering fluid and new fluid 
did an oil change last night
and.. i think that's it. Some people are suggesting the EGR valve or the IACV, do you thing it could be either of the two? 
Thanks so much!


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## jdg (Aug 27, 2009)

Check/adjust timing...
Check/adjust idle...
Run a compression check...
Put a vacuum gauge on the intake and see what it reads at idle, and also before/during/after if you snap the throttle open/closed...


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## tlhingan (Jun 8, 2009)

chrismariscal said:


> And what is the ECU?
> Thank you!!


Engine Control Unit (a.k.a "the engine computer"). It sits behind your central console.
1.To access it, remove the plastic panel next to where your front passenger would put its feet. It's a metal box bolted down right behind your heater and AC controls.
2. Remove the 2 bolts and yank the ECU loose (gently!) and don't disconnect anything. At the back of it there is a little screw, it may be covered by a piece of plastic tape.
3. Turn your ignition key to the "On" position but don't start the car.
4. On the side of the ECU that was originally facing your passenger's feet, a little red little should've come on.
5. Using a screwdriver, turn that little screw all the way (about half a turn) as far as it goes without forcing.
6. Count slowly to 2.
7. Turn the screw all the way back as far as it will go without forcing.
8. Look at the little red light, it should be blinking. Count the long blinks and then the fast blinks. The long blinks indicate the tens, the short blinks indicate the units.
9. Look-up that number in a trouble code chart. Code 55 is "No problem found".
10. The ECU will cycle through all the codes it needs to report. When you're done, turn the screw all the way over again, count to 2, then turn it all the way back and turn your ignition key to off.


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## chrismariscal (Jan 10, 2011)

wow, okay ill do that. thank you.


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