klondike

1989 Sentra. ECM under the passenger seat- has the 2 led's with the small adjusting screw right next to it for retrieving codes.
I have 5 trouble codes on it now- don't have them with me or I'd post them. May have been 12, 23 or 24, 45, and ? Basically ECM, injector, throttle position, and something else- sorry about the lack of info. I am not where the car is setting. The check engine lite isn't on- if it has one at all.
I've read everything I can on ecm's/GA16i's on this site and others; have one of the small Chilton's manuals which is some help.
I've got the nissan trouble codes for this engine off the troublecode website.
What I can't figure out is:
1)- how to change from the default mode 1 on the ecm to any of the other 4 it says it is capable of going to. Not that I need to do that, but I can't seem to get away from just showing the 5 codes.........
2)- how do you erase the codes. I'll erase them and go drive the car and see which ones return to show me current problems, not some I may have fixed!
Well, anyway, the engine has started to run rough at times in the last few weeks.
I got all the air cleaner off today. I checked and replaced a few vacuum lines underneath it on the engine.
One, which I would say was going to what Chilton's book called the A.B. valve-( on the passenger side of the engine near the firewall)- from the manifold was clogged with carbon looking sludge. Cleaned the carbon out of the manifold connection and put in a new hose. Vacuum tested that valve and it moved up and down on the inside ok.
The second hose went to a vacuum switch (with 2 wires connected)mounted up on the firewall. Hose looked bad so I replaced it.
I am a little hesitant to mess with the injector at this time, cause I don't want to damage something I can't fix. I did put in a new fuel filter yesterday. While I had the line off, I put the fuel line into a bottle and let the fuel pump run, and it seemed to put out a lot of gas. No idea of pressure. Starting the car, the pump runs for about 5 seconds and stops, which I think is normal.
I could see down into the throttle body through a little screen towards it front and to what I think is the little filmy wire which is the MAF sensor. That area all actually looked clean. I sprayed Electric motor/contacts cleaner down in there and let it dry. That stuff leaves no residue. I also removed the MAF wiring connector. Had green corrosion on the connector and in the receptacle, also. Cleaned it all out, sprayed it, and put in some dielectric grease to keep it in good shape. I don't think that stuff will hurt anything.
Then, I buttoned it all up and started it. Idled smooth, even with the AC going.
Took it for a test run. No problem until the engine got up to the speed where the tranny shifts from first to second. Then it acts like either it's starving for fuel or not getting spark. By the way, I put in a set of autolite plugs a few days ago--- I know, bad bad bad. Need NGK........
If you carefully hold your foot in one place on the pedal and don't change throttle position, the engine will run a bit, then you can feel it bog down, then it will pick up and run, then bog, and etc. Don't smell unburnt fuel, but I am moving when it is doing this so I am at a disadvantage there.
Any suggestions- Throttle position sensor cause problems like that? Injector dirty?
I appreciate any suggestion to steer me in the right direction. Answer as many questions as you can- I asked plenty

no1see2me

Had a simular problem with my 90 sentra at one time with the surging engine and it is was a dirty throttle body injector, had to replace it. Cost was $249.00 if I bought it new but I picked one up at a junk yard for $5.00.

Are you throttle body or carbureted?

klondike

This engine is throttle body. With the chopper wheel distributor
What does it take to work on the fuel injector itself? Just in case I find out that is where the problem is?

klondike

This AM the car ran so bad, barely made it uptwon to my shop.
Runs good now.....I replaced about all the small diameter vac. lines on the engine.
Removed the EGR valve and tested it. The book says that the plunger should stay up for 5 or so seconds after you remove the vacuum, but it didn't. It did move up and down, though, and seemed to seal shut.
A valve right next to it, the "BPT" I think, removed and tested and it was ok. Just like the book said.
Then the AAV OR AIV, can't remember which. removed and took it apart and put a vacuum to its vacuum pot and it seemed to function ok.
Couldn't quite get to the screw at the bottom of MAF sensor, so I didn't take it out. Too many hoses and wires in the way. As a matter of fact, I didn't take any of the sensors on that side of the throttle body.
There are 3 wiring harness connectors on the passenger side of the throttle body. 1 for the MAF sensor, and 1 for the throttle position sensor, and 1 other beyond it I can't figure out for what. Took all of them off and cleaned them and put dielectric grease on them to keep out corrosion.
I read about a test for the distributor- crank angle sensor and crank position (I think they were). I had my other non working distributor there, so I hooked the wiring loom up to it, like the book said, and did the test.
First test failed- crank angle- but the second passed- whatever the name of it was.
Put everything back together, and it started right up. Idles good with the AC going, and seems to drive just like it used to.
Really have no idea what I fixed. Only thing I replaced were various vacuum lines.
I still had the 5 trouble codes and that may be because I can't erase them.
Help me figure out how to do that, if you can

MNPULSAR

One way to erase the memory is to disconect the battery (about 12 hours). the other is to go to mode 4 then turn the screw fully counterclockwise. To access modes turn ignition on, turn the the screw on the ECU fully clockwise - watch the lamps after flashing once is mode one (Mixture ratio feedback control) Two flashes is mode two (Mixture ratio feedback control) three flashes is mode three (Self diagnostic system - trouble codes) (turn back counterclockwise to retrieve codes) four flashes are mode four (Switches on/off diagnostic system) after clearing the codes go back and check mode three to see that you have a code 55 ( no malfunction). I like to leave mine set with the screw fully counterclockwise when finished. It is amazing what a leaking vacum line can do to your performance. I too at one time tried another brand of plugs - I was very disappointed - switched back to NGK happy again.

Nissan300ZXZ31Turbo

For the car feeling like it is dying when you move to 2nd gear, it really sounds like vaccuum problems somewhere. If your EGR valve is bad, I suggest you rip off the complete EGR system, unless you live in a state with air emissions. EGR valves send dirty exhaust back into your engine to be recirculated, which results in carbon build-up and destroys engines. I had a similar problem on my 240SX when it had the original engine in it, I could not figure out what was wrong with it, it would idle sporatically and act like it was starving for fuel or air. After I pulled it out, replaced all the vaccuum lines, fuel lines, fuel filter, and fuel injectors, it ran like a champ. If you have replaced all the vaccuum lines, I would suggest pulling the entire intake manifold off and taking some time to inspect each part... it is alot easier to do without that massive manifold sitting in the car.