I am having some problems after replacing the injectors myself for my 94 maxima SOHC GXE. The CEL light isnt on now, but the car just stalls a few seconds after i start the car. I can step on the pedal and the engine runs ok. its still a bit shaky at about 2k-3k rpm. at 1k rpm its very shaky and is about to stall. at about 500rpm i can step on the gas to maintain rpm (yea its pretty bad to even run it at 500rpm) and a little more i can rev it back up into the 2k-3k rpm. its very difficult to keep the engine between 1k-2k since the TPS is misaligned.

I changed the injector b/c the CEL came on before and checked all injectors and found one that was bad (#2). replaced it with OEM injector from dealer and connected all hoses back and replaced a vacuum hose i broke. i double checked the color sticker (yellow) for my 94 maxima SOHC GXE.

When i disassemble the manifold i did change the two gaskets (upper and lower). however i didnt have a torque wrench so i tightened them up by hand and tried to be even (did them in reverse order according to the manual since the instructions were for dissassembly). I tried not to exert too much force on these screws. I only have one screw left over from the dissassembly and its a 10 or 12mm hex screw, no phillips head top.

The potential problems i can spot:
b/c i broke the injector clip and i couldnt find a way to get the injector fully into the fuel tube, the engine manifold was exposed to humidity for a day since it was raining. The hood is closed so it didnt get wet, but its a concern.

also, since i couldnt manage to get the injector all the way into the fuel tube, the fuel line was probably exposed to the air and/or the humidity.

the TPS is probably misaligned and when i attempted to recalibrate it, i had to pull the trottle to almost full to get the TPS to register. Havent tried to check the resistance yet but will when i get a chance to do a more comprehensive check on it.

The gasket between the throttle body and intake manifold cracked in half (top and bottom) and had to play around with it to get all 4 screws back in there. could this be the problem? i had ordered the gaskets and will be in tomorrow. not sure if i have time before class to put them in.


I tried to let the engine run (with me applying pressure to the pedal so it wont stall, kept it at around 2k-3k rpm) for at least a minute to try to eliminate the air bubbles and/or moisture in the fuel lines. After this time, the engine became a bit more unstable even at 2k rpm than when i first started the engine.

I tried searching around for solutions on google and forums.maxima.org through google and didnt really find problems people had after changing out the injectors. This is my first post and hopefully its not too far off topic.

Any suggestions would be great. A list of potential problems and trouble parts to look at would be great as well.

 

If the throttle body gasket is cracked and leaking, yes it could cause this problem. Air is sneaking into the engine after the MAF air flow sensor, so the engine is running lean and there is the vacuum leak because of it.
I would try dribbling a little carb cleaner or throttle body cleaner around this gasket area while the car's running and see if it smooths out when the cleaner is sucked into the crack. Don't get this cleaner on anything rubber or plastic and remember that it's flammable (smoking lamp is out).

 

Also,look back over your work area very thoroughly,on a big job like this,it is easy to over look a sensor harness/loose or broken vacuum line/etc..

Just give it good once over before replacing any more parts..

 

deff check for vacuum

when i did my KS replacement... i forgot to replace some vac lines

its ghey but you gotta do it
(i also have diff engine but vac line is a vac line )

 

Got a pic? That sounds really bad and other then a broken vac line is a likely cause. Are you leaking fuel out of any of the injector o rings or fuel lines? BTW I hope you put on all new fuel lines while you were in there....

~Alex

 

+1 for vaccum lines, might have routed them wrong, i've done it after replacing ve injectors, surge tank to somewhere it wasn't supposed to go

 

well i was in a rush to get it all back together cuz of rain/humidity so i didnt have time to replace the fuel lines. i didnt even touch them since if i did, thats prob one more issue i had to solve.

the only thing i was going to replace was the gaskets, which were extremely brittle in the first place.

i dont think its leaking fuel. i ran the engine at 3k rpm so it wud've prob saturated the entire compartment by now. I did successfully put in the injector fully in by just lubin the O-rings with clean motor oil (the kind for this engine). helped alot.

i didnt disconnect many vacuum hoses and they were mainly in different sections of the upper manifold so i dont think i confused them d=/. i will look at it once again to see which connections look out of place. i did make sure to look thru it all since i usually forget something. also, the only one i did crack i replaced. i have a whole reel of it so i can prob replace them all (going into manifold, of course). I'll prob go thru the tech. manual and follow where the hoses to the upper manifold go and make sure its all correct. very possible i swapped two lines, esp when i disassembled it on saturday and put it back together on tuesday.

my dad suggest just unplugging the spark plug on the new injector to see if the engine reacts the same. if so, then prob new injector bad. he then suggests to do it for each cylinder to make sure all of them are good. however, i didnt touch any of the other ones and i triple check their resistances to see if it was good and they were. is this a really bad idea? could the injector be bad even tho the CEL is not on?

also, going to a dealer is not a option since it'll prob need to be towed.

i have also read up on other posts and suggests to check ECU. in that guy's case, he did have CEL on. i'll check it out and see what it gives me.

i'll try to post some pics. what pics u guys want? i think the area of concern would be the place near the coolant line (upper right on SOHC manifold). theres a whole bunch of lines everywhere. i can try to take a few pics and then "stitch" them together. then u guys can just point to areas of interest so i can take more pics.

any other ideas welcomed and thanks for all the comments so far; weird stuff happens.

 

well problem solved. i had not tighten the IAC/AAC motor onto the manifold. i think i partially tightened it just to see if it'll crank. then i just forgot. once i tightened it, sounds like the engine from before.

thanks for all the help.

 

Glad you solved the problem without buying more parts...