Engine dies on slight acceleration under load, or sudden acceleration no load

[Rftomlin]

I have a 94 nissan Altima, when you first start the car, it is harder to start. It has never took more than several cranks to start. When car starts, and you quickly accelerate, the engine doesnt respond quickly, it wonts to die. like not getting air or fuel fast enough. if you accelerate slow it does ok. If you put in under load engine will only run with slow acceleration, if you give it to much acceleration engine will stall out and die. The ECM is leaving a code 34 which is the knock sensor but the car has ran with this code for several years, no problem. maybe the engine is getting worse, or the knock sensor has gotten worse and retarding the timing to the computer? I have checked maf sensor with dvm meter checks ok. replaced distributor, and cap, wires, spark plugs, checked egr, fuldel pressure 32-42 psi, checks ok, replaced fuel filter. no other codes left in ECM. Engine has been making a rubbing noise for several years, dont know where its coming from had a mechanic look at it he couldnt tell where it was coming from. but it has never affected engine performance. The engine leaks some oil i believe around the rear main. but i keep oil in it. I dont know what to check, if anybody has ideas what it could be or what I could check I would greatly appreciate it. I have usually been succesful with figuring it out my self with ECM error codes and A dvm, but this one has got me stumped. Thanks for any advice you could give Randall T.

[IvoryJ30t]

try to get a fuel pressure reading under load.

did the fuel filter help slightly?

[Rftomlin]

Thanks Ivoryj30t The fuel filter was partially stopped up, you could barely blow through it. after replacing it, it did not help any. We did put a gauge on it underload, the pressure seemed to remain around 32-40psi. we disconnected the fuel pressure regulator, made no difference in reading. The other evening after car was continually acting up, I disconnected the connector to the MAF sensor, car would not run it would die. Reconnected the MAF connector, it left a code for the maf sensor, and the code 34 for knock sensor, I cleared both codes in the ECM, after that i got in the car and the car did not stall or act up or die after that. I drove it several blocks no problem. it just quit acting up all at once. Its really crazy! Could it be the ECM glitching. Tried starting up yesterday. cold start, after about 5 min, doing same thing again. stalling lack of sudden acceleration. Cleared 34 code again. This time did not help. I have no clues Thanks for any help! RAndall

[IvoryJ30t]

sorry, ive been busy.

thats strange though.

one thing to try- open the hood at night [VERY dark]see if there is any arcing from the spark plug wires.

on my first DSM, i changed the spark plugs and wires. the car developed real bad hesitation at anymore than 50% throttle above 3k rpms.

i ran cans of combustion chamber cleaner, changed the plugs again, did everything i could but nothing worked.

until i opened the hood at 1am in the total dark. two wires were arcing really badly to the FPR. i taped a rubber block eraser to the FPR and the problem was completely solved.

basically, what i am saying is- dont overlook a single thing. check every ground- ohms from the negative batt terminal to the ground pin of the maf, ect...

try to get the specs for the sensors and check them all...

and change that knock sensor!! check the wiring also.

[Rftomlin]

THanks again ivoryj30t. its going to be a slow process, but I know thats what I need to do, to try to fix it myself. I will keep you posted. if you have anymore ideas, please let me know. Thanks againRandall