88 SE hesitation problems
 

Hey guys figured I would start a new post about this and whats going on now.
1988 max se 5 speed 98k

When I bought the car on my way home it had a little hesitation from 45 to 55 in 5th gear. and some hesitation from 1500 to 2000 at light throttle.

parts that looked new in the car
all rubber fuel lines
fuel regulator
fuel injectors
all the rubber hose look new

What I changed,
spark plugs
spark plug wires
all fluids
O2 because of code.
fuel filter
the cap, points and rotary looked almost new and nissan parts so I did not change them.
all three belts changed and both pulleys
alternator and battery because they died.

idle is perfect, cold 1500, and warm 700.

When it is warm and I come to a stop and with nothing running, no lights or heat/ac it will go down to 700 but then go back up to 1100 and do this back and forth and I can hear the exhaust like popping like its running lean. it then stops doing it in about 20 seconds and its random.

It still hesitation at light throttle but once it revs past 3k its fine or 1/2 or full throttle to 5.5k its fine.

But now it's hesitation on the highway even over 55 now so I can be going 80 and it's still doing and it seems to be getting worse. I kept it right at 2600 on the highway and I saw the revs going from 2550 to 2650 and they were in line with the hesitation. Rain or weather dose not seem to effect it either.

I did have a leak down and compression test done on it and it has bad blow by and compression was not good 115 to 125 in all 6. I was told this was the problem a deal with it but I do not think that's what the problem is. I think the car is running lean for some reason. It also started leaking oil from the rear valve cover:bawling: So it's a ignition, fuel or a sensor problem I think. But I have no idea how to figure it out. How did they find these problems in the 80s with out connecting/reading the ecu? I know you can read the lights/codes on the ecu but my year dose not tell you much. I asked around and no one even wants to look at the car.

If anybody has had this problem before or what part it has to be let me know.

Thanks

first pull the codes from the ECU it will tell you a bunch, next go though and replace all the vacuum lines, it's easy and cheep just do one at a time and take your time, odd things to check out, call Nissan and see if it's one that should have the injector recall done (depends on build date) a super odd thing to check is the fuel pressure regulator vacuum line make sure it has vacuum right at the regulator if not reroute the line from the regulator right to the intake bypassing the vacuum solenoid, the solenoid cuts vacuum to the FPR during hot starts but if it's stuck closed you will have full fuel pressure all the time and no change with intake pressure. Start with the recall and replacing vacuum lines, the idle control is mechanical for the most part, when you look at your intake there is the part that sticks out the back side on the left with 2 plugs one is idle up for the lights and heater motor and the other is higher idle for the a/c, the part that sticks out in the middle is the cold idle up...... but first pull the codes, and replace vacuum lines that is the best place to start.

no codes,

called nissan the car the injectors changed back in 2013 when it came out of storage.

I had friend that had a smoker so we tied it into the evap system we did not see any smoke coming from any of the vacuum lines at all. I figure if it was one of the lines it would show up then with the smoke.

it dose seem to hesitation more when it's raining out. outside air temp. dose not effect it at all.

I would test the water temp sensor and oxygen sensor first....then test your TPS....