shod

Asking for a little help on a 1998 Pathfinder 3.3 4x4.

Truck starts fine and idles all day long but when I put foot on the accelerator it just dies like I turned the key off. If throttle is pressed very slowly engine will rev up and above 1100 or 1200 RPM or when cold there is no problems. The problem does not trigger any trouble codes but I checked sensors anyway Sensors checked so far are, throttle position, full close/full open, temp, Mas, baro, but not the Map sensor yet. Also checked timing, vacuum hoses, air intake hoses and upper intake manifold. So far so good. This one has me stumped but good Any help would be appreciated. Thanks

rogoman

Several things to check:
- Possible major vacuum leak in the intake system. To check the intake system for a vacuum leak, attach a vacuum gauge to a full vacuum source. With the motor fully warmed up, the reading at idle should be 18 - 20 InHg. At 3,000 RPM, it should be around 21 InHg. If readings are under 18 InHg, check the intake manifold nuts to make sure they are tight. Also check the intake plenum bellows at the throttle valve and at the MAF for cracks or loose clamps.
- Possible bad MAF.
- Fuel pressure may be low or fuel pressure regulator may be bad. Tee-in a temporary fuel pressure gauge at the output side of the fuel filter. The reading at idle should be around 34 psi.
- Dirty spark plugs.
- Dirty air filter.

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shod

Thanks Rogoman, I've checked for vacuum leaks and not a one was found.
All rubber hoses where in good shape. Replaced MAF with known good one no improvement. Plugs, Fuel filter, and Air filter all new. air induction system clamps tight and no leaks that I could find. Fuel pressure I'll have to rent a tester to check. I did have a friends blue streak obd reader/analyzer on it and was getting some very odd timing read outs. Timing should be 15 btdc I was getting 7 to 10 btdc when warmed up but that was with tps still plugged in. His analyzer does not read real time it has about a 5 second delay. The replay show timing from -3 to + 63 degrees. A timing light at idle showed the timing to be right on the mark. The problem shows up only after warm up

FriendlyNismoTech

If the timing is changing that sporadically I would suggest looking into the Cam sensor, located inside the distributor. We've had several at our dealer where the little disc gets damaged and the engine will idle but will not take throttle. It would throw no codes either. That's where I would start.

shod

Thank you for your input Friendly, I finally got the time to check the cam sensor. The 120 degree checked at 5 volts in three positions and could hear relays clicking each time. The 360 degree checked 1 to 3 volts in most positions I would guess about 80 to 90 percent, with rest showing 4 or 5 volts. The manual that I have said should show from (zero)?)to 5 volts, could the weak output be part of the problem?
Thanks again for your suggestion.

shod

Thanks Friendly, you were spot on with the distributor, but not the cam sensor it was the coil leaking and shorting out intermittently I think it is because the shaft seems to be a bit worn. I could see it short all the way around easy to verify all six going off. Thanks to all that replied with their suggestions and thank you all for your time. Once again thank you FriendlyNismoTech.

FriendlyNismoTech

That's great, I had a good feeling you'd find it in the distributor but didn't expect a short internal. Glad I could point you in the right direction. If I can be of any other service please feel free to message me.