that blows that theory

[IVY MIKE]

so my 2000 sport with a 4.0 SOCH is having a surge issue. it will not get past 3500 rpm out of gear, but does have full range in gear. plugs, fuel filter, wires replaced. checked rail pressure, 60 ish PSI. thought that it might be a bad regulator, but from what i am gathering, that is nominal range. i did pull code, got a left rail lean.cleared code, no others logged at all.
with no codes, i dont know where to go.coil pack? sensors? pcm?
any help would be very much appriciated.
thanks

 

[Pensa]

I think the computer limits it to 3500 RPM when not in gear.

 

[Willard]

Correct it is limited in neutral and park. This is supposedly so you can't do a full on neutral dump on accident. Does the motor "bounce" off the 3500 RPM's?

 

[IVY MIKE]

Correct it is limited in neutral and park. This is supposedly so you can't do a full on neutral dump on accident. Does the motor "bounce" off the 3500 RPM's?

yes. but the engine also surged badly the other day, similar to a vapor lock. after a bit of cooldown, some power would return. no codes, fuel pressure 60 #. what do you think might cause this under load? what system is the limiter a function? PCM possibly? as i mentioned, i did have 1 lean left rail DTC, but have not been able to duplicate.
my '99 does not have this feature, so was this incorporated in '00?
the surging/balking does not seem to have a pattern. any suggestions on how to track down power loss with no code?
sometimes i think induction, sometimes ignition. i am stuck on troubleshooting without any direction to proceed, as i have hit what i think would be a logical course.
now i think TPS,MAF,MAP etc, but it throws no code.
suggestions on how to move forward?
thanks in advance

 

[IVY MIKE]

Correct it is limited in neutral and park. This is supposedly so you can't do a full on neutral dump on accident. Does the motor "bounce" off the 3500 RPM's?

would you happen to know if the fuel pressure is correct? '99 seems to be in the 40# range, 00 is 60#?
also, i cant seem to find any info about fuel press regulator. was this changed in 00, having a damper only and no regulator?

 

[gijoecam]

Fuel filter. You're checking pressures at idle. Put it under a load (revving in park isn't a load) and you'll likely see the pressure drop. Start with the fuel filter (and air filter if it hasn't been changed recently) and go from there. It could also be the pump or FPR (if it has one) but always start with the simple and obvious stuff first.

-Joe

 

[IVY MIKE]

both filters replaced already, and plugs, wires.
how do i determine if it has an FPR?
doesnt seem to be a lot of info out there on 'oo changes from '99 as far as an FPR