Idle Surge on 2005 4.0L V6 ST

[Peg Leg]

I drove my 05 ST to the the beach(windy) and when I got back home I noticed the engine compartment was covered with dirt, so with engine running I washed it off with a garden hose and sprayed with WD40. I took it for a 4 mile drive to dry the engine, and when I got back and parked it in the garage I noticed the engine was surging slightly while in park at idle. The next day I start it up and take off to the gym, and when I get there I put it in park, the engine surges drastically, shudders and shut off. To start it, I had to push on the accelerater pedal and and hold slightly when I put it in drive to drive it home. At some points it drove and accelerated fine but at other it would not take throttle at all, and I would finess the pedal to keep it going but finally made it home, Also on the way home the check engine light came on. I drove it over to Auto Zone and they pulled the codes. The codes were0191, P0190, P2198, and P2196.



Did I short out the MAF , which causes a report of a rich reading/condition(P2198) to the ECM which in turn tries to to lean to spec, but cannot because the MAF/O2 sensor is reporting a way rich condition, and the PCM reports a low fuel pressure(P0190) because it cannot supply the required amount of fuel to meet spec. When it surges low and shutters and dies, there is a bad sulfur smell and black smoke(rich) comming out of the tail pipe. Dont know which code it throws first, but if I did I would have a better idea where to start.



Also I added about 8 ounces of Lucas transmission additive to the auto transmission just before I washed the engine. Could this cause a false lean/rich condition to the ECM or PCM by gumming up the torque converter.



Has anyone had this or something similar happen to your ST, and where should I start to solve the problem. This is the first problem that I have had in 160k miles on this ST, and I clean the engine regurally with water and WD40. Thanks ahead of time for any help I may receive.

 

[EddieS'04]

Never wash a modern ECU controled EFI motor with cleaners or water hoses or steam clean.

To many critical low voltage sensors and connections. That may get contaminated or wet.

I wont use wd-40 on connectors nowdays either.



I will use crc electrical cleaner or other brands that are safe for plastics and rubber. To clean electrical connections. It is usaualy alcohol based. Evaporats fast and no residue.



You may have shorted some things. Or you still have wet connections that wernt sealed well. Or even the wd-40 causing intermitent connection problems.



If it was running ok before. It may need to dry out good or do some connection cleaning.

 

[Peg Leg]

Hey Eddie



Won't do it again, and the, water in harnass, is one of the causes for the ECM/PCM/ECU to throw the P2196 and P2198 codes.



I have the truck in an air conditioned garage, and I raised the hood and put 2 floor fans on it for 2 days, detached all the connecters and blew out with compressed air but, no change, still when I start it up it runs regular for 2 or 3 minutes then starts cycling/surging between 500 and 1500 RPM for about 2 minutes until it sputters and dies. will start back easy with a little pressure on the accelerator, but does the same thing again.



Looks like the O2 sensers are reporting a rich condition to the PCM and the PCM shuts off gas supply and the fuel rail pressure sensor reports low fuel pressure or vise-versa.

 

[EddieS'04]

If you threw cold water on the hot O2 sensors. You might have damaged them. That would be the 2 front ones. Or the wash down shorted the fuel pressure sensor. causing it to give the ecu a wrong signal. Or both are damaged.

I will try to get time to check my '04 ford manual. To see if there is a way to check the sensors with a vom.

Right now I have one of our members coming over. Do some work on his '07.

 

[Peg Leg]

Thanks Eddie



Don't know how you verify, but a Dianostic Trouble Code website, states that the Fuel Rail Pressure Sensor's(FRPS) VREF voltage should be between 4.0 and 6.0V. Cant find anything else that explains how to test a pressure sensor.



Do you know what VREF means.



The Auto Zone code tester reccomends, replace fuel filter, then replace FRPS, then replace Fuel pump if the first doesn't solve problem. I guess that's one strategy to start with, but I would like to test the components first because no one will take back electrical parts that have been mounted.



PL