99 Explorer Startup and Idle issue

[ExplodeRG]

Greetings all, I have idle run issues with my 99 explorer 4.0 OHV. July 6th, I replaced the plugs and wires, Bosch Platinum, Bosch wires, Put on a new IAC and it was not a cheap one either. Everything ran great afterwards. On the 11th of July, while enroute home, it began to idle rough at lights and started dying at full stops in gear. I looked under the hood and found the DPFE module had began melting, and the exhaust manifold side melted right off of the module. I replaced it along with new hoses, and still have the same problem. After clearing the "brain", both mine and the exploder's, It will start up and immediately jump to about 2k rpm's and then down to approx 500 rpm's , rough idle and death. New IAC and New DPFE Sensor, and hoses. I am going for the EGR valve since it has 137K miles on it, but everything always happens after you get the title in hand( No EVR locally, have to order). Anyone had same symptoms? I am getting a OBDII reader tonight, but have not had any lights show up like the IAC caused in winter time. (Which resulted in better gas mileage, also reason for the new IAC, goodbye great gas mileage this winter). I know I probably left out something important, but if asked, I will respond with the answer.

Thanks in Advance

 

[BradE.]

Bosch plugs are garbage, and Ford motors hate them. I'd yank them and replace them with Motorcrafts and see how much that helps the problem.

 

[ExplodeRG]

No more Bosch plugs

They are gone (the bosch plugs), although the problem still exhists. The code scanner didn't work, (ISO Fail connect) turns out the support tech knew how to resolve that issue, before I described the problem. MAF sensor, is clean, TPS is clean, and the EVR is the next thing to replace. Wish I could find one locally...

However things are a changing. I can now get the engine to idle, remove vaccume line from EVR and connect it directly to the EGR valve...although rough, and it will keep running, I am suspecting that the IAC has gone bad in 6 days of replacement. I can re-install the old one and it does not change anything. I am not sure what changed the symptoms, although this morning, It seemed to be back like it was when this mess all started. Won't idle and goes from 300 to 500 rpm to 3000 rpm back to 300 to 500 and dies... I have inspected 500 miles of vacuume lines, and only found a lot of greasy dirt, I didnt see on the engine at first glance.

The Bosch plugs looked good upon removal. Each one was firing, no oil, no carbon deposits and no cracks...not bad for 136,000 miles. My last Eddie Bauer had 155,000 when I sold it for beans...

I'm scanning the codes again tonight if it works, and will post the codes it reported later. I removed the orifice tube, cleaned real good, but it didn't have excessive carbon buildup.. Guess the new pool will have to wait, Like an idiot, I think I'll get me a new exploder, I need more drama in my life, ....

 

[budwich]

How did you clean your TPS???? Anyways, I had some problems with idle especially high surges. Replaced the TPS (after replacing the IAC about 6 months earlier because of the "noise" problem). Problem has disappeared. Shorts inside the IAC give the computer false indications of where it thinks your throttle pedal is which results in it trying to do other things to overcome where it thinks you should be especially with respect to emission control / feedback. Cheap fix at $30.

 

[BradE.]

When was the last time you replaced the fuel filter?

 

[ExplodeRG]

Problem Solved

After all I have been through, trying to resolve this problem, I now have an understanding of the evnts causing this problem.
1) EGR Valve was defective, Old age caused the valve to stick open, allowing the exhaust gasses to circulate all the way to the MAF... nasty heat..
2) this evidently caused the DPFE sensor to burn up...(pics available upon request) the damage is clearly visible, it had a meltdown.
3) High pressure side hose melted off, and became a jetted heat source to the upper intake manifold.
4) Hot air jet, blew a hole in the upper intake housing. Now the gaping hole in the intake, is the problem, put my finger over the hole, Idles fine...very smooth and quiet.

I'd post the nice pics I have of the damaged parts, but I dont seem to be allowed to do that

P.S. Replaced the Fuel filter about 20 months ago, Day I bought it, I have the nice fuel filter tool and changed it out cause I could!

80.00 ACtron code scanner is nice, Digital readout for 80.00 (obdII) Autozone
But I wasnt getting and codes, no sensor malfunction=NO CODES!