Newbie with a couple problems

[interceptor859]

Hello all! I am happy to now be apart of the Explorer forum of which seems to be a pure wealth of knowledge! I tried using the search feature, but could not come up with a definitive answer. I have a 99 Ford Explorer Sport 4WD 4.0 SOHC which is having idle problems. I was actually given this vehicle by a family member. The first time I started it, the CEL was on and idle was terrible. It would idle fine, then eventually idle down to the point it would shut off. The next morning I went to start it and the battery was dead. I had to replace the battery which in the meantime reset the CEL so I cannot scan for any active codes. I bought an IAC Valve today (slightly expensive) just to see if that would cure the problem. It seems that if it did help, that it was minimal. I am stumped. There is no active CEL to scan a code from, so im not sure where to start. The fuel pump does seem a little louder then most Explorers but not to the point that it would be going out. I would like to be able to return the IAC as it doesnt seem to be the problem and use those funds to put towards the real problem. Does anyone have an idea as to where to start? It will idle fine sometimes but if you are in a small area where idling at low speeds it nearly dies out and sometimes at a stop light it will idle down to the point of nearly stalling. As stated above, the IAC seemed to help MAYBE minimal at most. Thanks in advance for any advice!

 

[GreenMachine342]

Vacuum lines? Torque converter?

 

[Jstcruz]

Check out the TPS and clean your MAF. May help with the idel issue

 

[interceptor859]

How would I go about properly clenaing the MAF? I cleaned the throttle body, and as stated above I replaced the IAC. Also replaced all plugs and wires, as well as both upstream o2 sensors. I am purely stumped on this issue. It will not trigger the CEL is what has me puzzled most. My wife stated that back before her mother gave us this vehicle, that sometimes it would actually stall out when driving down the road at random. It doesnt seem to be trying to do that anymore, but the idle does still have some issue. It shows itself most when in an area where using the throttle at minimum and when I let off the throttle the RPMs drop WAY low and the lights will dim for a second until it recovers to regular idle speed. Thanks for the timely reply!

 

[interceptor859]

Oh and I forgot to say that there appears to be no vacuum leaks. I sprayed ether around all possible leak spots as well as listening and could not find the first sign of a vacuum leak.

 

[1992fordgreen]

Throttle position sensor. replace that and it should fix.

 

[Jstcruz]

Throttle position sensor. replace that and it should fix.

I would not reccomend replacing this - at least before it is tested. It is possable to "adjust" the TPS, which is also a good place to look for idel issues.

There are a lot of helpful threads on here about testing the TPS and cleaning the MAF. Unfortunatly -and Im sorry- I dont have time to get you the link but by using the search button you can find plenty to get you going.

 

[interceptor859]

I have searched, and cleaning the MAF sensor seems extremely easy. I will be cleaning it and replacing the TPS tomorrow. One thing I forgot to mention, there seems to be a very light fuel smell from time to time. I have eplaced the fuel filter, and re-checked all connections after replacement to ensure no leaks. Is there anything that would be causing the fuel odor? As stated above, the upstream o2 sensors were replaced which didnt seem to fully solve the problem.

 

[PRNDL]

lower intake o-rings

 

[2000StreetRod]

Park vs drive?

Does the engine idle too slowly when in Drive but OK when in Park or Neutral? If so, check the brake pedal position switch. It notifies the PCM when the brake is applied. If the brake is applied and the throttle plate is closed as reported by the TPS the PCM unlocks the torque converter.

If the engine idles too slowly in both Park and Drive then test the TPS and check the fuel pressure. See Ford Explorer - Ranger TPS Test Procedure and Ford Explorer Ranger Fuel pressure test procedure

Does the engine idle too slowly when warm and cold?

 

[1992fordgreen]

TPS is a easy to replace car part and isn't that expensive. Test it if you want, but if it had a problem before, you would probably want to replace it so it won't happen again. just sayin...

 

[1Aauto]

Welcome to the site

 

[interceptor859]

Just an update, I replaced the TPS and cleaned the MAF sensor. Still has some minor issues. The problem is most noticable when: I sit in park with the air conditioner on high, rev to 2000 rpms and once the compressor kicks in and begins to put a load on the engine, I let off the throttle and the rpms drop to below 500, (appears to be 300 or so) and nearly stalls. I cannot figure this thing out for the life of me. Any suggestions are appreciated. I have not noticed any coolant leaking either, just as a bit of background info. Thanks everyone!

 

[GreenMachine342]

Just an update, I replaced the TPS and cleaned the MAF sensor. Still has some minor issues. The problem is most noticable when: I sit in park with the air conditioner on high, rev to 2000 rpms and once the compressor kicks in and begins to put a load on the engine, I let off the throttle and the rpms drop to below 500, (appears to be 300 or so) and nearly stalls. I cannot figure this thing out for the life of me. Any suggestions are appreciated. I have not noticed any coolant leaking either, just as a bit of background info. Thanks everyone!

Theres something that is supposed to compensate for the ac but cant think of it for the life of me...

 

[1992fordgreen]

Check the throttle linkage bolt, which is under the plastic cover right above the TPS. If it is at all loose, tighten the bolt. Did you find the "sweetspot" with the TPS? The TPS requires a little bit of twisting and playing around with...

 

[anton008]

Anyone else have the problem of the TPS not checking ok? I have had 3 TPS 's I have put in , 2 of which the spring inside was busted, but even the borge warner one in there now I am still getting a code saying the Maf doesn't recognize the signal. Tried to test it it says .94 at an idle but when you open up the throttle the voltage doesn't increase. Any ideas?

 

[interceptor859]

I have encountered yet another problem. The explorer has now developed an extremely irratic idle during cold mornings (temp 45 degrees or lower) but smooths out once the engine reaches regular operating temps. During cold mornings it will idle up really high then idle down, going up and down repeatedly until it stalls out completely but as stated above it straightens out after the engine warms up. I have been directed by others to the intake gaskets that they must be leaking. Can anyone else confirm or deny this? I just need to get this issue fixed. Thanks everyone.

 

[GreenMachine342]

New intake and fuel rail gaskets, make sure to use dielectric tune up grease on the seals