98 AWD 5.0 Giving me major problems

[rbraden4]

I picked this Explorer up from a friend who scaps vehicles. I dont know the history behind it all I knew was it was really clean and did start up so I took it for 8oo.oo

Long story short, it had a bad miss I narrowed it down to cyl 8, tried swapping the plugs, wire, with no change so I went to check compression and it was good but when I relieved the psi the gauge shot fuel out. So I hooked up a Fuel PSI gauge and jumped the pump and sure enough the number 8 injector was stuck opened. I just finished replacing the injector and the shacking and missing at idle is gone. Motor seems to run smooth at idle.
But when you take it down the road anything above 35% throttle it seems like its missing hard and wont clear up. Today it got worse so I replaced the plugs and wires and still no change, cleaned MAF, checked for vacuum leaks, checked fuel psi driving. I still cant figure it out.

I have a scanner and notice at idle the TPS is showing 20% and to the floor I can only get it to read about 82% I do have 2 codes, O2 B1S2 which I can see is dead and not reading anything, and EGR flow because the EGR tube off the manifold is broken. I dont think these codes are making it do this but I could be wrong.
So far im thinking I jumped the gun and replaced the injector and thought it was good but number 8 might have washed the cylinder, or the excess fuel in the exhaust might have plugged the cats.

Tomorrow afternoon I will be checking compression on all the cylinders, and hooking a back pressure gauge up to the O2 sockets and seeing if the cats are shot.

Aside from that if these check out, can anyone think of anything else?

 

[1996BLKBauer]

I picked this Explorer up from a friend who scaps vehicles. I dont know the history behind it all I knew was it was really clean and did start up so I took it for 8oo.oo

Long story short, it had a bad miss I narrowed it down to cyl 8, tried swapping the plugs, wire, with no change so I went to check compression and it was good but when I relieved the psi the gauge shot fuel out. So I hooked up a Fuel PSI gauge and jumped the pump and sure enough the number 8 injector was stuck opened. I just finished replacing the injector and the shacking and missing at idle is gone. Motor seems to run smooth at idle.
But when you take it down the road anything above 35% throttle it seems like its missing hard and wont clear up. Today it got worse so I replaced the plugs and wires and still no change, cleaned MAF, checked for vacuum leaks, checked fuel psi driving. I still cant figure it out.

I have a scanner and notice at idle the TPS is showing 20% and to the floor I can only get it to read about 82% I do have 2 codes, O2 B1S2 which I can see is dead and not reading anything, and EGR flow because the EGR tube off the manifold is broken. I dont think these codes are making it do this but I could be wrong.
So far im thinking I jumped the gun and replaced the injector and thought it was good but number 8 might have washed the cylinder, or the excess fuel in the exhaust might have plugged the cats.

Tomorrow afternoon I will be checking compression on all the cylinders, and hooking a back pressure gauge up to the O2 sockets and seeing if the cats are shot.

Aside from that if these check out, can anyone think of anything else?

Damn, you have done some very extensive diagnosing, that is awesome. to be honest, I have ALWAYS been told to take care of any old CELs first, before blaming anything else. It may be a good ide to fix the 2 CELs, and see if that helps.

Last week we had a Jeep Cherokee in the shop, and it was a crank no start, we found that fuse #20 was blowing, which was for the ECM, we replaced it, it would blow again, and again. So we did some research, and found that it fed power to many other things including the o2 Sensors. We though that it didn't help us until we brought up the check engine light on the dash to the owner, he said that one of the o2 sensors was just floating around in the cat, and that it had been like that for a long time, well what we found was that the o2 sensor fell into the cat, melted the wires, and was shorting out. unplugged the o2 sensor, replaced the fuse, it started up, and ran fine.... long story short, follow up on CELs, because the issue you have now may be caused by them.

 

[FordGT55]

If the converter(s) were bad there would likely be a cat efficiency code. Also the converter that would be bad would be bank 2 so the O2 code would need to be on bank 2. Though both an oxygen sensor and egr can cause a miss. But likely the egr more so. Cylinder 8 should have a lower compression than the others if it was washed. Have you cleaned your throttle body or TPS sensor? Does it actually miss at higher rpms or bogging down? Sorry for the grammar on my ipad.

 

[rbraden4]

Damn, you have done some very extensive diagnosing, that is awesome. to be honest, I have ALWAYS been told to take care of any old CELs first, before blaming anything else. It may be a good ide to fix the 2 CELs, and see if that helps.

Last week we had a Jeep Cherokee in the shop, and it was a crank no start, we found that fuse #20 was blowing, which was for the ECM, we replaced it, it would blow again, and again. So we did some research, and found that it fed power to many other things including the o2 Sensors. We though that it didn't help us until we brought up the check engine light on the dash to the owner, he said that one of the o2 sensors was just floating around in the cat, and that it had been like that for a long time, well what we found was that the o2 sensor fell into the cat, melted the wires, and was shorting out. unplugged the o2 sensor, replaced the fuse, it started up, and ran fine.... long story short, follow up on CELs, because the issue you have now may be caused by them.

Yea forgot to say I was a mechanic for 5yrs lol Just dont have the shop at my disposal anymore...

 

[rbraden4]

If the converter(s) were bad there would likely be a cat efficiency code. Also the converter that would be bad would be bank 2 so the O2 code would need to be on bank 2. Though both an oxygen sensor and egr can cause a miss. But likely the egr more so. Cylinder 8 should have a lower compression than the others if it was washed. Have you cleaned your throttle body or TPS sensor? Does it actually miss at higher rpms or bogging down? Sorry for the grammar on my ipad.

I figured because one o2 isnt reading anything the PMM wouldnt set a cat code because it knows the o2 isnt working and cant know for sure, but it is a computer it doesnt know it all. Yes cleaned throttle body MAF and tps today when I did the tune up.

Its kinda hard to explain, it never backfires, but when you take of at say 25% throttle its goes smooth and shifts fine, if you increase it up to say 50% it seems like its struggling to get up there and you can feel the loss of power, then you can feel its almopst time for the trans to shift accoring to where the throttle is but wont shift because the motor isnt quite there. if that makes any sense its like a clogged main jet on a carb lol. seems the more load the worse.

 

[1998Exp]

Sounds like your guess about a clogged cat is the most likely reason. Unburned fuel from the stuck injector (who knows for how long?) might have done it. When you get the back pressure measurements, let us know, please.

 

[1996BLKBauer]

Yea forgot to say I was a mechanic for 5yrs lol Just dont have the shop at my disposal anymore...

Ah, I was sort of wondering that, an Average person does not go that in depth to find a problem. When you get the truck running good again, you should get many good miles out of it. Mine has been really good to me.

 

[rbraden4]

Fixed it... So I checked the back psi on both banks and had nothing, then checked compression all cylinders were good, so I starred at the scanner for like 30mins and noticed the Long Term Fuel Trims were at +23
So I thought whats going on if the computer thinks it needs to add so much fuel.
I went to check fuel pressure again but I left my Snap On gauge I used yesterday at my house. So I grabbed a friends cheap little gauge and hooked it up 25psi... Yesterday my Snap On gauge said 45ish
So I took it down the street and sure enough it was dropping to 20psi under load.

I actually went to a shop from there and asked em to hook it to there gauge once and sure enough the fuel psi was 25 at idle.

Long story short I replaced the pump today and its running great now, next I need to replace the filler neck cause the tubes are rusting away and going into the tank.
As for the Snap On pressure gauge I plan to drop it off at the shop that tested my pressure and hopefully have there Snap On guy calibrate it
Nearly 200 dollars for a gauge that dont work when I need it to lol.

Bright side the truck has a fresh tune up and fuel pump, when it gets warmer I want to swap the AWD case for the manual shift one, I plan to tow a boat with this and can already see the stress backing a trailer steering lock to lock..

Thanks for all your input, and let it be known just cause it says Snap On dont mean it works lol

Also if anyone is wondering all this troubleshooting wasnt done not with a expensive scanner like the Modis or something it was all done through a 13.00 dollar OBD2 adapter from eBay that connects to my phone via bluetooth. I recommend this 13.00 dollar purchase to everyone...

 

[1996BLKBauer]

Fixed it... So I checked the back psi on both banks and had nothing, then checked compression all cylinders were good, so I starred at the scanner for like 30mins and noticed the Long Term Fuel Trims were at +23
So I thought whats going on if the computer thinks it needs to add so much fuel.
I went to check fuel pressure again but I left my Snap On gauge I used yesterday at my house. So I grabbed a friends cheap little gauge and hooked it up 25psi... Yesterday my Snap On gauge said 45ish
So I took it down the street and sure enough it was dropping to 20psi under load.

I actually went to a shop from there and asked em to hook it to there gauge once and sure enough the fuel psi was 25 at idle.

Long story short I replaced the pump today and its running great now, next I need to replace the filler neck cause the tubes are rusting away and going into the tank.
As for the Snap On pressure gauge I plan to drop it off at the shop that tested my pressure and hopefully have there Snap On guy calibrate it
Nearly 200 dollars for a gauge that dont work when I need it to lol.

Bright side the truck has a fresh tune up and fuel pump, when it gets warmer I want to swap the AWD case for the manual shift one, I plan to tow a boat with this and can already see the stress backing a trailer steering lock to lock..

Thanks for all your input, and let it be known just cause it says Snap On dont mean it works lol

Also if anyone is wondering all this troubleshooting wasnt done not with a expensive scanner like the Modis or something it was all done through a 13.00 dollar OBD2 adapter from eBay that connects to my phone via bluetooth. I recommend this 13.00 dollar purchase to everyone...

THESE ARE AWESOME! Plus Torque is an awesome program on the Android Market. I have one myself, keep it on me at all times just in case.

 

[rbraden4]

THESE ARE AWESOME! Plus Torque is an awesome program on the Android Market. I have one myself, keep it on me at all times just in case.

Yea thays what I use is Torque. and it stays plugged in all the time lol.

Every now n then when Im bored I will connect to it on the way home from work just to see whats going on.

I only wish it would scan ABS. Damn ABS light is on and Ive replaced the left front already and rear with a used sensor but dont want to buy another hub till I see the code ya know.

 

[rbraden4]

I just noticed your in McHenry. I grew up there. I live just over the border now.

 

[Juni88126]

Did you hapen to replace the fuel filter when you replaced the fuel pump, gauge may not need redone I have seen fuel pumps read good pressure when they are cold but after they warm up the fuel pressure will sometimes drop.

 

[rbraden4]

Did you hapen to replace the fuel filter when you replaced the fuel pump, gauge may not need redone I have seen fuel pumps read good pressure when they are cold but after they warm up the fuel pressure will sometimes drop.

Yea I replaced the filter with the new pump. Before deciding the pump was bad I tested it for psi right off the sending unit and even there it only had 30psi

Truck runs great, replaced the o2 and egr hose, next friday its goin in for exhaust.
Removing the rear set of cats, and getting a magna flow muffler 2 into 1 put on with a new tail pipe.