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99 2.5L RUNNING HORRIBLY no CEL


Jethro_54

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New member to this site but I've been using it since I was 15. Finally got smart and became a member...11 Rangers later.

I just picked up a 99 Ranger XLT 2.5L auto 2wd with 158k miles. Bought it running REALLY ROUGH and drove it over an hour back home. Seems like it's running on 2 cyl's. Can't believe there's no codes. The catalytic converter has a hole torched in it from previous owner thinking it could be plugged. Brake pedal extremely stiff (possibly faulty brake booster or vacuum issue).

So far:
-po installed new coil packs
-po torched hole in upstream end of catalytic converter
-po removed DLC fuse #5 (assuming fuse for CEL) maybe trying to hide something...
-po installed new IAC valve

-I checked for correct plug wire routing
-installed DLC fuse #5 drove for 15 min still no CEL?!
-hooked scan tool up just to verify
-new air filter (was not one in it)
-unplugged MAF while running and engine stopped instantly

I will check for vacuum leaks here in a bit. Do I need to let the truck run longer than 15 min for a CEL to appear? Will the 2.5L run fine without a catalytic converter? Thinking about installing a pipe in its place temporarily unless these motors are picky with the catalytic converter. If it is I'll order a new one off rockauto which is like $156. I wouldn't assume it's a compression problem with only 158k but I can do a test.

Any input would be greatly appreciated!!!
 


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martin

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Sounds like a vacuum leak might be part of the problem, possibly from a bad brake booster. try pulling the hose from the booster and plugging the hose, see if that helps. It might also help to hook up a vacuum gauge to see if that will help to narrow down the problem.
 

Jethro_54

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Okay so I unplugged the hose from the booster and plugged the hose. Still ran the same and the brake pedal felt the same. I haven't done a vacuum test before...lol. I unplugged the hose from the EGR and plugged my vacuum tester into the hose...started it and it didn't even move the needle. Does it matter what vacuum line I plug the tester into? Also any idea what it should read? Typically I just spray carb spray on all the vacuum lines and wait for the idle to change...never used my tester. Carb spray did nothing. I also "tested" the coils I guess you could say by checking for spark on every plug of both coils.
 

Mark_88

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Check the vac lines for the heater control...I accidentally pulled one off and the truck ran like a carp...if you've pulled the heater control panel out for any reason (or someone else did) the vac lines can separate from the connector and cause really rough running.
 

Jethro_54

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Alright so I checked all the vacuum lines at the back of the heater control panel...they're all connected and they all work correctly. I just did a fuel pressure test. At idle it read 65psi...it also read about 65psi when i turned the key on just to power the fuel pump...Shouldn't it be more like 40psi?! Bad fuel regulator? or am I wrong with the suggested 40psi I read on another forum?
 

Jethro_54

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Just read in my Haynes manual that it should be 56-72 psi...so that's fine
 

Spott

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You definitely have a vacuum leak somewhere if your tester indicates no vacuum. Find and fix that before pursuing any other solutions.
 

Jethro_54

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Okay any idea on what the vacuum should be?
 

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Never more than 14.7 psi, and probably a good bit less than that.
 

Mark_88

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My vacuum (carbed) runs steady around 21...when you blip the throttle it should go to 0 or thereabouts, pop back up to 25, then drop back to 21...on a "normal and good engine"...that is...

Fuel injected might be a bit different, but I don't see why it would...
 

martin

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plug the gauge into the brake booster line, you need to be reading uninterrupted manifold vacuum.
At idle you should read somewhere between 18 and 22, carbed or fi makes no difference.
 

huh?

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when you have a few minutes to spare, try double checking the spark plug wire order.


a few years ago i ran out of gas and had to leave my sentra on the side of the road for about half an hour. by the time i got back someone had pulled my distributor and wires.

a friend gave me another distributor, but when i put it in i sequenced the wires believing the rotation of the distributor was the opposite of what it actually was. so 1-3-4-2 firing order was done instead of 1-2-4-3, so it ran on only two cylinders.

ran like doodoo but it did climb up hills and was able to get a fair amount of road speed.

by the time i figured out the firing order was wrong i had put a lot of time and effort into it. among one of the things i did: knock the guts of the converter out.
 

Jethro_54

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Okay so I threw a chunk of exhaust in place of the cat for now. I got my compression tester back and cylinders 3 and 4 only read about 25psi. 1 and 2 were good. Possibly carbon build up in the valves? Or head gasket?! I might try sucking seafoam through the brake booster hose and run it for awhile to hopefully break up any carbon buildup.
 

Jethro_54

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Yes haha first thing I did was check the plug wire order. I had a 94 a couple years ago that didn't seem like it had the power it should. I replaced the plugs and wires on it in the same order the other ones were installed. Sold the truck to a friend and he found out the wires were out of order lol. Definitely a dummy moment!
 

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A common place for the head gasket to go is between 3 & 4 so possibly that is the problem. Running seafoam through it might help if it is carbon on the valves...but I'd suspect something a bit more than the valves.

worth a try anyway...if nothing else it will clean it up a bit for when you have to remove the head...and that isn't as difficult as it may seem if you've never done it before...you will need to replace the head bolts...and the gasket(s)...and anti-freeze...but if you don't have to rework the head or replace any other parts you could probably do it for under $100 and a few hours of your time...

You might want to have the head milled a bit and checked for cracks while you have it off though just in case there is a major flaw somewhere causing it to loose compression...but I think if that were the case you'd have anti-freeze in the oil and vice versa.
 


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