start but wont idle after transmission install

[lunchboxlust]

I finally got the transmission installed and the truck wont run. It starts tight up like it should but wont idle. I can give it some gas and it kinda runs but it backfires and sounds like it is only firing once in awhile. Not drive-able at all. I have checked some vacuum lines and found none to be unplugged one was cracked so I cut it and reinstalled. The exhaust is mostly rotted off so I'm about to cut it off. I'm wondering if some critter made a home in it because the time I kept it running for a few minuets I could smell a burning smell that reminded me of when I had a rat nest in the exhaust of a lawn mower.

It had almost 3/4 of a tank from around last March so I put stabilizer in it and threw 5 gallons of 93 non ethanol still no help. I smell that it is rich after trying to keep it running and it back fires a whole lot. I talked to a buddy and he said to test the egr, map and the oil pressure sending unit.

It has oil pressure but from the reading I did I can only test the egr and map with the truck running and it wont do that so I'm at a loss of what to do. Any and all info would be greatly appreciated.

1999 ford expedition, 5.4 4r100

 

[poorboy1964]

Do you any way to scan it for codes? I'm thinking something did not get hooked back up is there a check engine light on?

 

[lunchboxlust]

Batt was flat dead so I replaced it. Had a friend stop by with a scan tool and no codes were throwing. Replaced fuel filter. I'm going have someone start it while I tap the iac.

 

[lunchboxlust]

Hitting the IAC was a no go. I think I'm going to drain all the gas next.

 

[1955moose]

Fresh fuel is definitely a good idea. A friend of mine picked up a 98 Eddie Bauer recently. He sprayed the throttle body real good, and ran it. He said it ran great after. Seems weird all your problems started after trans install. Look to make sure oxygen wires didn't get knocked or pinched.if you've got wonky Exaust it's going to run lean, and cause all kinds of headaches. Sounds like you have more than one issue. Keep in touch. Do a fuel pressure test, a failing or clogged pump will also cause headaches.


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[docraymund]

Remove all spark plugs and check if clean.

 

[lunchboxlust]

I cleaned the IAC and all I can say is Ford engineers are a bunch of bastards. Cleaning it did not help. I didn't get clear info on how much and how free the plunger inside of it should be. I can move it but it doesn't spring back either direction. Is that normal? It moves less than a 1/4. I tried asking the guys at the dealership I work at what they thought and no body really gave me an idea of where to start except drain the tank and our shop doesn't have a transfer pup I can borrow. I'm going to do a little more searching on how the IAC should function and if mine is moving like it should I will definitely drain the tank blow out the lines and change fuel filter next. With being able to smell raw fuel when I try to run it I'm concerned that I'm going to foul the cats.

and docraymund the plugs have less that 30000 on them. Could be far less id have to find my note book I was keeping that somehow disappeared.

1955moose I was very careful not to damage anything when doing the trans but I will look everything over again. But as far as connections go the harness was long enough that I could of plugged either speed sensors on the trans in to either plug and they look exactly the same. I also cut the exhaust off behind the cats. It was rotting off and I was kinda hoping that something made a home and that was the issue but no go on that.

IT might be the weekend before I can mess with it again. I don't get home from work till 6 and I don't have a garage so working in the rock driveway in the dark and cold sucks. thanks for all the help guys. This forum has helped me many times

 

[1955moose]

If your smelling fuel, it's possible your fuel pressure regulator is failing. Remove vacuum line from it, see if any fuel comes out of vacuum hose. Do the pressure test. Let us know what you've got. You'll get a high reading if the regulator failed. Probably 70psi or higher. I didn't notice, did you ever get any Dtc trouble codes with the scanner. Let us know this weekend. Moose.


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[docraymund]

You still need to inspect the spark plugs for fouling. Its the first step in diagnosis. And dont change any part unless proven defective. Start early morning so you would have more time to work.

 

[1955moose]

Why not just pull 1 or 2 and check. These Suv's are a nightmare with spark plugs. Why risk thread failure pulling all 8? Pull a couple of easy ones, sat 1 and 5, and check. If their fouled, then pull them all. Bottom line Doc, he's got to figure out why their fouling.


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[stamp11127]

Lunchboxlust, how did the engine run before the transmission removal?

 

[lunchboxlust]

Sorry for the lack of response. I work 12 hours so I go to work in the dark and come home in the dark. Still haven't figured this out. The veh. ran pretty good for having almost 200,000 on it. At idle the rpms did fluctuate 50-100 rpms but it never was an issue. I drained the tank, which took forever. Removed the fuel filter, removed the schrader valve on the fuel rail and blew out the lines and replaced the fuel filter. Still wont run. I got excited for a second because the second time it started it it ran twice as long as it was before I changed the gas. It only did that once and is doing the same thing again. The gas I removed had almost no water in it but the stuff on the bottom of the tank was pretty dark. I'm willing to bet that half of the gas was fine. It was a little yellowed but not bad. Oh, did I mention that I now have a socket stuck in the tank? I couldn't get the line to stay on the bottom so I zip-tied a socket to it and hours later I forgot about it and when I puled the line It came off with little resistance and the rubber line that I would of swore was fuel line was pretty soft. So on a plus I always know where that socket is. But I'm wondering if the zip-tie or the electrical tap I used to hold the tail of the zip-tie to the side of the socket will cause and issue with the pump.

Moose, I will remove a few spark plugs if you really think that could be an issue but I don't think it would be because when I first turn it over it fires right up like a car should then dies. I didn't find anyone that had a fuel pressure gauge I could barrow so today I will have to buy one.
I don't remember who said it but someone said that the fuel regulator could be going bad and to check the vacuum line on it. Is this the little sensor of some kind that is on the driver side fuel rail with a small vacuum line on it? I was thinking that if I don't figure this out by next weekend I'm going to go the the junk yard Saturday and grab a few IAC, MAF, MAP and EGR valves and switch them out before give up and pay a pile of money to have this diaged. Even if I brought it to my shop it would cost me almost 300$ just to get it there.

Thanks everyone for your help and ideas. I feel like stamp 11127 has just about helped me with every question I have ever had sense I first posted.

 

[stamp11127]

Your call on pulling the plugs. I think it is a waste of time. I've had engines sit for months without plugs fouling. If it isn't running while sitting how does it foul them?

With a problem like this it is better to get the facts - fuel pressure is first. You should have around 35psi being held with the engine off. Running should be 35-45psi. They run really bad if the pressure drops into the 20's. If the pressure bleeds down then it could be the check ball at the pump or leaky injector. A failed regulator that results in high line pressure will cause a rich condition and destroy the cats quickly.

FYI - the next you need to empty the fuel tank use the fuel pump if it is working. Disconnect the fuel line at the fuel rail, add a length of hose to the supply line then jump the fuel pump relay.

With 200,000 miles on the vehicle how many miles are on the existing pump? I consider replacing them around 150,000 as a precaution. They are going to fail eventually, this way I don't have to pay for a tow back home.

 

[lunchboxlust]

Thanks stamp. I kinda felt the same way about the spark plugs but if it meant still getting help on here I was willing to do it. I'm just waiting on the parts stores to open to get a fuel pressure tester. I was looking for info on what wires to jump to use the fuel pump to do the work. I have done it on an old mini van and a duster and if I remember right I just jumped power right from the batt but they were smashed cars I didn't care if I wrecked the pumps. I just couldn't find info on how to do it properly with our trucks.

 

[stamp11127]

Pull the fuel pump relay and jump pin 30 to 87 or 87a (dont remember which one) use 10 or 12 gauge wire. The pump will run as long as the jumper is in place.

 

[lunchboxlust]

Got the fuel pressure test gauge. When it fires up it is at 30psi then it dies it sits at 40psi. Did this 10 times. the pressure didn't immediately drop so Im letting it sit for a little bit to see if it leaks off.

 

[lunchboxlust]

Everything I have come across says I can not Test any sensors without the truck running is this true? IE: IAC, EGR, MAP, MAF. Also I did clean the IAC but I don't know if it is functioning correctly. Being that the plunger doesn't snap back freely. I can move it but it doesn't just move with a light touch and it moves less that a 1/4".

 

[lunchboxlust]

An hour and a half later and it leaked down about 20 psi. Ended up with a bad headache. Tomorrow after work I will test all the fuses. Haven't done that yet. Not sure why I didn't do that first.

 

[stamp11127]

If fuses are bad then circuits don't work - as in doesn't do anything. Doesn't hurt to check them though.

Fuel pressure is within spec to run, that leak down isn't enough to worry about for this problem. A fast leak down would be of concern.

Next up would be exploritory inspection of the intake system for blockage, injector harness for critter damage, egr valve vacuum test, damaged vacuum hoses.

If everything checks out the next step will risk the cats, crank up and hold at whatever rpms will keep it running long enough to throw codes. While running you can "shoot" each manifold exhaust port with an ir temp gun. Any cylinders that aren't firing will be a lower temp than the cylinders that are. Dump too much raw gas in the cats and they are toast.

 

[1955moose]

As Stamp said, your fuel pump, fuel pressure regulator, and all with the fuel delivery, are good enough to run decently. I'm trying to figure out in my mind what you did by r&ring a transmission. I read an earlier post that stated, a friend helped me, and I had no codes. Basically theirs fuel and spark, that make any engine run. The thing that stumps me is you say it starts then dies. What involving the motor did you disconnect, when you replaced transmission? Am I missing something here. Did it run fine before transmission swap? You need to back track every wire you disconnected, that involves drive ability. I just can't believe injectors, or any other sensor went south, doing a tranny swap. Make sure all grounds are clean and back where they should be. You've eliminated the fuel delivery from the tank, after all visual inspections, of any wires, or hoses, then it's time to read cylinder temps, and if you find one or more low temps, then it's injector firing, replacement of injector time. You'll need to use a noid light to be sure all eight are firing. Keep us posted, this one of the tougher ones.


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