4.0 Surges, Stumbles when I push the gas quick, has a slightly high idle, and has an intermitent fuel smell out the exaust. It smokes like hell + runs/smokes worst in the morning. About 55 K on engine.

Just changed all the plugs, all the old look perfect. New TPS, fuel pressure reg, PCV, air filter, fuel filter, O2, cleaned MAF. It runs worse with the new IAC so I put the old back on. Can't find any vac leaks no oil or coolant loss. Don't know what way to go next. Please help!!

I would have said fuel press. reg. but youve done that.
fuel pump? but that shouldnt make it run rich like you say.
Sorry not much help, but sounds like my 92 when regulator went south.

If it is not the fuel pressure regulator leaking, it is a fuel injector. Should easily hold pressure for 15 minutes with the engine off. Pulling the plugs should give you an indication if which injector it is.

I was thinking also a leaking injector they do have about 300,000 on them. The problem is the plugs look like they a burning fine. Maybe let the truck sit over night and pull the plugs one by one to see what cyl smells like raw fuel?

I just bought a set of new injectors pos is still not fixed! The engine runs better but I think it still smells like gas out the tailpipe. Don't know what else to try? It runs smooth but when I push the gas the engine speed revs up and takes way to long to come back down. The stumble is about gone.

New intake gasket, new crankshaft sensor. No egr or cam sensor on the truck. Runs good but still dose not idle correctly. I guess the only other parts it could be is fuel pump, pluged cats, or bad computer. Anyone have any thoughts before I have to hold up 7-eleven.

The new injectors are awsome!!! I bought the high performance set from FiveO motorsports for $180. The difference is amazing. It is so nice to have the ability to pass people going up a hill.

Thanks for ALL the help!!! 158 people looked and only two people tried to help. Thanks again.

Sorry your problem isn't fixed. Allow me to be #3 to chime in.
Did you ever put a fuel pressure gauge on it to see what the pressure was and to verify that it would hold pressure?
Did you ever check the operation of the injectors? A bad ground could cause an injector/one or both banks of injectors to get stuck open too long.
Have you ever run the EEC-IV diagnostic tests? The PCM is responsible for controlling the mixture by controlling the "injector pulse width"

Originally posted by Bronco_bill
Thanks for ALL the help!!! 158 people looked and only two people tried to help. Thanks again.

Title says pleas help. So I looked, but dont know how. Sorry :rolleyes:

Thank You! I cant begin to explane how frustrated I am at this point.

Was tring to avoid buying a pressure guage but I guess it may come down to it. Right know I am thinking the fuel pump might be bad since it kinda make the whine noise that others have described and is the only fuel delivery part that has not be replaced. My other thought is that the 5 speeds uses a differnt TPS than the auto and the Autozone universal dosn't work for me
Symptoms now: Cold start it smokes and smells like gas out the tailpipe. Rough/no fast Idle. When it warms up it idles at 1000 but smooth. When I rev the engine quick it sometimes stumbles going up in engine speed and takes to long for the engine to slow back down. Unless the fuel pump can cause these symptoms it seems to me that the computer may be bad, but my past experence has shown me that they are reliable. I will check for bad grounds.

Thanks

No codes came up in the diag. Replaced all injectors with brand new ones and I listened to each with a stethascope. All sound like they are operating the same.

Geeze, you are really having a bout with that thing. Going into overtime...hope you win

I had only but one thing come to mind or maybe two. Is there an air temp. sensor that would send info to the computer to richen the fuel during start-ups and cold weather? Sounds kinda like and old carb. problem, like the stuck choke.

And no vacuum leaks into the intake?

Too bad you couldn't have cut your losses short earlier and taken to a Ford mechanic. Maybe it's displaying symptoms that they are familiar with//

2med

New fuel pump. It runs very good but is still not right. I think it still takes to long for the idle to come down after steping on the gas. With the TPS unpluged it responds like it should, any thoughts? I checked the grounds all seem good. I am out of ideas seems to be that the only other thing it could be is the ECU.

What is your TPS voltage when it is closed (it should be .96v) and does it evenly progress as you open the throttle up to 5v? If not, something is amuck.

OK, looks like you tried the IAC so ignore my other post.

There is an air charge temp sensor in the lid of the air box but, I am thinking, if it was no good then wouldn't you get a code?

You can take it to a muffler shop and have them do a pressure drop test across the cat to see if it is plugged.

A fuel pressure test rig is about $40. Did you try that yet?

You might want to get an OEM TPS and try that. I had that problem with the fuel pump relay - AutoZone had about 4 different ones that were supposed to match. I finally had to get an OEM one.

Are you still having the rich cold-starting problem? You said 'it runs very good but is still not right'. My Ex does the same thing when closing the throttle; when coming up to a stop, I push in the clutch and the engine doesn't slow down to idle untll I've been sitting there about 2-3 seconds. Besides that it runs fine.

Put on my old original OEM tps and it responds the same way as the autozone so I think I could elimate it being a bad part. Still haven' checked the fuel pressure yet I figured that for the cost of it I just as well should put that money to a new part since they were all original but i guess I am getting to need to buy to eliminate. I am going for a good test run so I am going to reset the ecu again today and scan for codes when I get back. I will also test the TPS voltage. It ran good after the fuel pump install but last night i took it out and it seemed to run not so good. I will post my findings as well as symptoms tonight. Thanks for the sugestions.

Your high idle is likely to be caused by a vacuum leak, since replacing the IAC had a negative effect. I would make sure that the gasket for the IAC is in good condition. If you have extra (unmetered) air coming in, it will raise the idle speed. Your idle speed should be about 750 - 800 in N with a warm engine.

I been trying to track down a TPS code for a couple of years now. It's on my older escort I had before I bought my X, now I am getting a TPS code on the X too, but the TPS checks out fine (voltage and resistance).

Replaced TPS and ISC on escort and am still getting same code. All sensors seem to check out, MAF, O2, ISC, TPS, EGR. And the problem is intermittent. Will run fine for days and then I will start getting racing or sticknig idle when I come to light, the idle just doesn't return. The ISC seems to hold open the throttle for some reason. Even tried $20 ECU off ebay and it does same thing. I'm frustrated.

Maybe Autozone is selling faulty TPS sensors?

the only thiought i have a t the moment,,,,

.have you check the throttle cable... ford uses a spring to have the trottle return to normal after hitting the gas mybe it sticking or has lost its spring .. the spring is meshed with a throttle posistioner plastic bracket could have broke.

thats all i have because it looks like you have replaced every thing else...

Gary

Just thought, have you checked your intake manifold bolts. I heard these have a tendency to loosen up and cause a leak.

New intake gasket was installed after problem started. Didn't get a chance to check for new codes. For the heck of it I am going to replace the fuel pump relay since it is the only fuel delivery part not replaced. Was also going to put on a new set of wires. Symptoms are Idle at 1000 used to idle at about 700. Stumble when you push the gas quickly. Smokes and smells like gas during cold idle. Still smells a bit rich when warm. idle speed goes up slightly by itself and takes about 15 seconds to come back down after coming to a stop. I am just guessing at this point but dose anyone think that a VSS could cause this? Maybe the ECU thinks the truck is moving not at idle?

Originally posted by Bronco_bill
. I am just guessing at this point but dose anyone think that a VSS could cause this? Maybe the ECU thinks the truck is moving not at idle?

I think you could test this by unplugging the VSS. I believe that the VSS only will generate a signal when the toothed ring inside trans or t-case moves past it, so this doesn't seem likely, but it should be easy to test. It may set a VSS code, but you can see the effect on idle if any.

Went to autozone to have someone pull codes but no one new how to work the tester but I bought a pressure guage and hooked it up quick. At idle pressure was 28. With vac line disconected shot up to 40. When i turned the engine off it droped to 20 and held. Pressure seems low to me. I guess I got a bad FPR?

Your 'key on, engine off' (KOEO) pressure should be 35-45 psi. Your 'engine running ' (ER) at idle pressure should be 30 - 45 psi, so it looks a little low. My book says it could be a clogged fuel filter, a bad fuel pump or a bad pressure regulator.

Originally posted by Bronco_bill
Went to autozone to have someone pull codes but no one new how to work the tester
Ohh autozone.... typical typical autozone.


I'm gonna guess fuel filter or pump, not the regulator. Just a guess though.

Installed new regulator today. Presure at idle is 30 line vac line disconected 40. Pressure holds at 40 with engine off. When I first put new reg on key on engine off pressure was 20. turnned key off and back on again went up to 40. guess I should recheck since that dosen't sound right. I put my old TPS back on replaced the IAC motor with my old one took the computer conector off and reinstalled. It runs very good now. The idle is still a little high about 1000 but the idle dosen't rev by itself and lowers like it should. I will see how a cold start is in the morning. I think i still have a slight stumble but not nearly as bad as before. i think If I can eliminate that it will be perfect. At least it looks like there is light at the end of the tunnel.
Installed new coil the other day. I will check for codes as well as TPS voltage then check timing to make sure the PCM is working properly and go from there. Who would have thought that the new parts were no good. No i am worried about everything I put on from autozone. What untill I force them the give me my mony back for the shit parts they sold me.

Originally posted by Bronco_bill
Installed new regulator today. Presure at idle is 30 line vac line disconected 40. Pressure holds at 40 with engine off. When I first put new reg on key on engine off pressure was 20. turnned key off and back on again went up to 40. guess I should recheck since that dosen't sound right.


Actually, that does sound right. My book says that idle pressure should be a little lower than engine off pressure. The book says 39 psi with engine off, key on. When you disconnect the vac line to the regulator, it is the same as wide open throttle which should be about 39 or 40 psi again. When you are at idle, the pressure is lowered by the amount of vacuum applied to the FPR, which gives about 30 psi.

Stumped as to why I didn't get a code but the solution seems to be the ECT. To test I just pulled the connector off and the truck ran perfect. The solution was a $16 dollar part not that the other stuff didn't need to be done. The real test will be in the morning but I suspect the cold start will be fine and smoke will be gone. I will post again to let everyone know so hopefully this thread helps a few others. As of now it Fast Idles on a cold start at about 1800, steps down after about 30 sec to 1000, warms up drops to about 650 and idles perfect. No more stumble, gas smell or smoke so far. Thanks to everyone who helped.

What is the ECT?

Engine Coolent Temp

There are actually two different sensors on the Explorer - one is for the gage only - the other one feeds the temp to the PCM

Oh, duh, I was thinking electronic controlled something.

Is there anyway to test this, I am having some idling probs too, kinda rough and shaky. Cleaned MAF, IAC and checked TPS. It doesn't surge anymore, but it still is a little rough.

I get a TPS code, but sensor tests fine, varies voltage from 0.9 - 4.5 V, with no jumps.

ECT Chart

To test I just unpluged the connector. The one for the guage has a single wire, the one for the ECU has two. I believe it is just to the right of the thermostat. All smoke, idle, and rich symptoms are gone. the Truck runs perfect!!!!!

Glad you got it fixed! Woohoo!

So in the spirit of improvement, and to capture this for posterity, the question arises: How many of those parts that you replaced were really necessary, e.g. the coil? Do you suppose if you took the truck to Ford and paid them $80-plus for a diagnosis that they would have found the problem?

An example: When my '91 was doing this exact same problem, I took it to Ford and paid them $75 for a diagnosis. The concerns were (1) rough cold start, (2) raw fuel smell in exhaust, and (3) cruise control cutting out and stumbling at highway speeds. It took them two days to do the diagnosis so I had to rent a car for the two days ($120). So the total cost to me was a little over $200 just to find the problem. So I go to pick up the car and - they can't find the problem per se, so this is what they tell me they need to do to 'narrow down' the problem:

1) needs a major tuneup ($450) - they say they have to do this to eliminate unknowns

2) the 'tech' said that since my truck has so many miles on it (180k) that the oil pressure was low because the pump was worn, so worn pump means it won’t pump cold oil when cold starting the engine so the lifters won’t lift the intake valves all the way thus causing a rough cold start. Sounded like horse sh*t to me at the time but, having no other data or any way to disprove that at the time, I went with it. I asked him if he checked the fuel pressure – he said yes and that it was fine.

3) He couldn’t verify the cruise problem but said the only thing it could possibly be would be addressed by replacing the cruise servo ($350).

So the total repairs were over $800. I said fine, thanks, and took the truck home and posted my problem on this board. Dr. Alex said it sounded just like the FPR so I replaced it and – the truck runs perfectly. No more cruise stumble, either. Hmmmm…

The point here is that, had you taken your truck to Ford and paid for a diagnosis, they MIGHT have found it. In my case they didn’t, I would have paid over $800 for unnecessary repairs and I STILL would have the same concern! You did the diagnosis yourself and finally found the problem through a strategy of combined R&R, trial and error, and diagnostic testing. I am thinking it is likely you replaced some perfectly good parts during this time, but maybe not. And you had the use of the truck during this time and you didn’t have to fart around with rentals, getting rides, etc., having to put up with the dealer’s ‘tude, and all the other inconvenience.

It just astounds me how these techs are continuously unable to diagnose driveability problems even with a bay full of diagnostic equipment and years of experience. Sheesh.

Yeah, the way I see it, you can replace 3 parts for every 1 part the dealer replaces. By the time you pay diagnostic, part markup and install, it doesn't hurt to try a few things.

You may end installing some uneccessary parts along the way, but hey, you got new parts, rather than paying some guy who may or may not have been able to diagnose it anyway.

The good news is next time I have a problem I have good parts to try so it will cost very little to find the solution. I replaced just about every sensor on the truck all at once + it runs like new. I suspect that since all the parts were original and have a 250000 miles on them they would have been on there way out soon anyway.