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post #1 of 16 (permalink) Old 08-31-2013, 09:19 PM Thread Starter
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engine running poorly but not rough, help

95LX 4.6 100K

The car will not idle correctly, it will surge from 5-6 hundred to 1500 then back. It does this very smoothly, like it would if you were just pressing gently on the throttle.

Cruising at a steady speed with very little pressure on the pedal the car seems to hesitate just for an instant then recover. This is subtle enough that the car will not lose speed but it can be felt. very annoying.

I tried unplugging the ECT, and that helped the problem but only temporarily, it also made the fan run constantly.

I have replaced the MAF. Should the engine quit when the plug is pulled?

Is there anyway to check codes without using the connection under the dash (long story).

Could the TPS being lose cause these syptoms?

Thanks for any responses as the car is away from home and I am kind of stuck.
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post #2 of 16 (permalink) Old 08-31-2013, 09:25 PM
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Recent maintenance history?

First reaction is vacuum leak. There is no way to pull codes without a code reader on your car.

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post #3 of 16 (permalink) Old 08-31-2013, 10:08 PM
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There is no reason the Tps should be lose. What are you trying to tell us?

It could be anything---there is too much unknown. For example, does it do it IMMEDIATELY after the car is started at any temperature? Other conditions?
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post #4 of 16 (permalink) Old 09-01-2013, 11:06 AM Thread Starter
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Recent history...

Car had an intermittent fuel smell coming from extreme right front of car for a long time. Car ran perfectly...

Drove car 500 miles away no issues. the next morning drove the car a few miles, no problems. That afternoon while trying to pull out of parking space car stalled several times. when I could get it to run RPM's were around 350-400. car eventually drove back to hotel all but stalling per low RPM's. Found garage to look for help. While I was there they pulled the wire from the MAF and engine stalled, was told this was good. Left car, the next day they found the charcoal caninster had been chewed and was open. They more or less fixed that. (I later found another leak on a hose in the same area and fixed). Car ran a little better but now the RPM's at idle will surge, 750-1500 rpm. It does this randomly, You can also feel what is best explained as a cut out when cruising at a steady rpm with no load. They have also now replaced the MAF as well.

OBD... Just this week found out, when I had my car alarm installed about 10 years ago they cut several wires going to the OBD port on the passenger side under dash. So it is now useless. I had no idea! nor have any idea why they would have done that???? POed would be a major understatement.

Bottom line the car is still in the Charlotte area, I dont live there, and my car may or may not make it the 500 hundred miles back.

TPS... The assembly will move (rattle) about 1/8 inch back and forth. It will not pull away, just slightly rock back and forth (to the front and rear)

I hope this will help diagnose.

Thanks again to all for your time
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post #5 of 16 (permalink) Old 09-01-2013, 11:53 AM
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well for the TPS, you need to replace it. It should not move, period.

If that does not fix your issues, then you need to "have the car" to get anywhere. You likely have an air:fuel imbalance due to vacuum leaks. If the charcoal canister has been compromised, you can bet that you will have other unmetered air leaks as well. No one will know, especially over an internet connection, what exact issues you have until you are "there" to actually work on the car. If you do plan to work on the car, you main plan of attack is to get acquainted with each and every single inch of vacuum line on your car. You will likely need to replace them.
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post #6 of 16 (permalink) Old 09-01-2013, 12:03 PM
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Quote:
Originally Posted by harleybuc View Post
Recent history...

Car had an intermittent fuel smell coming from extreme right front of car for a long time. Car ran perfectly...

Drove car 500 miles away no issues. the next morning drove the car a few miles, no problems. That afternoon while trying to pull out of parking space car stalled several times. when I could get it to run RPM's were around 350-400. car eventually drove back to hotel all but stalling per low RPM's. Found garage to look for help. While I was there they pulled the wire from the MAF and engine stalled, was told this was good. Left car, the next day they found the charcoal caninster had been chewed and was open. They more or less fixed that. (I later found another leak on a hose in the same area and fixed). Car ran a little better but now the RPM's at idle will surge, 750-1500 rpm. It does this randomly, You can also feel what is best explained as a cut out when cruising at a steady rpm with no load. They have also now replaced the MAF as well.

OBD... Just this week found out, when I had my car alarm installed about 10 years ago they cut several wires going to the OBD port on the passenger side under dash. So it is now useless. I had no idea! nor have any idea why they would have done that???? POed would be a major understatement.

Bottom line the car is still in the Charlotte area, I don't live there, and my car may or may not make it the 500 hundred miles back.

TPS... The assembly will move (rattle) about 1/8 inch back and forth. It will not pull away, just slightly rock back and forth (to the front and rear)

I hope this will help diagnose.

Thanks again to all for your time
In descending order of proximity to Charlotte:

Myself, Slidebird, and RobertP are all in the Charlotte Area. RobertP and Slidebird are mechanics. My skills aren't up to theirs but I can provide basic support. If you're interested.

If you're in PA and the car's in the Charlotte area who's got the car now and where exactly in the Charlotte area is it?

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post #7 of 16 (permalink) Old 09-01-2013, 12:22 PM Thread Starter
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Quote:
Originally Posted by Trunk Monkey View Post
In descending order of proximity to Charlotte:

Myself, Slidebird, and RobertP are all in the Charlotte Area. RobertP and Slidebird are mechanics. My skills aren't up to theirs but I can provide basic support. If you're interested.

If you're in PA and the car's in the Charlotte area who's got the car now and where exactly in the Charlotte area is it?
The car is at the Charlotte airport at the moment, and I am staying at a nearby hotel during the week. I will be back in Charlotte today around 630 and will be there all week. I have obligations every day until 2 but can go anywhere after that. The car does drive, but I don't really trust it at the moment. So yes I am interested in any kind of help I can get, especially in light of the OBD problem, I really need the kind of knowledge found here about the MN12.

Thanks
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post #8 of 16 (permalink) Old 09-01-2013, 01:57 PM
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I have a OBD scanner I can pull the codes for you if there are any and take a look at it for you. Is it in one of the parking lots at the airport or at your hotel?

I'll PM you my phone number. This'll give me an excuse to take my car outta the garage. I live about 25 miles north of the airport.

It could be the IAC that's going out?

Give me a call.

Mods? Yea, I got mods ...
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Best 1/4: 1,320 nanoseconds @ 670,616,629.2 miles per hour

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See a list of my real mods and pictures of my car HERE. The true performance of my car was made possible by the Carolinas Crew Chief, RobertP at Rob's Tire & Auto

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post #9 of 16 (permalink) Old 09-02-2013, 09:02 AM
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Originally Posted by harleybuc View Post
Recent history...

Car had an intermittent fuel smell coming from extreme right front of car for a long time. Car ran perfectly...

You can also feel what is best explained as a cut out when cruising at a steady rpm with no load
During steady RPM the evap system is purged I believe.

There could still be an issue with the evap system leaking, causing a vac leak. They could have made things worse and broken some very brittle lines when they checked the canister. There is a tube that ends at the top of the PCV valve, and you can completely isolate this system. Plug (or pinch) the tube and see what happens. The PCV valve will have to be plugged if you remove the tube. Can't hurt to try!
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post #10 of 16 (permalink) Old 10-24-2013, 11:51 PM Thread Starter
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Update:
the car went from surging idle and the other symptoms described previously to acting like there is no choke. When cold, the car will barely run (idle to low) when warm, the car runs normally. The one exception there is no kickup in idle when turning AC on. Then the car decided to idle too high, around 1100 rpm. when slowing for a stop you can feel the car wanting to pull as though you are still on the throttle. Putting the car in neutral while stopping, you can see the rpm's climb to around 1500 then drop to around 1000.

Parts exchanged so far include Mass Airflow Sensor. Alternator, Throttle position sensor, and Idle air Control valve. None of these changed anything.

Any ideas are again greatly appreciated.
I have been unable to detect any vacuum leaks thusfar
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post #11 of 16 (permalink) Old 10-25-2013, 11:02 AM
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Update:
the car went from surging idle and the other symptoms described previously to acting like there is no choke. When cold, the car will barely run (idle to low) when warm, the car runs normally. The one exception there is no kickup in idle when turning AC on. Then the car decided to idle too high, around 1100 rpm. when slowing for a stop you can feel the car wanting to pull as though you are still on the throttle. Putting the car in neutral while stopping, you can see the rpm's climb to around 1500 then drop to around 1000.

Parts exchanged so far include Mass Airflow Sensor. Alternator, Throttle position sensor, and Idle air Control valve. None of these changed anything.

Any ideas are again greatly appreciated.
I have been unable to detect any vacuum leaks thusfar
Can you get some scan tool readings? LTFT, STFT? The fuel trims could give a clue. If you have an issue with the OBDII connector you can't do this any other way .

Cold/hot issues are usually some parts (like an intake manifold gasket) sealing at operating temp due to expansion. I sealed many of those thick vacuum tubes going into the intake. There are some behind the engine as well. Brake booster could be a culprit too. My idle is pretty smooth but I do get a bit of rough idle when it is 1/2 warmed up sometimes idling at a light or two. I attribute it to a tiny leak somewhere.

Fuel trim when hot and cold could give some hints.

Finally, if you are really out of aces try a junkyard computer. They are known to have some issues on 94-95s. Not exactly what you have but the air conditioner issue could be PCM related.
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post #12 of 16 (permalink) Old 10-25-2013, 11:08 AM
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it sounds to me like you have a host of electrical issues, many concerning the EMS. and i think they stem from the alarm installation. it sounds like the installers did a hack job to begin with, and now perhaps the alarm computer is failing.

i would start by thoroughly cleaning every electrical connector you can find, and using a little dielectric grease on the connectors to prevent future connection issues.

second i would remove, or have the alarm removed by someone competent, and repair any damage done to the wiring.

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post #13 of 16 (permalink) Old 10-25-2013, 09:20 PM
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yeah, definitely avoid aftermarket alarms... they usually butcher your wiring with tons of cuts/splices/scotchloks/extra relays/modules.... all of which will cause problems eventually.

factory wiring that's unmolested should last near forever, as long as the insulation doesn't rot off from heat in the engine bay, or some squirrels don't have their way with it.

as soon as you start cutting stuff without properly soldering/shrinktubeing it tight you will have corrosion issues from humidity or weather.

i could probably still count the amount of alarms i have seen removed on both my hands, but that's still quite a few, usually because of issues you are describing. some of them just wouldn't plain start also, or would if you figured some way of coaxing it by wiggling modules or battery disconnect. the fun ones would have random shutdowns while driving or erratic alarms.

anyway, if the car doesn't have a factory alarm, then leave it that way and i would advise you start removing your dash panels, and stuff, tracking down all the alarm hardware and removing it. then start matching up wire colors/gauge where they used to be, solder it all back together and seal it with shrinktube.

and as for you OBD connector, i cant imagine why the heck they would have touched the wiring for that either... but maybe if you repaired it with something even temporarily you might get a scan out of it. otherwise if the connectors damaged go get another one from the salvage yard out of any number of cars. make sure it has a couple inches of wire sticking out of each pin, then get out the solder and make it right. you can always tuck the extra wire up under the dash.

oh, and if you dont like solder you could always use some weathertight crimp connectors. they work fine, i install a lot of radios and stuff with em, and that's what i used on my intake swap for the wire extensions. couldn't find my old soldering pencil, and its not that great of quality anyway...

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post #14 of 16 (permalink) Old 07-09-2014, 11:40 AM Thread Starter
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resolution

The car is finally fixed, I ended up giving up and taking it to a Ford dealer.

They found that the PCM was bad. It was replaced and car is again good to go.

I hope this will help somebody else if they have a similar problem.

Thanks again to all that gave there input, and especially trunk monkey for his help and taking the time to look at my car.

I also like to add that trunk monkey has one bad bird, his car will definitely get out of its own way. Nice car!
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post #15 of 16 (permalink) Old 07-12-2014, 06:04 PM
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when I had the stock 95 intake on mine it did some thing similar.

but I checked the vacume hoses the three that came from the iac to the pcv were rotted and allowing air to not flow properly
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post #16 of 16 (permalink) Old 07-12-2014, 06:05 PM
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but thank you for the feed back if it was not one of the things not mentioned.

It is good to know it is running good again
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