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hard starting , rough idle
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tweety
Novice
Aug 10, 2009, 1:21 AM
Post #1 of 10
(9419 views)
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hard starting , rough idle
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After my 1990 Ford F150, 6 cylinder, 4.9 engine, two wheel drive, automatic transmission with 55000 miles on it had not been driven for a month or so I tried to start it. It would start but in a few seconds it would start running rough and die. It would do this several times and then continue to run but still run rough. Punch the gas and it would stall and die.
Since it had been sitting up I suspected something was sticking or gummed up. The last time it had been driven it ran fine.
I took it to the dealer, Brian Toliver Ford-Lincoln-Mercury in Sulphur Springs, Texas, expecting to get it back within a week. Three weeks later and at the cost of over $1200 I picked it up and it still does not run right.
Here is what they told me was done:
Solis setup/follow multiple code. Follow pinpoint test-replace EEC relay- retest- replace MAP sensor- retest-clean throttle body and idle air control valve- retest- sparkplugs gas fouled- lower exhaust and check for restriction- none found- replace sparkplugs- retest- code 96 unable to clear- install breakout box to isolate- processor internal failure to fuel management circuit- replace processor. Replaced fuel filter.
The parts they replaced are as follows:
1 r647 relay
1dy-527 sensor
1 60846 gasket
6 sp-452 spark plugs
112a650 PCM
1 fuel filter
When I went to pick it up the service manager said it was still not running right and suggested that I let them put on new spark plug wires. At this point I’m beginning to think of him as a parts salesman instead of a service manager. I said no and took it home.
I thought that with all their test equipment that they could find and fix it. Is it really that hard to find, are they incompetent, or were they just trying to make up for a bad economy? Which do you think it is? I don’t know but I’ve lost a lot of faith in Ford motor company.
When I checked under the hood I found covers at test sites missing, parts loose, and in two cases things in the motor compartment completely detached.
I have since tested the resistance of the plug wires and they range from 60 ohms to 8000 ohms. Checked all vacuum hoses. Checked fuses. Checked the distributor for cracks and wires for cracks. Put cleaner into the gas tank to clean the fuel injectors. Yesterday I remover the vacuum hose from the fuel pressure regulator. It started immediately, ran good for 30 seconds, then died. Put the hose back on, started immediately, ran for good for 30 seconds, then died. Took the plug off the vacuum tree, started immediately, ran great and kept on running until the key was turned off. When I punched the gas it revved up and didn’t stall. Today I tried it again without the vacuum plug. The first two times it started and died immediately. The third time it ran smooth. Put it in gear and it ran rough for a few seconds, then smoothed out. Drove it three or four miles, still running good. Turned the AC on at idle, still good.
I could run it like that but it’s probably not good to be sucking dust into the mix and also it probably is polluting or something and maybe even dangerous because something else might not work correctly.
If anyone has some ideas of what is going on I sure would appreciate hearing them.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Aug 10, 2009, 6:57 AM
Post #2 of 10
(9410 views)
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Re: hard starting , rough idle
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Arggh! Three weeks , $1,200 bucks and they had the audacity to give it back to you not running properly! They left stuff off, unplugged etc.?
That's just bad work, bad all around. If they truly lack diagnostic ability THEY should have refused the job but not sure dealers are really able (perhaps a car maker's rule for franchise) to turn down a vehicle they sell or at least tell you what is wrong and why they can't do it. No excuse for leaving covers off of things.
It's nearing or at 20 years old and there are some things that could be unavailable but they should have told you.
What I'm reading now - it runs fine with a vacuum hose off and runs rough with it back on - right? What does that vacuum hose go to or come from? What ever that changed it can only be covering up a problem so it isn't fixed.
I'd have that bill adjusted by management and seek a reputable independent shop.
Some of the 300CID/4.9 six engines did have an issue with stretched head bolts leading to leaking head gasket. If the turn to spec bolts they must be replaced new if that's the issue but the diagnostic time spent should have found this.
________________
Is this a random roughness or picking on a certain cylinder? You can feel that at the tailpipe then if one cylinder concentrate on why that one. Are plug wires original? Why for the low cost of those haven't you ruled them out with new ones?
  Price: $24.99
AVAILABILITY: SEND TO STORE LIST AVAILABLE Normally stocked at your local store. ******************* That's not enough money for parts that could have been done if you just were doing a PM tune up. An average DIYer can cancel one plug at a time grounding it at spark plug end and find the one cylinder (if just one) that's the trouble and diagnose that cylinder. This is a messed up way to do biz so talk to the person in charge of the whole place about this is my suggestion, T
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tweety
Novice
Aug 10, 2009, 12:58 PM
Post #3 of 10
(9395 views)
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Re: hard starting , rough idle
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Thanks for the reply, Tom.
Actually when I pulled different vacuum hoses off the truck it either dies immediately or runs for a few seconds and then dies. What let it run good for so long was when I pulled the plug off the vacuum tree. I'm probably not calling it the right thing but it is where a fitting that has no hose connected is plugged and where you would connect the vacuum gauge to run a test.
As far as why I haven't replaced the plug wires, I just got tired of throwing money at it and wanted to find out what was really wrong. Since it runs perfect with the vacuum plug off I can't believe replacing the wires would have any effect. I forgot to mention that I did check all the plugs to see if they were firing and they were.
I do agree that the problem may be vacuum connected, either something should open or close and it isn't.
I even replaced the heat sending unit because the temperature gauge wasn't giving a reading. I was hoping that was the cure. I now get a temperature reading but it didn't affect the idle.
If you have any other ideas I'm still listening.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Aug 11, 2009, 12:27 AM
Post #4 of 10
(9385 views)
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Re: hard starting , rough idle
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Ok: Old school thinking and you have a valid point with plug wires. The vacuum tree unplugged it's capable of running ok. Most engineering defaulted to an acceptable running engine but would lack the tweek controls observed by even mechanical vacuum devices.
Note: The high voltage of spark and anything electric is seeking ground. Plug wires and anything directing the secondaries (high volt items) are under stress with load on engine and may seek ground w/o making the plug do the last arc to fire the mix. All the items are forcing the spark to jump at the plug but doesn't care where it ends up. Again - load is harder for it to make that spark then no load.
The typical vacuum tree is sensing engine temps and routes vacuum to assorted controls as needed according to engine temp OR the load on engine to adjust fuel mixture, timing even as long ago as 1990.
I would need to know what the vacuum tree (there may be more than one) is controlling. The era stopped EGR from operation till engine warmed up and routed that vacuum to devices for that and more based usually on engine temp.
The gauge. That is separate from usually a two wire temp sensor placed near thermostat usually to tell how much fuel to deliver. I think default is richer not leaner but I'm guessing,
T
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tweety
Novice
Aug 11, 2009, 12:27 PM
Post #5 of 10
(9374 views)
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Re: hard starting , rough idle
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Tom, if you can hang with me for a couple of days I'll try to track down the routes of all those vacuum hoses.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Aug 11, 2009, 1:52 PM
Post #6 of 10
(9364 views)
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Re: hard starting , rough idle
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Just know - many cars/trucks back when has a decal sticker showing vacuum routing. At the age which is familiar to me look for that and plastic vacuum line that looks like wire - it can originate at a rubber part then to plastic which becomes brittle and breaks. In the infinite wisdom of auto makers they put them where then can break just checking fluid levels! Arggh! Bail out the stupid!
If broken plastic line is found, it can be spliced with window washer sized hose, FYI. Rubber elbows fail as well. Making a loop of hose out of harms way can create the right angle. Use automotive grade hose as needed if you find bad hose and elbows that tolerate heat and oils,
T
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tweety
Novice
Aug 12, 2009, 12:42 PM
Post #7 of 10
(9347 views)
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Re: hard starting , rough idle
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You're right about the schematic of the vacuum lines but it doesn't show all of them and I wanted to make sure they were accounted for. Here's what I got.
air bypass valve to SOLV tab
main vacuum to VRESER
VRESER to EVR
EGR to EVR
main vacuum to FPR
main vacuum to MAP
EFCA to PCV
main vacuum to power brakes
main vacuum to ac and heater doors
ERV solenoid bracket assembly to something that looks like a tin can.
main vacuum to a T or splitter. one line goes to another can and the other line goes to something about 6 or 8 inched round that has a hose coming out of it that goes into the passenger compartment. This thing also has a cable coming out of it that goes to the air throttle body and hooks the same place as the throttle cable.
I hope you make more sense out of this than I did.
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Loren Champlain Sr
Veteran
/ Moderator
Aug 13, 2009, 10:21 AM
Post #8 of 10
(9337 views)
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Re: hard starting , rough idle
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Pardon my jumping in;
tweety; First, agree with Tom; I'd be back in the manager's office. If this runs better with a large vacuum line off, that is telling me that it is running too rich. I see that they replaced the MAP sensor. It should have manifold vacuum going to it. Also, use your vacuum guage and tell us what reading you are getting at idle. If the vacuum is lower than 14 or 15hg, it could be causing the MAP sensor to go rich. If you can get to the injectors, take an ohm reading of each individual injector. Could have one or more bad. Take a fuel pressure reading (with the vacuum hose to the regulator connected). Also, note if there is any fuel visible in the vacuum hose where it attaches to the regulator. (do this with the engine off). If the regulator is leaking, fuel may come squirting out with the engine running. (this should also have manifold vacuum going to it...a loss of vacuum will cause it to go full rich). With the pressure guage still attached, turn off the engine and watch the pressure to see if it drops. Notice how many pounds it drops in, say, five minutes.
Of course, I wasn't there, but would have to agree with Tom, poor diagnostics. Sounds like they were just throwing parts at it.
Loren
SW Washington
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tweety
Novice
Aug 14, 2009, 7:21 AM
Post #9 of 10
(9326 views)
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Re: hard starting , rough idle
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Hey! All help appreciated.
I checked the vacuum and it runs at a pretty steady 20 inches. I believe that is about right for my part of the country.
It seems impossible getting to the fuel injectors without taking the intake manifold off.
The gasoline is under pressure at all times and I'm not sure how to handle that so I better leave it alone.
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Loren Champlain Sr
Veteran
/ Moderator
Aug 14, 2009, 10:54 AM
Post #10 of 10
(9318 views)
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Re: hard starting , rough idle
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tweety; In my humble opinion, you shouldn't have to be having to do these diagnostics, anyway. You have paid someone that should know, at least something, about Fords to repair your problem. If I diagnose a problem incorrectly, and believe me, it happens, I will put the customer's old part back on at no charge. Not his fault, mine. Like I said, just my opinion. Good luck.
Loren
SW Washington
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