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98 Ford Escort Rough Acceleration
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crimp111
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Oct 30, 2006, 7:02 PM
Post #1 of 22
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98 Ford Escort Rough Acceleration
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Hi, thanks in advance for your help. I have a 98 Ford Escort Sport 5 speed manual tranny with approximately 250000 miles. The motor was changed recently and it has 100000 miles on the new(used) engine. I'm having 2 problems that might be related to each other.
1. Idle speed - the idle speed is normal 50% of the time, 900 to 1000rpm, the other 50% it varies from 300rpm to 1500rpm. Most of the time when it goes wacky, it goes up to 1500 and stays there for an hour or less. Sometimes when I let off the gas, the revs seem to bottom out so much that the car does a nose dive for a split second before returning to a normal deceleration.
2. After accelerating above 2000rpm there is a very noticable hesitation, then it continues to accelerate and then hesitates again. It does this every 300 to 500rpms as its accelerating. If I hold the rpms steady, it doesn't hesitate. It seems to consistently hesitate at 2000, 2500, 2700, 3000 and 3300 rpms.
Neither of these problems cause the Check Engine Light to come on and no codes have been stored. Also, it does this whether the engine is warm or cold. It could be a coincidence, but the problem seems to clear up somewhat after unhooking the battery. But comes back within 10 to 15 miles. It seems to be worse when the outside air temperature gets cold.
Here's what I've done so far:
Replaced melted pcv valve housing and hoses
Checked all hoses for vaccum leaks
Replaced plugs
Replaced wires
Ran 3 cans of fuel system cleaner
Replaced the air filter
Cleaned the throttle body
Removed the fuel rail and checked the ends of the injectors for build up
Cleaned the Mass Airflow Sensor
Cleaned the Idle Air Control Valve
Checked for stored codes, none
Everything else seems ok, fuel economy is great, 37mpg and the car runs out on the road nice and smooth. It's just getting up to speed thats an adventure!!! Any help is greatly appreciated.
Greg
(This post was edited by crimp111 on Oct 30, 2006, 7:03 PM)
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otbmonkeyboy
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Oct 30, 2006, 7:22 PM
Post #2 of 22
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Re: 98 Ford Escort Rough Acceleration
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check the MAP sensor, and check the intake gasket. spray a little carb cleaner around intake gasket with car running to see if the idle goes up or down. you should be able to hear the change while you are spraying around the intake gasket.
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crimp111
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Oct 30, 2006, 7:33 PM
Post #3 of 22
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Re: 98 Ford Escort Rough Acceleration
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What is the MAP sensor. Mass Airflow? Thanks for your quick reply!
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otbmonkeyboy
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Oct 30, 2006, 7:53 PM
Post #4 of 22
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Re: 98 Ford Escort Rough Acceleration
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it is mass air pressure sensor. it is usually a small black rectangular box with 2 vacuum ports and maybe a connector. it works with the air temperature outside received by the sensor you have just replaced. it may be on the back fire wall in a "pocket" or indentation in fire wall. it is held on with two screws. it is an emissions device and can effect the proper workings of the motor
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crimp111
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Oct 30, 2006, 7:57 PM
Post #5 of 22
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Re: 98 Ford Escort Rough Acceleration
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Is there a proper way to check this sensor, or do I just replace it? If this is bad, wouldn't it cause the check engine light to come on?
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otbmonkeyboy
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Oct 30, 2006, 8:09 PM
Post #6 of 22
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Re: 98 Ford Escort Rough Acceleration
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there is no real way that i know to check. you have taken the right course so far. the check engine light would not come on. it only comes on for major emission problems or computer issues. the sensor has different ports and it would be very hard to pinpoint what port effects what in the system. the sensor is between about $20-$30 +/-. it is probably better to spend the cash than to drive yourself crazy trying to figure out whether you want to send it to a mechanic or the junkyard.
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crimp111
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Oct 30, 2006, 8:12 PM
Post #7 of 22
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Re: 98 Ford Escort Rough Acceleration
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Cool, I don't have a problem spending that small an amount of cash to try to fix the problem. It's been anoying me for the better part of 4 months now! Thanks for your help!
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otbmonkeyboy
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Oct 30, 2006, 8:14 PM
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Re: 98 Ford Escort Rough Acceleration
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no problem we are a ford family.
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crimp111
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Oct 30, 2006, 10:10 PM
Post #9 of 22
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Re: 98 Ford Escort Rough Acceleration
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After doing some searching (Haynes Manual etc), I don't think my Escort has a MAP sensor. Does this sound right?
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Oct 31, 2006, 4:04 AM
Post #10 of 22
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Re: 98 Ford Escort Rough Acceleration
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MAP sensors are monitoring the state of manifold vacuum in the engine which tells the car what to do with timing and fuel delivery. They may have integrated it with another device for you car but it's mandatory for the car to know that information.
It may be called something else in some cars. Intake manifold vacuum also called pressure, is key for the car to make adjustments for proper performance. They have needed this info since about forever whether mechanical or electronic. With emissions being a big concern they convert the info into an electronic devise to tell the computer. Even a vacuum leak to it which may go from a rubber elbow into what looks like wire has to be intact and the plastic line if applicable does get brittle and the rubber elbows can get splits and be the problem. Takes a hard look and if you find something it can be replaced with just high quality vacuum line and forget the plastic or splice it if you find something, T
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DanD
Veteran
/ Moderator
Oct 31, 2006, 5:35 AM
Post #11 of 22
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Re: 98 Ford Escort Rough Acceleration
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Your right crimp111 this vehicle does not use a MAP sensor the MAF has taken its place.
I’m not sure but I think the sensor that otbmonkeyboy is talking about is the EGR pressure differential sensor only because he’s talking about two hoses going to it. If so I doubt it would be causing the problem; plus these things will throw a code just by looking at them the wrong way.
I would get a voltmeter connected to the TPS return signal wire by back-probing the connector and then move the throttle from closed to wide open. Watching the voltmeter for a smooth consistent increase in voltage. At closed throttle you should see approximately .5 (1/2) of a volt and at wide-open 4.5 volts.
If while your moving the throttle you see a jump in voltage or a drastic change then you may have found the problem.
Dan.
Canadian "EH"
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crimp111
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Oct 31, 2006, 5:46 AM
Post #12 of 22
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Re: 98 Ford Escort Rough Acceleration
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Ok, I'll test the TPS. Thanks much for everyone's help! I've gotten more help in one night than in 2 weeks on any other forum!!!
Greg
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crimp111
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Nov 2, 2006, 5:08 AM
Post #13 of 22
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Re: 98 Ford Escort Rough Acceleration
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Ok, so I checked the TPS and it seemed to operate ok, but since a new one was only $17, I went ahead and replaced it. It didn't make any difference at all. I've still got the same hesitations as before. Any other ideas?
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steve01832
Veteran
Nov 3, 2006, 4:08 AM
Post #14 of 22
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Re: 98 Ford Escort Rough Acceleration
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You said earlier that you cleaned the Mass Airflow Sensor. If you cleaned it with carburetor cleaner, that may have caused more harm than good. Let the engine idle and tap the mass airflow sensor gently. You can also shake the air duct the sensor is mounted in. If the RPM goes erratic and or the engine stalls, replace the Mass Airflow Sensor.
Steve
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crimp111
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Nov 5, 2006, 2:37 PM
Post #15 of 22
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Re: 98 Ford Escort Rough Acceleration
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Cleaning it didn't make any difference either way, it ran the same after I cleaned it as it did before.
Today, I pulled the air cleaner apart while the engine was running and it started idling really rough. I didn't know if it had something to do with having more air and maybe it was already running lean or if this was a normal occurence. I'll try shaking it and tapping on it to see if it does anything.
Thanks for your help
Greg
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crimp111
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Nov 5, 2006, 7:15 PM
Post #16 of 22
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Re: 98 Ford Escort Rough Acceleration
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Ok, so I shook and tapped the MAF sensor housing and it did make a difference in the idle, it dropped way down and then leveled back out.
I also took the fuel pressure regulator out and 1 of the 2 o-rings on the end of it are broken. They are on a plug that fits into a hole on the fuel rail, one o-ring above the other, and the bottom one was broken. I removed it and put it back in. It still seals ok with the one, but I wonder if any of the peices from the broken one may have gotten lodged in an injector.
Also, I tried running it without the air cleaner and it runs horrible! I can't hardly take off, when I press the accelerator it just doesn't go. It spits and sputters at idle and dies sometimes. Once I get it going and get the rpms above 2000 it runs ok. After driving on the highway, I stopped at a light and the revs stuck at 2000 for about 20 seconds, then dropped to almost nothing and it eventually died. Does this sound like the MAF sensor? How can I check it? I don't want to blow $95 on a new one if thats not the problem!
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steve01832
Veteran
Nov 6, 2006, 3:08 AM
Post #17 of 22
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Re: 98 Ford Escort Rough Acceleration
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The only accurate way to check the MAF sensor is with a scan tool looking at the grams per mile on the datastream. The reason I told you to tap and shake it is to see if the MAF was subject to outside vibrations causing false readings. If you tapped it and shook it with the air cleaner assembly fully intact and the engine responded, replace the MAF sensor, cut and dry. That proves that the road vibrations and engine vibrations are causing it to give the PCM faulty information which the computer will try to compensate for.
Steve
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crimp111
User
Nov 6, 2006, 10:26 AM
Post #18 of 22
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Re: 98 Ford Escort Rough Acceleration
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I replaced the MAF sensor and I've still got the same problem. After I installed the MAF sensor I drove for 20 or 30 miles and the Service Engine Soon light came on, checked it and it has stored an Insufficient EGR Flow code. Any other ideas?
(This post was edited by crimp111 on Nov 6, 2006, 10:27 AM)
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steve01832
Veteran
Nov 6, 2006, 4:18 PM
Post #19 of 22
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Re: 98 Ford Escort Rough Acceleration
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Check the EGR to make sure it is closing fully. Remove it and look at the pintle to make sure there is no carbon buildup. If that checks out OK, you may need an EGR solenoid or a DPFE sensor.
If you have a vacuum pump you can test the EGR with the engine idling. Remove the vacuum line and install the vacuum pump to the port. As you start pumping the vacuum pump the EGR should start to open and the engine should idle rough. If you keep pumping the engine should stall. Make sure the EGR valve holds vacuum. When you release the vacuum, the EGR should fully seat closed.
Steve
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crimp111
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Nov 6, 2006, 6:23 PM
Post #20 of 22
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Re: 98 Ford Escort Rough Acceleration
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I had forgotten to plug the EGR valve back up after checking for vaccum leaks. Plugged it back up, pulled the battery cable and the CEL didn't come back on. Any other ideas on the hesitation? What about the O2 sensor? The motor has 115,000 miles on it and I don't know if it has ever been changed. One other thing. When I had the air filter out of it and it was running really worse, I noticed the shift light stayed on most of the time, could this indicate a vaccum problem, maybe low compression? I'm thinking it's running lean since taking the air filter out made it worse. I'm grasping for straws now.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Nov 6, 2006, 6:36 PM
Post #21 of 22
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Re: 98 Ford Escort Rough Acceleration
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This is being a pill for you! Check manifold vacuum and it could vary by the altitude you are at but at idle should read about 18Hg.
Many engines won't run well with the air cleaner not installed so that's inconclusive to anything. Keep at it. By all means check the EGR that its pintle moves in and out and isn't to crusty with carbor build up like Steve suggested. You will need a new gasket for it, T
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crimp111
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Nov 6, 2006, 7:16 PM
Post #22 of 22
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Re: 98 Ford Escort Rough Acceleration
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Cool, I'll check the manifold vaccum. Thanks for your help!
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