Rpm hang up and increase when shifting | Ford Escort Owners Association (FEOA)
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Rpm hang up and increase when shifting

Discussion in '3rd Gen 1997-2002 2.0L SOHC' started by 408dunnale, Aug 1, 2016.

  1. 408dunnale

    408dunnale FEOA Member

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    I converted my 1997 Escort 2.0 Spi from an automatic to a manual. Everything seems to be fine and I have put on about 5000km since the swap. But I have always noticed that when I shift, the rpm will increase about 500rpm and then slowly fall. Making it take forever to shift. There seems to be no vacuum leaks, I have tried changing the idle air control valve, cleaning the MAF, the throttle position sensor. Also, I have swapped the PCM from the manual car. I have tried test driving the car with the idle air control unplugged and it struggled idling (of course) but it had no issues when shifting, the rpm dropped like it should. As I said, I have tried changing the idle air control valve (and gasket). Any idea on what could be making the IAC stay open a little bit?

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  2. DrewsBrews

    DrewsBrews FEOA Donator

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    I think if you unplug the IAC it should stall. You may still have a vac leak somewhere or the IAC may need cleaned if it is sticking open some.
  3. 408dunnale

    408dunnale FEOA Member

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    I have cleaned and replaced the IAC, I believe I have eliminated any possibilities of vacuum leaks except for the EGR system, and the PCV. But there are no visable issues with either

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  4. Pizzaman5000

    Pizzaman5000 FEOA Donator

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    Sorry for being pessimistic, but we don't trust when new members say "no vacuum leaks" the only way to know is to either smoke the intake or spray EVERYTHING with aerosols. You'd be surprised how small a vacuum leak can be.

    But that does sound like a dirty egr problem, with the hanging rpms. Cleaning the dpfe is a good idea, that will at least either help fix the problem or help to get a correct CEL/DTC. But the egr valve itself just gets plain ole' dirty anyway, which will hurt mpg and power if it hasn't been cleaned. I know they can be not-fun to break loose the first time due to rusty exhaust, or seized bolts into the aluminum intake. That's why I say "figure out", no harm in letting some penetrating spray start the job a day before you do ;)

    BTW, how did you check for vacuum leaks? I check mine if anything changes in the way it runs, I am even AWARE of vacuum leaks that I can't be bothered to fix, but I at least know they are there, and they are small (throttle plate bushings). It only takes a tiny vacuum leak to be a real vacuum leak.

    That IAC seems suspect too. Unfortunately, they move fast, and its probably the one part that nobody has a good way to diagnose. If unplugging it cures the problem, it may be worth exchanging.
  5. 408dunnale

    408dunnale FEOA Member

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    I guess I truly can't be sure if there isn't a vacuum leak, I tried capping off different outlets on the intake manifold to isolate it, nothing made a difference. I tried cleaning the EGR valve and tube and cleaned and swapped the dpfe from a parts car. I also tried runnig the car with the dpfe unplugged and the vacuum actuator unplugged on the EGR valve so (endless the valve has a hole in it) the EGR shouldn't be suspect. I have tried cleaning and swapping 2 different IAC's from various parts cars (we love escorts). This has really got me stumped.

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  6. copcarguy

    copcarguy FEOA Member

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    My 1997 wagon has done this on & off when it feels like it. It is totally annoying. My car was born a stick.

    I've found that using a genuine Motorcraft PCV valve, a genuine Motorcraft air filter, and spray cleaning the MAF with CRC MAF spray every 2,500 miles or so make this rpm flaring "fixed" about 95% of the time. Even so for no rhyme or reason whatsoever it'll get pissed off and do this for a while and then be normal. It's like someone flips a switch on a sensor and throws off the cars thinking.

    I did my timing belt recently and found that the top gear was one tooth off. The car was PERFECT for about 3,000 miles and I thought that was the reason it was doing it. It has since returned occasionally.

    I have noticed a very loud click (like a relay or something, it'll make like 5 clicks) around the battery / wiper motor area that I have been unable to pinpoint that immediately precedes an rpm flare.

    I've changed or swapped out so much stuff to get rid of this issue it isn't even funny. Search back through my old posts and maybe we can find a fix. Two (or more!) heads are better than one...
  7. copcarguy

    copcarguy FEOA Member

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    As a band-aid, when the car is pissed I take my foot off the gas one second before I normally would, THEN push in the clutch and execute the shift.

    That one second delay of coasting uses up the time of the rpm flare and enables you to shift smoothly.
  8. copcarguy

    copcarguy FEOA Member

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    Any updates?
  9. 408dunnale

    408dunnale FEOA Member

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    No not really, I have swapped out parts from 2 separate parts cars and there has been no change. I have been using the same "band aid" to get around, but it's still annoying.

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  10. copcarguy

    copcarguy FEOA Member

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    Does your car do this all the time or just occasionally?

    Do you feel that it's a sensor / electrical issue too? I don't think it's a vacuum problem based upon the way it's there one minute and gone the next. Also because of the clicking noise I can hear.

    Would a slow reacting IAC be a contributing factor? I'm on my 2nd one, and it really didn't change anything.
  11. 408dunnale

    408dunnale FEOA Member

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    It's there all the time, and always consistent. I personally think it must be caused by switching it from the automatic to the manual. Possibly something in regards to shifting for the automatic? Maybe it doesn't want the IAC closed right away with the automatic? Not sure. But those issues wouldn't apply to you.

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  12. Pizzaman5000

    Pizzaman5000 FEOA Donator

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    I can see a vacuum leak on the EGR exhaust tube causing the rev, I wonder if your foot coming off the throttle is making the ecu think it's supposed to "coast down". Which I think would cause strange ignition timing, and probably open the egr to save fuel. But if it's expecting an auto trans to be dragging, maybe the egr is fine, and the ecu is just wrong. But if there is oxygen in the egr when there shouldn't be, I guess theoretically that could cause the rpms to hang. Egr makes the combustion slow down, but if it has oxygen being sucked in (like where the exhaust tube meets the valve) that could make the timing become advanced due to the faster flame speed with oxygen, but furthermore, that would probably register lean in an o2 sensor's eyes... Which would possibly lead to even more rpm hang.
    Or the ecu is just wrong. Putting high temp rtv on the threads of that double but thing for the egr isn't a bad idea. Can't promise an egr vacuum leak is even the problem though. Once you start swapping stuff out, the amount of variables multiplies.

    I really just don't have an accurate guess with an automatic ecu on a manual. Plus I never work on 3g's so idk.
  13. 408dunnale

    408dunnale FEOA Member

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    To possibly rid of the EGR issue, I took off the vacuum line from the top of the valve and plugged it, there was no change. So endless the actual valve has a leak in it... I am going to grab the ECU from our manual parts car and throw it in, can't hurt anything. And to my knowledge, the only real "brains" on these cars are the PCM (under the dash) and the ECU (under the intake) if I'm wrong please correct me.

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  14. rbailin

    rbailin FEOA Member

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    ECU is a synonym for PCM. The CCRM under the intake filter housing is just a collection of relays controlled by the PCM.

    There are separate, smaller computers (modules) for ABS, airbags and anti-theft.
  15. 408dunnale

    408dunnale FEOA Member

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    So the CCRM shouldn't differ from manual to automatic?

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  16. Intuit

    Intuit FEOA Member

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    Check the links between the ECU and clutch pedal switches, plus neutral switch. Check to make sure that they actually work, and the computer can read them. The prior generation 'scort has upper and lower switches for the clutch pedal; don't know about your 3rd Gen.
  17. 408dunnale

    408dunnale FEOA Member

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    I actually was looking at those switches, both are connected, but the upper one (first to be activated) doesn't have power going to any of the 4 wires when running. But I thought I read somewhere that that button was only for cruise control, which my car doesn't have.. Could it be my problem?

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  18. Intuit

    Intuit FEOA Member

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    Could be used for CC; I do not know. My older generation Escort was not equipped with CC and had upper and lower switches regardless. Regarding that older 'scort, I can tell you that I had not observed that issue while the lower and neutral switches were shorted. I don't recall observing that issue when the upper switch's operation was affected by the bumper-pad coming off. As a test, you might see whether it's behavior is altered when these switches are left shorted.

    The KOEO test would flag these switches if they were bad. I don't know of an equivalent test for the OBD-II vehicles however. Perhaps someone could chime in on whether such a test exists.

    One thing to note, when the A/C compressor engages, it will increase the idle in anticipation of the missing engine load, created by the compressor. For the prior generation 'scort, that would be a permanent observation though, and not temporary as you're describing here.

    Red herrings likely, but possibly some other things to consider...
  19. rbailin

    rbailin FEOA Member

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    They're identical.

    According to the wiring manual, there are 2 switches on the clutch pedal. The clutch start switch (red and red/white wires) disables the starter until clutch is pressed. The clutch pedal position switch (brown/yellow and lt. green/black) and the PNP (park-neutral position) switch on the transmission both tell the PCM (pin 64) when you're in neutral or when the clutch is pressed. Both switches should be easy enough to test with a meter. CPP is closed when pedal depressed, PNP is closed in neutral. Engine speed increases when both are open.

    If the PNP switch wasn't working, I would expect a low idle all the time if it's stuck closed, and a high idle in neutral only with your foot off the clutch if it's stuck open.

    If the CPP switch wasn't working, I would expect the engine to flare when you step on the clutch until you shift into neutral (if the PNP switch works ok). If you shifted into neutral without pressing the clutch, this wouldn't happen. (This is how my AT behaved when I was low on fluid: engine speed increased to 1200 when put into drive even when it didn't go into gear.)

    It's more likely for the CPP switch to fail.

    When the A/C is on, engine speed gets bumped up a little, whether or not the compressor is running.
    Last edited: Aug 9, 2016
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  20. 408dunnale

    408dunnale FEOA Member

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    In the "how to" forum I followed, it said it didn't require hooking up the neutral position sensor, so i didn't. I'm not sure where it would hook up or where to wire it up. But im definitely going to look closer at this switch, is there a way I could see this wiring diagram?

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