RPM wobble and stuck high

[mihalyn90]

I am getting fed up...
It's an older issue but here is the thing...when engine hot:
on clutch pedal press, engine RPM is stuck high or wobbles, and when the car comes to a full stop, it just drops to idle.
when engine is cold, the RPM just stucks up, won't wobble... for exemple ignition, 1st gear, goe couple of meters, press clutch, RPM is stuck high where the clutch was pressed... on full stop, it drops slowly to idle...

checked all the vacuums... found this:


Hose looks fine, but in the manifold it goes in out couple of centimeters... also the plastic gromet seems to be broken...
please drop a FINIS code for it as i can't find it :|

 

[grogee]

I think that's the brake servo connection. Here's a link to the part but it's quite spendy:

https://www.ebay.co.uk/itm/272377548437

I didn't want to spend that so I drilled it out, tapped it and put a brass fitting in there with a friction fit hose to servo. My manifold was off the car at the time so I was able to Hoover out all the swarf.

 

[mihalyn90]

that is a nice idea... the price is not big but doesn't ship to romania... also still don't know if this is the problem or not...

someone can confirm if the hose is moving front and back?

 

[mmc757]

If its like the fitting posted by Grogee, those can wiggle a little bit. They were also used on many other Fords of the same era so you may be able to find a good one at a junk yard. I can say with certainty that 2.5l V6 Duratec cars (Mondeo, Cougar, MPV) have two of them right on top of the engine.

Your idle problem sounds more like an IACV issue though. I would check that out before chasing fittings you aren't sure about. Start by doing a cleaning and inspection of the IACV, that doesn't cost you anything but a small bit of time.

 

[mihalyn90]

cleaned them...
also i have error Codes:
P1135
P0135

 

[DOH]

cleaned them...
also i have error Codes:
P1135
P0135

From using Google,both of the codes show that the heater element within the lambda sensor(Oxygen Sensor) is now faulty.
That will affect the idle smoothness, felt by holding the gear stick knob, but this won't be the reason for the fast idle speed.
That is likely to be the idle control valve . Have you cleaned it out with carb cleaner?


It is very simple to establish if the fitting on the inlet manifold you are asking about is sucking in air.

Using either a safety pin or paper clip and a Digital voltmeter(DVM) set to the milli volts (mv) range.

If you look at the Lambda plug that goes to the engine manifold, there are 4 wires . 2 of them are the same colour , iirc grey. anyway they are the heater wires . You then have 2 remaining .

With the engine running ,If you connect 1 lead of the DVM to ground , the red lead via the paperclip or safety pin inserted in the plug to the wire that shows a varying milli voltage, the value will cycle(vary) up and down .
That's the signal going back to the PCM.


With the engine running, spray with the straw of the Carb cleaner or WD40 around the suspected connection on the inlet manifold pipe.
At the same time observe the DVM , if its sucking in Carb cleaner , the voltage will change/cycle at a greater rate than before.

Have you got the ICV gasket fitted ?

Using the same method ,check for manifold leaks where the 2 halves of the manifold join together, and tighten the bolts if needed. :thumbs:

 

[CherryVimto]

P0135 Heated Oxygen sensor (HO2S) 1, bank 1, heater control - circuit malfunction - Fuse, wiring, HO2S, ECM

 

[mihalyn90]

Sorry was P1131 not P1135...

P1131: Lack of HO2S11 switches - sensors indicates lean

idle control cleaned, gasket is all fine, no problem, maf cleaned...

 

[DOH]

Are you now sorted after cleaning the MAF?
If not try looking at this

https://www.troublecodes.net/p1codes/p1131/

 

[mihalyn90]

I'll take the car next week to change the clutch... I'll ask the guys to look around

 

[Stonegarden]

I'll take the car next week to change the clutch... I'll ask the guys to look around

did u find the problem ? I have same issue

 

[mihalyn90]

Got to live with it...

 

[Gasher33]

I have the same problem and still no luck, I also replaced the TPS

 

[mihalyn90]

I cleaned MAF sensor, it is good. Cleaned TPS... I also changed the oxygen sensor... Only VSS sensor remaining to be a culprit...

 

[Gasher33]

I'm wondering if I could test the O2 sensor or the VSS before changing them.

 

[Gasher33]

I managed to figure out the problem when I unplugged the TPS and the revs went to normal. The TPS was new so I suspected the wiring and two pins from the loom coming the the TPS were dirty and after cleaning the problem is gone

 

[mihalyn90]

long story short... sorted... there was a black cable hanging in the air... got earthed... works fine

 

[Gasher33]

there was a black cable hanging in the air

could you say which cable was hanging. maybe that is my problem as well.

 

[RICHARD MANSFIELD2]

Hi Guys.

I have had this problem of erratic engine revs for some time. I have checked the obvious but no luck in sorting it. Yesterday I was in stop/start traffic on a long hill.

When sitting stationary with the hand brake on the tickover was normal at 800 revs. When I let the hand break off and without touching any controls allowing the car to roll forward at a slow (walking) speed the engine revs went up to 1000 and surged up to 1200 then back to 1000 this happened about 4 times then the revs dropped back to 800 whilst still rolling. I stopped by applying the handbrake. I repeated this about 6 times and the result on engine revs was the same. Weird or what.

Another weird thing is that if I coast for down a hill at about 50mph and put the car in neutral the engine revs will continually pulse between 1000 and 1500 rpm without going back to a tick over speed.

Has anybody any ideas?

Regards,
Richard.

 

[WideSam]

Hi Guys.

I have had this problem of erratic engine revs for some time. I have checked the obvious but no luck in sorting it. Yesterday I was in stop/start traffic on a long hill.

When sitting stationary with the hand brake on the tickover was normal at 800 revs. When I let the hand break off and without touching any controls allowing the car to roll forward at a slow (walking) speed the engine revs went up to 1000 and surged up to 1200 then back to 1000 this happened about 4 times then the revs dropped back to 800 whilst still rolling. I stopped by applying the handbrake. I repeated this about 6 times and the result on engine revs was the same. Weird or what.

Another weird thing is that if I coast for down a hill at about 50mph and put the car in neutral the engine revs will continually pulse between 1000 and 1500 rpm without going back to a tick over speed.

Has anybody any ideas?

Regards,
Richard.

My car does something very similar when rolling and definitely idles strangely when it’s up to temp (haven’t tried coasting in neutral at any speed). I’m yet to attempt to investigate what it is…
Mine dips/hunts slightly at first then rises. I’m assuming it’s probably ICV/vacuum related