Limp Mode

[chlblnz]

Hi,

I'm very new to this forum so if this has already been covered, a link would be really helpful.

I've bought a 2006 Focus 2.0 Duratec Ghia. The car is in limp mode and has engine problem written on the dash. The MIL light is also on.

I've run ForScan and it's come back with quite a few error codes (attached photo) 

The only one which reads it's Force Limiting RPM is P2100 (Throttle Actuator Control System). My first thought was to change the Throttle Body unit (2nd hand one) as a whole and conduct a Powertrain Control Module reset through ForScan. This hasn't changed anything except when I first started it up, I had my first on the throttle and it rev'd right up but then went back to being in limp mode again after only a second.

Next, I tested the output voltage of the throttle position over time using the ForScan oscillascope. One thing I noticed was the minimum voltages for each of TP1 and TP2 were quite different. One was 1.19V and the other is 0.69V. I'm not sure if they are out of the allowable difference and therefore tell the ECU to put it into limp mode?

Next i tested the output voltages of the PCM to the TPS. This is where the TPS connector is off and the ignition is on/engine off. I have 5V for the reference voltage.

I then went into the back of the connector whilst connected to the TPS and ignition on with paper clips and measured as follows.

Yellow./Blue Stripe = 1.29V (moves up to 5V with manual butterfly movement)

White/Blue Stripe = 5V

Brown/Blue Stripe = 0V

Blue/White Stripe = 0V

Black/Orange Stripe = 3.8V (Increases to 5V if I let the butterly snap closed. Another strange thing that happens is that the DC Motor in the throttle body housing is constantly winding when the ignition is on. If I remove the connector the motor (obviously) stops. This pin reads 1.29V whilst the motor is running and returns to 3.8V once I've stopped it.

Green/Orange Stripe = 0V

 

The colours might be a bit out as I was doing this with the headtorch this evening.

I spoke to a Ford specialist today and they think it might be to do with a faulty Instrument Cluster as this can bring up a lot of error codes like I have.

Has anyone heard anything like this before? If anybody has any ideas of what could be causing this limp mode, I'd be eternally greatful

[chlblnz]

I've found another oddity with the throttle. When I turn the key to position 2 (ignition on/engine off), the throttle body motor is on/rotating. And when I try and push the butterfly to open the throttle, the motor is holding is shut. 

 

Has anyone seen this before?

[iantt]

thats normal operation, ive seen the same dtc and that was an instrument cluster fault from what i remember. you do have alot of cluster dtcs. have you cleared all the dtcs and the above is what returns?

[Tdci-Peter]

On 05/01/2017 at 8:39 PM, chlblnz said:

Has anyone heard anything like this before? If anybody has any ideas of what could be causing this limp mode, I'd be eternally greatful

Those codes certainly look like the IC fault that is very very common on 2006 Foci.

Of the two signals from the accelerator, one goes to the IC, and is then sent to the PCM via the HS CAN bus. The other signal goes direct to the PCM. The IC fault often affects the HS CAN bus, so may well cause throttle deviations.

Try tapping the facsia around the IC. It may make it better, or worse (don't do it in the middle of nowhere!), either way would help narrow it down.

A simple resistance test can diagnose some faults on the HS CAN bus:

Stick a couple of suitable probes (un-bent paper clips can work quite well) in the diagnostic connector pins 6-14, put a DMM across the pair on voltage range, turn ignition on, note reading, turn ignition off, wait till voltage drops to zero (+/- 1 or 2 mV), switch to resistance range to check for 60 ohms.

It should be stable at close to 60 ohms, any deviations would indicate a problem.

I made a pdf about a repair to my IC. Some companies offer to repair them for about £100, a Ford dealer will relieve of over £800 for a new one. One caution: You do need to be fairly certain it is the IC at fault before sending it for repair. There are some connectors and other bits that can also have similar effects, but the IC fault is the most common.

PDF should be here: http://www.fordownersclub.com/forums/applications/core/interface/file/attachment.php?id=40491

[chlblnz]

Hi,

Sorry for the delay in replying, 

I did try and reset all of the DTCs but they came straight back. I will have another attempt this evening and tap the IC at the same time to see if it makes a difference. 

TDCI-Peter, thank you for your in depth response. PDF is great! I've got my paperclips at the ready and will test the diagnostic connector this evening. I'm not bad at soldering so think I can do this in house.

I'll be in touch with the results. 

Thanks again.

[chlblnz]

Good evening,

I've attempted to repair the 32 IC connector pins. I've run a soldering iron over the pins and hoped for the best.

This evening I've plugged the unit back into the car and reset the DTCs. Good news is all the IC DTCs have cleared. Bad news is the PCM DTCs have not. Picture attached.

Could this still be a case that I've not correctly fixed the IC or is the fact all the IC DTCs have cleared an indication that it's now fine and the problem lies elsewhere?

How difficult is changing out the PCM? Does it need coding to the car?

Thanks`

[Tdci-Peter]

3 hours ago, chlblnz said:

Could this still be a case that I've not correctly fixed the IC or is the fact all the IC DTCs have cleared an indication that it's now fine and the problem lies elsewhere?

P2008: intake manifold runner circuit has an open electrical connection bank 1

P0108: manifold absolute pressure sensor high voltage.

P0113: Intake Air Temperature Sensor High Voltage.

P2110: Throttle actuator control system-forced limited RPM

It is very difficult to blame the IC for these codes. The only one that may involve the IC is P2110. One of the elements in the Throttle control system is the pedal, and the pedal is powered by the IC, and one of its two outputs goes to the IC. The other output goes to the ECU. The ECU can read the IC input over the CAN bus, and compares it, and will flag an error if there is a significant difference. But there are specific DTCs available for this, logically it should not cause P2110, but the software in these cars often seems to defy logic!

It might be worth rechecking the pedal connections to the IC, pins 13,14 and 31 on the 32 way connector.

Otherwise they are errors relating to stuff directly connected to the ECU, with the error being in the ECU, so virtually ruling out communications errors

Before condemning the ECU, every other option has to be tested. The TMAP (combined temperature & pressure sensor) is a prime candidate. Two errors relate directly to this, and the airflows are calculated from this, which can relate to both the other errors.

The ECU is hard to change, and has a lot of vehicle specific info in it. Including the PATS (immobiliser) codes. It is not very easy to get at, there is a security bolt that has to be drilled or ground off. The ECU usually hides in the air duct in front of the n/s (left) front wheel, the wheel arch liner has to be removed (which is quite easy). You could have a look in there to see if there are signs of dirt or corrosion.

[chlblnz]

Hi,  

Again, thanks for your in depth reply. I've been trying to get this effing TMAP sensor out of the car. The bolt is quite inaccessible. I've attempted to remove the radiator fan to give a little more access. Have all the clips release but the fan shroud bumps onto the front cross member of the engine bay. Ford have placed a bracket directly above the fan shroud which prevents it coming up high enough to come away from the clips. PIcture attached. I've Google'd this quite extensively and have had little luck finding anyone with a similar problem. On all the cars I've ever worked on, the fan and radiator come out the top so scratching the head a lot.

[chlblnz]

Think I've found a problem [emoji12]

[Tdci-Peter]

20 hours ago, chlblnz said:

On all the cars I've ever worked on, the fan and radiator come out the top so scratching the head a lot.

I don't have info on the petrol engine variants, but for the 2L & 1.8L deisels, Haynes describes a slightly complex procedure for removing the cooling fan. It involves undoing the radiator support brackets, and replacing the front retaining bolts with long bolts. Presumably this allows some mevement while still supporting the radiator. Then after removing the intercooler hosesd (not present on the petrol version), the fan is lifted out.

For the 1.6 Deisel, the radiator is removed with the fan attached. It sounds like the radiator is lowered out under the car, complete with the fan.

Edit: i have just seen your post above, looks like you have may have got there anyway!

Edited January 29, 2017 by Tdci-Peter
Add note

[chlblnz]

Thank you Peter, it was just the loose wire into the connector. Need to solder it all up to make it permanent but all testing has been successful.