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[Rock]

After taking some advice due to some throttle / idling problems, today I removed the throttle body and gave it a good clean with carb cleaner. It is now sparkling and looking like new!

I re-fitted the throttle body, and re-connected everything i had disconnected. (2 hoses on the throttle body with circlips, and the small one that slides on underneath) Plugged the FBW throttle lead back in.

The only other thing I removed was the bagpipes at the front but i have re-fitted that, plugging the 2 connectors back in, and the 2 thin hoses. Everything looked good, and as it was when I started. The problem I have now is as follows...

Start the car, and the throttle does seem more responsive. Revved it up to 6000 rpm and it sounded loads better. When taking my foot off the throttle, the engine settles down to idle, and after a short while the TC light comes on, and then when I press the throttle right to the floor it only gets as far as 2500 rpm.

If i then turn off the ignition and start the car again i get exactly the same thing happen. Have I plugged something in wrong or has some carb cleaner got in to the electrics part of the FBW throttle??

I have linked to a video I took displaying what happens.

Link to video

[Chopsdad]

Excellent video & audio.  I don't have TC on mine but have the same erratic idle - but without the rev restriction - which is probably being held off by the ECU.

I'm sure one of the Experts will be along shortly to tell you which sensor is playing up & why.

Good luck.

[Rock]

Thanks, I hope so. The car is unusable now as the same thing happens when in gear and driving.

[Bo Bo]

Thanks, I hope so. The car is unusable now as the same thing happens when in gear and driving.

Mine's a '95 & has three electrictal connectotrs, maybe the '01's different?

[Marks DTM Calib]

Right, we need to know the TC fault codes which will require a tech2 or similar.......the TC on the later units has a CAN bus link into the ECU and this is putting the ECU into limp mode for some reason.....I suspect rpm signal fault or similar.....

Can you also measure the battery voltage when revving the engine, it shouldn't go much above 14V .......

[Taxi_Driver]

Thanks, I hope so. The car is unusable now as the same thing happens when in gear and driving.

Not sure what the prob is.....but im sure Mark can help  ....but what i can add is if gearbox is going into limp mode....use the shift to use 1st 2nd etc.....it works but a bit lumpy/snatchy  

[Rock]

Right, we need to know the TC fault codes which will require a tech2 or similar.......the TC on the later units has a CAN bus link into the ECU and this is putting the ECU into limp mode for some reason.....I suspect rpm signal fault or similar.....

Can you also measure the battery voltage when revving the engine, it shouldn't go much above 14V .......

I will go down to Vx in the morning and ask the service guy nicely to read the codes with his tech2. I don't own a multimeter so I will either get one in the morning or ask the nice Vx man to do it.

[sounds2k]

at a guess ... throttle position sensor? Or don't FBW models have 'em?

[TheBoy]

If you had bagpipes out, should be 3 electrical connectors:

Air intake temp, on 90 bend from air filter
MAF, just below it (the one we were pondering how it unclips earlier this week)
Front multiram (little way down, between the 2 bagpipes, near where vac hose goes on)


Also (though I know you haven't probably been near it), just check the connections to ABS unit, as TC is controlled primarily by ABS ECU...

[Rock]

If you had bagpipes out, should be 3 electrical connectors:

Air intake temp, on 90 bend from air filter
MAF, just below it (the one we were pondering how it unclips earlier this week)
Front multiram (little way down, between the 2 bagpipes, near where vac hose goes on)


Also (though I know you haven't probably been near it), just check the connections to ABS unit, as TC is controlled primarily by ABS ECU...

Mine definitely has only 2 connectors. There is no connector on the 90 bend from the air filter.

The red circle shows the one we looked at on thursday, and the blue circle shows where the other one would be if i had it. (I think)

[TheBoy]

Never noticed that before...

Anyone know where air intake temp is on 2.6/3.2 then?

[theolodian]

The following is based on my experiences with other DBW engines.  I've never touched a VX DBW.

Have you tried turning the ignition on without starting the car for 3-5 minutes?  Also try re-connecting the throttle body.  When you unplug DBW, the ECU has to go through an alignment process where it 'learns' the open and closed positions of the throttle plate.  If not, then you end up in a drastic limp mode like you described.  The TC button may be the cause as well, or maybe it is a symptom of the ECU limp mode.

Intake temp and MAF being completely unplugged should not cause the symptoms you are describing.  The best thing is to read the trouble codes.  Any OBD2 scanner would be a real help.

[TheBoy]

Worth measuring battery voltage as said by Mark, in case overvoltage is knocking out something in ABS/TC ECU, causing it to tell engine ECU to reduce power.

Also, get that emissions bulb replaced (10 min job) and see if that is illuminated...

[Rock]

Took the car down to Vx this morning and they have apparently spent some time diagnosing it. I am informed that bank 1 coil pack needs replacing.

When we read the codes with tech2 on thursday evening, it showed cylinder misfires on cylinders 2, 4 & 6. Would this fit in with them replacing the bank1 coil pack?

They also tested the voltage output from the alternator and said it was only 12.9V and that this might need replacing but that it was unlikely to be causing the erratic idling / limp mode problems.

[Marks DTM Calib]

lol.....cylinders 2,4,6 are on bank 2........what cylinder(s) was the missfire recorded against.....