Request for advice, car won't idle

[ChrisC]

There is little or no adjustment with the TPS of the standard Duratec plastic throttle body,   Remeber the ECU is permantly powered, so after you have made the throttle adjustments disconnect the power (battery or master switch if you have one) so the ECU can adjust to the new idle position.

[CtrMint]

Chris, to be clear you're still recommending I follow the guidance from James, but then reset by disconnecting the battery.  I think that's what you mean but I'm not sure as you say there is little or no adjustment.

[ChrisC]

Good point - Follow James guidance, and then disconnect the battery for a few seconds before you test again.    I found the ECU was permanently powered while adjusting my throttle cable / TPS which resulted in very strange map site readings i.e. an idle at throttle site 4.5, but a disconnect of the battery resolved it.    Later a review of the wiring diagram confirmed the permanent power connection to the ECU.

The comment about the little or no adjustment relates to the TPS and throttle body, both Ford components, which I assume don't need fine adjustment because they are connected to a more sophisticated ECU in their Ford application that learns the idle position.   Compared to the TPS used on ITBs where the mounting holes are slots.  

[anthonym]

What does this TPS look like? 

(We just spent a morning making mine adjustable with a drill... but entirely different 7)

 

 

 

 

[ChrisC]

It's this https://caterhamparts.co.uk/throttle-cables/4056-throttle-potentiometer-csr260-a-sigma-150.html

[anthonym]

[aerobod - near CYYC]

Hi Mark,

Yes, the TPS to throttle map values are hidden in the “locked” ECU.

The TPS on the Duratec doesn’t have any significant adjustment, about 0.02V with the slight slack under the screws. What I found though on my original ECU is that you want the throttle site to start moving as soon as the throttle is moving, in the map it has a minimum default voltage (probably what you are currently seeing), but if you are adding air by moving the throttle and the throttle site isn’t initially changing you aren’t yet at the voltage setting for throttle site zero - this will cause idle issues due to lack of air. Below throttle site 0.5 (I.e. still in site 0 for non interpolated values) the ECU is still applying idle conditions, that is why adjusting the throttle stop screw until throttle site 0.1 just displays will get you to the correct air flow for the mapped idle fuel value. 

[CtrMint]

Following the process I've significantly improved the start and idle.  The difference between 0.1 and 0.6 is tiny in terms of screw threads so its somewhere around there.  The car now starts and runs just as it used too.

I need to go a drive it to see if it stalls.

I do have a couple of faults showing up now, rad fan relay and shift light, these weren't present before I started the car.  Is there a way we I can clear them?  Or is it a dealer visit?

[aerobod - near CYYC]

You may have depleted battery power with any extended adjustments with the engine off, causing spurious faults when starting. There isn’t any reset I know of other than removing battery power from the ECU for a few minutes, then powering back up again (easy if you have the battery cut-off switch).

[CtrMint]

Generally speaking today has seen an improvement.
Initially I tried to start the car and it wouldn't continue to run without a little throttle, it just died at idle. Not a great start.

I plugged in with Easymap and made the adjustments suggested, including disconnecting the battery.  Afterwards the car started and idled perfectly 950 to 1k rpm, nice and steady too.  Perfect!

I took the car for a run.  Most notably it never wanted to stall and caught the idle when pulling up to a stop.  Everything is looking good.

During the drive I took the car up the mountain, so as to get it up to speed,  I then got caught in standing traffic on the way home.  It's a hot day,  causing the temps to rise and get the fan working.  

I have noticed now the car is thoroughly up to temp it wants to hunt a bit 1k - 1200 rpm.  There are no drivability issues that I can observe.  But it seems I've traded the stall for it hunting when at temp.  I tried tweaking the TPS value down but it's not resolved the hunt.

Thoughts?

Will have a video shortly

[aerobod - near CYYC]

When the temperature and engine is hot, check it still is below throttle site 0.4 at idle, preferably at 0.1. If it has shifted, your throttle cable may be a bit tight and is pulling the throttle off the stop slightly. It should stay within 0.1 or so from cold engine to as hot as it gets.

With Easimap, if you haven’t already found the function, you can log all the sensor data by default, so you can plug your laptop in and go for a drive and look at the throttle site data when you get back to see if it is returning to 0.1, or have the laptop belted in on the passenger seat to glance at when you come to a stop and it starts hunting.

[StevehS3]

It seems to me that there is fault rather than it requiring a bit of a tweak. Tweaks can be misleading because they may make it a bit better but isn’t actually getting to the root cause of the problem. A new, modern engine (albeit tuned for power) should run sweet as it did before. Assuming the ECU shows no faults I would try to determine if a set of circumstances cause the problem such as altitude or temperature. Just my thoughts for what it’s worth.

[CtrMint]

It's not the cable there's plenty of slack, I also pulled it out of the retainer.

Video is here, shows hunting from about 2 mins in.

[CtrMint]

Hang on.... have I made a mistake, am I supposed to make the adjustment with the engine running.

I made the adjustment when the engine was off, after adjustment it read 0.1 to 0.3.  I notice when the engine is started it jumps to around 2, with no throttle/cable pressure.  Is it supposed to read 0.1 when running? and I should have tweak the value when running to avoid that?

Potential noob mistake?

Thanks

[StevehS3]

Should it run that hot? Is that normal for Duratec?

[aerobod - near CYYC]

When on the idle stop, it should be the same within 0.1 of the throttle site whether the engine is running or not, nothing is mechanically moving the throttle off the stop is it? Otherwise, you may have a grounding issue somewhere if the TPS voltage varies a lot between the engine being on or off, assuming the battery is always above 12V when you are taking measurements. Also, wiggle the cables going into the TPS connector to ensure you don’t get any variation due to a bad contact there.

[CtrMint]

yeah, from what I understand its totally normal.

 

[aerobod - near CYYC]

The map seems to ramp up throttle voltage to throttle site very quickly. 1.24V for site 0.3 to 1.26V for sites 1.8 to 2.2. Back off your idle screw very slightly to get back to 1.23V with the engine running at idle, should still be at least at 1.21V then with the engine off. Best to fiddle to have throttle site at 0.1 with the engine off on the idle stop.

[Mark w]

Ive just arrived to this thread ---late .

A couple of observations. 

Re the earlier discussions on lambda , the lambda map is probably controlled by two criteria in the map , firstly the engine needs to be at a minimum temperature before it operates  , secondly the engine has to run for a predetermined time after starting before Lambda control kicks in.( at least thats the way the 620 is set up ) 

SO , if your engine runs fine cold but plays up hot or ,when playing up whilst hot ,corrects itself for a period of time after turning the engine off and on again and then on its pretty certainly the Lambda playing up . 

Secondly re idle theres two parameters that need to be met , yes the TPS needs to be at load site 0.00 but secondly the throttle needs to be open sufficiently to allow enough air through to enable the engine management to adjust the timing/ fueling to enable a smooth idle .Changing one changes the other .

I dont know how the 420 is set up but on the 620 using a combination of pressure and TPS mapping theres a proceedure to ensure correct idle setting .

Disconnect or fully loosen the throttle cable. 

Fully close the throttle by fully slackening off the throttle stop screw . 

Set the TPS to xx 

Open the throttle using the stop screw so that the TPS shows yy ( thus giving a pre determined angle of opening and thus air flow ) 

Check that the TPS sensor is at load site 0.00 and adjust TPS position if necessary .( yes i know if xx and yy  have been provided as exactly correct values this latter stage is not required however the values i was given for xx and yy did not result in load site 0.00 corresponding exactly with the resultant throttle position at yy .

Doing this properly allows the engine to hold the idle speed set in the map within a pretty fine tolerance .

If, for instance theres too much or too little air coming through regardless of the TPS setting the engine management may find it hard to control the other parameters sufficiently to provide a smooth idle .

 PS , i agree re the comments about TPS setting at idle , it should be the same regardless of engine temp ,running condition and the like .

[mic]

TPS is not adjustable.

[CtrMint]

Just got in and I think I've cracked it, fingers crossed!.

I read the advice James gave in #68, and subsequently set the throttle stop so it read 1.21V without the engine running.  This resulted in the site being 0.0.  I previously aimed for a site value of 0.1 without the engine running, regardless of the voltage (am assuming its voltage) guess I misunderstood something some where. Of course I reset the battery and went for blast

It's now running brilliantly.  No stalling idle or pulling up, and certainly not hunting, it is idling in the 900s according to Easymap although the dash says bang on 1k.  I'm happy.      

Before this I did check plugs and wires there were no obvious changes in values from wiggling stuff.

Thanks everyone for the help.  Have got a brief video coming from when I got back in, but its short as it was after 930 and I didn't want to annoy the neighbours.

Will double check tomorrow when its fully cold.

[CtrMint]

Here's the video showing it sorted.

[aerobod - near CYYC]

That’s great. Did you also manage to get it to 4.7V / throttle site 15.1 on the top end with the pedal to ensure you can extract all the power?

Also, from an Easimap perspective the panel for Baro Pressure showing a fault can be deleted, as Caterham doesn’t have a sensor input and the same should be true of the oil temperature, as there isn’t a sensor by default. Can free up a bit of screen space to add other sensor or parameter values.

[CtrMint]

Thanks James.

I've not attempted to sort the top end, I'm still trying to get that straight in my head. 

I actually sorted out my Easymap layout as you mention, configuring everything but for some reason it didn't save.

[aerobod - near CYYC]

On the top end at 4.15V, you are probably about 12 degrees from full opening, likely about 5mm of cable movement. If you can take that up with the adjuster without removing all the slack at idle, you can get full throttle easily. I would adjust a turn of the adjuster at a time until you can just get to 4.7V with the pedal.

I’m not in front of Easimap at the moment (just sitting on a plane after boarding), but I think there is an explicit save function for the specific screen where you have changed the panels.