Easimap question - barometric pressure

[Collidog]

Hooked up ECU (MBE 9A4) on my 420 to laptop for the first time. 

Even without running the engine, the ECU status reports a ‘barometric pressure fault’ which is also reported when running engine. 

SBD Motorsport did say that the cars are missing some sensors and will return a fault on Easimap. Is this the case here? Btw baro pressure seems to be set at 1040 mbar IIRC. 

Thanks a lot

[aerobod - near CYYC]

Yes, there is no dedicated barometric sensor used, as delivered by Caterham, the default 1,040mb pressure equates to 220m below sea level. If you have to do a lot of driving over 1,000m altitude, SBD can sell you a sensor plus an unlocked 9A4 ECU with an alphaN map that uses the barometric pressure and ignores the map sensor. It is fairly straightforward to add the sensor to pin 28 of the ECU plug.

My house is at 1,250m and I sometimes drive at up to 2,100m so I had to make the change to get my R400D to run without being up to 20% over fuelled.

[Collidog]

Thanks a lot James. Am hoping  to trace intermittent issue that sometimes strikes at ~5400rpm in 4th accelerating fats from 90. Always after a prolonged dual carriageway run. Prodding the accelerator is met with what I would describe as misfire or lean fuelling. Vibrations felt through car at same time and very slow build up of speed. CC had it twice now, and replaced battery terminals but not sorted. Am very confident I can replicate the fault while logging. Which parameters would you suggest I select?

 

thanks again

[aerobod - near CYYC]

I’m away from home at the moment, so can’t check what I typically monitor, but I normally take the default 30 or so parameters. I do have a wideband lambda setup, with the lambda values being my best starting point, with the default Caterham narrow band system it is difficult to look at accurate fueling, as you will only see the oscillation every second or so between lean and rich as the fuel trim is constantly adjusted while in closed loop control.

I would look for any spikes in reading and try and determine if there is a sensor problem causing any spike, that the TPS and throttle maps track the throttle pedal and provide map 0 and map 15 in the full range, that temperature and other sensors look logical when the car warms up and the battery voltage stays within a narrow 1V or so range and isn’t too noisy. I would also check that lambda operation is in closed loop after warm up, goes open loop above about half throttle and half revs and that fuel injector values map cleanly between open loop and closed loop and increase in a fairly linear manner with higher throttle and revs, basically tracking the power output and getting richer at higher loads.

[Collidog]

Thanks James. Appreciate the pointers. 

Maybe I’ll get lucky and have a simple sensor fault!

[ChrisC]

Log everything, you can always exclude the trace when viewing the results.  Good luck and fingers crossed.  

[vertew]

I spent a long time trying to fix an issue with some similarities - accelerating hard from low to high revs, then around 4,000rpm I'd get an occasional misfire / 'cough'.  A kind L7C member (Mic) sent me a PM suggesting I check for a poor earth on the immobiliser, and that turned out to be the issue.  Seems that CC have a habit of attaching earth terminals to paint-covered body panels - not ideal.  Take a look at the thread with fix details here.

Generally, I'd suggest checking out all the earth connections you can find and making sure that they secured to bare metal, in good condition and tightly secured.

Hope you find the answer soon ...

tks, Andrew.

[chris.neeves]

I had same issue on mine when I changed to 9a9 ecu. However the fault existed when I had the 9a4 fitted. It was the wiring the wrong way around on the sensor... been like that from new.. swapped the outer 2 wires around and was all sorted. Make sure you know what you are doing though first. Worth checking.

 

chris.

[mic]

Be careful swapping pins around, the mapping strategies could be different. Either TPS based or pressure based, the sensor will be wired differently.

[Collidog]

Thanks Andrew. Yes, I read your thread with interest a couple of weeks ago and followed your recommendations. Still have the intermittent issue though. You issue turned out to be loose wiring on the MAP sensor, right?

Cheers - Neil

[Collidog]

Hi Chris - which sensor are you referring to?

Cheers - Neil

[vertew]

Hi Neil,

There were two unrelated issues that (unfortunately) happened in sequence.  The first was the occasional misfire / 'cough' that had been a long term issue and eventually the annoyance car factor drove me to look for the cure, which was the immobilser earth.  The second issue, which happened a few days after the fix for the first, was a loom-side break in one of the plug wires connecting to the MAP sensor.  This resulted in regular and obvious misfires on acceleration.  Easimap helped me diagnose this and the fix was to open the plug and resolder the pin.

One more thought - perhaps try sharing a screen grab of the easimap map trace of the fault taking place ... could help others chip in with more suggestions.

Best of luck with it, Andrew.

[Collidog]

A few screen shots for any experts that are interested:

First, 3 faultless hard accelerations from 90 on the left to serve as controls, followed by 'misfiring' when flooring it from 90 between 17-19 mins:

Faultless tests zoomed - nice smooth throttle angle peaks:

 

Bad tests zoomed - rough throttle angle peaks, not getting at high as controls. Vibrations felt through car and much slower increase in engine speed:

Engine stutter after pulling away (after idling to check if pheasant I had clipped had damaged car!) and at 23min20s. The voltage drop in Stands out:

The following stutters/misfires occurred when going through villages in 1st/2nd/3rd gear:

Stutter 21min 25s - battery voltage changes

Stutters/misfires between 26min40s and 28min

Stuttter between 34min50s and 35min

Faults logged : Injector faults (A-D at different times), Baro sensor fault, wheelspeed2 signal noise

Appreciate any thoughts/suggestion for further data to graph/collect.

Will be sending files to Caterham also.

Cheers - Neil

[chris.neeves]

Neil, it was the separate baro sensor not on manifold or combined temperature type. I didn’t have any intermittent fault it was simply wrong wiring from when a previous ecu change was done on the car by previous owner and I think the sensor added then.

 

chris

[vertew]

Hi Neil - as you mentioned in the notes for your third 'bad tests' pic, the throttle peaks look slightly odd.  If these don't match the throttle inputs you think you were applying at the time, then this might a good place to start + also an indication that the problem could be electrical.

You've probably already done this, but worth doing a wiggle test on key cables / connectors, esp TPS + checking connector terminals / cleaning.  There's various info on the forum for doing TPS diagnostics here and here.  

tks, Andrew.

[Collidog]

Thanks Andrew - I think it is clear that the TPS signal is dropping out. Caterham say so aswell after looking at the data. Car is booked for a week so they can do a thorough investigation. Hopefully will just involve a new TPS. 

Will be interesting to feel how it drives after as it was likely having subtle detrimental effects in addition to the obvious issues when pulling hard from 90 etc  

Nice explanation here

 

 

 

 

[vertew]

Sounds like your well on your way then.  It'll be like having a whole new 7 again when the misfire is gone !!

[Collidog]

Resistance across the TPS is 4.23 kilo ohms (4230 ohms). One of the links above stated 430 ohms so perhaps it was a factor of 10 out. 

Checked the voltage across the signal pin when circuit live. 1.23 volts closed throttle; 4.73 volts  WOT. 

Does anyone know what’s what with the correct voltages etc.

Cheers

[ChrisC]

I have an ECU reading of 1.21 volts TPS idle.  I don't have a WOT reading, I still need to do some work on my car to before I can get that.