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Problems with Vipec- going rich every so


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Hi there,

I am using the vipec v series plug n play on my MINI Cooper S. I am first owner of this ecu and bought it new around 2 years ago, sadly my tuning process was slow because I was not driving this car a lot.

There is some strange issue happening to my engine that drives me crazy. First I thought this issue was tuning related but now my map is close to perfect and I am getting still this issues.

The ECU seems to make some dropout on its own and it makes the AFR go rich a lot (more than 10%), some minutes after the afr-s are back to normal. I am speaking here from going from around 11,8 target to around 10,4. this happened today and I have made a nice log where this happend on first 2 runs where I have given it WOT, and some miles later on wot the AFR was back to normal.

Does anyone have a clue what could cause the ECU to add around 10% of fuel on its own? This happens every so, 4 days ago I got one such an event where I was accelerating through 4 and 5 gears and afr go down to around 10,4 and car has not accelerated as it should, minutes later it was normal again. then last 3 days the car run great, no problems, stable afr, and today again this events with around 10% rich afr on WOT once of a sudden, some minutes later everything good again.

I have attached the log file, please take a look if you can see something strange?

Is there any possibility that the VIPEC ECU could be faulty and its making strange things or what could cause this occuring events? Would be glad to get your help because right now I have my tune close to perfect but it is very confusing that such problems still occur.

What I was thinking of, is it possible, that in the ECU is a fault and it does not make the IAT corrections as it should every so? But the IAT corrections look normal to me in the log files.

The next thing I was thinking about, I am using the map switch function through the Aquamist controller, i got such similar thing with the afr go reach to around 10.4 when the fail safe triggered before i tuned it correctly. What does control this richening when the failsafe triggers? Maybe this kicks in sometimes on the normal map and causes this issues?

Just thinking, will appreciate your help.

I cant attach the llg file?

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I had a quick look, and so far with just the quick glance it seems your AFR corrections are produced accordingly to Intake Air temp correction table.

This was a mini cooper?

does it have the original topmounted IC?

where is the AIT sensor mounted?

On the first pull your intake temp drops midrange in the pull and statys quite low, and AFR drops low accordingly, but on the later pulls intake temp increases linear with the rpm.

(where all the pulls made on flat roads or with different resistance/hills etc?)

Ie. the pull made with lower IAT makes richer AFR than those with high IAT, the values in that first one are a bit rich.

For constant AFRs then the IAT correction table could be adjusted a little i guess. But that depends on how (far) its tuned in respect to ignition and EGTs.

I cant really say exactly what AFR you should run over the internet, but lower than 11 i do not expect is needed on your setup.

I suggest some road tuning of the fuel accel table also, it seems to tight at low rpms and to loose at high rpms (use Delta TPS as y axis, as its currently only a RPM based table)

I post the pictures of the pulls in your log here so others may have a look and chime in.





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thank you for taking a look.

I have sent you in the email that I am using 2 maps (one with methanol injection and one withouth) with map switching through the aquamist controller. The methanol sprays after 3500rpm, therefore the iat drop down midrange on the first pull. my target afr is 11,8 and it holds it most of the time, it gets out of everything when this strange thing happens and the car makes this big enrichment you see on 2nd run after 6000rpm.

On the first wot run i am on the meth map (ignition and fuel map 1), on the second run i am on the normal map withouth meth on normal gasoline (ignition and fuel map 2), on the 3rd and 4th run i am as well on map 2-normal gasoline.

because of the methanol the iat are that much lower on the first run. but on both runs (especially on the 2nd run) the afr goes with a big jump rich from the target 11,8 to around 10,4. You see this very good on the second run after around 6000rpm, where there is a jump down from around 11.5 to 10,4. then you see it on the 3rd run still on the map 2 ( normal fuel map) and everything is back to normal again, stable afr of around 11,8 to 11,9. when this enrichment as seen on run 2 after 6000rpm does not happen both maps are very close tuned to my target of 11,8afr and it holds it pretty well. But every so it gets a break out and does the hard enrichment as you can see in the log of the second run.

this jump is not IAT related, as you can see on run 2 there is a jump in afr, in the run 3 there is no jump in afr, IAT is very much the same on this 2 runs. all runs were done just minutes apart on same road.

i have stable afr of 11,8 much the time, but sometimes the jump down happens like on the second run/log after 6000rpm. Any idea what causes this? My problem is this jump that is very big.

car is a mini cooper S, it has a upgraded topmount IC. AIT sensor is in the intake manifold just before the air enters the zylinder head.

thank you for the suggestion about the fuel accel table, will tune it further like you suggested. you mean here the accel enrichment table?

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to understand exactly what is going on is to use the PC LOGGER, set to 40 Hz.

Select all parameters to be logged.

Do a couple of pulls with the engine at normal running temp.

After you have done a pull on normal fuel and then on Meth.

Go through the data logs , but you need to go through all the logged parameters and select all FUEL and IGNITION CORRECTIONS, as well as the basics such as RPM, MAP,TPS, etc etc.

Look for any added % enrichment or timing changes that may contribute to this issue.



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Active corrections on his map;


- IAT (0@20dgc and +/-2,5% pr 10dgC change)

- Closed loop lambda (700-5000rpm and MAP <110kpa)

- Cylinder trim +1.5% constant at Cylinder 3

- Dual table, activation via DI.8 (table difference +18% in discussed area, 6000-6500rpm at 180-190kpa)

- Injector timing single zone at 330dg

- Open loop AFR table is NOT active for master fuel calculation.

Ill show the AFR Target table anyway;



- ECT , reduction from above 110dgC

- IAT , reduction from above 60dgC

- Dual table, activation via DI.8 (table difference -0.5 degrees in discussed area, 6000-6500rpm at 180-190kpa)

There is no other relevant or data with impacting values to be presented from the log.

(ie, values for corrections etc etc that does have 0% troughout the pulls are not shown here)

The log show these paramenters from the pulls;


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how should I proceed either than the 40hz Log file?

I will try making a new log with 40hz and all parameters with the same enrichment hapening. it is strange because there are days where the car runs great and then once of a sudden out of nowhere I get this enrichment that is present just for some time and disappears afterwards.

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do you have a FUEL PRESSURE sensor connected to the ECU.

What is the ECU status through the logs, ECU INTERNAL TEMP and VOLTAGES etc

Thanks for the earlier information Kristian G.

Also what wideband unit are you using.



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I sadly have no sensor connected to the fuel pressure regulator.

Will try to find the data about the ecu internal temp and voltages.

wideband i am using a zeitronix zt2 kit, it is mounted before kat in the collector (where 4 pipes of the exhaust manifold come into 1 pipe- its a 4-1 exhaust manifold).

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Hi minir15,

see what you can do about checking and logging fuel pressure fuel.

Also are you able to borrow a second wideband unit from a friend etc and connect to a spare analogue volt input and data log it also as wideband 2, just to compare both widebands do the same thing.

This will rule out possible sensor or controller errors.

Remember wideband sensor don't last for ever especially in an overly rich condition.

I am simply giving you some pointers here.

I actually own 4 wideband units , but I do a lot of tuning, it is very good to have a second meter to compare against.



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I have been driving today again and I now I really think that the sensor is bad. :( the current one i have on the car for just 2000km. I think there is something not right with this Zeitronix ZT2 Wideband system because it is frying the sensor so often. My current kit uses the bosch 4.2 lsu. The funny thing is that my first sensor lasted for over 3 years and over 30kkm, then it started freezing. I purchased then a new sensor from a Zeitronix dealer and it started freezing just after 400km driven, so was bad again. then I got a new one on warranty and this 3rd one seems to have lasted for just 2000km when it started doing this false readings of a too rich afr for around 1,0 afr.

I have purchased now a new afr kit from plx devices with a bosh 4,9lsu sensor and hopefully this one will work as it should.

Today when I was driving the first 5 WOT runs have been consistent, then after that i got this rich afr of 10,4 again. I checked the injector deadtimes and pulsewidths and they are consistent comparing the 11,8 afr run to the rich run with afr of 10.4 that i got some minutes later. So this has to be just a faulty sensor? We will see soon.

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