Decat Downpipe - Limp mode

[Klerr]

Hi,

A few days ago I installed a decat downpipe with a lambda sensor spacer by the second lambda.
After 100 miles the car went in limp mode. The lambda spacer, with the lambda on it, was not completely screwed into the downpipe. I fixed that but still the car went in the limp mode.

Only when I unplug the 2 sensors of the lambdas (under the hood, close to the battery) the Fiesta ST will not go into limp mode, only MIL light stays on.
Even when I only unplug the sensor of the second lambda and plug in the sensor of the first lambda the car went in limp mode.

The car has no remap yet, will do a remap soon.

Only thing I didn't tried and think about now is to disconnect the battery for a few minutes so that the ECU will reset itself.

Anyone that can help me?

 

[MOFiST]

Welcome.
If you have a smart phone grab Torque on Android or Dash Commander for iOS. You also need to purchase an wireless OBD2 dongle to talk to the car. Try ebay for the dongle. This will let you clear codes.
That said if there is still a problem then the error will return.
A tune is your best bet but obviously but im curious if you can get the car running OK with the defouler.

 

[Klerr]

Update: disconnecting the battery didn't help.

But, when I only unplug the sensor of the first lambda (close to turbo) the car doesn't go in limp mode. So I guess the first lambda doesn't work anymore, because the sensor of the second one is plugged in.
Maybe a wire broke by using the oxygen sensor wrench? It looked a lot like this:

Looks easy to break or disconnect a cable inside...

 

[koozy]

that socket could have damaged wires. I'd recommend one that doesn't compromise the wires like this one

 

[Klerr]

that socket could have damaged wires. I'd recommend one that doesn't compromise the wires like this one

Yes, that was a better idea. It was the only socket I had and without that socket I couldn't get the Lambda loose
Tommorow I will take a better look from underneath the car.

Edit: Will a remap for a decat system turn off both the lambda sensors or just the second lambda?
If a remap turns off both I don't need to buy immediately a new lambda sensor, saves me some money.

 

[koozy]

i'd suggest trying to inquire your tuner/tuner device manufacturer with your questions. They'd be in a better position to answer for you. U.K and U.S run different systems. But it does seem like you need a tune for that de-cat downpipe you now have.

 

[JPGC]

I would be nice to see if you could you see what the factory wideband was reading for a/f. If it is locked at 14.7 then the upstream O2 sensor is damaged. Since your not remapped though, I'm assuming that you have no way to read a/f. I wouldn't be driving with heavy throttle or wot. If the sensor is damaged, you could possibly be really lean...especially if your resetting the ECU and getting on it before it goes into limp mode.

 

[Klerr]

Update:

Have a tune now since a week of 3-4.
Still the car goes into limp mode if the first lambda is pluged in. The tuner thinks the first lambda doesn't work anymore, because when I unplug the first lambda the problem is solved. At least we thought: Now, with the first lambda pluged out, the car went into limp mode again...

I did some research and I found out that the Injen air intake can cause a limp mode by a EU Fiesta ST, which I have.
Is this true? Can someone recap the problem with the Injen on a EU fiesta for me? And can the problem be the Injen instead of the lambda?

Sorry for my bad English.

 

[MOFiST]

I'd say the intake is the issue. Two issues that it has is that the inner diameter of the MAF housing is likely a different diameter to OEM intake which affects the amount of measured air flow per engine stroke and also the evap return line is after the MAF sensor unlike the UK after market intakes.

 

[Klerr]

I'd say the intake is the issue. Two issues that it has is that the inner diameter of the MAF housing is likely a different diameter to OEM intake which affects the amount of measured air flow per engine stroke and also the evap return line is after the MAF sensor unlike the UK after market intakes.

Thanks for the fast reply. Looks like the position of the return line could indeed be the problem since the EU Fiesta is MAF tuned and the NA not.
Going to fit the stock intake now. Will keep you updated.

 

[MOFiST]

Yes my Aussie FiST is MAF tuned as well. Hence I've taken an interest in these things. Good luck in sorting it. Let us know how it goes.

 

[Klerr]

Problem is solved I think. I just drove 40km (25 miles) with the stock airbox & the first lambda connected... No limp mode!
The engine check light still lights up by start (not the wrench/limp light), but I thinks that's normal and goes only away with a visit to a garage/tuner?

 

[MOFiST]

Did you try an OBD2 dongle with your phone? That's the cheap convenient way to clear codes. Otherwise a dealer or mechanic should be able to clear it for you.

 

[CanadianGuy]

Wouldn't disconnecting the battery clear the trouble unless the condition is still present? Did that on a few cars in the late 90s.

 

[MOFiST]

Wouldn't disconnecting the battery clear the trouble unless the condition is still present? Did that on a few cars in the late 90s.

You may be right here? I'd get the dongle anyway myself to read the codes. But doing that may clear them?