Limp mode and the dangers of same.

UrbanFret

Anyone else think this feature should be made illegal?

Twice in the past 12 months my Honda accord has gone into limp mode in the middle of shall we say a decent speed overtake leaving me high and dry on the wrong side of the road at about 1500 rpm.

This is a really dangerous situation. The fault " Fuel Rail Pressure Too Low"

turning engine off and back on returns full power (not ideal in the middle of an overtake)

mikeecho

Maybe you should keep your car properly maintained

Killer K

It comes down to what would likely happen if the car didn't go into limp mode.

XsApollo

Why are you over taking someone at 1500RPM.

Cookie_Monster

https://www.boards.ie/discussion/comment/118837399#Comment_118837399

limp mode drops it to that when it kicks in.

Toyotafanboi

Yes, i agree. Easiest way to avoid this would be to get the car fixed.

UrbanFret

Car drops from 4000 rpm to 1500 when it happens. I'm not trying to overtake at just above idle

UrbanFret

Getting it fixed or keeping the car maintained wouldn't stop this from happening to be honest. If it's as I suspect the sensor is faulty as we have changed the fuel filter and checked all the fuel lines. It could happen at anytime , well maintained or not.

Point I was making ls it's a bloody danger.

UrbanFret

As to what would happen If it didn't kick in? Nothing I would imagine.

As soon as you restart the engine it's runs fine. I have drove it for thousands of miles since With the engine management light on. Unfortunately for the NCT I had to clear the Fault and after about 2 weeks it happens again.

mikeecho

https://www.boards.ie/discussion/comment/118837810#Comment_118837810

Toyotafanboi

https://www.boards.ie/discussion/comment/118837789#Comment_118837789

Be more dangerous if you didn't have a limp feature in the ECU and it bricked all your injectors or put a rod out through the block or something.

If anything, having limp mode has enabled your engine to prevent itself **** the bed which has in turn enabled you to not repair it.

Every Accord doesn't do that overtaking, your car is faulty, you need to fix it.

antodeco

https://www.boards.ie/discussion/comment/118837789#Comment_118837789

Not to sound pedantic, but if the fault is the sensor, why havent you replaced the sensor to prevent it from happening?

mikeecho

Can we try some Dipetane ?

bazz26

It really amazes me the daft logic that some people create in their head. A car has a fault that causes the car's ECU to reduce power in order to protect the engine from further damage until the issue is addressed. Yet the driver now calls out this safety mechanism as a danger rather than getting addressed the issue that is causing it. Sure might as well do away with all warning lights too, sure they only tell you stuff.

Either the OP is not at the races or this is some attempt at a wind up.

alias no.9

Just because it seams ok after restarting doesn't automatically make it a sensor issue. If its happening under high load, could suggest there's either a restriction upstream of the high pressure pump, a leak downstream of the pump, the seals in the pump could be on the way out, could be a small air leak in the line from the tank to the pump that only manifests under high flows. Lots of possible faults really, limp mode is giving you a chance to fix a small problem before it becomes a big problem.

mikeecho

Maybe the OP could have the limp mode deleted :D

Fitz II

OP its a safety feature to allow you to complete your journey without blowing your engine. The car cannot tell the difference between a sensor fault and the fault the sensor is there to detect. So just be glad its there. If its happening when you are overtaking its probably not a sensor fault.

blackbox

What is the OP suggesting should happen when a fault is detected?

Would he prefer if the engine simply stopped?

tabby aspreme

If it's Diesel you should use a genuine Honda fuel filter, spurious filters can cause bother

UrbanFret

https://www.boards.ie/discussion/comment/118838081#Comment_118838081

it would certainly not be more dangerous. Crazy statement that. I cant think of a much worse situation than been stuck on the wrong side of the road meeting the oncoming traffic.

UrbanFret

https://www.boards.ie/discussion/comment/118838147#Comment_118838147

I have one in the post. Will be installed next week

UrbanFret

https://www.boards.ie/discussion/comment/118839902#Comment_118839902

Nope. Just flash up the engine management light without trying to kill me.

UrbanFret

https://www.boards.ie/discussion/comment/118838243#Comment_118838243

How the hell can leaving you stranded on the wrong side of the road be in anyway safe?

Toyotafanboi

https://www.boards.ie/discussion/comment/118840201#Comment_118840201

It would be far more dangerous.

Your engine wouldn't reduce power on you and let you get to a point of safety, the engine would just simply die when the fault occurs and damage itself in the process.

So to be really clear because you dont seem to be grasping it, instead of reducing your power in the outside lane allowing you to keep control, the engine would shut down so you would have zero power in the outside lane, you'd also lose your vaccum assisted braking and your power steering, so you'd be out there unable to accelerate, brake or steer if limp mode didn't exist.

For folk like yourself though, that would probably be better if it didn't exist, at least if the engine broke itself it'd force you to repair rather than putting us all at risk limping that yoke around because you are too mean to sort it out.

Del2005

https://www.boards.ie/discussion/comment/118840201#Comment_118840201

You know that you have a car that goes into limp mode regularly yet you blame it when you get stranded on the wrong side of the road with no power. As said if there's no limp mode then the engine will blow, so you'd still be on the wrong side of the road with a blown engine and no way to get to safety.

Don't overtake if it's not safe and your car isn't safe to overtake in till you fix the problem that's causing it to go into limp mode.

mickdw

I got caught out once with an Alfa losing power mid overtake. Not nice but until fixed I was only overtaking where there was acres of space ahead and nobody behind to ensure that I didn't get into any danger.

bazz26

https://www.boards.ie/discussion/comment/118840268#Comment_118840268

The car has an intermittent fault, yet you ignored that and continued to drive it. Safety didn't seem to bother there. Time to man up, this one is on you.

UrbanFret

https://www.boards.ie/discussion/comment/118840330#Comment_118840330

How do you know I'm too mean to sort it out?

I get it you think its a good system and thats fair enough.

I just happen to think it's not.

Honda engines aren't known for blowing either so I doubt that would happen.

Far too much bloatware on modern cars. No need for the half of them.

Toyotafanboi

What would you propose?

UrbanFret

https://www.boards.ie/discussion/comment/118840675#Comment_118840675

Engine management light come on coupled with an audible warning. Not a loss of power. or at least not activate the limp mode until you have stopped and restart the engine.

Anyway looks like we are not going to agree on this matter so I'm going to leave it at that.

By the way it doesn't happen every time I go to overtake, In fact it mightn't happen for months and then out of the blue it does it again.

kirving

I would have suggested a 10 second warning perhaps before power is cut, but if I understand correctly, the OP's engine management light is already on anyway, for a *long* time?

https://www.boards.ie/discussion/comment/118838243#Comment_118838243

Limp mode is more likely to activate only when the engine is pushed hard so I can see the logic in giving the driver maximum power availablity, say for 10 seconds, *if at all possible*, in case they are actually in the middle of an overtake when the fault happens. If the engine is damaged, so be it.

Boost leak in my last car affected power somewhat during all driving, but if I floored it for a few seconds, limp mode would absolutely kill it. No engine light on before it first happened, and it would reset when you turned off the car.

Now to be fair to Merc (despite the fault happening in the first place), the auto box would drop a few cogs to keep you moving as best as possible, but I can see how in a manual it could be more dangerous.

I was very surprised to see in my 3 Series, that once the fuel range goes below 50km, the car warns you not to overtake, as engine power may be reduced with low fuel.

Lastly, I don't think it's fair to jump to the "wind up" line, just because the OP's opinion is at odds with most. It's a fair question, so IMO the better approach is to explain why it occurs (prevent damage to engine).

mickdw

https://www.boards.ie/discussion/comment/118840655#Comment_118840655

As an example, a cylinder running lean due to lack of fuel can pretty instantly superheat and literally melt your piston.

Both outcomes would be similar in terms of being on the wrong side of the road with pretty much a total loss of power. The limp mode at least means you have not written off the entire engine.

tabby aspreme

Your revving the engine to 4000 rev's to overtake, is it petrol or diesel

Toyotafanboi

https://www.boards.ie/discussion/comment/118840708#Comment_118840708

I think that's where we are disagreeing.

Limp mode is the engines last line of defence. It's not an advisory. It's either limp mode or engine damage.

UrbanFret

https://www.boards.ie/discussion/comment/118840719#Comment_118840719

Just to clarify if I dont clear the "Fault" and leave the engine management on it wont happen at all. I only clear the fault when Its going for NCT.

Thanks for the reply .

UrbanFret

https://www.boards.ie/discussion/comment/118840723#Comment_118840723

2.2 Diesel. The 150 hp version.

mk7r

This is definitely not a faulty sensor.... It will be either an injector(s) or else the high pressure pump is getting weak. The reason the car goes into limp mode for this problem is that it thinks there is a leak in the high pressure circuit, which can be very dangerous.

The reason it doesn't happen all the time is it will only likely show under load. If you accelerate hard in 4th gear 3 or 4 times uphill in a row i bet it will happen. The ecu is looking for 1500bar of pressure and if the pump cant sustain 1200bar or more you get that fault. The high load scenario of overtaking etc puts the pump under the most pressure so in normal driving the rail pressure req vs delivered will stay matched.

mikeecho

The long and short of it, as I see things.

The op believes that limp mode is nothing but a hindrance, and it shouldn't exist. EML or no EML, but he does like to have the EML on. But the op is a shy guy, and doesn't want the guy down the NCT to be looking at his EML.

EVERY F UCKIN BODY ELSE , Thinks this is a wind up, or the OP is a nucking fut, and that limp mode is there to prevent catastrophic damage.

And then there is the 3rd opinion, which quite simply is Atari Jaguar.

tabby aspreme

https://www.boards.ie/discussion/comment/118840779#Comment_118840779

Have you heard of torque, no need to be revving it to 4000 rev's, you must be making idiot overtaking moves

Killer K

https://www.boards.ie/discussion/comment/118841411#Comment_118841411

You lost me at the third option.

listermint

I'm just asking, the OP knows they have a faulty fuel delivery system.

Yet they're driving the car around and over taking people.

Has the OP considered.. I don't know.

Not overtaking and just driving the car a little handier whilst he's waiting on parts ....

mikeecho

https://www.boards.ie/discussion/comment/118841479#Comment_118841479

Ah. GOD no... Drive her like you stole it.

Shur the op seems to think limp mode is a complete inconvenience.

mikeecho

https://www.boards.ie/discussion/comment/118841448#Comment_118841448

You must be new here :D

UrbanFret

https://www.boards.ie/discussion/comment/118841426#Comment_118841426

Old school. Drop her a peg and floor it.

UrbanFret

https://www.boards.ie/discussion/comment/118841230#Comment_118841230

Some sound advice . Will change the pump so.

Thanks.

Lewis_Benson

OP sounds like the typical Irish motorist.

"Sure I'm not spending money fixing that, I'll turn the light off the d'NCT and that'll do her"

dickdasr1234

https://www.boards.ie/discussion/comment/118840769#Comment_118840769

I have a brother who is just like you - mean!

You have had this dangerous problem for years but avoid fixing it. Mean.

As a consequence, you put yourself, your family and other road users at risk.

BEYOND MEAN.

IDIOTIC!

UrbanFret

Whether I fix it or not doesn't in my opinion change my first Post that this "feature" is a **** danger . It has to happen for a first time sometime.when it does to you you'll most likely change your opinion.

TherapyBoy

When it happens to me for the first time I’ll most likely get the problem fixed as soon as possible.

UrbanFret

https://www.boards.ie/discussion/comment/118842773#Comment_118842773

Unfortunatley You might not get the chance.

mk7r

https://www.boards.ie/discussion/comment/118841781#Comment_118841781

Test the injectors first, pump would ideally need to be new not second hand as they all wear and they aren't cheap.