High RPM misfire, dealer says it’s normal!?

[n_123]

So I’m on an on ramp yesterday and accelerated hard. Top of third gear (little under 7k RPM) and I get a blinking check engine light. Immediately shift into 6th and before I got the chance to pull over it went away (probably around 30 seconds). No loss of power or anything out of the ordinary. Took it to the dealer this morning and they tell me “yeah it’ll do that, normal” and that it had a generic code. I’m not one to argue over the phone with anyone in customer service but I was close. Is there even an ounce of truth to what they said?

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[135Hoser]

"we built a 480 or 500 hp v8, but if you try to use that peak power, the engine will misfire and limit output"

Could be a bad tank of gas, Next time you fill up throw 91 or 93 in it, see if you can duplicate it.

In short: A factory engine misfiring on the stock tune under load is *not* normal. Your dealer is being lazy.

I just had my dealer check my car because I had suspension concerns and it drove funny. They said everything was fine. Took it my regular mechanic, he checked the alignment and the front toe was well out of spec. This also might explain why my front tires would heat so much when driving. Dealer also recorded on the work order the same in/out mileage despite saying they took it for a test drive, and the odo reading 40km higher when I picked it up.

 

[n_123]

"we built a 480 or 500 hp v8, but if you try to use that peak power, the engine will misfire and limit output"

Could be a bad tank of gas, Next time you fill up throw 91 or 93 in it, see if you can duplicate it.

In short: A factory engine misfiring on the stock tune under load is *not* normal. Your dealer is being lazy.

I just had my dealer check my car because I had suspension concerns and it drove funny. They said everything was fine. Took it my regular mechanic, he checked the alignment and the front toe was well out of spec. This also might explain why my front tires would heat so much when driving. Dealer also recorded on the work order the same in/out mileage despite saying they took it for a test drive, and the odo reading 40km higher when I picked it up.

I always use shell 93, car hasn’t seen any other type since I bought it new. The weird thing is it didn’t limit power at all.

 

[smurfslayer]

Is there even an ounce of truth to what they said?

No

what code was found?
if it’s a misfire, probably a coil/plug issue. it’s not normal, it’s not expected. The Dark Horse R doesn’t do it, neither should yours.

you may want to see if you can replicate the issue under a controlled test and reassess.

Do you have any mods to the car?

 

[Pmamba]

The check engine light there is for a reason - to show there’s a problem that needs to be checked. It’s not a shift indicator.

If the light comes on, wouldn’t it store/save the code?

 

[n_123]

No

what code was found?
if it’s a misfire, probably a coil/plug issue. it’s not normal, it’s not expected. The Dark Horse R doesn’t do it, neither should yours.

you may want to see if you can replicate the issue under a controlled test and reassess.

Do you have any mods to the car?

Short shifter and drop in filters is all. I was told it was a generic miss-fire code. No specific cylinder.

 

[Q6543]

Are you sure it wasn’t a traction control or abs light?

 

[n_123]

The check engine light there is for a reason - to show there’s a problem that needs to be checked. It’s not a shift indicator.

If the light comes on, wouldn’t it store/save the code?

It was on for 30 seconds and then went away by itself. They said there was a generic misfire code, no specific cylinder.

 

[n_123]

Are you sure it wasn’t a traction control or abs light?

Very.

 

[smurfslayer]

I take it you’ve not seen this before. How long have the filters been in?

I’d try to replicate - maybe in first or 2nd... top of 3rd is a bit... ambitious.

 

[Farmer Fran]

And i got bitched at by someone "take it to the dealer"...

Yeah

 

[n_123]

I take it you’ve not seen this before. How long have the filters been in?

I’d try to replicate - maybe in first or 2nd... top of 3rd is a bit... ambitious.

Since around 1000 miles. Even if they were just put in I fail to see any possible correlation between drop in filters and a misfire.

 

[smurfslayer]

I agree, but, it’s the only known change to the engine, your shifter is divorced from the production of power equation.

 

[Crew4991]

 

[Neggytive]

the CEL only flashes for misfire when the amount of misfires exceed the allowed value

The code will be cylinder specific (P0301 to P0308 on a 8 cylinder engine telling the tech exactly what cylinder was not firing off correctly, or if there are multiple misfires it will be P0300 and then other P030X codes.

You can have misfires, usually sporadic that are not enough to trip the light and set a code, you find those by doing a dive into Mode 6 data, then cylinder contribution, and you will see misfire counts for every cylinder, and when you see one or two that far exceed the value the rest of the cylinders are showing those are the cylinders that are misfiring.

Now the question is if you were bouncing it off the rev limiter, and the computer was dropping fuel by not pulsing the injector or not firing the coil, would it show a flashing CEL indicating a misfire.

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