I really need some help

[AutoEuphoria]

A few months ago, my engine blew. Threw a rod or something...doesn't matter at this point, it was completely toast. Wasn't covered by warranty, so I ended up paying a LOT of money. Had to sell all of my aftermarket stuff to help offset some of the cost.

Car has a brand new engine right now, and is just as stock now as it was when I brought it home from the dealership.

I have an issue now, though, that I can't seem to figure out. My car wasn't stock for long, so I can't remember if it acted this way when it was. I'm guessing not, but honestly I don't know what to even look for at this point.

If I go WOT in second I sometimes get a slight misfire. This happens much more often in third, fourth, fifth, and sixth (happens at partial throttle in 5th and 6th...I never go WOT in any gear higher than 4th, and that is rare). Always happens under boost, and it seems like it's some kind of fuel cut or boost cut or something...just a series of misfires.

I do not get any CELs, my fuel pressure look fine, my AFR looks fine, no knock, boost temps are low, etc. The ONLY thing I can think of is the shop may have used inferior (or wrong) spark plugs when they installed the engine...that or it's perfectly normal. I'd hate to think any stock car would run this poorly, though, even on bad winter gas.

So, any ideas? Any parameters I should log to help give more insight?

 

[mcb]

are you flooring it under under 3k RPM?

 

[AutoEuphoria]

I'm not 100% sure...I haven't been paying attention to that specifically.

 

[AutoEuphoria]

Nobody has any ideas?

 

[boosted1]

Maybe the car needs an ECU update. The dealer may have a TSB for a flash to the ECU.

 

[AutoEuphoria]

That could be...it seems to have gotten better the last week or so, but I might see if the dealership can flash the ECU for me. Thank you for that suggestion

 

[Joebmsp]

i would double check all the clamps on the intercooler,intake, may be a small vacuum/boost leak

 

[Darth Vader]

Plugs, plugs, plugs. Pull them and check them for condition and gap. They are your window on the engine's true operation.

Some twat probably put NGKs in there with a .055 gap.

 

[Speed3Rookie]

Plugs, plugs, plugs. Pull them and check them for condition and gap. They are your window on the engine's true operation.

Some twat probably put NGKs in there with a .055 gap.

ditto...make sure the gap is ~028.

 

[MSMS3]

I concur on the spark plugs. Your car is acting just like my mildly modded car was acting a few months ago when I thought I was getting load cut. Turned out to be that the plug gap had opened up due to a lot of miles and very spirited driving. If the gap is too wide, the boost can literally blow out the spark when the engine is under load.

I think Darth is right that some bozo put NGK's in with the super wide gap that they come pre-gapped with. Don't get me wrong. I love NGK's and tend to use them in all applications, but for our car, they have to be regapped. Get the stock heat range and make sure of two other things, both of which may have been ignored by the shop that installed your engine:

1. They must be thin wire iridium center electrode tipped, which pretty much limits you to either Mazda OEM plugs, Denso or NGK, as far as I know.

2. The gap needs to be in the .028 to .032 range, preferably on the low side.

If this does not fix your problem, get back with us, but I think the plugs are your problem.

 

[spdjnke]

I have the same problem it's been there since the day I got my car, doesn't do it all the time just sometime, been to the dealer many times and they alway say "nutting wrong with your car" so I just gave up. I have my plugs at .028 and still does it so maybe it is just the nature of the beast..or I'm just more anal about the way the car performs.

 

[Darth Vader]

Tried the stick coil spring stretch mod?

 

[meicalnissyen]

I would make sure my plugs are gapped evenly and below .030

 

[meicalnissyen]

Tried the stick coil spring stretch mod?

another good idea

 

[AutoEuphoria]

Just an update...I checked the plugs today. They installed AutoLite plugs, and they were gapped around 0.045". I replaced them with NGK Iridium plugs at 0.028". Going to go try it now to see if it's any better, but I have to think that was causing at least some of the issues I was having.

 

[AutoEuphoria]

After driving the car around a bit, I'd have to say that it feels like it is working 100% better. No stuttering in third that I experienced, although the snowy roads made it difficult to really try anything out.

 

[boosted1]

After driving the car around a bit, I'd have to say that it feels like it is working 100% better. No stuttering in third that I experienced, although the snowy roads made it difficult to really try anything out.

Good to hear!