Jump to content
The mkiv Supra Owners Club

Misfire: what to check?


Guest hemogoblin

Recommended Posts

Guest hemogoblin

Hey guys, I have this stupid misfire problem which is causing me to not boost the stock 11-12 psi. At idle it misfires a bit, and in boost, it misfires even more. Nothing crazy or violent, but its just not smooth.

 

Ive checked my tdc point, compression, swapped ignitors, tried ngk 6097's (bk7re) at .28 and brand new 6097's at stock gap, and replaced coil pack clips which didnt seem perfect. Still misfiring. Can anyone guide me on what else I should check out before having to leave the car at a shop?

Link to comment
Share on other sites

PLugs and Gapp.

 

Chuck some Denso IK 24's in there @ 0.0028"

 

Like he said but dont mess with the gap. I had a misfire aswel and i had ik24's, changed to bkr8's then really smooth. Then i had it running lumpy when just on turbo no1, Cleaned my O" sensor and changed a few rubber hoses.

Link to comment
Share on other sites

Guest hemogoblin

I dont think its the plugs since ive tried a brand new set, and mine at .28 are pretty good looking, dosent even look like im running rich. Im starting to understand misfirng at idle is normal with a downpipe, but is my misfire under boost ignition or fuel?

 

It seems to have trouble once in boost, then smoothens out, but still stays rough. If that makes sense. Im not able to reach and hold factory boost, I stay at 5-8psi. I took it to one shop and they said my boost issues are almost 100% caused by this misfire.

Link to comment
Share on other sites

Either a misfire is causing low boost or a boost leak is causing misfire-like symptoms.

 

By misfire at idle, do you mean it occasionally misses a beat in the sound? That's the normal closed loop operation that you can't hear with a stock exhaust system. If it proper misfires at idle it should be just the one cylinder that's bad. Is it just on boost and idle or at cruise and gentle acceleration as well?

 

This article may help as well, possibly.

 

-Ian

Link to comment
Share on other sites

Guest hemogoblin
Either a misfire is causing low boost or a boost leak is causing misfire-like symptoms.

 

By misfire at idle, do you mean it occasionally misses a beat in the sound? That's the normal closed loop operation that you can't hear with a stock exhaust system. If it proper misfires at idle it should be just the one cylinder that's bad. Is it just on boost and idle or at cruise and gentle acceleration as well?

 

This article may help as well, possibly.

 

-Ian

 

Well at idle its not the occassional 'pop' most bpu cars do, its a bit more. Not a whole lot more, but a bit more. Lets say a bpu does the pop 3 times every 10 seconds, mine does it about 5-7 times.

 

Its usually on boost and idle, but sometimes when driving very slow in second on gentle idle, i get a misfire that rocks the car back and forth. The same misfire happens once in a while when im coming off the gas pedal slowing down, while still in 2nd gear.

 

And yeah, i checked out that article. Great stuff.

Link to comment
Share on other sites

Guest hemogoblin

Hey guys, I tested out different coilpacks, still the same thing. Someone installed cams/timing belt before I dropped this motor in, but TDC looks like its on point. Could the cams or something be the issue?

Link to comment
Share on other sites

Please sign in to comment

You will be able to leave a comment after signing in



Sign In Now
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. You might also be interested in our Guidelines, Privacy Policy and Terms of Use.