gsr misfiring at 5500rpm?

[Mister_Resister]

Got my old girl running today sounds nice.
But when the revs get to approx 5500 it starts to misfire.
Have done some research and thinkin it could be coils or plugs?
Also wondering while im doing them anything else i should check for ?

 

[bazeng]

Which plugs?

 

[evo-gsr]

Also...what leads are you using??

 

[Mister_Resister]

Havent checked haha. what is recomended gonna get new ones anyway.
to me it sounds like spark related issues

 

[Gianni]

Did u reset/check your timing.

 

[Mister_Resister]

No i havent gianni am gonna do that when i put new plugs and leads in and oil change

 

[Gianni]

If timing is along way out it'll limit ur revs to an extent

 

[Mister_Resister]

Awesome thanks gianni will be getting on to it this week

 

[GSRWRC]

Check the cheapest things first

Plugs - Regap to 0.8mm. if that doesn't work, replace.
Track down a spare coil pack/ignitor to try.
Move on to leads.

After that, it could be an ECU thing, or be unrelated to your ignition system.

 

[Mister_Resister]

Gonna get new plugs and leads anyway there old.
Check my timing and see how it goes if it still does it ill be taking it to my mechanic

 

[khubner1]

also check your afm (clean it with electric contact cleaner) and tps both could cause your issue

 

[Mister_Resister]

Will do

 

[EvoMayhem]

I had something similar. Driving along and all is fine. Hit 5,500rpm and it would sound like it was misfiring like crazy, but would clear at just over 6,000rpm.

I changed plugs twice, gapping, leads, swapped from back speed density to MAF and back to speed density, pulled fuel and timing, then added more. Changed CAS, changed ECU, changed the chip, changed the fuel pump, went back to 510cc injectors, then back to 1,150cc, changed the engine loom twice.

It turned out it was mechanical. One of the valve rockers had lost its bearing, and then fell off the top of the valve. Essentially, I was running a 15 valve engine! :lol:

Hopefully it's not whats happened to you, but its worth bearing in mind...

 

[Mister_Resister]

Hmm hope not too aye but shall see what happens when i do plugs leads abd timing

 

[blackvr]

It turned out it was mechanical. One of the valve rockers had lost its bearing, and then fell off the top of the valve. Essentially, I was running a 15 valve engine! :lol:

Hopefully it's not whats happened to you, but its worth bearing in mind...

Thats funny ! 15 years ago I had a VR4 with a similar issue... tracked it down to a rocker that had some how fallen off !! It had been to 5 other workshops before it was sussed out ....

 

[Mister_Resister]

Uh oh getting scared now lol

 

[EvoMayhem]

Uh oh getting scared now lol

Ah don't worry, even if it is one of the rockers. A cheap part to replace, along with the rocker cover gasket if required.

It's caused no other issue with my engine since that either, so personally I wouldn't be too worried.

 

[Mister_Resister]

Alright thanks mate gotta get a gasket anway will check while i replace the gasket

 

[EvoMayhem]

Just FYI, here is what I found in my cylinder head...

...and back to back comparisons with the knackered rocker (right) and a good rocker (left)...

If this is what has happened to you, be sure and get a good magnet down each oil drain, and also check the sump. I found a large bit of the bearing in the sump, and a large bit had blocked the return right next to the valve in question.