Misfire

[Kristian_Wraae]

Did the ignitor grounding mod and no change at all.

 

[Kristian_Wraae]

You are currently running -2 I & +3.5 E cam timing at 119.5 lobe centre & 25 degrees valve overlap.

Have you filed the dizzy slot so you can retard the exhaust cam more & obtain more static advance as the distributor drive on the cam is out of sync?

I have filed mine down to 1mm from the end & can retard my exhaust down to -4 & still obtain 15 degrees timing.

You need to retard the exhaust more to pick up power.

Try altering your cam timing to -3 I & +1.5 E, giving you 118.5 lobe & 27 overlap. You wont loose any torque down low & will pick up power after 4500.

How do you calculate lobe and overlap from the cam timings?

I set the cam at +4E & -6I. The engine seems to idle very well at that setting but still misfires. I'll have the timing set at +4E and tune from there.

 

[supra_ed]

never mind my previous post. still misses....almost like im down a cylinder during acceleration. i even put in different coil packs. ill keep an eye on this thread. hope u get it figured out....im in the same boat as u, maybe worse.

 

[BLACKCAT]

I use the DYNO2000 engine analyzer software to determine the figures.

The BC264 cams have the following specs, at 0 & 0 setting:

IO 22 BTDC
IC 62 ABDC
EO 70 BBDC
EC 14 ATDC
36 degrees overlap
114 LSA

You have to double the crank degree variation for any cam alteration, ie 1 degree cam variation = 2 degrees crank variation.

At your setting of I-6 & E+4:
Overlap is 16 degrees, hence the better idle
LSA is 124

As you reduce the overlap your idle will improve but you will sacrafice mid/top end power.
Maybe someone that has fitted these cams in a 7MGTE might provide their cam settings for you as all my trials have been with the N/A which tolerates a LOT more overlap.
Personally the first mod I would do is to file the dizzy slot, retard your exhaust a lot more & advance your intake & reset the base timing.

 

[Kristian_Wraae]

How much overlap do the stock turbo cams have?

Where can I find the specs?

 

[Kristian_Wraae]

I just noticed that the resistance between the terminals on the coil packs all measure 0.8 ohm. The TSRM says 0.3-0.5 ohm.

Does this mean I should exchange them on that basis?


EDIT: Nevermind. It was my multimeter whcih is out of calibration by 0.4 ohm.

 

[BLACKCAT]

Specs for the standard Toyota cams @ 0.05" lift (probably).
Maybe you should modify the title to include 7MGTE cam timing to attract someone that can give you a good starting point with these cams.

 

[Kristian_Wraae]

Maybe we need a separate 7mgte thread for the BC cams.

 

[Kristian_Wraae]

So we have 9 degrees overlap on stock cams?

 

[IJ.]

#5&#6 being down like that would make me suspect either HG or Valves either of which could account for the miss.

The Cam overlap is a bit of a red herring at this point if it were reduced cylinder pressure from overlap it'd be across all 6.

 

[BLACKCAT]

Yes 9 degrees for Toyota & 8 degrees for the BC.
I have given you two lots of figures: one for seat-to-seat & the other for .05" lift.
You should probably start another thread to find out what other people have found to be good cam settings as there should have been dozens sold & installed by now.
From previous experience finding usefull tuning info on these cams is like getting blood out of a stone.
Good luck:biglaugh:

 

[Kristian_Wraae]

@IJ

Ok. You think the compression test is not ok?

I was told it was good and that there always would be small differences.

So you still think that there could be valves not closing correctly.

When I put my ear to the engine I seem to hear more noise around the 5 and 6 cylinders valves.

The engine has a new 2 mm HKS stopper gasket and both the block and the head have been resurfaced. Actually I had to provide the engine builder with three heads before he got one that he accepted as been good enough (not the slightest warped).

I have used ARP bolts and the head has been torqued with 100 nm.

The engine has not been driven hard yet. Only just touched 4000 rpm once.

 

[Kristian_Wraae]

Yes 9 degrees for Toyota & 8 degrees for the BC.
I have given you two lots of figures: one for seat-to-seat & the other for .05" lift.
You should probably start another thread to find out what other people have found to be good cam settings as there should have been dozens sold & installed by now.
From previous experience finding usefull tuning info on these cams is like getting blood out of a stone.
Good luck:biglaugh:

Didn't you just say that the BCs had 36 degrees overlap?

I'm confused. :wtf:


I know nothing about cams. So I guess I should ask in an other way:

If I choose +4E where how much should I retard intake to obtain stock overlap?

 

[Kristian_Wraae]

I have recorded a sound clip of what it sounds like close to the injectors.

The laguage is danish so you wont understand what I'm saying. But I can tell you that I'm saying 1. injector, 2. injector etc all the way to 6. injector.

What I notice is that there is a rather sharp high pitched squealing noise around the 6. injector (around 1:05). I assume it's from the cams. I don't know if it's supposed to sound like that. But it sounds very different up there compared to the other end.

http://www.japanerfusk.dk/dyser.wav

 

[supra_ed]

i believe supra store recommended starting with e+3/ i-1 and use a dyno to go from there

 

[BLACKCAT]

There are two methods of measuring cam specs ie seat-to-seat & lift @0.05" thats why it appears confusing.
At intake +3.5 & exhaust +4 (cam timing) overlap will be 9 degrees.

What are your valve lash (clearance) settings?

 

[Kristian_Wraae]

There are two methods of measuring cam specs ie seat-to-seat & lift @0.05" thats why it appears confusing.
At intake +3.5 & exhaust +4 (cam timing) overlap will be 9 degrees.

What are your valve lash (clearance) settings?

Thanks.

I don't know what valve lash settings are. I'll ask the guy who build the engine tonight.

 

[IJ.]

@IJ

Ok. You think the compression test is not ok?

I was told it was good and that there always would be small differences.

So you still think that there could be valves not closing correctly.

When I put my ear to the engine I seem to hear more noise around the 5 and 6 cylinders valves.

The engine has a new 2 mm HKS stopper gasket and both the block and the head have been resurfaced. Actually I had to provide the engine builder with three heads before he got one that he accepted as been good enough (not the slightest warped).

I have used ARP bolts and the head has been torqued with 100 nm.

The engine has not been driven hard yet. Only just touched 4000 rpm once.

Time to do a leakdown test Kris.

 

[Kristian_Wraae]

Time to do a leakdown test Kris.

What is a leak down test? To test for bhg?

I don't think it has a bhg. I had that before the rebuilt and this is different.

 

[IJ.]

It's a test that will determine cylinder leakage and will show if you have a valve hanging open for any bizarre reasons....

Look it's just a non invasive test suggestion that may give you a better understanding of why it's missing.

Cam timing as I said earlier has 9 parts of fuckall to do with this or it'd be missing on all 6.