Intake manifold help, unequal air distribution
This is not on a honda, but an old pushrod toyota.

Here are some pictures of the intake in question



and just a picture of the car


Here is the problem I am having. I keep fouling out the #4 spark plug..it is a dry foul with black soot.
The number 1 plug will look perfect
#2 plug is slightly blacker,
#3 a little blacker then #2
and then #4 is pretty much fouled

It does this with just idling for a good 10-15 minutes.

I have changed plug wires numerous times, coils, checked timing, moved it around a bunch with no change. Even changed injectors 3 times. I have also had it from a pig rich idle 10:1 to a ultra lean idle 15:1+ Pretty much the same thing happens just at a more extreme amount.

Is the fact that my throttle body is so close to the #1 runner causing this problem?
'm just about ready to cut the plenum off, level off the runners and then weld a much bigger plenum on. But getting the throttle body out further will still be a chore as I don't have the much room between it and the intercooler.

Thanks
Randy

 

What is that? This is interesting.

 

You said something about leveling off the runners? Are they not the same length?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by MidShipCivic &raquo;</TD></TR><TR><TD CLASS="quote">What is that? This is interesting.</TD></TR></TABLE>

The car is a 1982 Toyota starlet, motor is a pushrod 1.8l 3tc

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by beepy &raquo;</TD></TR><TR><TD CLASS="quote">You said something about leveling off the runners? Are they not the same length?</TD></TR></TABLE>

They are all even, but they stand into the plenum a little bit.

 

What is your fuel pressure?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by MidShipCivic &raquo;</TD></TR><TR><TD CLASS="quote">What is your fuel pressure?
</TD></TR></TABLE>

Fuel pressure is 42# with the vac line off. Injectors are new 1000cc, also tried two sets of new 650cc injectors with a small tuning change with the same results.

Engine management is Meagsquirt2+extra, ignition is dead on and strong using a 36-1 trigger wheel, DSM ignitior and coil pack running wasted spark.

 

I think your Intake manifolds is fine.

It might be the hardware/software. MS does batch fire right do you have it alternating between injectors so pressure isnt affect much?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by MidShipCivic &raquo;</TD></TR><TR><TD CLASS="quote">I think your Intake manifolds is fine.

It might be the hardware/software. MS does batch fire right do you have it alternating between injectors so pressure isnt affect much?</TD></TR></TABLE>

I have it set for alternating with two squirts. It holds a good idle and whatever a:f I'm shooting for. Except you can here and feel the one cylinder starting to load up and start to miss fire.

Engine is fresh, arp everything, eagles and wiseco's. Head is also all redone, big valves, springs, welded and ported. Turbo is nice and tight and ic pipes are nice and dry.

 

swap injector channels and injectors around to be sure its not hardware related.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mopar junkie &raquo;</TD></TR><TR><TD CLASS="quote">swap injector channels and injectors around to be sure its not hardware related.</TD></TR></TABLE>

Done that also, even stuck some smaller injectors in and ran them in batch with no change.

 

You also might try switching the direction of the fuel flow through the fuel rail. If it is an issue with fuel pressure variation within the rail, the problem should move to the #1 cyl.

I assume you've checked compression and it is equal on all 4.

That plenum looks a little on the small side to me, but I've never been able to find good data on the 'correct' size for a plenum. I know the one I built for my 1.5 Civic turbo motor was a lot bigger than that. What's the harm in having the plenum a little bigger (other than packaging and the fact that you've already made it).


-Chris

 

http://www.celicatech.com/foru...28698

 

The MS should have no trouble keeping up with demand. Sure, it's batch fire, but that shouldn't be the problem. I think in this case your fuel system just isn't keeping up. Not enough fuel flow, which could just be an old fuel pump. Or have you replaced that too? The fuel pump should be able to keep up at idle unless it isn't working properly.

 

Fuel system is all -6 braided, aeromotive a1006 regulator, aeromotive filter, walbro 255hp inline pump. Fuel tank is a cell with a -8 feeding the filter.

 

the mini coopers have this problem as well, and it IS intake manifold related on them

im gonna be working on a new plenum for a local mini shop owner...if we figure anything out i will let you know

 

If it's happening when idling, it's not an intake manifold problem.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tony1 &raquo;</TD></TR><TR><TD CLASS="quote">If it's happening when idling, it's not an intake manifold problem. </TD></TR></TABLE>

hmm, that is true, i shouldve read better,,,,if it were an intake manifold problem at idle itd have to be a horrible intake manifold

 

I have nothing insightful to say other than 'nice car.'

 

its the megashit...get a different EMS.

 

umm...how close are your spark plug wires to the injector wire? Maybe a little inductance? move your coil pack away from your wiring or run a shielding wire on the injector wiring.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by .RTErnie &raquo;</TD></TR><TR><TD CLASS="quote">its the megashit...get a different EMS. </TD></TR></TABLE>

The MS is only as good as the person who puts it together. I have had my share of problems with it but after working the bugs out I am confident that it will work in almost any application.

Having said that, and since the fuel system isn't OEM, I would have to agree with RTErnie. There must be something wrong with the MS. You said you moved the injector channels around... But still to be on the safe side I would just replace the injector transistors. 10 minutes of work.

I had months of ingition problems with my MS, running a DIS ignition, and almost gave up. Tested everything in the MS and it seemed fine, but I finally fixed it just by replacing all the transistors.

 

how hard would it be to make an equal length IM?

 

This car that I just finished building has a similar intake manifold that I made and doesn't foul #4...and its also running Megashit.

Is your 60-2 wheel keyed?


Modified by .RTErnie at 3:18 PM 9/10/2007

 

The majority of intake manifolds are equal length. Not in terms of how far the air has to travel from the throttle body to each valve but in terms of runner length. I would think that if you were to make a setup like the one in your picture you would probably lose efficiencies at partial throttle from wave interferience.

 

eric wtf is up with the steel charge piping?? are you the sux w/ alu welding?