Kevin BC

I haven't updated my build for a while as I have a miss which I have tried to resolve myself to no avail. Maybe I can't see the forest for the trees, so I'm looking for some help.
First - I am not a mechanic, this is a hobby.

Specs - I built my own engine
383 - Scat crank and 5.7 rods
9.6:1 compression
Comp Cams XR269 - Hyd roller, comp lifters
- LSA 112 degree, 108 centerline
- intake dur 269, dur @.05" 218, lift .495
- exhaust dur 276, 224 @ .05", lift.503
Aluminum heads - 180cc, 2.02 in, 1.6 ex, 64cc chamber
Edelbrock RPM Air Gap intake
GM small cap HEI with external coil
1 5/8" headers
Holley Terminator EFI

Break in on dyno. Ran great
436 hp, 480 tq

Installed in my car and I have a miss.
Cylinder #1 constantly fouls.

What I have tried: most of these have been done several times
checked plug wire resistance - checked ok
changed plug wire
changed distributor cap and rotor
changed distributor
changed coil
Compression check - ok
Compression leak down - ok
pulled heads and checked valves and guides anyway - ok
no vacuum leaks
changed EFI tune
- tune from dyno tuner
- self learn tunes
swapped injectors on EFI throttle body
dyno tuner - holley efi specialist cannot resolve - ride along with laptop adjusting tune. He has been very helpful and rechecked everything I have done but not resolved.
Adjusting the tune has temporarily helped but keeps coming back.

At first miss was at 1500 to 1800 rpm. cruise speed. Tach would jump
after the ride along tune that miss was gone, but would crap out on acceleration. lean condition so increase fuel on acceleration. still a problem.

Called Holley, all they could suggest was that maybe there is a flaw in the intake manifold. I have not swapped the intake.... yet.

It's been a learning experience for me, but the EFI is not learning!

Does not make sense with throttle body efi that only #1 cylinder has an issue. I thought a problem with one cylinder should have been able to be diagnosed with the tests I have done.
But like I said, I am not a mechanic and I must be overlooking something.

Interested in all ideas.

Kevin

mikem350

WELL..seems like you covered it all...You did change or swap the spark plug and wire to another cyl?
Only thing left is the intake. Maybe its bad or developed a leak at the intake gasket.

OR this is what I found after a bud scrapped a nice 427...the intake valve stem seal was bad. Oil was getting sucked in, fouling the plug. You can inspect the seal(s) from outside top of head. This would not show up on comp or leakdown test.

Did you put the same head back on the same side? If you swapped them the bad cyl would be #8. Good luck.

Kevin BC

Thanks,
yes I swapped the plug wire and tried a completely different one.

Plug doesn't seem oil fouled though? It should take a lot of oil to foul a plug within 10 minute run time.

I did not swap the heads side for side.

mikem350

If its not fouling, what does it look like? You 100% sure the miss is only cyl #1?

Another route would be to go to a shop that has a ignition analyzer scope that can look at all 8 plug wires. This would eliminate the ignition as a problem source.

A lean condition can cause a miss, as will ign timing

Kevin BC

Plug is black, but not crusty like what I would expect from an oil fouled plug. Initially I thought fuel fouled.
Leaning the tune did not help so we (dyno tuner) considered that plug was starting to foul due to lean and then efi would add fuel and it would look like it fouled due to being too rich. This is why we enriched the tune at that rpm and it seemed to clear up the 1500-1800 miss. Hope this makes sense. You can tell by descriptions I likely know just enough to be dangerous.

Scope is a good plan and I hope to do that next week.

toobroketoretire

Do a compression check of all 8 cylinders. If the compression is low in #1 only its a possibility you set one of it's valves too tight.

Once a spark plug gets fouled with oil or carbon it'll likely stay fouled until its either cleaner or replaced.

There is a possibility you have a big carbon track in your distributor cap from moisture being in it at one time so check that out. While you have the cap off inspect the rotor's brass tang for signs of damage.

Check to see if the #1 wire even throws out a good blue spark about an inch long.

Kevin BC

I have re-set the valves several times.
Compression in #1 is on the high side of the average.
Yes, I have replaced the plug too many times to count.

inside distributor cap is dry, track on each contact is the same.
I have replaced both cap and rotor also.

I haven't got a spark tester and understood that it wasn't a good idea to try to test for spark by removing a wire to see if it jumped to the plug or to the cap. The electronics don't like it? Is that fact or theory?

pauldana

my story on my 427 FAST EFI......

when i first got her going it "seemed" and "felt" like it was randomly missing.... i chased my tail for a month like you have done... everything you did.... I got so frustrated that I actually brought her down to a very large well known speed shop in so-cal here... and they agreed.. missing... they said it was the #8.... did everything I did again,,, which was everything you did... lol.... finally they said they could not figure it out and had me pick her up.... Had a friend come over that all he does for a living is tune carburetors... He took her out for a drive... came back after about a mile... said... she blubbering... to rich,,,, run her for a while.... so i ignored the "miss" for about 300-400 miles and let the EZ EFI 2.0 "learn" sure as chit.... it got better and better,,,, and now all gone:-)

So, a pro shop and myself chased our tail for 2-3 months total, just to find out it was the EFI running rich until it learned the tune...

Not saying this is you also.... but it was my situation.

Good luck brother:-)

toobroketoretire

Do you happen to own an infrared heat gun that you can point at your #1 exhaust and see how it compares to the others right after a startup? They're real inexpensive and it would be handy to have in a situation like this.

Can you take a few pictures of your EFI so we can see what you're dealing with? If the system uses 4 injectors I'm wondering if one of them may be partially stuck open and over-fueling that #1 cylinder. A few pictures may help us solve your problem.

Kevin BC

So I only have another month to go
I hope that is the case, but my logic says I should be able to figure it out.
You're saying I should drive more and quit tinkering.

Thanks Paul

pauldana

If this is a throttlebody which I think it is, like mine....it is not because you have a stuck injector or they all would be having the same problems not just one and you've done everything you can think of on that one piston so I'm thinking you're probably in the same boat I was in .....drove me freaking crazy.... don't listen to anybody unless they run a throttlebody EFI..... Things in these system work so differently than the standard systems .... Of corse theory is the same... Spark.. Proper A/F and so forth.... But setting them up and tuning them are vastly different then the standard carb/dist set up

toobroketoretire

Is the Holley EFI have a 180 or 360 degree intake manifold? My '82 has the CrossFire Injection system that has a 360 degree manifold with a large plenum with small 7" long runners at the bottom and each throttle body uses a single large injector over the top of the bore. Does the Holley use a single injector over the top of each bore or are they in the sides? If you had a 4-bore throttle body with 4 injectors and a 360 degree design I could see a possibility of having a bad injector causing fouling of the front left cylinders.

Give us a few pictures please......................

Kevin BC

I have swapped injectors and it did not help, did not move the problem to another cylinder either.
Best place for a picture of this if at Holley. https://holley.com/products/fuel_sys.../parts/550-405

toobroketoretire

If you have an infrared heat gun see how hot your #1 exhaust compares with the other 7 cylinders at idle because it may be the low intake velocity at idle that is fouling your #1 plug rather than the EFI system.

The Air Gap intakes have very large diameter runners which really slow the incoming air/fuel charge down so they don't work well at idle speeds and with high final drive ratios. If you're fouling the #1 at idle then continue to foul it at higher rpms it'll stay fouled. A simple intake manifold change might be all you need.

For an example an '82 with it's TH700R4 and 2.87's would be completely incompatible with an Air Gap intake because of it's super slow velocity at idle and at cruising speeds which is why the CrossFire Injection intakes has such small diameter runners.

pauldana

Keven, how many miles have you put on your EFI? and what type of driving?

Kevin BC

I have about 600 miles on it, but Because I have recalibrate do tune so many times it would be more like 200 miles on this tune. I am trying not to make any changes an drive it for 500 to give it a chance. It's pouring rain here this weekend so that won't be until late next week.

Kevin BC

I know you use the AFR Titan manifold. Which top piece and how is it in lower rpm range. I don't plan on using one but interested in comparing. Local Holley tuner says a single plane would be better, with Eli dual plane does not have any positive benefits. Says dual planes are designed for carbs? When I asked Holley they said to use a dual plane.
I still plan to drive it and give it a chance

diehrd

Where is your 0/2 sensor located ?

What is timing with vac advance at 1500 to 1800 or what ignition are you using ?

What transmission and gears ?

If you run at 2k does it stop missing ?

Kevin BC

O2 sensor on drivers side in exhaust pipe about 1" after collector flange.

Small cap hei, no vac advance. Initial timing set as per Holley instructions and Holley ECU controls timing advance.

700r4 with 3.55 rear gears.

Yes miss goes away with RPM increase. Are you thinking it may be related to runner velocity?

Kevin BC

What intake do you have?