Ronny

iTrader: (1)

seems to have occurred this season. 5000+ it just misfires.

Causes could be ???

Maybe lack of battery voltage. I tested battery at B Plus and failed at like 85%. New battery purchased. Same result

Maybe VAFPR is providing too much fuel as I have increased FP to 26 lbs(75 lb injectors) last fall to accomodate N20 and changed the BPC/VAC table accordingly and reapproached the VE table settings. I am at value of 58-60 now at that rpm/map.

I cant get BLM at higher RPM/MAP can I? I may try to hold 5000-5500 rpms at 90-100 map and see if I get a hit in Learn. Seems all my BLM Learn data is < 4500 rpms even when getting on full throttle for prolonged period to 100 mph

WB shows 13.0x/1 during event but that is expected due to misfire occurring.

Would a ignition box(mallory6) help? Along with a Petronix Module and Pet external Coil or same from Mallory. Or is GM Delco a better choice on module?

All ign wires properly routed.

EagleMark

Just an overall issue with ECM/PCM I have encountered is 4000 -4500 RPM is hard to not be in PE and when in PE your BLM learn is disabled.

So many times I have bumped into a perfect running car that breaks up WOT in high RPM usually starting 4500 up and have simply replaced spark plugs with new stock units like whatever car had from factory. With Nitrous a heat range or 2 cooler has helped and also no bigger then 30 to 35 gap.

Fancy multi tip, U grove and all that snake oil plugs just causes issues. If not at first then soon, not if but when. Smaller tips get hot and glow!

Small cap EFI distributor cap and rotor is another issue. Have had problems with quality units at less then 5000 miles, have seen them totally destroyed with no button left and still run fine but not at high RPM. Even have recent pictures of a MSD cap and Rotor FRIED less then 10k with no multiple spark box. With a MSD box you have three times the wear. Still ran and drove fine but break up WOT high RPM.

So a new set of plugs cap and rotor may be all it is. Has happened to me in person many times.

25 or so years ago we had a big block 67 Nova built in high school shop couple months before Hot Rod Magazine came out with the how to! Few years later with motor built we had issues with breaking up. Jungle Jim Lieberman before he passed away came by our pit as he was watching us as young kids and knew of our high school auto shop build car. He said how many runs you got on those plugs? We said about 10! He laughed and said change the plugs and see how many runs you can get without breaking up. We did. 4 runs, fifth run car started to break up, sixth run had break up, changed plugs and no breakup. We never ran more then four rounds on a set of plugs after that and never had a high RPM breakup again...

Ronny

iTrader: (1)

Thank you.

Plugs are new late last summer early fall.

They are 2 heat ranges cooler/Champion/.035 gap. I have maybe 2 sprays on them late last year.

I think a new rotor and cap is in order. At the same time I will look at plugs as one of 8 fouled out last summer as well. Prior had 2 hotter heat range.

I think an mallory ign box(6) and petronix remote coil and petronix module may be going in same time as well.

EagleMark

Plugs cap and rotor are just cheap for good quality parts and like I said in high performance applications some times plugs just go away fast. Come out looking fine and I don't know why but it works.

If you still have an issue I don't think upgrading ignition is going to help. The GM module and coil are really good stuff! Long lasting good stuff! Unless it's time has come? I'd spend money on new GM module and coil before aftermarket. The GM EST module is known to fail and still run... but still outlasts any aftermarket I have ever had.

I also don't like to mix and match aftermarket parts, if your going to add a Multiple Spark Box then get a coil to match, actually match the entire system. Have seen MSD and ACCEll fail way to early after being installed, never dealt with Pertronix other then for ponits replacement which was always excellent. HTH!

Ronny

iTrader: (1)

I have a Accel module and Accel coil in cap.

Dist cap and rotor have 50K on them. I think I will replace that and see how it responds.

Thank you for your help.

EagleMark

Most of what I had mentioned was for small cap EFI dist. But the button in large cap has same issues. 50k? Oh yeah! Your do for cap and rotor! Your breaking up will be gone.

I'd be curious on how it looks after that many miles, if the button is still left or any cross firing going on? Is it Accell cap and rotor too?

Ronny

iTrader: (1)

cap rotor is bosch. It was the best they had at AutoZone.

also I forgot to mention my AutoMeter tach is breaking up as well >4500 rpms. Must be the misfire causing it.

morgsie

iTrader: (1)

Make sure to get/use the "369" ICM, I believe it is ACDelco p/n D1943A.

https://www.thirdgen.org/forums/post...17-post26.html

InfernalVortex

iTrader: (4)

Just my 2 cents on it...

I had the same problem, coudln't ever figure it out. Replaced my module 6 months later in mid summer. A few months after that my new module failed. Both were Accel modules - the newest one was a Borg Warner module and it's still working in the car just fine and that was about 2 years ago. BTW I had Accel modules because I switched to an Accel coil.

Edit: To be clear, I had two accel modules, both new, that exhibited this problem, and after the second module failed, I replaced with a Borg Warner stock replacement module and the problem went away. I was pretty distracted when I wrote that earlier, LOL.

Ronny

iTrader: (1)

My ign module appears as such:
[IMG][/IMG]

this is 369 D1943A:


Is 369 compatable to my distributor pigtails for module?

I suspect not. where to buy pigtail?

EagleMark

You can get an AC Delco replacement for your distributor, you picutred it first. Plugs right in!

Second picture and link to thread is for small cap EFI distributor talking of differences found in latency between 2 modules found in this distributor.

morgsie

iTrader: (1)

Do you have a large cap distributor? I would use the correct GM ICM and find latency tables from a mask that used a large cap distributor. The correct table should be in the thread I posted.

Ronny

iTrader: (1)

Yes large cap.

I thought the 369 was the more desireable for higher RPM as I rev to 5800 for my cam?

I am aware of the latency tables in that post.

morgsie

iTrader: (1)

You could mount a small cap ICM externally.

Ronny

iTrader: (1)

Thants what I was thibnking. Where to get pigtail ???

ALSO :Above Q from RBob

Tuned Performance

iTrader: (92)

for a heat sink external mount a Lt1 icm bracket may work. The wiring is from 87-92 tbi and tpi f-body's or tbi trucks.

acdelco pt757
acdelco pt169

http://www.ebay.com/itm/firebird-tra...#ht_500wt_1075

morgsie

iTrader: (1)

I assume you are talking about the connectors for the small cap ICM. If it were me I would go to the wrecker and cut them off just about any TBI truck, van or full sized car. If you want new try eficonnection.com. This topic has been discussed before, hopefully rbob will chime in with what type of wire (and if it needs to be twisted) to run from the pickup coil to the externally mounted ICM. I would also mount the ICM on a heat sink if you go this route. I am probably going to go this route even with my small cap. I do not have enough room to mount a heat sink under my dist as rbob suggested to me.

Dominic Sorresso

Ronny,

If you are using a high discharge box like MSD, are you using the low resistance
"button" in the distributor cap?

Ronny

iTrader: (1)

I am using a Accel module and same on coil. Both are stock replacement items.

Not sure is I mentioned it but I got a hard CE code about 2 weeks ago after loading a new .bin. I reloaded same bin and it went away BUT WP showed a residual soft CE(#3). Disconnecting the batt cleared. A week later I noticed again a soft hit in WU but went away. I oreder a AC Delco module yesterday assuming it is failing and will install with new quality cap and rotor. I never got around to changing out the coil for external and adding a Mallory 6 ign box. That will come later this summer when finances allow.

I see the post on latency in this thread and will check out my values. I ordered module # 19179581 for stock 1984 Vette chosing not to run 19179578 external mount. Anyone agree on that ???

RBob

iTrader: (1)

Ronny, I would replace the spark plugs, cap & rotor. Double check the coil ground strap while replacing the cap. For coils & ignition modules I prefer GM stuff. Good aftermarket is OK for cap/rotor/pickup-coil.

If that doesn't do the trick then plug wires would be next.

The large cap distributor is a good set up. I wouldn't go small cap in place of it.

RBob.

Ronny

iTrader: (1)

When you said plug wires a point came to life. Mine are new mallory and decent quality about 2 years old. Plugs are new 1000 miles ago. Two heat ranges cooler due to N20 with about 6 pulls on them with N20 last fall.

Now I remember splitting a boot when I changed out the stock plug wire retainers as the old ones were brittle. I used a tiewrap(ghetto i know) as I could not find the boots locally. I forgot till now ! Can that be it? Losing voltage arc to header. I think 3/8 inch clearance on #4.

Dominic Sorresso

Ronny,

Not a fan of Accel coils. Even guys using them on LT-5s have some issues wth them I have used MSD stuff w gret reliability and currently use MSD coils on the ZR. I think I may still have an Accel IM from my 84 and that would work fine for the most part.
I had tried the Dyna... something IM and would end up w a 42 flickering. Getting heat sink grease on the pad was key there.

Ronny

iTrader: (1)

My Accel stuff is about 6 years old so a change is coming soon. I think a lot of aftermarket auto parts are going to China. I plan on going to Mallory for ign box 6 and ext coil. MSD has a neat HEI dust cover to feed the ext coil. It looks like that support member on drivers side near the break reservoir can be tapped and a plate placed there for box and coil.

I am aware of the heatsink grease. I expect the part will come with the grease in box. I will report if is dry on current module. seems placing all that in HEI cap is a bit much.

Fast355

iTrader: (2)

Sounds like your typical injector going static to me. What is the DC% when it starts breaking up??? If its over 80% you need more fuel.

Ronny

iTrader: (1)

INJ duty cycle is about 65%. Keep in mind I bumped FP by 5-6 lbs to accomodate the N20 at 50-70 HP shot.

UPS just delievered new cap rotor and ign module yesterday. so will swap out old and see how it runs. Also I have a split boot on #2 that will be replaced. New battery too last week.

Fast I sent to you a PM about a month ago?

Fast355

iTrader: (2)

Sorry I must have either missed your PM or forgot to reply. I recieve 2-3 PMs a week and sometimes go a month before logging on.

Well then your fuel seems ok, you might have a legitimate igniton issue. I never had an issue clearing 6,000 and even 6,500 with the TBI setups with a short enough pulse width. Even the small cap HEI with an ignition box had no issue reaching that RPM. The problem I had igniton wise was crappy wires and weak coils. I replaced my stock based msd coil with an older accell super coil and it stopped the break up above 5,500.