spark plugs for a full top end ported engine

[phrogs]

What are some of you using in your ported top end cars.

Mine has thottle body, heads, injector housings and plenum ported

I have the AC FR2LS plugs gaped at .35 in the car and I have a high idle and the car is running rough low on power one day I was driving and the car just felt wired It felt like I lost a cylinder very rough even at 65 in 6th gear the car is strugling shaking like a leaf in order to do 65 I have to be in 5th gear otherwise the car starts to shake itself to death.

I have newer accel injectors about 4,000 miles on them
older LT5 wires probably 25-30K miles on them and ac delco coils no idea the mileage its an old set I had on the self to replaced cracked screamon deamon coils that were on the car.
car has the chip DRM burned for it after the porting work they did.


Now tonight I pulled the plugs and looked at them all but one spark plug looked ok #6 was black the rest looked normal but I am running very rich black soot on my exhaust pipes I know im running rich.

so I swaped out #6 with another plug to see if it looks different tomorrow after I drive it to work and back home just to make sure that plug is working.

I drove it tonight removing every wire trying to locate a dead cylinder and everyone of them gets worse than it has been with them all pluged in so it seems all my cylinders are firing.



what you guys think?
do I need a hotter plug perhaps?
Im willing to try the cheap aproach first.

im going to keep messing with it but looking for ideas.

perhaps new plugs wires and coils and go from there?

[flyin ryan]

Can't see it being plug temp. John, that's one of the hottest plugs available you have right now. Maybe a dead plug, if anything but those are few & far between as well. Let us know what tomorrow brings.

[tomtom72]

JMHO, but this proly ran thru your mind already!

Only #6? Then I suspect that (those) injector(s)? Or the wires & coils like you say just for general principal because they've been on the car a long time. No DTC's right? What's a scan look like?

Damn, where do you get FR2LS plugs from? If you are using the OE stuff from waaay back, then I'd try a new set, 42-601's are what I've been using. They don't stay in the sweet spot for much more than 10k miles but they're cheap enough to toss every yr.

:cheers:
Tom

[jonszr1]

i had a cylinder problem like your on my blk car . did a compression test which came out fine . after tlking with jerry downey ,who said he had heard that coils have had one side go out , bottem line replaced the coil and all is well . hope this helps

[Locobob]

Can't see it being plug temp. John, that's one of the hottest plugs available you have right now. Maybe a dead plug, if anything but those are few & far between as well. Let us know what tomorrow brings.

:iamwithst

FR2's are on the hot side for this application, going hotter is not a good idea.

[phrogs]

well Ill do all my checks later on today and see what I find with the wires and the coils.

The damn injectors better not be bad on this thing!


Now if my old spark plugs are on the hot side should I get something a bit cooler?

[A26B]

Johnny,

A "weak" spark will show up more as a "miss" when the engine is under load such as 65 in 6th gear, than it will at higher revs or at an idle. It's not a dead cylinder problem until it's under a load like you described.

When you check spark, put an old plug in a plug wire, lay it on the plenum & start the engine. It should jump a nice, blue spark 3/4"~1" as you pull the plug away from the engine. If you see an orange spark, it's weak.

I have personally seen at least 3, single cylinder, weak spark issues fixed by replacing the coil, mine included.

Easy to check, no cost.

[phrogs]

I checked the spark and its kinda white not nice a blue so its pretty weak maybe damn near dead.

So it looks like coil packs thats what I figured at first but wanted to see what people were using for spark plugs on these cars.

My plugs have probably been on this car for to long and need to be changed so ill look into that as well.

jp

[Jeffvette]

John, anything that comes into me gets the NGK iridium plugs. I've been extremely happy with them on my 368 and other cars I've used them in.

[phrogs]

well I had a chance to check a spare set of coils I have.
they are a old set but the ohm out just fine, primary and secondary so now that I know I have a back up set ill check the car here in a little while and see what I get.

As for spark plugs the only ones carried local to me are the replacment AC delco's so Im going to use them so I don't have to ship a set of plugs right now.




jp

[flyin ryan]

John, anything that comes into me gets the NGK iridium plugs. I've been extremely happy with them on my 368 and other cars I've used them in.I use them on my cars as well as on some of the better engines I build. They are spendy but worth it, I feel. Sounds like your creeping up on it Johnny :thumbsup:.

[phrogs]

I use them on my cars as well as on some of the better engines I build. They are spendy but worth it, I feel. Sounds like your creeping up on it Johnny :thumbsup:.


Well I changed the plugs and while It felt a little better anything up in 5th or 5th gear at lower MPH say 40mph and I mash the gas it shakes like the damn car is comming apart.

so looks like Ill be in for a plenum pull to see WTF is wrong.

Anyone have a tech 1a I could borrow? its the one tool I still don't have.

[phrogs]

well heres what I got

I swaped the plug to another cylinder and it was clean in that one, the one in # 6 was getting dirty like carbon or oil?


But I checked the wires and coil packs without pulling the plenum and heres what I have.

1/6 20.6
2/3 21.3
4/7 19.0
5/8 20.2

so I guess its time to check the injectors man this sucks.

[flyin ryan]

so I guess its time to check the injectors man this sucks.Yup:censored:...but gotta be done :-x :icon_scra.

[phrogs]

Ok now I'm really at a loss


Checked the injectors hot they all rear around 15 ohms.

I even changed out the secondary injector relays with my spares and it didn't change anything.

now heres the kicker I was hammering on it this evening just now after I did this nice hard pulls untill around 5K and it stumbles but then keeps going but when Im around 60 in 2nd gear I get a SES light.

checked the code and Its damn 61 secondary port throttle system WTF:dontknow:

[XfireZ51]

Sometimes 61 is accompanied by an Lean O2 Sensor, I think its code 55.
If its not lean then the ECM is shutting down the secondaries due to insufficient vacuum, so differential MAP sensor is sending a signal voltage to the ECM of less than .7v if IIRC.
Secondary vacuum leak? Weak Fuel Pressure? :dontknow::confused:

[rhipsher]

Ok now I'm really at a loss


Checked the injectors hot they all rear around 15 ohms.

I even changed out the secondary injector relays with my spares and it didn't change anything.

now heres the kicker I was hammering on it this evening just now after I did this nice hard pulls untill around 5K and it stumbles but then keeps going but when Im around 60 in 2nd gear I get a SES light.

checked the code and Its damn 61 secondary port throttle system WTF:dontknow: The old code 61. Don't you love it. Secondary port throttle failure seems to be the most common problem that I read about on here. But I'm sure you are already familiar with the method for chasing down and fixing that. When it happened to me I don't remember my car shaking. But I do remember it running out of breath at 4500rpm's and then the ses light and the H61. The secondaries weren't working when I bought the car. And at that time I knew nothing about the car. Let alone how to fix it. But I found an article about secondary port throttle failure on the corvette action center "with pictures. I like pictures" and it really helped me understand how it works and what to check for. It took me a month to close in on the bad component. And just when I was about to throw in the towel thinking I had made a big mistake buying this car. I found it. A $36 part causing the problem. It was the secondary vacum solenoid. Buttoned the plenum back up and for the 15th time took it out for a drive and crossed my fingers and prepared to mash that peddle. Wow! What a difference. The rest is history. I hope its somthing simple like that.:mrgreen:

[phrogs]

Im thinking about just removing the secondaries, I mean I do not have smog check so I really don't care about them being there.



The old code 61. Don't you love it. Secondary port throttle failure seems to be the most common problem that I read about on here. But I'm sure you are already familiar with the method for chasing down and fixing that. When it happened to me I don't remember my car shaking. But I do remember it running out of breath at 4500rpm's and then the ses light and the H61. The secondaries weren't working when I bought the car. And at that time I knew nothing about the car. Let alone how to fix it. But I found an article about secondary port throttle failure on the corvette action center "with pictures. I like pictures" and it really helped me understand how it works and what to check for. It took me a month to close in on the bad component. And just when I was about to throw in the towel thinking I had made a big mistake buying this car. I found it. A $36 part causing the problem. It was the secondary vacum solenoid. Buttoned the plenum back up and for the 15th time took it out for a drive and crossed my fingers and prepared to mash that peddle. Wow! What a difference. The rest is history. And I have never had another secondary failure again. I'm sure I will eventually but now I know what to look for and how to fix it.:mrgreen:

[flyin ryan]

A $36 part causing the problem. It was the secondary vacum solenoid. That was the problem on my 90 as well. Secondary Port Throttle Control Solenoid...the thing with the little filter on it, LOL. 'Think' the GM number is 1997222...don't quote me on it :o.

[jonszr1]

that was the problem on both cars . that little deal with the filter on it .i have a sppare if you cant find one

[phrogs]

Is there anyway to test these off the car?

Or without it running with the plenum off I want to be sure thats it.

just wondering if anyone had a write up before I thumb through the FSM

[XfireZ51]

John,

Run a hose from the air pump directly to the Differential MAP sensor bypassing the solenoid. Cap off the lines going into and out of the plenum area. See if you are then able to use secondaries. I'm assuming your secondary vacuum pump is working.

[phrogs]

UPDATE

I folded and bought a tech 1.

Well I didn't even have a instruction manual but it seems to have everything else.

I checked the injectors and low and behold when I turn off # 6 the motor runs the same so like I thought something is up with # 6 Im guessing its that damn coil so what im going to do it swap the coil and a injector and see if it moves cylinders then I can see if its that coil!

johnny

[Jeffvette]

UPDATE

I folded and bought a tech 1.

Well I didn't even have a instruction manual but it seems to have everything else.

I checked the injectors and low and behold when I turn off # 6 the motor runs the same so like I thought something is up with # 6 Im guessing its that damn coil so what im going to do it swap the coil and a injector and see if it moves cylinders then I can see if its that coil!

johnny


John, isolate the cylinder. Once you have that figured out, ohm the injector. If the injectors check out fine, it's the coil.

As far as an instruction manual for the tech 1, it's easy to navigate.