422 cam on 8.6:1 CR causing surging and no idle?

[brock1949]

Alright as some of you guys know whats going on i built a typhoon motor with a custom 2114 intake 65# injectors, custom giant plenum with lsX throttle body, forged internals, cryo crank, 4 bolt splayed billet mains etc etc all done at Hitech/McCoy racing, worked over 01 vortec heads with comp pro mag roller rockers, manley valves, beehive springs.. etc etc

Well i'm running there "custom grind big cam" from back in the day where they made like 750+ RWHP and i guess set some records. Well its basically a 422 cam by todays standards as long as he is telling me correctly.

Now onto the problem, I am running this truck on megasquirt fuel injection (brand new motor never ran on MS before clean slate on all acounts in a 94 s10)

Well its running terrible, its starting ok.. but then wants to surge really bad like its not firing for so many cycles then it fires all cylinders fine for a second then it does only really fast. The piss off is its reading like 21 AFR yet i still smell raw fuel and its still running.. so i know its pumping out some unburnt fuel and by the time i try to get the AFR's down when i hit about the 15-17 area its smoking black/white in fuel.

So the guys on the megasquirt form tell me basically i don't know what i'm doing and you can't run that cam 422 with a low compression motor... said it will never idle under 1200-1500 rpms. But the fun part is i had it running about two weeks ago with idle pretty smooth around 650 rpms and was actually able to drive it with only a couple bad spots i needed to work out of the tune.. then over a 2 day period it went to shit.

Any ideas? The plugs are all equal and by equal they are all jet black when i pull them out. I've replaced cap and rotor.. some MSD combo, the plug wires Crane 25ohm fire wire race wires, Plugs TR6, and the coil and ignition is MSD 6al with MSD HVC2 coil 50,000 volts at like .5-.7 amp or something.

i've tried different timing tables tons of crap.. as i add timing it gets way worse.. seems to like nearly no timing.. something like 10-15 degrees but at 4 degrees i had the headers starting to glow .

ANY pointer? is this cam that rough? what am i missing...

And of coarse a link to the thread on MS forum..

http://msefi.com/viewtopic.php?t=27359&start=0&postdays=0&postorder=asc&highlight=

 

[10secTy]

Re: 422 cam on 8.6:1 CR causing surging and no idle?

That cam will run fine on that comp ratio. Surging is usually a lean mixture at idle and if it is to lean it will miss fire and send unburnt fuel out the tail pipe. This can also trick your wideband O2 into thinking it is lean as well. Make some big changes to see if it gets better.

Add a bunch of fuel at idle to see if it gets better( in the 12-1 or13-1 range) If it does not start looking at your distributor and timing to make sure it is 100%.

I usually will have a combo like that idle with 28 degrees of timing.

Nolan

 

[brock1949]

Re: 422 cam on 8.6:1 CR causing surging and no idle?

10secty thanks a million for the input there Megasquirt guys are coming down hard on me ignoring the fact the truck barley runs and chalking it up to i've just got to much cam and to low of compression...

So what type of idle rpm range should i shoot for?

The truck does some really weird stuff and it keeps worrying me because everytime it gets to rich it starts smoking white/black and i instantly start thinking i'm counting days till the rings are gone. But at the current moment it keeps completly throwing off the wideband. Its like it will be reading 20-21AFR running terrible at 1000rpms and under idle and if i try to richen it up it starts smoking and running terrible. Also during this if i add more timing it usually just starts running so bad it dies.. or does this thing where it not running anymore but you still hear light little fires and the motor rolls over 2-3 times.

If you think there is anything you could figure out looking at megasquirt datalogs i will get you links to the viewer and give you a log.. its pretty strait forward if you had any interest.

Thanks again. I will try just bombing these tables and pulling out tons of fuel or adding fuel and see what happens.

Also i keep checking the timing and its within the accuracy that i can read it.. withing .5 degree or so.

 

[turbodig]

Re: 422 cam on 8.6:1 CR causing surging and no idle?

If I had to venture a guess, you've either got a big vacuum leak, and/or a stuck open injector.
Like you have 5 very lean injectors, and 1 pig rich one. (Makes your AFR do funny things)

That cam will purr like a kitten even with some fairly hefty injectors.

Check your plugs... see if there's one that's wetter/blacker than the others.

Also possible - incorrect injector wiring to the MS...

 

[brock1949]

Re: 422 cam on 8.6:1 CR causing surging and no idle?

Well i've checked the plugs on and off and changed them more times than i'd like admit.. however at least i've got it down to like a 15-20 minutes process lol.

But they come out looking like uniform $hit coated in black and not wet from what i've seen.

Also i just tried running a old tune that got the truck running awhile back and it did indeed get the truck started again but it was smoking like crazy again,.. white/black/grey ish smoke smelling like burnt oil, and raw fuel.


but it was running smoother not like hard motor shaking coming on and off, but its still doing some crazy stupid stuff reving up then slowing down reving up and slowing down.. but not by air changed its all fuel and AFR ratios..

ANYONE want to look over logs etc i'll get you setup so you can look at them and see what the deal is.

 

[Maxtor]

Re: 422 cam on 8.6:1 CR causing surging and no idle?

You have already heard from two of the biggest experts on this BB, but I can throw in my experience and tell you I run the 422 cam with 84# injectors and idle around 900 rpm with 28 deg. of timing. I have virtually no surging at idle. You can tell it has a larger cam than stock at idle, however, as Nolan/Dig suggests it is still very smooth.

 

[protosy]

Re: 422 cam on 8.6:1 CR causing surging and no idle?

sorry for the perhaps ignorant question. are you running closed loop off of the wbo2?

 

[James Thomas]

Re: 422 cam on 8.6:1 CR causing surging and no idle?

Lunch says vac. leak. Could be timing though and I would include cam timing. I run th 422's on N/A & forced induction with no problem, both F.I. & carb'd. The 422 hate's advanced timing (cam or Ign.).

____________
James

 

[ed hess]

Re: 422 cam on 8.6:1 CR causing surging and no idle?

>>>its smoking black/white in fuel.<<<

guess everyone missed this one.

I kinda think you have 2 issues.

one is why its rich.

the 2nd is why the white smoke.

white smoke is from coolant.

I suggest you pressure test the cooling system and check for leaks.

then do a leakdown test with the radiator cap off and watch for radiator level to rise.

does the white smoke appear allways or only after warmed up or only when cold.

ed

 

[E-Rue]

Re: 422 cam on 8.6:1 CR causing surging and no idle?

first off the cam is not a 422.... we measured it. its got a lot more duration on the exhaust side than a 422, and a very narrow lobe separation...... however i have had the luxery of tuning one and its not hard to get it very smooth at about 950-1000rpm. you will find this cam has almost no torque below 2000rpm but really starts to sing about 4500rpm. my biggest complaint with the cam was the complete lack of torque when the TC locked up on the highway at steady cruise and pulled the RPM's down. otherwise it made a pretty decent dragracing setup.

second, it sounds like your running crazy rich, and you need to lean it out. once you get it to sit there and idle try to figure out why your O2 is reading incorrrectly. i dont care what your WB reads if the plugs are black and its blowing raw fuel out the tail pipe its rich. if it was running decent a few days ago and now its not them something changed.... its not uncommon for a new motor to need the lower manifold bolts retorqued after heat cycling, and its also common for the upper intake manifold to vibrate loose if your using solid motor mounts with a built motor. in fact we have to locktight every bolt on the motor and trans when we do built motors with solid mounts. both of these conditions will give you a vacume leak that will cause the symptoms you are describing.

the surging sounds like a vacume leak to me. theres 2 things that cause surging, a lean condition and a vacume leak. based on the black plugs i doubt you have to worrie about a lean condition. take a sewer cap from lowes, or home depot, and make your self a pressure tester. place the cap on the front of the turbo, and hit it with some air from the air compressor. a huge vacume leak will be come immediately obvious behind some air pressure (will hiss and/or whistle) and you can make the repair. obvious places to check are the intake manifold bolts and the vacume lines.

e

 

[James Thomas]

Re: 422 cam on 8.6:1 CR causing surging and no idle?

my biggest complaint with the cam was the complete lack of torque when the TC locked up on the highway at steady cruise and pulled the RPM's down. otherwise it made a pretty decent dragracing setup.

e

E

Are you refering to the actual 422 or this cam that you have measured that is not a 422?

James

 

[4C FED]

Re: 422 cam on 8.6:1 CR causing surging and no idle?

He's talking about McCoy spec. cam that brock1949 has.
I had that cam, POS fell apart.

 

[brock1949]

Re: 422 cam on 8.6:1 CR causing surging and no idle?

He's talking about McCoy spec. cam that brock1949 has.
I had that cam, POS fell apart.

Well that part doesn't sound awesome.. What exactly do you mean fell apart?

IT is a cam that Hitech (in with McCoy) sold me that definelty only has 4.3L stamped in the end of it but he told me the specs a couple days ago again and it was dead nuts for the 422.. 270 276 500 510 110 centerline 114 lobe sep. Now is he lying? who the hell knows but he seemed really excited he still had a cam left and everyone at the shop went on about how great the "big cam" was.

The white smoke ish stuff kinda bugs me and i am indeed loosing some coolant but it doesn't seem like enough that its burning it. I think its from the overflow dumping on the ground right now.

That and when i get the timing above 10 degrees.. 15 degrees or so area it stops smoking all colors just starts running like $hit.

The megasquirt guru's have rained down though, a guy in VA called a guy in columbus ohio and he sponsors a SCCA autoX driver who's big into Megasquirt and lives about 20 minutes from me.. Between these guys and some others on the MS forum they decided i have a wiring problem. I think more specifically i have a ground problem thats now making my IAT and coolant temps.. and RPMS randomly spike stupid high for a couple frames. It just kinda took some people who knew what the heck they were talking about on tunning megasquirt to realize it wasen't a tunning, or engine build problem.

I think the ground problem roots back to another guy that i thought was a megasquirt expert telling me to centrally ground all sensors to one spot.. which now the local guy tells me is a bad move and creates tons of feedback that can cause these problems.

However as i look back to datalogs where the truck was idling at 650-700 rpms 55KPA, and reving smooth and drove great.. in those logs, no freaking spikes of anything. I actually suspect i'm going to find a melted wire somewhere.

Now back to the coolant leak,. IF i have a coolant problem i'm afraid its actually loosing it in the oil from the arp head studs. I have one head stud outside the valve covers thats constantly got a wet look to the threads. But i've changed the oil 4-5 times to this point and noticed no coolant.

Thanks a million for the responses and all the help! I will keep you guys posted.

Brock

 

[brock1949]

Re: 422 cam on 8.6:1 CR causing surging and no idle?

Also this is a 2114 intake that i layed out for MPFI and had my local machine shop help me and a freind tig weld it etc etc with a custom plenum i made based on the numbers the turbo engineering books told me to do with a LSX throttle body. yada yada. But i had the machine shop check the angles of the intake to make sure it was still square and it never leaked on the last motor. But i will definetly check all the bolts again thanks for reminding me.

Head gaskets are cometics, used a calibrated Torque wrench and did it all to specs putting the heads on. However by chance i happen to know what this truck burning mad amounts of coolant is like from (ROL head gaskets on the stock bottom end and a blower... ) and it doesn't seem anything like that. When it head a ROL spilt it acted really funny and like loaded down and the smoke was different color of white if it makes sense.

I've got a million things going on with this truck hard to keep track of them all.

Thanks again everyone i started this built ty engine/ turbo swap / megasquirt / 2114 lsX plenum etc etc start of may last year and its just wearing me down after seeing it pretty good then fall apart etc etc.

 

[10secTy]

Re: 422 cam on 8.6:1 CR causing surging and no idle?

#1 I would do a leak down test to make sure the motor is still 100%.

If all that checks out go the the gm dealer close to you and get some sealing tabs. We get seeping problems with head studs and cometic heads gaskets.

We always send the GM coolant sealing tabs with motors that have heads studs and cometic heads gaskets.

Nolan

 

[4C FED]

Re: 422 cam on 8.6:1 CR causing surging and no idle?

I had the bigger cam. I think he said .525 lift.

Here is what it looked like after 5k miles.
Almost every lobe looked like this. Coulda been a bad core, I guess. It's just my experience. YMMV.

 

[brock1949]

Re: 422 cam on 8.6:1 CR causing surging and no idle?

wow that is nuts, and ya that rough like machine work between the lobes thats the same style my cam is definetly from the same maker or who ever.

I didn't feel completly confident that the cam specs he was giving me were the right ones. He played some games with it saying it wasen't really a advertised cam or specs and that it was the same cam they set records on in the McCoy truck from the same run and it was from his personal stash kinda thing.

However i did take every part of the motor once he was done to my local machine shop that does some high end stuff 50-60k dollar true cobra motors, tractor pull motors, circle car motors etc etc. and they told me the machine work was top notch and that they were using some good stuff. Said the finish on the cylinder walls was exceptional.. dart competition finish or something. But then i put the motor together so who the hell knows what could happen lol.

The cooling system on this truck is a real pile of shit which kinda makes me mad. Its the stock 40k mile radiator, and i've got a family member we'll call it that works for ASC (water pump manifacture) who picked me up this pump claiming it was the best flowing yada yada HD pump. Then i put a 3600cfm taurus SHO fan with a flex o like 55amp HD 2 stage controler. Well the coolant lines like won't get tight until the motors been ran reved up and hot seems like the pump isn't moving enough water at 2000 to 0 rpms.

 

[brock1949]

Re: 422 cam on 8.6:1 CR causing surging and no idle?

first off the cam is not a 422.... we measured it. its got a lot more duration on the exhaust side than a 422, and a very narrow lobe separation...... however i have had the luxery of tuning one and its not hard to get it very smooth at about 950-1000rpm. you will find this cam has almost no torque below 2000rpm but really starts to sing about 4500rpm. my biggest complaint with the cam was the complete lack of torque when the TC locked up on the highway at steady cruise and pulled the RPM's down. otherwise it made a pretty decent dragracing setup.

second, it sounds like your running crazy rich, and you need to lean it out. once you get it to sit there and idle try to figure out why your O2 is reading incorrrectly. i dont care what your WB reads if the plugs are black and its blowing raw fuel out the tail pipe its rich. if it was running decent a few days ago and now its not them something changed.... its not uncommon for a new motor to need the lower manifold bolts retorqued after heat cycling, and its also common for the upper intake manifold to vibrate loose if your using solid motor mounts with a built motor. in fact we have to locktight every bolt on the motor and trans when we do built motors with solid mounts. both of these conditions will give you a vacume leak that will cause the symptoms you are describing.

the surging sounds like a vacume leak to me. theres 2 things that cause surging, a lean condition and a vacume leak. based on the black plugs i doubt you have to worrie about a lean condition. take a sewer cap from lowes, or home depot, and make your self a pressure tester. place the cap on the front of the turbo, and hit it with some air from the air compressor. a huge vacume leak will be come immediately obvious behind some air pressure (will hiss and/or whistle) and you can make the repair. obvious places to check are the intake manifold bolts and the vacume lines.

e

What gear ratio were you running when you had that cam? I am just wondering because i've got 3.42's right now with a 4l60E.. kinda 4l60E were still missing a little bit of a wiring diagram to get it to start shifting and not being a awesome 1 speed. I may later on goto a TH400 that a freind of mine who builds modified stock cars has from a 800+HP 400 small block car that only had 6 laps on it. I'm sure i would need to change some stuff to make it work with my 5500 rpm motor instead of his 7000-8000 rpm motor but i guess those trannys from the stock cars are nuts. Internally lightened, SFI case, parts made out of Ti,.. i dunno he offered it to me for 350 bucks since his class no longer runs them and they use some weird 2 speed manual now. So if i go TH400 it may put my rpms high enough it wouldn't be to bad on the highway. but honestly i don't see allot of highway time in this things future.

And awesome idea for the sewer cap.. i'm all over that tommorrow!

 

[E-Rue]

Re: 422 cam on 8.6:1 CR causing surging and no idle?

stock gear ratio.

any updates on your tuning issues?

e

 

[brock1949]

Re: 422 cam on 8.6:1 CR causing surging and no idle?

I spent a weekend cutting trees down and dealing with a idiot freind of mines crooked car deal he got into on a used crew cab dodge 2500. Didn't even get to touch the truck yet, Next goal is to go through or pull out sections of harness and rewire the harness and start again.

A local car lot that deals in High end sports cars only, vettes all years, a ton of the german sports cars yada yada has a Syclone sitting in there showroom (next to some 50K dollar vette) that says spotless low low miles for 12,000.. oh how much easier it would have been lol.