Misfire plus more **UPDATE**
 

I think the title really doesn't give the extent of the wonderful problems I am having.

Here are my issues:

- Misfire under load
- Won't idle, not for anything
- Revving the engine just results in a stall, or if light throttle, barely any engine speed increase, just misfires and more misfires.

Here is what happened. Fired the car up initially [after the top end rebuild], car ran excellent. Sounded great, engine seemed to be in perfect order [ask jrs3800.. he's the only member who heard it]. Next day I go to start the car, runs, but has a decent misfire. The engine still ran good, idled fine, everything, but as soon as you gave the engine throttle; misfire. Day after that, I pull the intake due to an oil leak. Put it back on, start the car up, misfire is gone for the first minute of the engine running. But returns after that. Switch the Delco Ignition, same results. Change plugs + plug wires [Belden 8mm and TR55s] same results. Bolt up the MAF Sensor Body, EGR Valve, and other misc little shit. Same results.

This is where things get a little weird. When I pulled the intake, I also retorqued my rocker bolts with a fucked up torque wrench. My guess, is that I torqued it wrong. But the other weird thing, is I didn't torque them when I initially fired the engine.. just put them on 'good enough.' I also never put thread lock on when I initially put the rockers on. But why would the engine not show signs of a misfire that day, but show them the next? I can definitely tell you running a car with just headers makes the whole engine shake like hell.. I mean like a TON of shaking.. so it is a very viable option that the bolts became loose [although they seemed fine].

I keep thinking this is an electronic issue, but it just doesn't add up. No codes, nothing. AFR trick leads to nothing but constant flashes [5-7x /sec, but it's consistent, never faster never slower]. Nothing in the ECU would make it fire like this.. unless the ECU is fucked. The only thing I have not tried, is cutting the wire which gives 5v to the ICM to tell it to back down, and let the ECU take over the timing. With the ICM controlling timing, I would only get 10* advanced, and of course it would throw a code, and I believe the ECU will never go into closed loop.. but I could be wrong about that.

I only have $65 for any sort of tools or whatnot. So whatever you guys suggest, suggest the cheap stuff first ;). I want to pick up a torque wrench at Sears, and use that to double check all my torques, because I really think the one I had from autozone was fucked to the max right when I got it.

What are your opinions? I'm stumped on this one. Situations such as these, are where experience pays off, and I am sure it shows I have none.


-justin

Check your voltage and wiring going to the ICM?

Start with your basics first-always remember the KISS rule ;)
Go back & re-check all your connections & wires.
Triple check your plug wire routing since youve been in there.
TPS voltage correct? MAF working right (tap tap)? IAC working right? Checked fuel pressure yet?
Also check your oil & antifreeze to be sure theyre not getting mixed anywhere. I think you did a great job so far so this is doubtful, but worth looking at.

I'm gonna say your rocker nuts are fine. Most factory rocker arm nuts are staked (they will look as if someone hit them across the top with a bladed chisle). This is so the nut will dig into the stud & stay there, eliminating the need for Loctite. Thats also why they wont just "spin" on like a normal nut would on a bolt. Stock ones will usually be good for a few removal/installations before they are trash, so you should be good. (This is a pedestal style valvetrain right? There is no lash adjustment, just torque down the rocker nuts & its done?)

No worries about wiring, trust me, its good. And the misfire is only under load. If I just have light throttle, the car is fine. Or when it did idle, it was fine also.

Can't get the car to idle, and my mom is too retarded to start the car [takes some pumping.. i'd say it's about five times harder than cold starting a carb]. So I can't test the MAF Sensor, but the car doesn't change anything with or without it. EGR Valve too. TPS I have not checked.. but it's on my list. I have not checked the Fuel pressure, however I do not think there is anything wrong with it, since it worked fine that Monday.

Yes, the rockers are a pedestal-based setup. Torque 'em down, and you are done. And yes they can just spin out. The bolts can't come out of the pedestal, but the pedestal can come out of the rocker body.. if it gets that loose. I have loctite on them now.. but I have a feeling I should go and do the tightening I did previously and see if that helps.

No coolant/water/anything in the cooling system as of yet. Can't really test for leaks when you can't keep the damn car running. I have yet to have the car running more than 2 minutes at a time, so it's not that bad. It does get a little warm.. but it has yet to burn me.

lakeville: Why do you suggest testing the voltage to the ICM? And would you care to share how to do that? I'm guessing I can just turn the ignition on, and use a DVM on one of the terminals [I can find which terminal it is, I should test].


-justin

I don't know which terminal to check, or what the values should be off the top of my head though. Also even though your wires are new....I would still check the resistance on them to be sure that they're good. I've had wires bad out of the box before.

fuel problem perhaps?

misfire
 

I'm going to say fuel problem or mechanical.
If you want to start with the cheap solutions try isopropal gas dryer in tank along with mystery oil. Rislone in the crankcase. You could have an intermitten valve sticking open until it wears in. Did you do head work? Compression check?
All low cost suggestions.....

Tons of head work. Everything was cleaned and lubricated, valvetrain wise. Replaced the Valve Stem Seals, too.

I'm not sure why a fuel problem would cause a misfire?

The weather is acceptable tonight, so I will go back and do what I did initially to torque down the rockers. I know why the engine doesn't want to rev, it's because it is super rich. I forgot to mention I fouled my new plugs. So that does kinda constitute a fuel problem, but it certainly isn't a lack of it.

I'm also going to go out and triple check all connections and whatnot when I delve under the valve covers.


-justin

I would definitely check the fuel pressure although fouling the plugs could be caused by multiple attempts to start the engine. I don't remember if you did the extensive mods to the deck height or had the heads shaved extensively, but do you know how much preload you have on the lifters? They could bleed down so it starts okay, but hangs one or more valves open when they pump up a bit? Running way rich could be caused by many things, a bad MAF sensor, very high fuel pressure (maybe), a vacuum leak, bad plugs, wires or swapped spark plug wires, maybe an injector stuck open (usually only one cylinder affected), possibly a bad temp. sensor (reads cold with engine warm), even a bad ECM. If it won't idle, the IAC could be stuck closed too, although pressure on the throttle would bypass that.

Aye.. vacuum leak you say? I don't have any vacuum components connected. The vacuum distribution block isn't even on the intake. It's just a big empty hole. Could that be it, maybe? My biggest worry is a bad ECU. That seems to be what everything is pointing to.. but idk?

You might be right about the lifters bleeding down and whatnot.. because that seems to make the most sense. The car initially starts good, but then after it runs for a minute, it will stall then never want to start back up. It'll fire and sounds like ti wants to, but it just won't.

I just purchased a Craftsman Torque Wrench [a cheapie.. but it's a whole lot better than the Autozone loaner I had]. I took a nap instead of working on my car today, so I will get right on it tomorrow. Torque 'em down to specs, and go from there.

Hopefully you are right about the lifter bleed-down.. that's gotta be it :).


-justin

Well, it sure doesn't help things any. For one thing, the engine is getting way too much air to idle properly. The fuel pressure regulator is vacuum controled. There's a great many reasons to connect your vacuum lines. I'd try that, it's free.

Also, you're not running with any coolant? Granted, you won't overheat in 2 minutes, but what about your poor water pump?

My FPR is hooked up. But everything else isn't.

It'll have to make due without coolant for the time being. :). It'll survive. If the problem keeps going any further, I will get the cooling system hooked up anyways. It'll give me something to do.


-justin

Guys, got some awesome news for ya. Engine.. running AMAZING! Holy shit does she run like a dream now. All the problems magically went away, except for the idle. Car still won't idle, but with the way she runs, I don't give a damn.

Since the car ran so well, I threw in some water, fired her up, and saw my oil pressure had fallen 10PSI. I thought, ah fuck, the water mixed with the oil. Sure enough, check the dipstick, milky mess. Raise the car up, drain the oil [it may have burned the fuck outta my hands, but at least engine damage isn't going to happen]. Pulled the Lower Radiator hose, and drained whatever water was left [just in case if more wanted to mix]. I found my problem, though. That damn POS autozone torque wrench.. only torqued my intake bolts to 60-ish ft lbs. Instead of 150! So, I went to retorque the first bolt.. what does it do? Snaps! So, now I am going to go pick up some new intake bolts, EGR Bolts, a few other gaskets. Even though I have the oil I need to change the oil, I cannot afford to just waste it like that, so if I do it, I am going to do it right.

All-In-All, it was worth it to hear her start up like she did. Boy does she run great! :-D


-justin

Mmkay, you have all these problems, but you run the engine without coolant and blatently open vacuum ports.

It'll run like crap with vacuum leaks like that. And without coolant, it'll over heat in a matter of a minute and destroy all your hard work.

Please fix these issues before you run it again. It's the only way to trouble shoot other problems.

Alright guys, heres a little update for ya.

Took car around the block Monday, she ran pretty good, IMO. Certainly doesn't sound as though she has any problems. Get her home, everything seems fine. Oil still seems a little watery, but certainly improved [don't worry about this guys.. ]. Start the car up today, and she sounds good.. walk around to the tail pipe and she sounds a little sick. So I listen, and it sounds good, then bad. Like the one set of cylinders aren't firing good [perhaps like the front?]. I thought maybe she was running rich, so I put my hand under it, and I feel liquid touching my hands, look at my hands, and what do I see? OIL! God damnit. Shut the car off immediately. Don't even wait 30 seconds and go right for the front valve cover. Break out my new torque wrench, FUCKING BOLTS ARE AT 45FT LBS!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

I'm super pissed right now, because I torqued them with the autozone special torque wrench [loan atool]. I currently have a Craftsman needle-type one.. which I have fallen in love with. So I know it is accurate.

Now what should I do here? Obviously shit is getting past in the head gaskets. Do I need to pull the heads and replace the head gaskets? Or can I just re-torque them down? I really, REALLY don't want to pull my heads, because then I know I will need new head gaskets, which I cannot afford. And since my head bolts were never torqued down properly, I am assuming they are still good?

Your responses are much appreciated!

-justin

I've lost track of what engine this is, but a 3800 uses torque to yield head bolts. A base torque is used and then turn a specified angle. Retorquing may work, but if there is fluid in between, or a spot got eroded in the gasket, it may not. It is hard to say what may happen as local hot spots from no coolant may have warped the heads? IMHO you need to pull the heads and start over.

Personally, it seems as though you may have a head gasket leak.

From what I know (quite a bit about head gaskets without ever actually DOING an HG job, lol, so my words != gold), extra torque or retorquing head bolts can either save you (I don't know if it will in this case), or hasten the gasket blowing altogether.

Head wasn't machined, was it?

You NEED to plug up all vacuum openings if you run the engine, otherwise you can't diagnose it correctly.

I did, I did.. all rubber vacuum lines were replaced [I used a few old ones for the initial drive, and that was a mistake].

It was definitely the head gasket leaking. No doubt about it. How else could I get oil coming out of the tail pipe? There is no way I have that bad [and consistent] blow-by. I talked to a few engine friends, and they said torque it down, if that doesn't work I have to take the heads off and replace the head gaskets again. Along with the head bolts.

And FYI, I know about the torque-to-yield bolts, but there is no way that these bolts were ever torqued to 100ft lbs. I know how much strength I had to put on them originally, and that is NOTHING to what I had to put on yesterday. My whole [right] arm hurts like one mother fucker, and it never did that before.

I'm going to re-torque the rear head, and then see what happens. Got 4 quarts of fresh oil ready to go in, along with a hose filled with water.


-justin

With a 24" torque wrench, it is not that hard, lug nuts on alloy wheels are supposed to be 100 lb-ft.

Secret to head bolts is that threads must be absolutely clean and all sealer removed from bottom of hole. Have seen a GM block with the head bolt threads so crudded up that you had to fight the bolt all of the way out. Cannot get an accurate torque reading that way.

Is a good idea to check by running the bolt in by hand at least to several threads below where the bolt needs to stop. If the bolt sticks, the threads need cleaning (and yes I know, some GM manuals say not to clean the threads. Trust me, they must be clean and you must be able to spin in by hand). I also use a drop of anti-seize on head bolts.

Don't worry about that. I was able to hand thread ALL bolts freely. I could probably spin them in there [exaggeration]. So I know all threads were clean. The head bolts cam pre-applied with thread-lock, but I put my own on just to be safe. They went in smooth as glass.. but I am also not all that strong. And my torque wrench is only 18" I think. I know it isn't 24" that's for sure. Which could add to my weakness. It's not that bad, but it it isn't easy. I'm alright now.. my arms feel much better. I know I can tackle the rear no problems now.


-justin

Just got out tape and my 1/2" torque wrenchs range from 15 to 19 ", it is my breaker bar that is 24". Of course if you install per the 1990 service manual, why new bolts are required becomes evident (tighten to 35 lb-ft in sequence, then 130 degrees in sequence, then 30 degrees in sequence.

1992 "L" procedure is the same except only the center four bolts are rotated the final 30 degrees.

1988 service manual has a different method - start at 25 lb-ft, then 90 degrees, then an additional 90 degrees. Has caveat: Do not exceed 60 lb-ft which would probably be about right for all years, not sure where 100 lb-ft came from. (I did not bother to look up before).

So basically with new bolts, 25 lb-ft then a half turn more.

90 manual did mention that the GM head gaskets are not interchangable and have an arrow that points to the front, no idea about aftermarket.

Yeah, mine had an arrow. And my FSM said 100ft lbs, and nothing about starting off lower and whatnot. Although I did go from 45-60, 60-75, 75-90, 90-100. I wasn't strong enough to keep going all the way, but I knew about starting off slow and whatnot.


-justin

Just so I have this straight. Your '90 manual gives a torque reading rather than angle dimension?

If you guys were standing right here, I would just hug you all!

I LOVE THIS FUCKING CAR!!!!!!!!

I've been working on her since 11:30 only taking a 1hr lunch break. And a few other '2 minute' pauses for water. And guess what? She is running like a champ! This is the best she has ever ran, EVER! I betcha she runs better now than she did at the factory. That's how damn good she runs.

All head bolts torqued down. Everything all good to go. Changed oil [once again]. No water! :-D. Put coolant in, put too much, got it coming out the overflow nipple :oops:. Car got up to ~190ish, tstat opened, dropped down to the lowest temp she's ever been! Not even to the 1/4 mark. Probably around 140-150. Idles at a beautiful [never seen by me] 800RPM. Super smooth. Engine, quiet as can be. And she just jumps to life when you give her some gas.

I had to move her to get closer to the hose [I'm kinda lazy, didn't feel like dragging the hose all that far]. Threw her into Reverse, and I didn't even know it engaged! That's how smooth it was! No "clunk." The whole car didn't shake, nothing. Smooth as glass. Same thing for all gears. Instant engagement, and all smooth as can be. I used to have to give a significant amount of gas to move the car around in my driveway, now I just need to tap it lightly. Sometimes I can just idle! And that's on gravel/grass/plywood!

I am just so god damn excited! I wish I could take her out right now! It's very tempting not to! [my mom is already asleep].

Thank you guys! You have no clue how good I feel right now. Just what all went down today.. just feels so incredible! And to think, just a few weeks ago, she was in shambles.


-justin

tear up your neighbor's lawn, you dont need a licensed driver with you to do that. :twisted:







j/k. congrats on the whole thing from start to finish. sounds like somebody is gonna have fun tomarrow :D

Hell yeah! Just hope I can get my mommy to come along. Because driving without a license is bad, I shall no longer do that. [seriously].

I've got something better for my neighbour :twisted:.


-justin