hesitation and excessive shaking

Giro

Registered User
I just finished putting my car back together, changed the intake manifold gaskets, replaced the spark plugs with xp103's gapped at 0.40, and new BWD spark plug wires. Fired her up, she burned off some residual coolant, and now shes idling kinda rough, almost as if it had a bigger cam installed. The car shakes more than it used to.before, and when I give it some.throttle, it seems to hesitate, and almost makes like a gargling sound (best way I can describe it). It's idling at around 800ish. I double checked the wire order on the coil to the correct one (1-2-3 5-6-4) and double checked to make sure the worse were properly installed and secured on both.the plugs and the coil. Is there something I may have overlooked, such a wire harness connector? Seems like everyrhong is hooked up properly though. What should I look at for the most probable cause? Thanks, and sorry for any spelling mistakes, I'm in a hurry and sending VIA my pho.e, and I hate touch screens.
 
I forgot to mention that I suspect the head gasket to possibly be blown. I'm hoping that Its not and that It's another issue, but do you guys think It's the head gasket or something else? Thanks.
 
agreed.

its hard to say without seeing it

it sounds like a bad vac leak
I'ld Check the vacuum gauge for vacuum (is it less than it used to be or the needle bouncing?), Look for a forgotten vacuum hose, Check the IC tubes. If nothing obvious do a compression check to confirm that head gasket issue or not. If you have one, might as well replace it. Be sure to double check your work on the intake manifold during the tear down (the gasket may have slipped).
 
I set the firing according to that picture. My vacuum gauge is at 21 inches at idle. I'm sure the intake gasket didnt slip on installation. I'm suspecting either a wire harness I missed, or possibly the headgaskets. I have scp headers, making a compression test very difficult.
 
You could have pinched the injector harness or another harness or pinched the fuel rail rubber hose. How well did the injectors sit back down in the head? How far did you take it apart to do the intake gasket? I would be checking everything that I took off or touched to check for issues. I hope its an easy fix
Jerry
 
I took the supercharger, IC tubes, and the brackets that hold the accessories and pulleys, I made sure everything got.hooked back up, no pinched wires. I pulled the new plug wires and one as messed up, the crimped end stayed on the spark plug. Replaced with my old magnecors, started her up, and confirmed my problem. Blown head gasket again.
 

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I took the supercharger, IC tubes, and the brackets that hold the accessories and pulleys, I made sure everything got.hooked back up, no pinched wires. I pulled the new plug wires and one as messed up, the crimped end stayed on the spark plug. Replaced with my old magnecors, started her up, and confirmed my problem. Blown head gasket again.

Oh yeah you definitely have blown HG's. Sorry man. That sucks. Alll of us here know that isn't an especially easy job on these cars. How long did these HG's last? Were the heads resrufaced? Did you use studs or TTY bolts? Did you use a composite or MLS gasket? What is the current status of your cooling system?
 
They lasted 2500 miles, used arp studs, 30-60-90 torque, composite fel pros, heads were resurfaced, cooling system status is unknown, those 2500 miles are all I've put.on her since I bought the car.
 
That is super quick for head gaskets, are you using water or do you see it in your oil? What did the plugs look like and is it smoking? I hope it aint the luck that I have, I had my heads checked at the machine shop and they tested good for vacuum. When he was putting the new seats in, it started leaking under the seat. The casting was weak and leaking water. I still would bet on something besides the HGs unless you got it super hot in those 2500 miles. Why did you do the intake gaskets by the way?
Jerry
 
They lasted 2500 miles, used arp studs, 30-60-90 torque, composite fel pros, heads were resurfaced, cooling system status is unknown, those 2500 miles are all I've put.on her since I bought the car.

That is way too soon. Something isn't right!
 
You mentioned you have headers, what else do you have done to this car and how hard do you drive it? Do you have a tune on it all? My guess is that you have crazy detonation and are running very lean.

Chris
 
Jerry-it never overheated after I replaced the head gaskets. One day my friend.showed up to my house to pick me up, (in my car) and when he turned it back on, it started smoking. He said it was fine on the way there. I did the intake gaskets because the intake manifold bolts were loose, and I suspected that to.be the reason for coolant leaking into the combustion chamber. I redid them using copper spray, cleaning tje bolts and bolt holes, using thread dealer (not thread locker), and water pump/thermostat dealer around the coolant ports. The smoking was 2500 miles after doing the head gaskets the first time.

S Mazza- yes it seems strangely and suspiciously way to soon. I'm hoping I got had gaskets and that It's not a bigger issues.

90sc35thann- my air fuel ratio gauge never showed an excessively lean condition, if anything it would be rich under WOT, but under normal driving, it was pretty much stoichiometric.

mywhite89- http://www.sccoa.com/forums/showthread.php?t=123557 that's the link when my car was being sold, all those mods were done by the previous owner. I believe a tune was mentioned in there, but I don't know any details in regards to It. The car was driving hard maybe about 6-7 times.

Thanks, and i appreciate your help.
 
You might try taking a valve cover off and double-checking the torque on the head studs and nuts. (If you only torqued them once, the gasket may have compressed over time and loosened up the nuts.)

Graphite composite Fel-Pro gaskets are the standard for a typical repair. They have worked fine for me. My 1989 non-supercharged T-Bird got 100,000 miles out of a set.

Could you have possibly installed the head gaskets the wrong direction? One end should have been labeled, I think. Just another odd thought.

There could be a crack in the head, as someone mentioned. Or even a cracked block (although that is very rare with these engines). But I hope not.
 
Do you have a coolant system pressure tester? Have you pulled the plugs and inspected them? Does the smoke go away after awhile? How much water are you using and what does your oil look like?
 
S Mazza- I'll double check the torque on the studs today. I vaguely recall seeing orientation marks on the gaskets, so I'm sure they are in the correct direction. I hope nothing is cracked also, but with my luck, it wouldn't surprise me

Jerry- I do not have a coolant system pressure tester, and I see how that would be useful in regards to a head gasket possibly being blown. Before starting her up, I replaced the spark plugs, new xp103's gapped at 0.40, when I pulled out the old set, what stood out was #2 had coolant on it. I actually suspected the head gasket at that point. I've ran it for about 15 minutes, smoke seem to go away and come back, seems in sync with the thermostat opening. I'll check my oil, and i don't know how much water I'm using, haven't ran It for very long to get an estimated amount.
 
So the oil was fine, full and not contaminated. I just noticed that the cars running rich. Smoke went away for now. Could those xp103's gapped at 0.40 be an issue?
 
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