Sputtering after HG replacement

RoccoRock05

Registered User
My head gasket blew out on me a couple weeks ago. I didnt drive it for more than 2 miles then parked it and immediatly drained all of the oil and coolant. The car sat for about a week waiting on parts. I replaced both head gaskets, and all of the gaskets associated with the top end, used ARP head studs, had the heads redone with new seals and they were milled and cleaned. I started her up and she ran fine, but there was a lot of white smoke for a little while, (most likely coolant in the exhaust). Then i drove it home and when i went to pass this guy in 3rd gear doing about 40mph it started sputtering bad. It only does it when i try to get on it. I replaced all the plugs today with autolite's and its still doing it. Its a 94 SC with a 5 speed.
 
Im using the LiveWires, (2 years old) from supercoupeperformance. The O2 sensors seem to be fine, i didnt get any check engine light. It only does it under WOT. Well, not even. If i press on the gas slightly hard it sputters. But i can drive it around normally if i dont gas it.
 
That really sounds like a spark issue to me. What heat range plugs did you use and what did you gap them at? If the heat range/gap is good I would try new wires (stock wires are as good as anything else out there). If that doesn't help buy one spark plug and substitute it for each plug. The last time I changed plugs I got a bad one and it took me all weekend to figure it out. I could also drive it around just like normal but anything around half throttle plus and she bucked like a bull. Good luck and let us know the outcome.
 
Blew my HGs on the dyno last year. Went through the replacing HGs, Heads, and got it up and running. Went back to the dyno and it wouldnt make any power. Took it home and the car died in the middle of a busy road. To make a long story short, the rod bearings were shot. They were probably not real good anyway with 145,000 mils on them but the anti freeze was the death blow. I did change the 02 sensors and I had the white smoke for a long time before cooking it out of the mufflers. I hope you dont find out you are in the same boat I was in.

Ken
 
Your O2 sensors can foul out and not throw a check engine light but will throw a lean condition code while the motor actually runs real rich. I'd check for codes to be sure.
 
I can't see it being wires....normally if they are not in the right positions you'd have a hard time getting the car up to 20 much less 40. Nevermind the fact she'd be coughing and weezing the whole time. You'd know immediately if that was the case.
Ive had stuff like that happen with fuel pump issues before...
 
All i used were the stock OE replacement plugs from autolite. They were gapped at .047 for all of them. I know they're recommended at .054, but i read on another post that its recommended to run between .034 and .045. So I figured that the gap they came with out of the box is sufficient. I highly doubt it is the plug wires, since they arent very old and everything was working fine until the HG blew. Its sounds and acts more like a semi with a jake break when i put the car under load. Could it be that the coolant clogged one of my cats? I forgot to list my mods in case it makes a difference : MP 3" intake with K&N Cone, 73mm C&L MAFS, 75mm TB, MP raised top, kooks mid-length headers, SCP down tubes with high flow cats, SCP full cat back (2 1/2-3-2 1/2), LiveWires, March underdrives, 10% SC pulley, 40# injectors with correct sampling tube for MAFS, BHJ SFI balancer.
 
Hmmm. now that I think about it, I have had a similar problem with clogged cats on my old Cutlass. Around town it was OK, trying to drive it at any high speed wasn't happening though....sputtered bad....
 
My first car was a 93 SC 5 speed. I was driving on the parkway, dropped it in 4th to pass someone, and it just stalled out. Tried to turn over but it wouldnt. Hollowed out the cats and it was good. BUT, there were no symptoms with that before it went out. Thats why im unsure about it. One other thing, it wont do it when im just sitting there. If i rev the engine and im not moving its fine. This is kind of out there but what clutch slippage? I know thats a shot in the dark but im just trying to eliminate what i can. The clutch is about 1000 miles old. (Spec stage 2 with Spec Billet steel flywheel)
 
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Dont discount the plug wires just because they arent very old its real easy to mess up the inner conductor without evev knowing it. I have messed up brand new ones just removing them and I am a trained professional :D. Its real easy to crack a plug when installing them I'd check them too.
 
I forgot about the cats it's been so long since I've had any. Yeah, cats don't take too kindly to being at opp temp and having coolant sprayed on them. If your symptom involves just loosing power at 40 mph then I'd vote on clogged cats/o2 sensor problems. If your symptom is bucking at 40 mph that is more than likely an ignition issue whether it be fuel or spark or both the only way to tell is to start replacing things one at a time. I had a situation where the one of the prongs got pushed to the side on my coil pack when I plugged it in once and I would randomly drop 2 cylinders. Make sure all the connections are clean and aligned. I have also messed up a brand new plug wire its not that difficult to do. Sputtering/bucking tells me your not getting enough gas, air, and/or spark. Just dropping power could be cats, o2's, left a ground strap off(also happened to me), etc.
 
Could a vacuum leak cause this problem? Small enough not to affect normal driving, but in boost it could cause it to sputter?
 
Wouldnt it have to be a pretty big vacuum leak in order for it to have that great of an effect on the car? Why wouldnt it do it as i sit and rev the engine? Ill double check all the vacuum lines, all the connections, make sure everything is down tight, and hopefully its something small. Ill be replacing one of the O2 sensors since only one had gotten coolant on it. If i find anything ill be sure to let everyone know. If there are any other suggestions you wanna throw out there, ill be glad to hear them. Thanks guys
 
Still sounds like plug wires to me. They will show a problem more often when they are under load and not just reving the engine.
 
Problems with vacuum leaks tend to be idle related, problems as you describe tend to be spark related. I am still betting on Plugs or wires
 
Ok, like I said, just a thought. I will say when the HGs blew on my 91, I didn't replace the O2s and it ran fine with no CEL after doing HGs. However, the O2 on the side the HG blew was toast and the computer wasn't getting a signal from it and ended up making the other side of the motor run rich and clogged my cat. So do make sure the O2s are good.
 
spark

Pop the hood in a completely dark location - no street lights, etc. Then goose it from the throttle body, I bet your gonna see some arcing. 2 years is fairly old plug wires in my opinion. I once identified a bad plug (brand new) by pulling them one by one, the plug appeared to be in perfect condition too... It's a pain but...

good luck
Bob
 
Still no luck guys. I changed the O2 sensor and it didnt do anything. I had the car running and i removed the plug wire at the coil pack one by one and each of them had an affect on how the car was running; which tells me that the plug wires are in good shape......unless there could be more to it. I traced all the vacuum lines and there are all in the right place. Most of them only go to a certain connector. Im still stuck here. I highly doubt that it would be the cat. Ive got a pair of magnaflow high flows that are about 2 years old as well. Wouldnt i have driveability problems constantly if they were clogged? Should i get a new set of OEM wires and see where that gets me? im runnin out of options here.
 
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