We had a similar popping sound under high boost. It turned out to be exhaust related. The engine torqued itself over enough under boost to squeeze the 3 inch downpipe on the control arm causing an exhaust leak that gave a loud popping sound. The torque strap wasn't enough to control motion with a stock rubber motor mount. A poly motor mount on the passenger side solved the problem.
popping under boost and hard starting (long)
- Thread starter at7we2
- Start date
Still sounds like fuel pressure is too low!!!!!!!!!! I will bet that your wiring to the fuel pump is faulty and the pump is not getting the proper voltage intermittently causing a drop in pressure. It is a known problem and that is why you need a hot wire kit. I have the race tronics hot wire kit and a walbro pump. You will see it is fuel pressure causing the intermittent popping.
Few years back I had a pop under boost, turn out to be a bad corrosion inside the negative battery cable. Replace it & it was fixed.
Had a good friend with the symptoms that you are describing, minus the hard start ….turn out to be a wiped cam & dished lifters.
Had a good friend with the symptoms that you are describing, minus the hard start ….turn out to be a wiped cam & dished lifters.
WOW! a lot more information again! You guys are all over this!!! THANK YOU! Ok...let's see...
Rick87GN - no problem, I didn't want to sound ungrateful myself - I really do appreciate any and ALL help and suggestions - ALWAYS!! If someone takes the time to post, I do my best to read and understand what they say. I should have been more clear about the intermittant nature of the popping.
mikestertwo - headgasket? hmm....you're the second one to mention that. oil and coolant look perfect so there's no sign of cross-contamination. the "popping" is only under boost and it's *definately* out the pipes not under the hood. still think head gasket?
RT87 - this isn't an exhaust leak - the engine actually stumbles, falls flat on it's face while it's popping. and I've been using the term "popping" just because that's what most local guys call it and that's what it sounds like when you're listening to someone else's car do it while going down the track. when you're sitting in the car, it's actually what *I* would call "back-firing" although technically a "back-fire" occurs with an intake valve open and exits through the intake path. this is definately the other direction - out the pipes. B-B-B-BANG!!!!
njbadboy - I have to say that right now I think you're right, it may very likely be fuel press. related. the car already has a Casper's hotwire kit and 340 pump, but they've been in there a while. I will check the wiring. unfortunately, I just haven't had time to check anything else over the last few days. I should have time to spend on the GN tomorrow (Tues.) evening.
getchasum - since the popping is intermittant I belive it just about *must* be an electrical issue - bad ground, bad power lead to fuel pump, something along those lines. I'm thinking the hard starting issue might be a symptom of the same problem - NAH! I wouldn't be lucky enough to kill two birds with one stone.
Rick87GN - no problem, I didn't want to sound ungrateful myself - I really do appreciate any and ALL help and suggestions - ALWAYS!! If someone takes the time to post, I do my best to read and understand what they say. I should have been more clear about the intermittant nature of the popping.
mikestertwo - headgasket? hmm....you're the second one to mention that. oil and coolant look perfect so there's no sign of cross-contamination. the "popping" is only under boost and it's *definately* out the pipes not under the hood. still think head gasket?
RT87 - this isn't an exhaust leak - the engine actually stumbles, falls flat on it's face while it's popping. and I've been using the term "popping" just because that's what most local guys call it and that's what it sounds like when you're listening to someone else's car do it while going down the track. when you're sitting in the car, it's actually what *I* would call "back-firing" although technically a "back-fire" occurs with an intake valve open and exits through the intake path. this is definately the other direction - out the pipes. B-B-B-BANG!!!!
njbadboy - I have to say that right now I think you're right, it may very likely be fuel press. related. the car already has a Casper's hotwire kit and 340 pump, but they've been in there a while. I will check the wiring. unfortunately, I just haven't had time to check anything else over the last few days. I should have time to spend on the GN tomorrow (Tues.) evening.
getchasum - since the popping is intermittant I belive it just about *must* be an electrical issue - bad ground, bad power lead to fuel pump, something along those lines. I'm thinking the hard starting issue might be a symptom of the same problem - NAH! I wouldn't be lucky enough to kill two birds with one stone.
marred4life
Banned
- Joined
- Mar 15, 2002
vacume leak, very possible. check all vacume hoses and intercooler hoses.
- Joined
- Feb 18, 2006
turbohye said:i second that. i had a wiped cam lobe. The pop nearly blew off my air filter.lol
And I third, Actualy I was the first to say cam. But I'm not looking for a pat.
I would be pulling the valve covers also. You will find your problem. Pushrod, Rocker arms, Cam and Lifters are all posibilitys.
Robert Kastle
New Member
- Joined
- Mar 12, 2004
Cam/valve train related, Rocker, push rod. I also would have to agree that it is probably on the exhaust side.
mikestertwo
Well-Known Member
- Joined
- Sep 13, 2006
The head gasket may be leaking between cylinders so you won't see any contamination in the oil. Do a compression check. The car I encountered with this problem only showed a slightly lower compression in two adjacent cylinders before the gasket finally let go big time! The gasket was leaking under high cylinder pressure ie. boost, until it finally let go dumping all the coolant into the oil pan! I'm not saying this is your problem, but it is something to check.
thanks again guys for all the posts! great information and I've got a long list of things to check.
worked late again tonight so it's still just sitting there
Hopfully I'll get home in time to work on it tomorrow night. gotta keep working so I can buy more Buick parts, right?
Thanks again to everyone that has posted on this thread. I will post up information as soon as I have time to tinker on it.
THANKS!
here's to hoping it's *not* valvetrain or headgasket.
worked late again tonight so it's still just sitting there
Hopfully I'll get home in time to work on it tomorrow night. gotta keep working so I can buy more Buick parts, right?
Thanks again to everyone that has posted on this thread. I will post up information as soon as I have time to tinker on it.
THANKS!
here's to hoping it's *not* valvetrain or headgasket.
I would have to say that if it was a valve train issue the problem would be constant. A bad cam or lifter would be apparent in any condition but since the popping is only under acceleration and boost pressure I still stick with a fuel pressure problem. I am not trying to be right and get a pat on the back. I would like to see the resolution to the problem so we can all learn. I know that when I turned down my fuel pressure below 38lbs my car would stumble & pop as if there was a miss in the engine. I could not believe what a difference fuel pressure made to the engine!!!! The turbo would boost as if there was nothing wrong and if I did not turn down the pressure my self I would have bet my house that it was an electrical issue like a bad plug wire or coil pack problem. I would not think that a blown head gasket would cause a popping type problem but I would say that it could cause the hard starting. Checking compression is easy enough to do so it would not be a painful exercise to check compression & it is always nice to know how healthy the engine is. I hope you find the problem and post what it was so we can all learn. The battery cable problem that getchasum mentioned seems possible too, & to change both the positive & negative cables would not hurt either. Kirban's sells reproduction cables that are perfect replication of the original GM cables made for our cars. Keep us posted & good luck
FINALLY!!!...the "exciting" conclusion....
let me just say I'm sorry I took so long to post a conclusion to this thread, but I just haven't had hardly any time to work on my Buick for several months now. *HOWEVER*.....it's finally fixed!!!!!! :biggrin: :biggrin: :biggrin:
My bizzare and irratic symptoms were caused by two problems:
1. Bad coil module
2. broken/damaged spark timing signal wire at the coil module plug
The whole thing started with the car dying and not restarting while in traffic. This was due to the thermal failure of the original 20-year old coil module. After weeks of frustrating attempts to diagnose this problem I finally decided to replace the module. The very next day I noticed it wasn't dying in traffic anymore, but it was popping under boost.
Welll....*apparently* when I replaced the module, I "disturbed" the damaged spark timing signal wire. It had been spliced into at some point and then very poorly repaired. (Thanks previous owner! )
As far as I can tell, when the engine was under boost, the engine would torque over and push or pull or move the wire harness going to the coil module and momentarily break the connection causing the module to loose the timing signal from the ECM. It would misfire and "un-torque" and restore the connection then resume normal firing briefly and re-torque and pull move the wire again and loose the signal again. The process repeated in a fraction of a second and would continue as long as I left my foot in the gas. The problem would go away if I disconnected the wastegate, but I'm guessing that's because the engine wasn't making enough torque to torqe over in the engine mounts without the boost.
The bottom line is, I had tried two different coil modules and three different coil packs and the problem wouldn't go away. I actually found the damaged wire accidently when I was groping around in the dark looking for the power lead that goes to the underhood light. I usually leave this wire disconnected since I almost always leave the hood open when the car is at home in the garage. The engine was running and I was groping around the back of the engine. I wiggled a vacume line and the engine died. I was pretty sure I was on to something at that point. It turns out, the vacume line was what was pushing on the damaged wire. As soon as I found the damaged portion of the wire and cleaned up the connection and spliced it back together properly. I took it for a test drive and VOILA!!!! no more popping!!! :biggrin: :biggrin:
I have since put about 150 miles on it and I've been pounding the snot out of it and it hasn't missed a beat! WOOOO-HOOOOOO!!!
I'd also like to say THANK YOU to all the guys that took the time to respond to this thread. That's what make this board great!
Rob
let me just say I'm sorry I took so long to post a conclusion to this thread, but I just haven't had hardly any time to work on my Buick for several months now. *HOWEVER*.....it's finally fixed!!!!!! :biggrin: :biggrin: :biggrin:
My bizzare and irratic symptoms were caused by two problems:
1. Bad coil module
2. broken/damaged spark timing signal wire at the coil module plug
The whole thing started with the car dying and not restarting while in traffic. This was due to the thermal failure of the original 20-year old coil module. After weeks of frustrating attempts to diagnose this problem I finally decided to replace the module. The very next day I noticed it wasn't dying in traffic anymore, but it was popping under boost.
Welll....*apparently* when I replaced the module, I "disturbed" the damaged spark timing signal wire. It had been spliced into at some point and then very poorly repaired. (Thanks previous owner!
) As far as I can tell, when the engine was under boost, the engine would torque over and push or pull or move the wire harness going to the coil module and momentarily break the connection causing the module to loose the timing signal from the ECM. It would misfire and "un-torque" and restore the connection then resume normal firing briefly and re-torque and pull move the wire again and loose the signal again. The process repeated in a fraction of a second and would continue as long as I left my foot in the gas. The problem would go away if I disconnected the wastegate, but I'm guessing that's because the engine wasn't making enough torque to torqe over in the engine mounts without the boost.
The bottom line is, I had tried two different coil modules and three different coil packs and the problem wouldn't go away. I actually found the damaged wire accidently when I was groping around in the dark looking for the power lead that goes to the underhood light. I usually leave this wire disconnected since I almost always leave the hood open when the car is at home in the garage. The engine was running and I was groping around the back of the engine. I wiggled a vacume line and the engine died.
I was pretty sure I was on to something at that point. It turns out, the vacume line was what was pushing on the damaged wire. As soon as I found the damaged portion of the wire and cleaned up the connection and spliced it back together properly. I took it for a test drive and VOILA!!!! no more popping!!! :biggrin: :biggrin: I have since put about 150 miles on it and I've been pounding the snot out of it and it hasn't missed a beat! WOOOO-HOOOOOO!!!
I'd also like to say THANK YOU to all the guys that took the time to respond to this thread. That's what make this board great!
Rob
PowerKraus
New Member
- Joined
- Sep 4, 2006
Also do a quick check on your spark plug gap. If the gap is too wide, you'll get popping under boost. You may want to pull the plugs and check and/or just narrow up the gap and see if some of the popping goes away. Try something narrow like .030 or .028.
Good luck
Good luck
FINALLY!!! Somebody asked about plugs and gap. I was going to jump in with it this morning, but you beat me to it.
onefastcar
mono e mono
- Joined
- Oct 5, 2005
Seeing you have a ttop car i would pull ecm connectors and look at them if ya see corrosion clean it out with electronic cleaner and then use a paper clip and run it through each connetion to make sure the spring loaded connectors are good these are in the middle if ya want to really look at them you can pull the clips off and look at each one, my t-top when i first got my car was leaking water at that area and causing all sorts of issues, good luck.
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