IHADAV8.com - Turbo Buick Tech, and Nonsense
Tech Area => General Buick Tech => Topic started by: shmed on August 14 2015, 11:37:15 AM
-
Ok heres a stumper lol the boys car 4.1 pulls great at first...
what i mean start it up let it get up to temps go out make a couple 3-4 wot blasts zero knock 800 o2s 18 psi 91 oct chip TT
ook go get fuel drive another say 5 mins pull of to the side road stop.. floor it just as the boost starts to come on pop pop pop ok zero on knock gauge
try again this time stop an slowly roll into full throttle same thing 1st ok hits 2nd starts to come into boost pop pop pop?? think the wide band was reading 12ish when it happened zero knock again,
this only seems to happen after its been driving for a little while
he's running 62 62 bb turbo 3 " dp 50 lb ins hot wired an racetronix pump stock convertor can't recall the cam
anyideas
-
Need more info. But I would start with the coil and change out the spark plugs since they are fairly cheap.
-
The stock IC may be getting heat soaked after a run. 18 PSI on 91...would be pushing it...at least to me. Popping going INTO boost...is the fuel pressure rising with boost? A PL log would be extremely helpful. As Forzfed says...ohm the coils out...and fresh correct plugs if they aren't already in.
-
forgot to mention he's running a eastern front mount,
sorry all we have is a scan master an a wideband
ill swap out the coil pack an module i have a brand new new I've been keeping for my car
we swapped out the plugs new ac 43s gapped at a tight 30
-
Run a brand new hose from the turbo to the wastegate and zip tie or safety wire the hell out of it.
-
Do like Earl says...and use reinforced vacuum hose. Here's yours truly...being stupid...using regular vacuum hose between the port and the wastegate. The hose collapsed. Plug your ears boys and girls. I never did find the head gaskets...and the boost spiked so high it twisted the drivers side head. And this is the number one reason I use graphite head gaskets. They act like a fuse if something horribly goes wrong. Headgaskets are cheaper than replacing a rotating assembly.
https://www.youtube.com/watch?v=ZHtT8SfMXC4 (https://www.youtube.com/watch?v=ZHtT8SfMXC4)
-
I know for a fact that a leaky wastegate signal can overboost so fast, it can cause popping and backfireing WITHOUT showing on a boost gauge.
That's the first thing to change anytime you're chasing an odd potentially boost related issue. You just can't tune around a leaky wastegate circuit.
-
ok homed the coil pack got 11.6 on the first 2 then no reading on the last four?
so changed coil cack checked it 11.6 on all 6
went for a ride pop pop pop
so off to the store for some hd hose an gonna try earls idea
fingers crossed
-
Might want to check your meter too. If you have two pairs of coils reading open, you should have been running on two cylinders. The car should have sounded like a 2 cylinder riding mower.
-
Bad module is my guess
Sent from my LG-H810 using Tapatalk
-
update on popcorn machine...
ok new module, coil pack, msd wires an plugs. still popping.
new vac line from turbo to waste gate actuator, i bypassed the boost solenoid, still popping.
turned down the boost as low as the hd actuator will allow I'm hitting about 16-17. still pop pop pop
tried different maf ran worse an still pop
could this be a sign of the flat tappet cam going south?
going to try to install the oem actuator an lower the boost even more hoping its just boost or octane related, yes i should drain the tank but its almost full
any other ideas
-
and the fuel pressure is behaving properly?
-
Still waiting to know if your fuel pressure is rising 1 for 1 with boost. Can you post your SM numbers with the engine warmed up.
-
yes fuel is running up along with the boost
are there any sm numbers in particular or you just want a warmed up idle number?
-
Give us da' works...tho I'm curious what the BLM's are. :) CC's moving around okay?
-
Give a thorough check of the up pipe hoses/clamps. I think Brian Harper here in town had the same problem...and going to T bolt clamps on the up pipe hoses solved it. Was drawing air in under boost...making it sputter/pop.
-
Under boost a leaky uppipe would vent, not suck.
-
Under boost a leaky uppipe would vent, not suck.
Suck...vent... whatever. It'll pop. :) He was getting so pissed off with the car he was ready to part it out. :icon_eyes:
Now...here's a question for everyone. If the exhaust cam lobe was going south...could the air/fuel mixture get forced out the intake valve...cuz it can't get out the exhaust...maki ng it pop?
-
give us the o2s when it is popping
-
Under boost a leaky uppipe would vent, not suck.
Suck...vent... whatever. It'll pop. :) He was getting so pissed off with the car he was ready to part it out. :icon_eyes:
Now...here's a question for everyone. If the exhaust cam lobe was going south...could the air/fuel mixture get forced out the intake valve...cuz it can't get out the exhaust...maki ng it pop?
It would depend on what cylinder during the event. More than likely the exhaust heat and pressure would overcome the vacuum with the intake valve open, and to what extent the intake valve is open. Nightmaring back to the carburetor days, if we dealt with a car backfiring (popping) through the carb, (in this case I figure intake plenum?) it was a timing issue (dist. cap included) or a lean misfire. So let's throw a turbo at it and lean becomes a whole other issue, like Earl said: wastegate performance. Just a thought.
-
Venting .vs sucking is more than trivial in a MAF setup. Sucking raw air will introduce unmetered oxygen into the mix with can result in a lean misfire. Venting from a boost leak will just waste performance.