Itali83
1/2 ton status
Ok here it goes... I own an 86 oldsmobile cutlass supreme with the 307 v-8 and 4bbl E4MC carb on it and an auto. I drove the car from maine to nashville where i"m going to school. The car has a habbit of pinging when under a load and it's driving me nuts + it's not good for the motor. This is the list of what I've done to it to try and rectify the pinging.
TPS was bad so that has been replaced.
O2 sensor was dead so I replaced that
MAP sensor was iffy so I changed that
Full tune up including, rotor,cap, wires, plugs.
Timing was set at factory spec and double checked many times.
These are the things I've checked to make sure are working.
EGR. It is operating properly and I can feel it open with my fingers. EGR passages are also not blocked because if I open the valve at idle, it will kill motor.
I've put a snap on scan tool on it many times and there are no codes present, and all of the sensors look in check and nothing out of order. Temp sensor is reading correctly as well as the new TPS, MAP, and others.
I put a dwell meter on the mixture control soleniod, and when in closed loop, it's varying between 30-40 degrees which is text book perfect, if I hit the gas quick, it goes down to 6 degrees, followed by almost 56 degrees and then back to 30-40 degrees.
As for the pinging here are the symptons... driving around anywhere in 2nd gear or higher, any hill I come to it'll start pinging, or clacking I should say, but it's only at a certain throttle position, if I put my foot more into it it'll go away. If I put it in drive and power brake it without spinning the tires, it'll clack. I had my friend stick his head under the hood and it sounded like the clack was only coming from the drivers side bank, or it was definitly louder on that side.
The only thing I'm thinking it can be is the computer is not taking control of timing (does not have vacuum advance). But if the computer is leaving the timing at the base (20degrees BTDC) I would think that it would run like a total piece of junk and probably clack a lot more than it does.
I run regular gas in it, but I've also run two tanks of super with two bottles of 104+ octane boost with no change in clacking.
I've pulled the plugs and they are white with no black oil or carbon on it. Clean burning plugs if you ask me.
I'm totally stumped on what the F@ck is wrong with the car. I don't feel like burning any pistons up and I need this car for another 6 months and a 1300 mile road trip back to maine. I really want to have it stop pinging/clacking. If anyone has any ideas or ways to test stuff, or personal experiences or anything please help me out. Thank you very very much for reading it all and for the info. Thanks
Ben 87 Jimmy + 89 Blazer
/forums/images/graemlins/usaflag.gif
Update. I've now used a timing light and found out that the computer is taking control of the timing, it's not stuck at base timing.
Now I'm wondering if from the factory they had a problem with pinging, after enough were found with this problem, they sent out a service bulletin saying that the factory prom is know for this and they came out with a new prom to rectify it, and my car never got that prom. I'm going to do a cross reference on my Prom number to see if it's been superceeded for that reason.
If anyone has more ideas, please let me hear them and thanks a bunch in advance!!!!
TPS was bad so that has been replaced.
O2 sensor was dead so I replaced that
MAP sensor was iffy so I changed that
Full tune up including, rotor,cap, wires, plugs.
Timing was set at factory spec and double checked many times.
These are the things I've checked to make sure are working.
EGR. It is operating properly and I can feel it open with my fingers. EGR passages are also not blocked because if I open the valve at idle, it will kill motor.
I've put a snap on scan tool on it many times and there are no codes present, and all of the sensors look in check and nothing out of order. Temp sensor is reading correctly as well as the new TPS, MAP, and others.
I put a dwell meter on the mixture control soleniod, and when in closed loop, it's varying between 30-40 degrees which is text book perfect, if I hit the gas quick, it goes down to 6 degrees, followed by almost 56 degrees and then back to 30-40 degrees.
As for the pinging here are the symptons... driving around anywhere in 2nd gear or higher, any hill I come to it'll start pinging, or clacking I should say, but it's only at a certain throttle position, if I put my foot more into it it'll go away. If I put it in drive and power brake it without spinning the tires, it'll clack. I had my friend stick his head under the hood and it sounded like the clack was only coming from the drivers side bank, or it was definitly louder on that side.
The only thing I'm thinking it can be is the computer is not taking control of timing (does not have vacuum advance). But if the computer is leaving the timing at the base (20degrees BTDC) I would think that it would run like a total piece of junk and probably clack a lot more than it does.
I run regular gas in it, but I've also run two tanks of super with two bottles of 104+ octane boost with no change in clacking.
I've pulled the plugs and they are white with no black oil or carbon on it. Clean burning plugs if you ask me.
I'm totally stumped on what the F@ck is wrong with the car. I don't feel like burning any pistons up and I need this car for another 6 months and a 1300 mile road trip back to maine. I really want to have it stop pinging/clacking. If anyone has any ideas or ways to test stuff, or personal experiences or anything please help me out. Thank you very very much for reading it all and for the info. Thanks
Ben 87 Jimmy + 89 Blazer
/forums/images/graemlins/usaflag.gif
Update. I've now used a timing light and found out that the computer is taking control of the timing, it's not stuck at base timing.
Now I'm wondering if from the factory they had a problem with pinging, after enough were found with this problem, they sent out a service bulletin saying that the factory prom is know for this and they came out with a new prom to rectify it, and my car never got that prom. I'm going to do a cross reference on my Prom number to see if it's been superceeded for that reason.
If anyone has more ideas, please let me hear them and thanks a bunch in advance!!!!
