What's the point of having a GN if you can't accelerate? Its been going on for about 1 1/2 yrs. and appears to be getting steadily worse. Normal driving is fine. If I go over about 1/4 throttle the car backfires and I have to let off. Can you say Embarassing? It doesn't do it everytime. I've changed the coil, wires, ESC, ignition module, knock sensor and ECM. The EGR and solenoid are new but deleted via champion irons. Ground wires are tight and all vacuum lines new. No malfunction codes appear on the Scanmaster. Any help with this intermittent backfire is greatly appreciated. Joel
Backfires When I Accelerate
- Thread starter TurboGN
- Start date
Read this link:
http://www.turbobuick.com/forums/showthread.php?s=&threadid=86152
I think he ended up re-setting the cam sensor and his problem was gone. I had a similar problem and it was the cam sensor too. Its something to try that wont cost you anything. If you have a voltmeter then you can do it.
Cam sensor setting procedure:
http://www.gnttype.org/techarea/ecmsensors/ecmpage.html
http://www.turbobuick.com/forums/showthread.php?s=&threadid=86152
I think he ended up re-setting the cam sensor and his problem was gone. I had a similar problem and it was the cam sensor too. Its something to try that wont cost you anything. If you have a voltmeter then you can do it.
Cam sensor setting procedure:
http://www.gnttype.org/techarea/ecmsensors/ecmpage.html
UNGN, it gets no detonation, i.e., 22-24 psi with minimun O2s around 790. I believe the alky supplementation helps keep it from running out of fuel. However, 50's are on my list. I don't have direct scan so the pulse width and duty cycles are unknown. The backfires occur prior to WOT so I've eliminated static injectors from the potential problem list. Joel
BlackBandit
God loves Buicks!
- Joined
- Mar 29, 2003
Have you tried turning your boost down. I had the same problem. Fixed it with a walboro gss340 
Maybe you should quickly test your coilpack. Set your multimeter to 20K ohms and it should read between 11-13 ohms. Just connect the coils on the same pack. If it tests bad replace it. If it tests good, it could still be bad. On my car with a bad coilpack it drove fine normally and got steadly worse the longer I drove it.
Good Luck,
James
Good Luck,
James
machinegun
Active Member
- Joined
- May 25, 2001
First I would get a scan tool and record some data. This will go far in helping. I did not notice anything about your MAF sensor. Have you tried a known good one? This will also create issues like you are experiencing. Also what plugs and wires are you running? Let us know.
Machinegun, Direct Scan and laptop are on my list. The MAF is a 3" (Impala SS) with Translator (not +). Translator is set at ON, ON, ON, OFF for the dipswitches, 3 for base and 0 for WOT. All wiring/connections have been checked and rechecked. I'm running Autolite 25's with 10mm Magnecors. Switched out the Magnecors with a new set of OEM and made no difference. I will be replacing the plugs with AC's this week although they look like new. Joel
James, I replaced the timing chain/gears with a Dynagear, the springs were installed by Tom Allen (Champion) and, yes, its driving me nuts. I will surely post the fix if I ever find it. I've been reluctant to post in the past in fear of it being something stupid. It backfired the first time in late January of 02. The setup was essentially the same as now with no components recently replaced when it happened. I've been checking and replacing everything short of new injectors, chip, and Direct Scan. I appreciate all suggestions. Joel
- Joined
- May 26, 2001
A backfire is "usually" associated with an electrical problem. If you have changed or tried different sensors and chips, it could be more difficult like crank sensor, cam sensor or balancer.
We usually start troubleshooting problems like this by driving and watching T-Link or similar for unusual occurances. Scanmaster is not sufficient to observe and obtain data.
A 1/4 throttle is not indicative of a valve train problem unless it is in initial stages of wiping a cam. Mechanical problems are usually consistant, not intermittant.
First item, change the chip and completely remove the direct scan stuff.
We usually start troubleshooting problems like this by driving and watching T-Link or similar for unusual occurances. Scanmaster is not sufficient to observe and obtain data.
A 1/4 throttle is not indicative of a valve train problem unless it is in initial stages of wiping a cam. Mechanical problems are usually consistant, not intermittant.
First item, change the chip and completely remove the direct scan stuff.
Nick, changing the chip has definitely crossed my mind but it was there long before the backfiring began so I'm reluctant. Its a RA and seems to work really well (when it doesn't backfire). I don't have direct scan and I agree that the Scanmaster is not sufficient. I'm really starting to envisage a laptop with scantool right now. I plan to check the bolts on my balancer and re-recheck the cam and crank sensors this week. Thanks, Joel
