BrandonHall10
Solving problems
Alright, so I've got this car: [ http://www.grandprixforums.net/threads/97109-Grandpa-s-2001-Silver-Metalic-GTP-Now-with-P0172!/page6 ] that I'm trying to figure out.
A brief history: Did a trans swap, rad replacement, valve cover replacement, and some other minor maintenance things. Shortly thereafter it presented with a P0121 (Throttle position sensor fault) and very little boost. Also, it would hold gear way too long while accelerating. I attributed that to the TPS issue. I replaced the TPS with no change. (I can't believe I though it would be so simple as, read code, replace part. When does that ever happen?) Further investigation showed a broken/cracked vacuum boot at the MAP sensor. I replaced EVERY vacuum line on the engine and got my boost back. This also resolved the P0121 (TPS) code.
HOWEVER, after fixing the MAP vacuum line issue, it started having a pending P0172 (bank 1 rich) code. Trims have slowly been creeping down to the point where a pending P0172 became an active P0127 (between -15% and -20%). Here's what I've done so far with no resolution;
1.) Verified O2 sensor activity between 0.2v and 0.8v while oscillating the throttle watching the graph on VCM Scanner. Seems to react as quickly as it should.
2.) Cleaned the MAF, throttle body, and IAC. For grins, I also swapped the MAF with a known good unit.
3.) Briefly checked all wiring and extensively for the O2 sensor. -All good
4.) Checked fuel pressure during operation, and after key off for bleed down. -Within range (43psi)
5.) Disconnected the purge solenoid from the throttle body, and capped both sides.
Things I haven't done or plan to do in this order;
A.) Put fresh fuel in it. Unlikely that it's contaminated, but I have to rule it out. (Doesn't this typically cause a lean condition?)
B.) Swap the MAP with a known good unit. Sure it would be nice to test the "proper" way, but I don't have a hand vacuum pump. Best I can do is swap it.
C.) Swap the purge solenoid with a known good unit.
D.) Swap the front O2 with a known good unit.
E.) Say Eff it, burn 2 HPT credits and scale the cylinder gain to about 1.3125.
Anyone have any other ideas for a P0172 on one of these?
A brief history: Did a trans swap, rad replacement, valve cover replacement, and some other minor maintenance things. Shortly thereafter it presented with a P0121 (Throttle position sensor fault) and very little boost. Also, it would hold gear way too long while accelerating. I attributed that to the TPS issue. I replaced the TPS with no change. (I can't believe I though it would be so simple as, read code, replace part. When does that ever happen?) Further investigation showed a broken/cracked vacuum boot at the MAP sensor. I replaced EVERY vacuum line on the engine and got my boost back. This also resolved the P0121 (TPS) code.
HOWEVER, after fixing the MAP vacuum line issue, it started having a pending P0172 (bank 1 rich) code. Trims have slowly been creeping down to the point where a pending P0172 became an active P0127 (between -15% and -20%). Here's what I've done so far with no resolution;
1.) Verified O2 sensor activity between 0.2v and 0.8v while oscillating the throttle watching the graph on VCM Scanner. Seems to react as quickly as it should.
2.) Cleaned the MAF, throttle body, and IAC. For grins, I also swapped the MAF with a known good unit.
3.) Briefly checked all wiring and extensively for the O2 sensor. -All good
4.) Checked fuel pressure during operation, and after key off for bleed down. -Within range (43psi)
5.) Disconnected the purge solenoid from the throttle body, and capped both sides.
Things I haven't done or plan to do in this order;
A.) Put fresh fuel in it. Unlikely that it's contaminated, but I have to rule it out. (Doesn't this typically cause a lean condition?)
B.) Swap the MAP with a known good unit. Sure it would be nice to test the "proper" way, but I don't have a hand vacuum pump. Best I can do is swap it.
C.) Swap the purge solenoid with a known good unit.
D.) Swap the front O2 with a known good unit.
E.) Say Eff it, burn 2 HPT credits and scale the cylinder gain to about 1.3125.
Anyone have any other ideas for a P0172 on one of these?
