Thread: 04 GTP Surging and P0172

Helping my brother out here.

Last year we did headers, intake and a pulley and a tune from pcmforless. Since the install it sometimes surges at 2100ish RPM usually in 4th gear at about 55mph.

It has a code P0172 not sure if it is related. So far I have checked for exhaust leaks and intake leaks and couldn't find any. Plug wires look good.

Car runs pulls great just has this extremely annoying surge sometimes. At this point we are lost.

p0172 is system too rich. check the front o2, maybe replace that...but that doesn't sound like it would cause the surging. any way he could use the stock pcm and see if that changes the surging? could be in the tune...i've never heard of pcmforless.

1. did you check the plugs?
2. did you check for vac leaks?
3.what size pulley did you put on?
4. is this at WOT or just while cruising?

1. Haven't checked the plugs yet.
2. How should I check for vac leaks. I do have a mity vac
3. 3.6" pulley
4. Only happens when cruising typically around 2100 rpm and holding your speed steady.

id bet the farm its the plugs...especially if they are stock and its been a while since theyve been changed...

and just take some window wash or something and spray it on the vac lines then look for bubbles...

vac leak, spray some carb cleaner around the vac lines at a idle and see if the idle surges. soap you need to see, carb cleaner you can hear it.

Originally Posted by scottydoggs

vac leak, spray some carb cleaner around the vac lines at a idle and see if the idle surges. soap you need to see, carb cleaner you can hear it.

thnx forgot about that^^^^^

Plugs were brand new last year. Will check for vac leaks.

Its the 02. Mine did the same thing after I got my tune. Mimics a vac leak cuz I chased it for a month. Plugs were all fine. Its the 02. Ill say it again its the 02

Any way to test the O2's ? Would it be possible to unplug one of the O2's and see the they symptoms go away? Or even swap them?

only way to do it is a swap...just do the front not the rear..

Here's what I did. Bought a ****ty bosch for like 80 bucks...pluggged it in and it went away. Returned the bosch and bought a delco