Engine Performance problem
2005 Buick Terraza 6 cyl Front Wheel Drive Automatic 128000 miles
My 2005 Buick Terraza starts of in the morning. After it has run for only a few minutes and warmed slightly you can shut it off and when you try to crank it will start, run a couple of seconds, and die. The only way to get it to idle is to press on the accelerator slightly until the rpm's is sufficient. Then you can let off the accelerator and it idles. The other problem is the van has lost highway power and the gas mileage has gone down. I have used a scan tool. No codes are present or pending. The scan tool did say the EGR, o2, and catal mon were inc. Not sure what the tool is telling me. I have also checked the fuel pump pressure. When the key is first turned on it goes to 62 psi then drops back to around 58 psi. While running the pressure is about 56 psi.
To give a complete diagnosis please post codes in P0xxx. Also any recent repairs? How many miles since last tune?
Let me know
Thanks for donate
July, 31, 2010 AT 11:18 AM
There are not any codes stored in the PCM and the service engine light is not on. Spark plugs and wires are original. Engine does not act as if there is a misfire. Also when engine is idling and you try to rev the engine up there is a hesitaion and the max engine speed in park is 3300 rpm. This seems to be a little low. Thanks for your quick response. I don't know if this is appropriate but if you would like you can call me 270-875-3182. If not I understand. Thanks again
July, 31, 2010 AT 11:40 AM
Possible causes intake manifold gasket leaking or EGR pintle not seating. Would consider new plugs 128K a lot of miles also fuel filter ever replaced air filter? Another thing CAT maybe particaly blocked put vacuum guage on intake port idle vacuum 15-20 inch reise engine RPM up to 2000 does gague fall?
July, 31, 2010 AT 1:47 PM
Air filter has been replaced. I can replace plugs but what keeps coming back to my mind is that there are no codes tripped. If it was a cylinder issue I would think there would be a misfire code or something. I did hook a vacuum gauge to the intake, at idle about 17" -18", but when the engine is revved up the gauge drops as it should but after a couple of seconds as the engine levels off at a speed of say 2000 rpm's the vacuum gauge go back up to 20" or more. It goes up higher than idle levels at 3000 rpm's also. Could this be a TPS?
July, 31, 2010 AT 1:50 PM
I forgot, fuel filter is built onto the fuel pump on this model. But again there is 56-60 psi of pressure.
July, 31, 2010 AT 3:04 PM
No TPS has TAC system cabeless throttle. One thing that can cut engine power is the MAF get some MAF cleaner and clean. see diagram
Believe getting to point where needs to be diagnosed by a diagnostic scann tool such as MODIS
August, 8, 2010 AT 7:47 PM
FYI, Did install plugs, air filter was not as good as I thought so changed, this helped problem maybe 30%, took van to local independent shop, they cleaned MAF & TB, also did fuel induction service. Don't know if problem was corrected w/o induction service or not. Only a few dollars more and I wanted the problem fixed and it is. Thanks for you help. Kenny
August, 9, 2010 AT 12:52 PM
That is great news sometimes maintence can be the cure. You saved $$ by DIY if you just took it in and said fix it you woul; d have needed a GOV bail out.