2000 prizm P0171 code

[flynlow3]

I have a 2000 prizm that i installed an 05 pontiac vibe motor in. I swapped over the manifolds/sensors ect. I replaced the motor due to oil consumption. When I started the car with the new engine, I threw a P0171 code. I cleaned the MAF sensor and the car seemed to run much better. I still have better throttle responds up to 50% acceleration but the car seems to bog at full throttle. I replaced the Oxygen sensor twice with no luck on the code. It intermittenly goes off and comes right back on. The only unusal things the car is doing is the throttle responds seems bogged down anywhere beyond mid throttle. I have better acceleration mid throttle than i do full throttle. My gas mileage is in the twenty's MPG when it was up around 34.

Any ideas?

Thanks!

Also, The car has all new NGK iridium spark plugs. The fuel injectors are the originals with 122k miles on them. I sprayed carb cleaner around the engine bay and did not spike any idle.

[fishexpo101]

The lower than expected fuel economy could be showing an ignition issue, fuel injection issue, or bad O2 sensor. What O2 sensor did you use, was it the OEM type or universal?

Possible that one or more of the injectors are sticking, have you pulled the plugs to see what they look like? Verified the plug gap on the iridium plugs (they "should" be gapped from the factory, must it doesn't hurt to check - just make sure you don't chip the electrode in the process).

Issue with the VVTi system is another possibility - though that generally will not run a lean code unless the VVTi system is fubar. Also note that the cam profile is slightly changed in the 9th gen Corolla engines from the original cam in the 8th gen Corolla/Prism. Shouldn't be enough to cause problems, but some ECMs can be picker than others. Could also be a "relearn" phase for the ECM, could take a few start/stop cycles to see if it works like it should.

Missing chassis ground points, loose or dirty connectors, etc. - could be a number of possible culprits. If you stick with fuel, ignition, and timing - should be able to narrow this down pretty quickly.

[flynlow3]

Question about vvti...This is based of the weight of oil you use correct? I am running mobil 1 15k mile extended performance with a lucas oil additive which runs thicker. Could the thicker addititve be throwing off the VVTi?

I had an OEM one to start with and I ran a Bosch direct replacement. No splicing needed. code did not go away so i picked one up from a guy off ebay who did not use it. Unsure what brand but it to was a direct plug in purchased for 98-02 corolla. The o2 sensor head was slightly smaller than the original one I removed. The bosch o2 sensor had a different head style but it fit.

I did not have to splice either sensor. They were all 4 wire direct plug in units.

I am thinking I have a fuel issue or my timing is off due to oil?

[flynlow3]

When i swapped motors, I used my original gasket. It is a metal one. I was going to get a new one but no one had them in stock. I sprayed carb cleaner around the intake with no rise in rpms but could this still be my issue with bank 1 running lean and getting terrible fuel economy?

[sam333]

The thicker oil won't make a difference in the way the VVTI works. Why are you using lucas? How many miles on the vibe engine? Have you done a compression test on the new engine? Using a non denso sensor will make a difference. You are getting milage in the 20's , are you mashing the throttle down at every start to "test " the new engine? Did you replace the injector o-rings? Did you replace the exhaust doughnut? Really none of the gaskets or o-rings should be used again for obvious reasons.

[hardtopte72]

Never use Lucas in new engines. It has been shown time and time again the aerate the oil which can cause a mess of problems. When you replaced the engine did you use a new intake manifold gasket or a used one. This can definitely cause a vacuum leak and lean condition. Carb cleaner is not always the best indicator of a vacuum leak. The Maf might be failed as well as one of your vsvs on the airbox. All of these and even a brake booster can cause lean conditions. I would start with the Maf and vsv. And of course changing out that Lucas before you destroy your engine. Run a good quality oil like Mobil 1 or equivalent and you should be good. Also if you didn't already you should have replaced every seal and gasket when the engine was out. This included the front and rear main seals. Front pump deal on trans. Axle seals, intake and exhaust gaskets. Valve cover gasket and so on.

[fishexpo101]

Originally Posted by flynlow3

Question about vvti...This is based of the weight of oil you use correct? I am running mobil 1 15k mile extended performance with a lucas oil additive which runs thicker. Could the thicker addititve be throwing off the VVTi?

I had an OEM one to start with and I ran a Bosch direct replacement. No splicing needed. code did not go away so i picked one up from a guy off ebay who did not use it. Unsure what brand but it to was a direct plug in purchased for 98-02 corolla. The o2 sensor head was slightly smaller than the original one I removed. The bosch o2 sensor had a different head style but it fit.

I did not have to splice either sensor. They were all 4 wire direct plug in units.

I am thinking I have a fuel issue or my timing is off due to oil?

As mentioned in the other post - definitely use a Denso O2 sensor. The small difference in price is well worth the reduction in headaches trying to debug any fuel/fire issue.

VVTi is pretty sensitive to the oil you are running. There is a oil filter associated with the OCV (Oil Control Valve) that can get clogged with particulates and sludge. If that filter is plugged, you can have a lean run condition and/or poor fuel economy.

Personally, not a big fan of Lucas products - maybe they changed the formulation, but they have shown no improvements in performance in almost any engine I've run them in. If you wanted to clean up the donor motor - I would have run a couple of quick oil changes with a good detergent/dispersant motor oil and then settled onto a quality convention or synthetic motor oil.

Additives can cause all sorts of headaches - especially if you are trying to diagnose something at the same time. Some can cause engine leaks, poor oil pressure, too much oil pressure, starve bearings for oil, loosen too much gunk in the engine, and/or foul sensors/sparkplugs.

It does sounds like you have a fuel / fire issue. Vacuum leak could still be a possibility. Damaged wiring from the swap is another.

[flynlow3]

My check engine light disappeared today. I purchased a new intake manifold gasket for it and had it swapped out in 30 min. I also changed my oil and am running straight 5w30 synthetic.

I just put 50 miles on my car with no light and the gas gauge has not moved!

I was not accelerating heavily on it to get the 28mpg. Just a combination of dirty maf sensor, bad o2 sensor from carbon build up from old motor oil burning situation, and a leaking intake manifold gasket...I think the manifold gasket caused the lean code causing the ecm to dump fuel in compinsate = poor fuel economy. So far problem is fixed!

[hardtopte72]

Good to hear. It was probably most to do with the intake.