Car intermittently cuts off engine power

[LegendaryOG]

Hey fellow members. I've been having an issue with my GS for a few weeks now, ever since a trip back to NY from NC. As I was cruising thru the interstate at 75, I wanted to pass a slower vehicle in my lane as well as give room from another one next to me, so I gave it some gas and as I did that, I felt like either gas or spark just cut off for 2 seconds, then came back followed by a CEL. I found that unusual and stopped at the next service station to fill up from 1/2 tank and jumped the service connector, which brought up code 2, right O2 sensor. I shut the car off, and after 30 minutes continued my trip. CEL did not return and the car drove normal again. About a week later, when I started my car in the morning (<30 degree weather) it took a few turnovers to finally start, running rough and the CEL came on, gave me codes 6, 14, and 2, but I never reset the ECU so that one might have been from before. After the engined ran for a few, I turned it off and restarted, CEL off and idling fine. Next day same thing. After a few days, I noticed loss of power, as well as cutting out at anywhere from 3500rpms on, if i press the throttle more, sometimes I hear a backfire but still rpms drop, and if I put in neutral and rev it, will limit way below redline, at different revs, sometimes will cut at 5000, cut out til it reaches 2500, come back up and either rev a little more, or less than before and repeat it, but will not reach redline. Any ideas? Sorry for the long post.

[LegendaryOG]

Forgot to mention, saturday it was losing power whenever I needed to accelerate, no matter where in the rpm band I was. It also died on me twice, once while cruising and another after I exited the parkway. Both times the car did not want to start up for a while, the first time I kinda banged the dash to see if the Main Relay was the culprit, and it started, the second time didnt have the same luck but when I pressed the throttle a bit it came back to life. I'm really scratching my head bald with this one.

[holyabish1]

Try searching each code available on the wiki link below:

http://www.acuralegendwiki.org/index...nd_Definitions

IACV could be a culprit, but it also sounds like a fuel filter issue, so dunno.

[LegendaryOG]

Alright, I cleared the ecu codes and drove it around for a bit until I started feeling the power loss again. Every time I gave it gas it stuttered for a second then got power back n started jerking as it was on n off. I mainly noticed this happens most as the car takes turns, tcs and ABS are both inactive, and there are backfires, sound like cylinders fill with fuel and spark cutting off or not being able to ignite the fuel. After a few minutes of pushing it the cell came on for right O2 again. I drove back homewithout shutting car off, problem still existing and rechecked codes, which also gave me left O2. Before resetting the ecu I was troubleshooting by disconnecting coils, tps, iacv, O2s, until I came upon the map sensor, which gave me a similar symptom, will tach out at 4000, backfire now and then, and the exhaust tone changed to a more "throaty" sound, as if fuel mixture changed. Could that be the culprit? Also, my tcs light comes on every once in a while when I start the car, and gives me a pgm-fi code. Its happened way before this, but could have noticed the problem before it actually became a true issue

[Wes]

Well the car's self diagnosis system is there for a reason. It's working and you're reading the codes. You don't have a chipped ECU do you? I'd like to rule that out also.

I would check the connectors on the O2 sensor to make sure they are connected. And then maybe check the voltage on them. Your symptoms sound pretty extreme for the O2 sensors being out, but I'm not going to second guess the computer. If you've reset the ECU and the only codes that keep coming up with the problem are O2 related, I would start by putting some fresh ones in.

[Quaraxkad]

Originally Posted by LegendaryOG

I came upon the map sensor, which gave me a similar symptom, will tach out at 4000

That doesn't mean there's anythong wrong with the MAP sensor, but you did put the ECU into "limp mode" which keeps the car under 4k RPMs and ignores feedback from pretty much every sensor in the car and uses default values.


Just before the original problem began, had you done any work or maintenance on the car? What did you find while unplugging the coilpacks? Did unplugging each of them make the idle a little rougher? Have you followed the troubleshooting steps in the service manual for any and all codes you are getting? All of the CEL code troubleshooting flowcharts are available online in the wiki page linked above (LegendWiki - G2: FAQ: Error Codes And Definitions). Here's the flowchart for CELs 1 and 2: LegendWiki - G2: FAQ: Error Codes: CEL 1, CEL 2 (it basically just tells you to do the tests for 43/44: LegendWiki - G2: FAQ: Error Codes: CEL 43, CEL 44).

[LegendaryOG]

Thanks guys. My ecu isn't chipped, I was also thinking the O2s but wanted to get others opinions, like maybe another problem causing the O2 to give error codes. The symptoms do seem extreme to me also, especially it happening mainly on turns. I'll diagnose them in a bit to be sure.

Another question, shouldn't the engine stall when I remove either the map or tps? My car doesn't unless I remove both, I noticed a friends L did when I had unplugged her tps.

[Chrispy]

Originally Posted by LegendaryOG

Thanks guys. My ecu isn't chipped, I was also thinking the O2s but wanted to get others opinions, like maybe another problem causing the O2 to give error codes. The symptoms do seem extreme to me also, especially it happening mainly on turns. I'll diagnose them in a bit to be sure.

Another question, shouldn't the engine stall when I remove either the map or tps? My car doesn't unless I remove both, I noticed a friends L did when I had unplugged her tps.

That would lead me to beleive it was fuel pump or main relay related. At what level is your gas tank when this happens? Is it below 1/2? Below 1/4?

[LegendaryOG]

Originally Posted by Quaraxkad

That doesn't mean there's anythong wrong with the MAP sensor, but you did put the ECU into "limp mode" which keeps the car under 4k RPMs and ignores feedback from pretty much every sensor in the car and uses default values.


Just before the original problem began, had you done any work or maintenance on the car? What did you find while unplugging the coilpacks? Did unplugging each of them make the idle a little rougher? Have you followed the troubleshooting steps in the service manual for any and all codes you are getting? All of the CEL code troubleshooting flowcharts are available online in the wiki page linked above (LegendWiki - G2: FAQ: Error Codes And Definitions). Here's the flowchart for CELs 1 and 2: LegendWiki - G2: FAQ: Error Codes: CEL 1, CEL 2 (it basically just tells you to do the tests for 43/44: LegendWiki - G2: FAQ: Error Codes: CEL 43, CEL 44).

Before taking the trip to NC, I had done oil change, coolant flush as well as bleed all air out, and the upper ball joints up front. The car was fine driving down and the few days I stayed, the first symptom started halfway back home but went away after I stopped for a bit.

[LegendaryOG]

Originally Posted by Chrispy

That would lead me to beleive it was fuel pump or main relay related. At what level is your gas tank when this happens? Is it below 1/2? Below 1/4?

At first I thought it was happening when the car reached 1/2 or below, but Saturday I had over 3/4 and was still doing it