Loss of Power

[Charlie Smith]

1998 Camry 2.2L 5SEFE. Intermittently losing power when accelerating at low speed. No code triggered. After 2 minutes, car backfires, then normal acceleration Any ideas?? scan tool data frame 6and 7

MIL STATUS OFF
ABSLT TPS % 28.2
ENG SPEED RPM 1222
CALC LOAD % 94.9
MAP KPA 95
COOLANT F 170
IAT F 80
IGN ADVANCE DE 1.0
ST FTRM1 % -14.5
LT FTRM1 % -25.6
VEH SPEED MPH 6
FUEL SYS 1 CLSD
FUEL SYS 2 N/A
O2S11 V 0.670
ST FTRM11 % -14.7
O2S12($10) ---
OBD2 STAT CA
Frame 6 Time 20.7
MIL STATUS OFF
ABSLT TPS % 26.2
ENG SPEED RPM 435
CALC LOAD % 98.8
MAP KPA 98
COOLANT F 170
IAT F 80
IGN ADVANCE DE -1.1
ST FTRM1 % -21.7
LT FTRM1 % 3.9
VEH SPEED MPH 6
FUEL SYS 1 CLSD
FUEL SYS 2 N/A
O2S11 V 0.670
ST FTRM11 % -18.6
O2S12($10) ---
OBD2 STAT CA
Frame 7 Time 24.1

[fenixus]

have you checked the pending codes? they tend to disappear after engine has been shut down, so you may need to replicate the issue again and then scan it at idle for codes, see the pending ones.

next time wait until car is fully warmed up, your coolant temperature sensor shows only 170F, that is below operating temperature when warmed up (should be at least 185F normally). if that temperature never goes any higher you may have a faulty ECT for EFI sensor.

Ignition Timing Advance looks odd, like it was completely retarded, but maybe this value is something else (IGN ADVANCE DE) because in second frame it's negative?

also fuel trims (first frame) suggest running very RICH at 1.2k rpm, but then I see you kept your foot at almost same position on gas pedal and RPM reported is only 435 (is that when it backfired and choked?) ? that was when total fuel trim (ST+LT) was still showing running RICH and oxygen sensor reading confirms it.

make sure there is no restriction in air flow, clean the Throttle plate's edges (maybe it's sticking) and IAC valve, make sure you have a clean air filter in there (no ice, dirt or leafs).

[camry6]

Originally Posted by fenixus

have you checked the pending codes? they tend to disappear after engine has been shut down, so you may need to replicate the issue again and then scan it at idle for codes, see the pending ones.

next time wait until car is fully warmed up, your coolant temperature sensor shows only 170F, that is below operating temperature when warmed up (should be at least 185F normally). if that temperature never goes any higher you may have a faulty ECT for EFI sensor.

Ignition Timing Advance looks odd, like it was completely retarded, but maybe this value is something else (IGN ADVANCE DE) because in second frame it's negative?

also fuel trims (first frame) suggest running very RICH at 1.2k rpm, but then I see you kept your foot at almost same position on gas pedal and RPM reported is only 435 (is that when it backfired and choked?) ? that was when total fuel trim (ST+LT) was still showing running RICH and oxygen sensor reading confirms it.

make sure there is no restriction in air flow, clean the Throttle plate's edges (maybe it's sticking) and IAC valve, make sure you have a clean air filter in there (no ice, dirt or leafs).

I was thinking the same things as I was reading down through the data. The engine temp does look odd. The ignition timing is really retarded, and yea, what's up with the negative advance? it looks to be firing after TDC!!! this would certainly cause loss of power (normal should be somewhere around 25 deg. advanced???) As for the 435 RPM, it must have been dying out........if not, then could there be something wrong in the tach circuit?...................OR worse, is the ECM loosing its mind?? The calculated engine load looks really high 94.9% @ 1222 RPM @ 6 MPH???.....could be a bad calculation due to the low ignition advance.....?

[fenixus]

exactly. I don't know exactly how ECU calculates the load but that high number might just be based on wrong input data caused by other trouble, fooling the ECU ... or ECU is going south - but that should be last option in troubleshooting.

Timing belt alignment to marks should be checked also.

[camry6]

Diddo!