Power, No power. Repeat. (video)
- Thread starter IwantMKIII
- Start date
Have you got the injectors flow tested? I know they come with a flow sheet, but just to rule out the possibility.
AF1JZ said:
problem 1 is this is my DD.
Problem 2 is, where the hell do i do that at and how much will it cost?? money is tight right now
ok, are you having any driveability problems, or are you thinking that there is a problem just because of your afr gauge?
some facts about regular o2 sensors:
in closed loop (note: not WOT) the o2 sensor should fluctuate between .2 and .8 volts. that is the max and min range on your narrowband gauge. in other words its fine. the stock o2 sensor can only read from like 14.65:1 to 14.75:1 afr's
ninja edit: oh yeah at WOT you should see the narrowband gauge go full rich. and on decel it should be full lean.
i really couldnt make any other assumption because it looks like you are revving the car in neutral. what does it do while driving?
some facts about regular o2 sensors:
in closed loop (note: not WOT) the o2 sensor should fluctuate between .2 and .8 volts. that is the max and min range on your narrowband gauge. in other words its fine. the stock o2 sensor can only read from like 14.65:1 to 14.75:1 afr's
ninja edit: oh yeah at WOT you should see the narrowband gauge go full rich. and on decel it should be full lean.
i really couldnt make any other assumption because it looks like you are revving the car in neutral. what does it do while driving?
MmmBoost said:
Driveability. Not just in my head by any means. very noticeable, oscillating power loss especially when engine is cold. AFR guage is my only lead as it is in sync with the power loss and availability.
i did it in neutral because it does the same thing while driving UNLESS its under full throttle in which case it reads a steady rich for obvious reasons HOWEVER i still feel the power loss, its just less noticeable. As the the AFR oscillates, so does the power
take note, while cruising on the highway at a steady speed it is not noticeable, but its when you accelerate you notice it but that is expected
My question is are you basing this on a cold start and driving it right away? Are you warming the car up and then it's fine? Some cars kinda stumble when it is dead cold and not warmed up yet.
Yeah, my car surges a bit under moderate to hard acceleration when very cold. That being said, I no longer try to run it hard till I see the temp needle starting to rise off the peg. As for the AFR's; as mentioned above, the AFR should occilate slowly at idle, and rapidly through full range at cruise, so that's looking normal.
hellraiser456 said:
i havn't checked yet, it is a new engine built by a guy who races 7m's professionally so im hoping its not that. I can't do anymore testing until i get my new IC hardpipe.
im seeing similar issues w/ my car.
im looking strongly at ignition timing issues.
at part throttle acceleration, the car "Surges". the power comes and goes as if i were peddling the throttle between 10% and 40%. the problem is, my turbo can spool at 25% throttle. i can get full boost at 2100 in 5th gear.
the car doesnt misfire one bit. i have VVTi coil packs and Denso Iridium plugs. i think my injectors are clogged since they seem to hang open and flood the motor over night. aside from that, the car runs and drives fine. if i am accelerating part throttle and its surging in and out of power, i can give it more throttle and the surging will stop. but if i shift and start out at part throttle in the next gear, it has repeated the surging process.
also, when i back off the throttle (not sure if this is related), the car bucks once or twice. i dont have a Bov so my preliminary diagnosis is that air is surging out the compressor and giving an erratic AFM signal. i can see the HZ spike when i drop throttle and get compressor surge but its not always accompanied by the bucking. it usually only bucks when i roll out of the throttle Slowly and Before the throttle plate is fully closed.
would oil leaking out of my CPS and getting on the pick-ups give me messed up timing curves at part throttle or what? im really thinkin its timing issues since timing advance is supposed to take a shit when you open the throttle up. then the timing will advance as the rpm's increase to build power as long as theres no knock. i think i caught my erratic timing advance red-handed since the power curves on my dyno sheet are uncharacteristic and i occasionally feel the car "lay down" at the top end over 5000rpm. my DSM used to do this all the time and id KNOW i was getting timing pull due to knock. the exhaust note would change, the car would stop pulling hard and itd blow black smoke out the exhaust.
im looking strongly at ignition timing issues.
at part throttle acceleration, the car "Surges". the power comes and goes as if i were peddling the throttle between 10% and 40%. the problem is, my turbo can spool at 25% throttle. i can get full boost at 2100 in 5th gear.
the car doesnt misfire one bit. i have VVTi coil packs and Denso Iridium plugs. i think my injectors are clogged since they seem to hang open and flood the motor over night. aside from that, the car runs and drives fine. if i am accelerating part throttle and its surging in and out of power, i can give it more throttle and the surging will stop. but if i shift and start out at part throttle in the next gear, it has repeated the surging process.
also, when i back off the throttle (not sure if this is related), the car bucks once or twice. i dont have a Bov so my preliminary diagnosis is that air is surging out the compressor and giving an erratic AFM signal. i can see the HZ spike when i drop throttle and get compressor surge but its not always accompanied by the bucking. it usually only bucks when i roll out of the throttle Slowly and Before the throttle plate is fully closed.
would oil leaking out of my CPS and getting on the pick-ups give me messed up timing curves at part throttle or what? im really thinkin its timing issues since timing advance is supposed to take a shit when you open the throttle up. then the timing will advance as the rpm's increase to build power as long as theres no knock. i think i caught my erratic timing advance red-handed since the power curves on my dyno sheet are uncharacteristic and i occasionally feel the car "lay down" at the top end over 5000rpm. my DSM used to do this all the time and id KNOW i was getting timing pull due to knock. the exhaust note would change, the car would stop pulling hard and itd blow black smoke out the exhaust.
Well i recently swapped my entire ignition system except the CPS with an 89 with 73000 original miles. I even traded ecu's with another '88. no changes.
HOWEVER, i have noticed something which was interesting last night. I recently bought terrible gas from sheetz. it was 92/93 and my car wouldn't even fucking idle, i was pissed cause we went through so much troubleshooting work in frigid weather and come to find it was the gas. Anyway i dilluted it with other gas and through in dry gas. I notice this surging is much more noticeable with the bad gas still in the system.
This would be obvious since its bad gas but, what occured to me was i never really had this problem when im at home in PA. I'm curious if maybe its the gas causing this problem. Yes, i always use premium. I'm going home this weekend and will be testing this theory more in depth. It would be surprising if it is this and dissapointing. but it would put my mind at ease if i target the problem and it isn't my car.
HOWEVER, i have noticed something which was interesting last night. I recently bought terrible gas from sheetz. it was 92/93 and my car wouldn't even fucking idle, i was pissed cause we went through so much troubleshooting work in frigid weather and come to find it was the gas. Anyway i dilluted it with other gas and through in dry gas. I notice this surging is much more noticeable with the bad gas still in the system.
This would be obvious since its bad gas but, what occured to me was i never really had this problem when im at home in PA. I'm curious if maybe its the gas causing this problem. Yes, i always use premium. I'm going home this weekend and will be testing this theory more in depth. It would be surprising if it is this and dissapointing. but it would put my mind at ease if i target the problem and it isn't my car.
well if it is shit-gas, perhaps its knocking and pulling timing over and over? maybe its the ethanol or oxygenated fuels and such...
flubyux2 said:
possible, but i don't register knock levels when under acceleration typically even from bad gas. At idle i do but only up to 20Hz or so.
flub: sounds like your issue is the TPS... check the resistances and I bet they're off...
also, the OP says that it doesn't do it at home... it could be the gas OR that the tune is for a different altitude, though that shouldn't matter if the tune is too extreme it might...
also, the OP says that it doesn't do it at home... it could be the gas OR that the tune is for a different altitude, though that shouldn't matter if the tune is too extreme it might...
Poodles said:
I calibrated the TPS before i put the TB on back in may or so. everything was as it should be so IDK. plus, when i monitor the TPS voltage on the SAFC, there are no spikes or dips or anything. it looks perfectly fine...