-20% fuel trim
Jun 25, 2017 | 04:26 PM
#1
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Joined: Aug 2012
Posts: 59
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From: Long Island, NY
-20% fuel trim
Hey all,
I have a 93 pickup that had a 3.0 in it, recently got a 3.4 swap in the truck and started having some issues with it.
Its a 3.4 from a 1998 4runner, with a m/t computer and i noticed i was having difficulty accellerating, it feels like im constantly working the gas on and off and on, sorta like stuttering down the highway.
it worked fantastic for about a week and then i charged the a/c and seemed to develop this issue
Its throwing p0130 and p0133 codes
I replaced the rear and front o2 because the rear was unresponsive, i did a ground and signal wire check at that time on both and it seemed to be good
I have new plugs, wires and injectors with ~6k on them in that were reconditioned previously (oside tiger off ebay).
I also have new/known good coils, they also check out ohm test wise
Im getting -20% fuel trim once the o2 kicks in and before that when i mash the gas it backfires, bit of a stumble at low rpm but seems to clear up once i give it some gas.
when i changed the plugs i noticed 5 and 6 were black in color and the rest seemed to look fine, not wet black but just black
i havent torn off the plenum to check all the fuel injectors, but the three on the pass side all have the same ohm rating
i have checked the ohm of all injectors from the ecu, all except 5 and 6 are within 1ohm, 5 and 6 are sometimes 5-10 ohms under from the harness, im assuming it may be because they heat up a bit more being near the back of the engine.
ive cleaned my maf
one thing that may or may not be related, my a/c idle up currently does not seem to be working and the compressor will randomly decide not to kick in, i assume i had a shim issue from the new pully on it as far as engagement goes but the idle up i could see possibly being related.
my vacuum (as seen on scan tool) seems to be around 21-23 i have yet to check with a physical gauge
i had a little corrosion on the efi and a/c fuses but noticed no change with a new fuse
before i rip the plenum off and swap fuel injectors from a known working engine in desperate hope its the problem what else can i check or do to try and figure out the issue?
I have a 93 pickup that had a 3.0 in it, recently got a 3.4 swap in the truck and started having some issues with it.
Its a 3.4 from a 1998 4runner, with a m/t computer and i noticed i was having difficulty accellerating, it feels like im constantly working the gas on and off and on, sorta like stuttering down the highway.
it worked fantastic for about a week and then i charged the a/c and seemed to develop this issue
Its throwing p0130 and p0133 codes
I replaced the rear and front o2 because the rear was unresponsive, i did a ground and signal wire check at that time on both and it seemed to be good
I have new plugs, wires and injectors with ~6k on them in that were reconditioned previously (oside tiger off ebay).
I also have new/known good coils, they also check out ohm test wise
Im getting -20% fuel trim once the o2 kicks in and before that when i mash the gas it backfires, bit of a stumble at low rpm but seems to clear up once i give it some gas.
when i changed the plugs i noticed 5 and 6 were black in color and the rest seemed to look fine, not wet black but just black
i havent torn off the plenum to check all the fuel injectors, but the three on the pass side all have the same ohm rating
i have checked the ohm of all injectors from the ecu, all except 5 and 6 are within 1ohm, 5 and 6 are sometimes 5-10 ohms under from the harness, im assuming it may be because they heat up a bit more being near the back of the engine.
ive cleaned my maf
one thing that may or may not be related, my a/c idle up currently does not seem to be working and the compressor will randomly decide not to kick in, i assume i had a shim issue from the new pully on it as far as engagement goes but the idle up i could see possibly being related.
my vacuum (as seen on scan tool) seems to be around 21-23 i have yet to check with a physical gauge
i had a little corrosion on the efi and a/c fuses but noticed no change with a new fuse
before i rip the plenum off and swap fuel injectors from a known working engine in desperate hope its the problem what else can i check or do to try and figure out the issue?
Jun 25, 2017 | 08:23 PM
#2
-20 is on the long term or short term? Ecu is trying to pull a lot of fuel at -20. Do the o2 sensors match the year/make of ecu you are running? What are the maf readings? Are you having any misfire or dead cylinder issues? What does the fuel trim do when you bring idle up to 1500, 2500rpm?
Jun 26, 2017 | 05:27 AM
#3
Thread Starter
Registered User
Joined: Aug 2012
Posts: 59
Likes: 2
From: Long Island, NY
The o2s should match the year and make of ecu (as far as i can tell at least).
Im not sure how to interpret the maf readings, one chart says 10 g/s when idling and the other shows in cfm ill have to double check but i think it was around 80-90cfm at idle and it fluctuated with rpm i'll confirm later.
Is there an easy way to check for misfire or dead cylinder issues? I dont audibly hear anything that sounds like low compression when i start, i tried pulling the plug boots on driver side when i first had the issue and could hear the three cylinders not firing when i did.
I dont have any misfire codes although i think 5 and 6 may be having issues, after testing injectors i took it for a drive and accidentally left #1 unplugged, on that drive i got multiple cyl misfire codes for 1, 5, and 6, but after plugging #1 back in the misfire codes did not come back even thought 5 and 6 were untouched within that timeframe.
from what i remember it was giving me -20% short term while idling and that would go down to 0 and change over to -20 long term while driving. occasionally it would "fix" itself and put both short and long term at around +3 or +4 until i took it around the block and it would again return to -20. I havent taken it out of the driveway in about 2 weeks due to trying to diagnose the issue so my memory may be a little off. i can drive it around after work to confirm.
Im not sure how to interpret the maf readings, one chart says 10 g/s when idling and the other shows in cfm ill have to double check but i think it was around 80-90cfm at idle and it fluctuated with rpm i'll confirm later.
Is there an easy way to check for misfire or dead cylinder issues? I dont audibly hear anything that sounds like low compression when i start, i tried pulling the plug boots on driver side when i first had the issue and could hear the three cylinders not firing when i did.
I dont have any misfire codes although i think 5 and 6 may be having issues, after testing injectors i took it for a drive and accidentally left #1 unplugged, on that drive i got multiple cyl misfire codes for 1, 5, and 6, but after plugging #1 back in the misfire codes did not come back even thought 5 and 6 were untouched within that timeframe.
from what i remember it was giving me -20% short term while idling and that would go down to 0 and change over to -20 long term while driving. occasionally it would "fix" itself and put both short and long term at around +3 or +4 until i took it around the block and it would again return to -20. I havent taken it out of the driveway in about 2 weeks due to trying to diagnose the issue so my memory may be a little off. i can drive it around after work to confirm.
Jun 26, 2017 | 05:40 PM
#4
Thread Starter
Registered User
Joined: Aug 2012
Posts: 59
Likes: 2
From: Long Island, NY
i took it for a spin around the block.
MAF is at 10 g/s at idle
fuel trim was 0 long term and -20 short term at idle before the ride
while driving the long term went up to -20 and the short dropped towards 0
on idle again short term started going back down towards -20 and long term seemed to stay the same at -20
MAF is at 10 g/s at idle
fuel trim was 0 long term and -20 short term at idle before the ride
while driving the long term went up to -20 and the short dropped towards 0
on idle again short term started going back down towards -20 and long term seemed to stay the same at -20
