What else is left to check? SC still "stuttering"...
05-17-11, 08:22 AM
#1
Driver
Thread Starter
What else is left to check? SC still "stuttering"...
I have searched this site and several others for ideas and tried everything I can find or think of. I need suggestions on what else it could possibly be.
First off, NO CEL ever in this entire process...
93 SC400
When cold it runs fine, as soon as it warms up, rough idle, hesitation when taking off from light. Once I am rolling at around 35-40MPH if I push the gas it "stutters". If I stomp on it, or if I am on the freeway going 55+ it runs fine.
Smell of fuel sometimes, cats sound like Jiffy Pop after long drive.
Things I have checked/replaced:
Fresh plugs and cables (as of 10k miles ago, pulled each one, all spark, all dry)
New fuel filter
New Air filter
replaced MAF sensor with "known good" one
Jumpered the fuel ECU (heard fuel pump whirring, drove 10 mins, no change)
Tested both coils (Bought a new coil, swapped out each side in turn and no change, returned new coil)
Replaced Engine Coolant Temp sensor
Cleaned IACV and verified it was able to move etc.
Checked TPS for position.
Replaced caps and rotors
swapped out ECU with known good one, no change
running Premium Fuel, ran a can of Seafoam through to clean injectors etc.
no smoke or strange sounds
What else is there that CAN cause this issue?
Would O2 Sensors do this and still not produce a CEL?
First off, NO CEL ever in this entire process...
93 SC400
When cold it runs fine, as soon as it warms up, rough idle, hesitation when taking off from light. Once I am rolling at around 35-40MPH if I push the gas it "stutters". If I stomp on it, or if I am on the freeway going 55+ it runs fine.
Smell of fuel sometimes, cats sound like Jiffy Pop after long drive.
Things I have checked/replaced:
Fresh plugs and cables (as of 10k miles ago, pulled each one, all spark, all dry)
New fuel filter
New Air filter
replaced MAF sensor with "known good" one
Jumpered the fuel ECU (heard fuel pump whirring, drove 10 mins, no change)
Tested both coils (Bought a new coil, swapped out each side in turn and no change, returned new coil)
Replaced Engine Coolant Temp sensor
Cleaned IACV and verified it was able to move etc.
Checked TPS for position.
Replaced caps and rotors
swapped out ECU with known good one, no change
running Premium Fuel, ran a can of Seafoam through to clean injectors etc.
no smoke or strange sounds
What else is there that CAN cause this issue?
Would O2 Sensors do this and still not produce a CEL?
Last edited by MuGGzyx; 05-17-11 at 01:51 PM.
05-17-11, 01:24 PM
#2
i just had this issue with my sc300.... when you try to drive it normally it jumps and stutters but when you romp on it the car runs fine right??
check your tps i had just replaced mine and even then it went out like 2 months later.
find someone with a datalogger and give em 50 bucks to hook your car up and see whats wrong but my money is on the throttle position sensor as mine never threw any codes eaither.
check your tps i had just replaced mine and even then it went out like 2 months later.
find someone with a datalogger and give em 50 bucks to hook your car up and see whats wrong but my money is on the throttle position sensor as mine never threw any codes eaither.
05-17-11, 01:57 PM
#3
Driver
Thread Starter
yup you about described it perfectly.
When the car is cold, first thing in the AM, it seems better, but once it warms up it starts getting weird.
If I start out gradually and get to normal "in town" speeds everything is fine. Once it is warm, sitting at a stop/idle it just kind of makes a "whoomp whoomp" sound that is barely audible under the normal sound of the engine every few seconds.
Once I get to traffic speed, like 35-45 with the engine around 1500-2000 RPM and try to accelerate to 45-50 it "stutters" making a sort of "blop blop" sound and hesitates. If I let off a bit and then stomp it the engine roars like it used to and it will surge off and accelerate. So basically, if I RACE from stop to stop, it's great, if I try to drive sanely/legally, it's really rough.
I did the resistance test in this thread:
https://www.clublexus.com/forums/sc-...on-issues.html
and it had resistance as described until I secured it right AT the point it loses continuity.
It's just very frustrating when there is no CEL and you try EVERYTHING you can find online via searching.
When the car is cold, first thing in the AM, it seems better, but once it warms up it starts getting weird.
If I start out gradually and get to normal "in town" speeds everything is fine. Once it is warm, sitting at a stop/idle it just kind of makes a "whoomp whoomp" sound that is barely audible under the normal sound of the engine every few seconds.
Once I get to traffic speed, like 35-45 with the engine around 1500-2000 RPM and try to accelerate to 45-50 it "stutters" making a sort of "blop blop" sound and hesitates. If I let off a bit and then stomp it the engine roars like it used to and it will surge off and accelerate. So basically, if I RACE from stop to stop, it's great, if I try to drive sanely/legally, it's really rough.
I did the resistance test in this thread:
https://www.clublexus.com/forums/sc-...on-issues.html
and it had resistance as described until I secured it right AT the point it loses continuity.
It's just very frustrating when there is no CEL and you try EVERYTHING you can find online via searching.
05-17-11, 02:02 PM
#4
yeah!!! EXACTLYYY!!! one time i drove mine 900 miles without turning it off but AS SOON AS I TURN IT OFF it would do the stuttering.
screw the resistance test go get a datalogger and check it out. mine passed all the tests my mechanics had until we put a datalogger on it and it was not working
trust me im willing to bet its the tps.... my sc3 has been sitting for a year cause me nor the head mechanics at lexus or any of the local lexus shops could figure it out.... soon as i got a hold of a datalogger we figured it out
FIND SOMEONE WITH A DATA LOGGER and buy them a beer only
your having the EXACT problems i did and mine was the tps.... mind you i just changed my tps 6 months prior and it failed.
screw the resistance test go get a datalogger and check it out. mine passed all the tests my mechanics had until we put a datalogger on it and it was not working
trust me im willing to bet its the tps.... my sc3 has been sitting for a year cause me nor the head mechanics at lexus or any of the local lexus shops could figure it out.... soon as i got a hold of a datalogger we figured it out
FIND SOMEONE WITH A DATA LOGGER and buy them a beer only
your having the EXACT problems i did and mine was the tps.... mind you i just changed my tps 6 months prior and it failed.
Last edited by sj408; 05-17-11 at 02:06 PM.
05-17-11, 03:53 PM
#5
Driver
Thread Starter
So the guys at O'Reilly as well as a friend that has a regular "code puller" type of little handheld that can check and clear CEL codes all looked at me like I was crazy when I asked if they had, or even knew what a "data logger" was.
What else can I call it or who would likely have one of these? Is it exclusively for auto diag or is it used in other applications too?
What else can I call it or who would likely have one of these? Is it exclusively for auto diag or is it used in other applications too?
05-18-11, 06:38 AM
#7
Driver
Thread Starter
Trending Topics
05-18-11, 10:04 AM
#8
Driver
Thread Starter
well I was just told by the local "Independant" Lexus/Toyota repair shop that my car (being OBD1) wouldn't have the onboard "Data" system that a "Data Logger" (damnit he called it something else) would connect to and capture from.
However he said to check my EGR valve because if one of the ports is clogged it would do what I am experiencing. Back under the hood I guess.
Edit: Pulled EGR after work and cleaned it well, verified it had travel and cleaned a bunch of carbon build up out of the mount/knuckle area. Didn't help....
However he said to check my EGR valve because if one of the ports is clogged it would do what I am experiencing. Back under the hood I guess.
Edit: Pulled EGR after work and cleaned it well, verified it had travel and cleaned a bunch of carbon build up out of the mount/knuckle area. Didn't help....
Last edited by MuGGzyx; 05-18-11 at 04:32 PM.
05-19-11, 09:59 AM
#9
Driver
Thread Starter
Well I sucked it up and took it in to the shop. I got lucky, or so I think so anyways, and the local shop that does Lexus/Toyota said they would do a free diagnosis.
It turns out that my #7 injector is functional but only barely. He did some test and my exhaust is shooting 1100PPM of whatever the carbon stuff is they measure, and it is supposed to be like 200PPM. So he said I was deff at risk of burning out a cat if I continued to drive it like it is.
So, in response to the many many dead end threads on this issue, I am posting what the end solution was. A bad injector, and I could have saved myself $400+ in parts and 2 weeks of back killing evenings after work trying different parts if I had just taken it to the shop that did the free diag in the first place. Live and learn.
I am now off to research how hard it is to replace an injector. :-D
BTW, he recommended a brand of fuel injector cleaner called "Berryman" that he described as "As potent and caustic as you can get without needing a permit" that he suggested I use after replacing the one injector for a while to clean up the others.
It turns out that my #7 injector is functional but only barely. He did some test and my exhaust is shooting 1100PPM of whatever the carbon stuff is they measure, and it is supposed to be like 200PPM. So he said I was deff at risk of burning out a cat if I continued to drive it like it is.
So, in response to the many many dead end threads on this issue, I am posting what the end solution was. A bad injector, and I could have saved myself $400+ in parts and 2 weeks of back killing evenings after work trying different parts if I had just taken it to the shop that did the free diag in the first place. Live and learn.
I am now off to research how hard it is to replace an injector. :-D
BTW, he recommended a brand of fuel injector cleaner called "Berryman" that he described as "As potent and caustic as you can get without needing a permit" that he suggested I use after replacing the one injector for a while to clean up the others.
06-18-12, 01:15 PM
#10
Driver
Thread Starter
Just wanted to post an update since most of these threads go dead with no follow up.
In addition to the above steps. I have now replaced both cam sensors.
I have now replaced all 8 injectors.
Problem persists.
Taking it back into the shop today and demanding the mechanic drive around with me to witness the issue.
In addition to the above steps. I have now replaced both cam sensors.
I have now replaced all 8 injectors.
Problem persists.
Taking it back into the shop today and demanding the mechanic drive around with me to witness the issue.
06-18-12, 02:13 PM
#11
It really does sound like your tps, you may just want to swap it out for a known good one.
the adjustment is sensitive, the IDL has to be triggered right or you can get symptoms like that on all toyotas.
if you want to try different adjustments just mark it so you know where you started and can reset it if needed.
also if you already lost a injector, you may want to check your fuel filter.
the adjustment is sensitive, the IDL has to be triggered right or you can get symptoms like that on all toyotas.
if you want to try different adjustments just mark it so you know where you started and can reset it if needed.
also if you already lost a injector, you may want to check your fuel filter.
02-04-13, 01:10 PM
#12
Sorry to dredge up an old thread, but was this problem ever resolved? My son's '99 SC300 has the very same symptoms described as the OP. I was reading elsewhere on the site that someone suggested looking at the coilpacks for cracking as arcing can result causing the rough and stumbling idle issues.
12-05-13, 05:31 PM
#15
Sorry to dredge up an old thread, but was this problem ever resolved? My son's '99 SC300 has the very same symptoms described as the OP. I was reading elsewhere on the site that someone suggested looking at the coilpacks for cracking as arcing can result causing the rough and stumbling idle issues.
If so what was causing the problem?