Does anybody have a true answer to the 40MPH hesitation/Jerking
07-21-13, 12:20 PM
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Does anybody have a true answer to the 40MPH hesitation/Jerking
I bought a 1994 Lexus SC400 that I am slowly re-building, I have the 40MPH hesitation/jerking, I have found 4 threads regarding this issue but there was no true answer to this.
I was wondering if there is anybody out there that figured this out?
Thanks in advance.
Kai
I was wondering if there is anybody out there that figured this out?
Thanks in advance.
Kai
07-21-13, 01:26 PM
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Happened to me man. It would feel like the tranny is slipping but it wasnt...kinda like minor slipping? And once i hit past 50mph or so it would go away. If you have the same issue then tighten your tranny cable, theres a thread on the proper distance, it helped my issue, then adjusted the tps and issue totally disappeared. This was about 8k miles ago, currently at 222k.
Edit:also a 94
Edit:also a 94
07-22-13, 10:37 AM
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could possibly be a fuel pump ecu issue....just do a search, fuel pump ecu is located behind the drivers side rear passenger seat panel. DIY's on how to replace....pretty easy and cheap ($40?)
07-22-13, 05:02 PM
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https://www.clublexus.com/forums/per...nd-40-mph.html
Is this the problem?
Bucking, jerking, surging, feels like a thump underneath the center console, you can catch it just at 43 MPH or so?
Well, 2 things fixed it for me. The TPS, and mostly the o2 sensors. All of them.
Is this the problem?
Bucking, jerking, surging, feels like a thump underneath the center console, you can catch it just at 43 MPH or so?
Well, 2 things fixed it for me. The TPS, and mostly the o2 sensors. All of them.
Last edited by SC400slide; 07-22-13 at 05:03 PM. Reason: oops
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07-23-13, 01:05 PM
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https://www.clublexus.com/forums/per...nd-40-mph.html
Is this the problem?
Bucking, jerking, surging, feels like a thump underneath the center console, you can catch it just at 43 MPH or so?
Well, 2 things fixed it for me. The TPS, and mostly the o2 sensors. All of them.
Is this the problem?
Bucking, jerking, surging, feels like a thump underneath the center console, you can catch it just at 43 MPH or so?
Well, 2 things fixed it for me. The TPS, and mostly the o2 sensors. All of them.
07-25-13, 09:24 AM
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Update:
So I did the transmission cable adjust and TPS, it looks like the jerking is gone but need to test it when its warmer, it started raining here so the temp was cooler, but now it threw a code of 31 which is the Air Flow Meter Signal...
It threw this code when I was done testing, the Idle was steady at about 800RPM then it would drop for a quick second and jumped right back up, it would do this a couple of times then it would die.
So I did the transmission cable adjust and TPS, it looks like the jerking is gone but need to test it when its warmer, it started raining here so the temp was cooler, but now it threw a code of 31 which is the Air Flow Meter Signal...
It threw this code when I was done testing, the Idle was steady at about 800RPM then it would drop for a quick second and jumped right back up, it would do this a couple of times then it would die.
07-25-13, 10:13 AM
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Could possibly be a bad AFM. But before you start replacing parts make sure all your engine electrical connections (and connectors) are good. Next make sure ALL your rubber intake boots are secure with no cracks or leaks. While doing that you may as well check ALL your vacuum lines as well.
08-02-13, 09:47 AM
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Update:
So far I have adjusted the transmission cable and TPS, this decreased the hesitation and jerking, it still does it but not as bad, I ordered a AFM which arrives today and will replace and test.
I also purchased a Fuel ECU or Controller to resolve the issue of it dying when you start it after being parked for about an hour after a drive, got here yesterday, replaced it and issue is now gone
That's all for now on my quest to put this car back in tip top shape, I will update this as soon as I replace the MAF this weekend.
So far I have adjusted the transmission cable and TPS, this decreased the hesitation and jerking, it still does it but not as bad, I ordered a AFM which arrives today and will replace and test.
I also purchased a Fuel ECU or Controller to resolve the issue of it dying when you start it after being parked for about an hour after a drive, got here yesterday, replaced it and issue is now gone
That's all for now on my quest to put this car back in tip top shape, I will update this as soon as I replace the MAF this weekend.
08-12-13, 11:57 AM
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A little update:
I replaced the MAF and no difference, it still jerks a little bit at 40MPH.
I did notice that if I turn O/D off it does not jerk at all so I am thinking it may be transmission related, i've never worked on Automatic cars so I will need to brush up on how the transmission works.
I did also notice that the previous owner must have taken off the thermostat since the radiator had a leak when I purchased it, the temp gauge fluctuates too much, it will get warm then cool down to almost the first or second line when I start driving.
I have a T-stat and a gasket on order and will install. Not sure but maybe the water temp has something to do on how the transmission shifts?
I replaced the MAF and no difference, it still jerks a little bit at 40MPH.
I did notice that if I turn O/D off it does not jerk at all so I am thinking it may be transmission related, i've never worked on Automatic cars so I will need to brush up on how the transmission works.
I did also notice that the previous owner must have taken off the thermostat since the radiator had a leak when I purchased it, the temp gauge fluctuates too much, it will get warm then cool down to almost the first or second line when I start driving.
I have a T-stat and a gasket on order and will install. Not sure but maybe the water temp has something to do on how the transmission shifts?
