OrRunner

iTrader: (1)

alright guys, I need a little help! I have been reading many threads on the tps adjustments and o2 sensor problems, and this is what my thought are.

I got my motor in and done and it seems to be running great, however, I am having 2 issues:

1-a slight "hicup" at idle, when warm not cold, the motor just stubles a tiny bit and it seems to repeat every 60 or so seconds, I think this may be timing related, how ever when Jumper the T-E1 terminals in the diagnostic box I dont get an idle down, like its not bypassing what its supposed to. I have tried this warm and cold? any input?

2-I am also getting a slight hesitation when under load, seems very sporadic, cant nail down a patter. I am thinking this may be due to a tps adjustment as my tps tested fine, also could be related to my o2 sensor which was replaced (with a bosch). I ordered a denso o2 today and will install on sat morning. When this is done should i disconnect neg term on the battery to reset computer? or does the o2 sensor just need to run and it will correct the ecu on its own?

little more info:
no check eng light, no codes, other than that everything seems to be good, including vacum lines. No apparent or noticable vacum leaks or ehaust leaks. I did not do anything with VAF? or what ever that sensor in the air box is called? But i did not have any issues with the airbox before the new motor. Last, the the "hicup" i am refering to above was also present with the last motor so not realy sure its timing relate but i guess it could be.

any reccomendations or information on these things is greatly appricated!
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thook

Well, try adjusting the throttle sensor. If it tests out fine, it may just need that or the wiring needs to be tested at the ECU connector. In that case, you'd run the same tests you did for the TPS only your meter will be probing the connector.

You could try adjusting the throttle sensor by starting the engine, get it up to temp, loosen the screws on the TPS, pivot the sensor forward and back again until you find the point at which the idle will change. If it does change, set the sensor on the low idle side of that point. This is when the ECU is reading the idle position. If it doesn't change at all doing this, test your wiring.

No need to reset the ECU when you install the new O2 sensor. Fuel trim adjustments made by the ECU are done gradually, so disconnecting it is pointless unless your trying to erase a code. Short term fuel trim memory is also erased, but that happens anyway everytime you turn the key off.

I'm not going to say the Bosch sensor is/was the cause of your little misfire, but you are better off with the Denso unit. The TPS is probably your cause there.

OrRunner

iTrader: (1)

Thook,

Thanks for the quick response, I wont have any time till saturday to retest and adjust the tps and install the new o2 sensor, quick questions for you my friend,
do you have any thought as to why i cant get the idle to "drop" when i jumper the timing with a paper clip in the diagnostic terminal? i have tried warm and cold and still dont see any idle change. I am sure it could be many things, but the terminal and all of the wires are in great shape visualy and my truck seems to be very unmodified except for what i have done, no wire splicing ect. Thanks again for the help! much appreciated!

thook

Uh....well.....unless the ECU's bad, which I doubt, the idle's not dropping because the ECU is unable to read the IDL circuit of the throttle sensor. IDL simply means the idle signal. The ECU has to be able to detect if the vehicle/throttle is at idle before it can even begin to regulate ignition timing properly. To explain in sort of a bastardized way, the IDL signal is a reference point from which the ECU is able to advance timing as needed according to whatever throttle position/driving conditions. Without being able to detect the idle, the ECU is kind of at a loss. Might as well be open throttle as far as it's concerned. This also affects it's ability to accurately meter fuel injection. So, you get misfires, to whatever varying degree, and a loss of performance under load.

Does this help?

OrRunner

iTrader: (1)

Yes it does help, so if I am understanding you correctly,as an example, because the tps setting is incorrect, the ecu may see a wide open throttle signal at idle and thus the ecu cant accomadate the bypass of jumping the diagnostic terminal to get the idle to drop for timing..

so get the tps setting correct then i should be able to jumper the diagnostic terminal to dial in the timing right?

thook

I guess I didn't really answer the question well the first time. It's more complicated than that. IOW's, it all has to do with how the circuitry operates and how it's all interconnected electrically. To be honest, I understand it basically fairly well, but I suppose not enough to clearly describe exactly how it works. But, since now you've asked and I would like to be able to explain better, I'll do a little more reading and post back.

For now, if you get the TPS to adjust and the IDL circuit is still operable, then yes.....you will see the idle RPM drop signifying the ECU is bypassed, and you can then set the base timing without the ECU advancement.

OrRunner

iTrader: (1)

Sounds good! Also, if you have a good link to read up on this issue and how the circuitry with the ecu and tps stuff works, i would love to learn about it. I will keep loooking through y/t and do some more research. Again, thank you so much for the information, its has shed a whole new light on this situation i am having!

thook

This is my favorite technical site, so far:

http://www.autoshop101.com/

I stumbled upon another not long ago......within the last two weeks........but, I don't remember the name of the site and how I found it. It's in my history somewhere, I'm sure.

So, read the tech articles, eh. It doesn't go into a lot of detail as far as troubleshooting or anything, although it does give guidelines on how to. The crux of the site is in explaining how Toyota EFI systems, etc. work. Once a person understands how everything works, then the process of troubleshooting different situations makes much more sense........of course.

I figure it'll take you a good while to absorb much of this info. Unless you have a photographic memory or know how to speed read? Those are two things I wouldn't mind developing more.

Anyway, this is where I'll be reviewing what I've already studied on the subjects in question here. I'll be back!!!

Cheers, mate......

OrRunner

iTrader: (1)

Thook,

This weekend i replace my o2 (bosch) with a denso. Also, from your suggestion, i reset my tps and found that it was way out. I followed the testing instructions from 4crawler's site under cheap tips and tricks. Once I reset the tps I found that the diagnostic terminal worked when I jumper the T - E1 terminal, so i was able to get the timing pinpointed, however the timing was almost dead on. So with the tps adjustments and the new O2 sensor, I have aliviated all of my problems regarding the hesitation, and minor hicups. Thanks againg for the Information, and the links, still lots of info to soak up but with time, I will learn!

Thanks again for your help!

thook

You're welcome! Glad everything went well and easily. I haven't blown off giving a better answer about the circuit, btw. I just haven't found the details I'm needing.

Sansocal

FYI, I wouldn't mind reading what you had to say