johnchi

Hi,

I have a 250 but looking to get advise from IS-F owners that track their car but if anyone else experienced this your input would be appreciated.

I am slowly getting my is250 to where it will truly be track worthy. Some of the details on the changes are in previous threads I posted in the 2gen IS section.
The latest challenge I am facing has come to light after this weekends autox event. It was a relatively twisty layout this time and once I got to really pushing the car I got frustrated with the fact that whenever there are fast direction changes on slower parts of the course the steering would get real heavy to the point where by the time it "freed up" I would be 10-15 feet further into the turn and obviously missing the next apex or losing a whole lot of time. Its a .5 to 1sec delay. Its almost like trying to turn the wheel when the cars powered off.
The only way to overcome this was to be much much slower with steering input and slower entry speeds. "slow in fast out" is something I follow diligently but the steering wheel not responding quick enough is the problem in this case because the chassis and the setup can actually handle it.
I do pretty good at faster layouts and no such issues on mountain runs at all.
I have noticed this on a few drifting practices (I use my silvia for it but thought I should give it a try) but it wasnt as severe due to high speeds but the steering did get heavier.

I realize the ISx50 may not have been designed to be a track specialist - I have had quite a few of those - I just want to see if anyone has any input that can help.

Has any one ever experienced this with the IS-F?
I am thinking that using some IS-F electronics may help in tackling this problem but I cant be sure.

I have looked at part number differences between the steering components of the ISx50 and the IS-F.
The only difference is in the "steering computer" located under the battery tray.

IS-F Steering computer 89650-53040
is350/250 Steering computer 89650-53020

IS-F 44200 LINK ASSY, POWER STEERING 44200-53130
ISx50 44200 LINK ASSY, POWER STEERING 44200-53130
IS-F 45250 COLUMN ASSY, STEERING 45250-53061
ISx50 45250 COLUMN ASSY, STEERING 45250-53061
IS-F 89227 COMPUTER, MULTIPLEX TILT & TELESCOPIC 89227-30020
ISx50 89227 COMPUTER, MULTIPLEX TILT & TELESCOPIC 89227-30020

So there are no IS-F over here to try and swap the computers so unless I find one from a wrecked car in the states I will need to buy it and hope it helps.

I will check the wiring diagrams etc to see if they can be swapped from that perspective.

If anyone has any other ideas, throw them out. It will be appreciated.

tenspeed

iTrader: (1)

I'm sure you checked the fluid level. Could it be something like low RPMs in the corners. A slipping belt might reduce the power assist.

onihc

iTrader: (1)

n/a
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lobuxracer

iTrader: (2)

Wow. How about you pop the hood and take a picture of the reservoir so we all know where to put the fluid when it's low?















Surely you missed the part about the steering assist being ELECTRONIC not hydraulic? When will the blind stop posting these kinds of things? The 2IS has been on the market for 5 years and we still get this kind of useless commentary. Why?

For the OP I have tracked my F, but not done autocross, only road courses. Autocross is its own world, so saying I have not experienced what you are dealing with doesn't mean much. Sorry I can't be more helpful.

johnchi

Thanks none the less I know this may be a long shot.

ming15237

iTrader: (3)

I do AutoX my F and can say I have never experienced what you have referred to with regards to the steering. Via your description is sounds like the processor is not sending a signal fast enough to the assist motor to provide p/s boost. Does this happen all of the time or only on occasion? The function of this type of system is all controlled via the power steering ecu, if there is built in lag time in the processor this issue may not be curable for your intended usage. As you stated earlier you are really using this vehicle outside of it's "designed parameters".

johnchi

Thanks.

It happened every time on the same 2 segments. All segments were at speeds about 25mph with sharp direction changes.

just had a look at the service manual and it kind of follows my thought about what would be causing this as well as what you noted. Its not overheating - one of the possibilities, 1 of the segments is right at the start of the run.
Now need to look at the electronics/wiring etc and source an ISF one. I need to get this fixed otherwise will need to get extreme which I want to avoid at this point in time



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johnchi

If anyone has access to the IS-F service manual can you look this section up - or whatever its called on the ISF one that show the Power steering ECU terminals. This will be a great help and show if this would be a easy swap or what degree of modifications it may require.
ELECTRONIC POWER STEERING SYSTEM > TERMINALS OF ECU

ming15237

iTrader: (3)

I just checked my online manual and the connectors are exactly as you pictures for the isf.

johnchi

Thanks a lot for confirming.
So one could assume that if the only part different between the steering associated systems is the steering ecm that MAY help to change the issue I described.
I will triple check all the items and go for it i guess.
Ming15237 - pmd you.

ming15237

iTrader: (3)

pmed you back