tps

[mappyCB7]

my car idles back and forward from 1k to 2k rpm untill it warms up and it shuts off.

I was told this was cause by a bad throttle position sensor

how accurate is that??

[fatboy1185]

probably need to clean the ivac or whateva

[deevergote]

Clean/adjust the IACV and FITV.

It COULD be a bad TPS, but it's not necessarily so. The TPS requires proper calibration to install, so check the things that are less of a pain in the ass first.

If you do end up changing the TPS, get a hacksaw and notch the "rivets". It looks as if it's riveted on there, but it's actually just held on by headless screws. I've known people to buy entire throttle bodies because they didn't know this!

[Granite CB7]

^Agreed, go w/ the IACV and FITV first. In fact, while the engines doing that, remove the intake to expose the bore of the t/b, plug each of the 2 holes 1 at a time, did the problem stop during this? If it's the top hole, it's FITV/idle screw related, bottom would be IACV related. I think I have that right, I don't have a t/b and plenum in front of me! My hunch is if the car is warmed up and doing that, it's the IACV.

[mappyCB7]

yeah!!! it idles really high like at almost 2k rpm and when it warms up it drops and rises and it just keeps doing it.

I took off the intake and plugged the holes one at a time and it stoped doing it when I plugged either one so I'm guessing I need to clean the FITV and adjust the IACV???

is there a diy on how to do this?? if so shoot me a link I'm going to start looking.

[dakiid]

clean both the IACV and the FITV and tighten the white piece inside of the FITV with a flat head. You need a philips to unscrew the top of the FITV.


Good Luck, I need to go do mine also. Cause mine is doing that to and I have a CEL for the tbs.

[johnl]

A bad or incorrectly adjusted TPS tends to cause power output problems (i.e. low torque). I'm pretty certain this is related to incorrect calibration of the TPS causing either lean or rich fuel mixtures.

I recently checked my TPS voltage output (to the ECU) calibration and found the closed throttle (CT) voltage was 0.44v when it should be 0.5v (WOT voltage should be 4.5v, mine was 4.52v). The CT voltage didn't seem too far off but I decided to adjust it anyway. So, not expecting much I decided to calibrate it by adjusting the throtle stop (TS) until the CT increased to the spec 0.5v.

Increasing the CT TPS voltage output by adjusting the TS also slightly opens the throttle plate, so in my case this caused the idle rpm to increase by about 100rpm. I re-adjusted the idle using the idle screw. So, the WOT voltage was now 4.52v, and the CT voltage was dead on 0.5v.

The result is a very surprisingly significant increase in torque at light throttle openings. This makes the engine much more responsive to small changes in throttle position from closed to lightly open, and from lightly open to somewhat more open (the vast majority of driving uses only light throttle openings, it's where we spend most of our driving time).

The car now feels a lot more responsive and pleasant to drive. Taking off from rest is quite noticably easier, it's now not necessary to slip the clutch / feather the throttle nearly so much (and my learner driver son finds it much easier to not stall the engine).

There is no change to how the car performs when I floor the throttle pedal, but then only the CT voltage has been adjusted (which only affects TPS output voltage at CT and lighter throttle openings), I haven't adjusted the WOT voltage.

There are two reasons I haven't adjusted the WOT voltage;

1) It was only 0.02v off spec (WOT spec = 4.5v).

2) To adjust the WOT voltage it's necessary to very slightly rotate the TPS relative to the TB.

This requires cutting slots in the TPS attachment fastener heads to unscrew them, which means the TB has to come off, and I was either too lazy or time pressed to do it at the time (though I do plan to do it at some stage soon).

Note that when checking voltages at the TPS, the yellow wire is the live feed and should read 0.5v at all times (that the ignition is on), the green is the earth, and the red is the feed to the ECU. It's the red wire that should be at 0.5v CT and 4.5v WOT.

The easist way to probe the wires (to read the voltage with a multi-metre probe) is to insert some metal wire (e.g. paper clip wire) deep into the grey plastic connector beside the red and green wires where they enter the connector, leaving short lengths protruding from the connector next to the wires. Once you are sure there is continuity between the electrical wires and the inserted metal wires, you can refit the connector and read the output at CT and WOT from the protruding metal wires (i.e. voltage measured from between the green and red wires).

TPS voltage output is the reason why idle speed should never be adjusted with the TS screw, only with the idle screw. It only takes a small change in CT voltage to have a very significant affect on the light throttle torque output and thus the 'drivability of the car.

[drzcb7]

i got the same problem i cleaned the iacv i dnt know which is the FITV=/ can someone help me out pics would b koool! lol...

[johnl]

I strongly suspect that the TPS voltage being low causes a lean fuel mixture.

An interesting thing, prior to adjusting my car's TPS voltage as above, the cooling fans would nearly always come on a minute or so after shutting down the engine. However, since adjusting the TPS voltage I haven't heard them come on even once. Weird? Maybe not...

This may make sense if we consider that lean fuel mixtures burn much hotter than mixtures that are adiabatically correct or rich, so, the metal of my engine may previously been dumping more heat into the cooling system than it is now.

Previously, with a lean mixture (as I'm assuming...), the combustion temp is higher, and metal casting of the cylinder head may have been at X temp. After shut down this heat must have been conducting into the now (after the water pump stops operating) more slowly circulating coolant, raising it's temp to the point that the fan thermo switch triggers.

Now, with a less lean mixture (as I'm assuming...) the combustion temp is lower, and thus the metal of the head may only be at X- temp, so after shut down there is not enough heat is in the metal to raise the coolant temp high enough to trigger the fan switch...?

This makes me wonder how much incorrect TPS calibration may affect engine temperature with cars having marginal cooling systems?

Another intersting thing; since adjusting my TPS calibration, the engine takes two or three more kilometres before the temp gauge needle starts to rise. Fits with the idea that a richer mixture burns at a lower temperature...

[mappyCB7]

well I googled "94 accord fitv" and found some very good step by step instructions

I cleaned and adjusted the fitv and cleaned out the iacv which was fucking filthy

it solved the idle problem it's idleing like a dream right now at a steady 1k rpm

it still has a check engine light and I think I know why...



oh yeah my car is a cd7 not a cb7

[johnl]

Facing the front of the car, the FITV is to the right of the IACV with the throttle cable passing over it. It has two small diameter coolant lines attached at the bottom and on top there is a plate attached with two Phillip's headed screws. Can't miss it..

[johnl]

it solved the idle problem it's idleing like a dream right now at a steady 1k rpm

Too high, it should be about 750 + - 50. You need to re-set the idle speed (using the idle speed screw), but first you need to disconnect the electrical connector from the IACV. The idle speed with the IACV not functioning is the 'base' idle speed, i.e. the speed the engine idles at with zero interference (or assistance, depending how you view these things..) from the IACV.

Note that the IACV can only increase idle speed above the base idle speed when base idle is too low, it can't reduce base idle if it's too high. I suspect your base idle is way too high. After setting base idle speed to spec, reconnect the IACV.

[Oja]

niice thread !!