SignShop85

I've got a bonestock 99 Civic EX with aprox. 230,000miles.. The issue I'm having is when it's started the car idles at around 1600rpm.. I've changed the TPS, cleaned the ACV, bleed the coolant an still I've gotten no where.. I'm beginning to think it's a vacuum leak.. Sounds like I can hear a slight leak but not 100% sure.. I did notice on the air-intake there is a crack in the bongle where the line comes from valve cover to intake.. Wasn't sure if that would effect it or not, it is after the sensor on the intake.. Would it ? Also when I pulled codes with scanner it came back as TPS, which is what made me change it.. New TPS does same thing as old TPS.. I was told that high idle without a surge is generally the ACV, that's why I took it apart an sprayed it all out with throttle body cleaner.. It wasn't really all that nasty.. With all that said, where should I begin looking now ? I've sprayed all around the vacuums lines with starting fluid to see if I can detect a leak, no revving from the starting fluid.. Also this issue occurred while getting off interstate after a 45minute ride.. Any info will be greatful.. Thanks..

ezone

Possibilities might include

Vacuum leak
Stuck IAC
Inaccurate TPS
Inaccurate ECT
Cold running temperature/t-stat
Low coolant level
Throttle cable issue
Cruise cable issue

Cold fast idle is normal. Hot and too fast isn't.
Lack of surge tells me the TPS isn't at CTP voltage, and/or ECT is too low for fuel cut to be in effect.

What is the TPS voltage reading at fully closed throttle position ---- as seen by the PCM --- read on a scanner datalist?

SignShop85

Ok.. I've done a couple things since posting.. Like I said earlier in the post I had cleaned the IACV, well I took the intake off the throttle body an put finger over the port for the IACV, I was told that if the idle doesn't change its probably a vaccum leak.. Well I done this an the idle dropped to normal.. So I'm assuming there isn't a vaccum leak.. I went ahead an changed the IACV just to make sure.. Same situation.. I haven't checked the voltage on the TPS yet only cause I was told that wouldn't effect my situation.. I do plan on checking it.. Voltage is suppose to be .5 at idle an 4.5 WOT correct ? So, do you suggest I make sure voltage is correct on TPS ? Will do that tommorow morning.. Temp seems to be normal, coolant may be a little low now since I've purged radiator a second time..

What is the sensor on top of the throttle body ? Would it have anything to do with my situation ? It's the only one I haven't changed that's on the throttle body.. What does ECT stand for ? New one to me.. Any info will be greatful..

ezone

How many ports in the throttle body? 2? Cork off both with your fingers, the engine should stall or almost stall.



Thereabouts, and at the moment I only care about what it reads while the engine is running.

On a scanner datalist, 99% of the cars will show exactly 0.49V at closed throttle.

Honda is damn consistent on this throughout the entire car line, that's probably one reason they only sell the throttle body with the TPS already set and locked down.

I don't type this stuff just to hear my keyboard click.

When you have the high idle RPM, what does the TPS voltage read at that moment?


MAP sensor. (guess, since I can't see it)
Seriously doubt it. Is there a code for it?

Engine Coolant Temperature.

The computer doesn't use the same sensor as your gauge on the dash. It could be skewed and inaccurate, you'd never see it on the dash and it might not set codes if the reading is plausible. That's another of many reasons why I look at live data on my scanners.

SignShop85

I recently set the TPS .5 at idle an 4.5WOT same results.. I played with the idle screw just to see an no matter which way I turn it nothing happens.. Local Honda guy told me that the throttle bodies can form a internal leak an cause this type of response.. Is there a way to test a throttle body before I buy one ?
An when I plug off both the map port an IACV port on the throttle body the car does try to stall.. So I ruled out vaccum leak..

SignShop85

Also after resetting the computer by disconnecting the battery it's stuck in park.. Checked fuses an all are fine.. Now I gotta use the lock beside shifter to remove from park.. What can cause this?

ezone

Did you use a volt meter to do this, or a scanner?
Now that the problem is active, I'd want to know what the TPS and PRNDL inputs look like to the computer, in a live data list.
While the problem is active.
Say whut?


I can think of 3 possibilities on this at the moment:

* you tried to adjust this while the idle speed was way too fast

* the computer i still actively in control of the idle speed (using the IAC) regardless of your adjustments.

*the air passages for the adjustment screw are clogged with carbon.


Lunch is over, gotta run

SignShop85

I dont have access to a live data scanner but I recently pulled code again an no longer read tps.. now shows iacv circuit failure.. any tips?

ezone

Just because there is no code for the TPS doesn't mean there is no issue. The computer won't set a fault code until it sees the TPS voltage at an impossible voltage. It can still read wrong without setting a code. This is why I'd have my scanner on it, I want to know what the computer is seeing.


The IAC code, is that a current fault or a history fault? If you had it unplugged and turned the key on, that can set the code, and it would still be in memory unless you cleared the memory. Got freeze frame data?

SignShop85

Ok. It's been a while Since I've posted about this. So after changing all the sensors on the throttle body I changed entire throttle body off a friends car. Same results. Iacv has power so does tps. I know you mentioned live data scanner an I just don't have access to one. I feel I've eliminated all possibilities of it being a sensor or throttle body. Need suggesTions. Thanks.

ezone

Which problem(s) does the car have now?
High idle?
Shifter stuck?





There's a reason I wanted to know what the computer is "seeing".
There is an interlock control unit, but the PCM gives input to that controller.
If the PCM doesn't like what it sees (brake switch and TPS at desired voltages), it won't allow the shifter to release.

That's one reason why I wanted to know what it's seeing.
The other reason has to do with the high idle.

eat5

i had a loose ground and my A/C unit was bad. i tightened ground wire and cut of A/C belt and car is fine.....

ezone

Great! Which ground?

SignShop85

The shifter now releases when in park, car still has surge 1500-1600rpm. Also fans only work when jumped, changed thermoswitch still not working.. After changing the switch I let the car run till it was boiling out of overflow, temp guage in car read normal ? That threw me off.. Not sure if one problem is causing all the problems or what..TPS is currently reading .5 closed, 4.5 wot, or VERY CLOSE to those numbers.. I understand the urgency of a data scanner honestly wish I had one..

ezone

Surges repeatedly after warmup?

Low coolant level? IAC gets screaming hot with hot antifreeze?
(Is your IAC on the bottom of the throttle body, or on the back of the intake?)


You jumped wires at the thermoswitch and the fans do run?

Might look for other things that would let it look like boiling, like cap can't hold pressure or low coolant level, or head gasket combustion leakage.

TPS voltage sounds close enough, but what does the computer think it is?
Same for coolant temperature, since the computer uses a separate temp sensor from the gauge.