NorthCyprus

Please read this;

It's been nearly one year since i brought my 02 s2k with 36,000 KMs on it. (20,000 miles) Like i mentioned it here like 9 months ago, i have a problem with the car. Similar to the classic MAP problem but it never goes away. Everytime the mechs touch the engine, like take the injectors out and clean or take the throttle body out and clean, the problem seems to go away but it defineltly turns back everytime. The problem happens after driving a while like 10-15 minutes and when the eangine heats up. The more it heats up, it gets worse. The problem is big loss of performance and the car simply dies. When i give more throttle, goes more slower. Qrter - half throttle, does it less but still, dead.


Now, i know u gonna ask me what mods i have on the car, what's my driving style, petrol i use, anything i did to solve the problem or any parts i changed.

Let me tell you one by one. (Most under the warranty of the dealer)

ECU changed, MAP changed 2 times, Coils changed, Spark plugs changed 3 times, Throttle body cleaned 2 times, Injectors changed to 550cc, than back to 360cc, Clutch changed to ACT, Thermostat changed to Mugen (with fan switch), Air filter changed to Trust, than back to stock, than back to Trust again, All the visible sensors on the throttle body exchanged from another s2k (exctly same model), Fuel filter (new), Fuel Pump (from another s2k), Cannister (from another s2k), Exhaust changed (not cat) (form another s2k), valve adjustments done, no CEL, honda diagnosis done, ECU reset many times (seems to make it ok for a while) Different types of oil used, 0-40, 10-30, 0-60, Different types of fuel used (91, 95, 98, 100 oct), Greddy E-manage installed to set the new injectors (550cc), didnt do any difference, E-manage and 550cc's out, back to stock,, same. When the problem happens, the car runs much more richer, AF readings and all the other readings are f%&ed up. I drive normal, to tracks no drags nothing. Just normal.

The car's checked by 2 Honda dealers, 1 Crypton approved technician (best in biz here) none of them found what it is.

I think it's something to do with detonation. I was told bad fuel causes detonation, i usually use 91 but same thing when i was using 98 all the time.

What's going on?

Thanks for any help, appreciated.

jojipoji

have you thought of getting a hondata intake manifold gasket?

Wildncrazy

Clean your grounds

Billman250

Best guess: Coolant temp sensor skewed....

NorthCyprus

What do you mean by cleaning the grounds? (bcoz english is my 2nd language i might not understand some things)

Detroit_Doc

I'm new to the Honda world, but have some experience with other fuel injected vehicles. So here is my $.02.

Sounds like you are running too rich. If it is happening during partial throttle we are talking about closed loop operation.

I'm going to assume everything is mechanically correct and we are dealing with a sensor problem which is causing your ECU to overfuel.

I come from a MAF background, but my understanding is that the intake charge is measured by looking at the intake manifold pressure (MAP sensor) and the intake charge temperature( IAT sensor). Then during closed loop operation the O2 sensor (front O2 sensor, not the rear O2 sensor) measures the amount of O2 left in the exhaust stream. The ECU looks at that and then adjusts the fueling.

So we have 3 major sensors used in closed loop operation. The MAP sensor, the IAT sensor (is that what they call it on an S2000?) and the front O2 sensor. The rear O2 sensor is only used for emission purposes and shouldn't have any bearing on how the car runs.

You've changed out the MAP sensor, and it sounds like you may have already swapped the IAT sensor with another car. So all that is left is the front O2 sensor. Can you swap that with a friend's car?

Fuel trim is "learned" over a period of time in a lot of cars. So if the front O2 sensor really is your problem, you will also need to reset the ECU after swapping it out. This is also probably the reason that your car runs better for a while after the mechanics get a hold of it. They reset the ECU and then it takes the ECU some time to re-learn it's bad habits.


Anyway swap out the front O2 sensor, reset the ECU and let us know the results.

NorthCyprus

Sorry for not mentioning in the post before but i did change the o2 sensors two times. There's one on the exhaust manifold and another one on the cat, both changed 2 times. You mentioned that it takes some time for the ecu to sense it's bad habits, i think that's why everytime i reset the ecu, it's ok for a while.I know it's a sensor problem, when the ecu gets confused and the AF readings are a mess, the problem keeps on so the ecu gets messed aswell, causing the problem to get worse.

I think the cooland temp sensor is a possibility.

Any idea where it's located? any diagram links if possible?
PS i still dont know what 'clenaing the grounds' is?
any help appreciated, thnx.

Detroit_Doc

Yes if you've changed the front O2 sensor, the MAP sensor and the IAT sensor, then the coolant temp sensor would be the next most likely culprit.

I've only had my S2000 a couple weeks and don't have a shop manual yet. I just went out and took a look and my guess is that the coolant temp sensor is the white sensor in the intake manifold over the rear most intake runner.

Billman probably knows off the top of his head.

NorthCyprus

If i see a diagram showing the coolant temp sensor i'll know for sure if i changed it or not, bcoz like i said bfore we changed some sensors on the throttle body but i dont know if we changed coolang temp sensor.

I need a diagram to see, and if anybody else with any other thoughts please post.

Detroit_Doc

I was incorrect... The sensor at the back of the intake manifold over the last runner is the IAT sensor.

I did a little searching on yahoo and found some install instructions that mention the coolant temp sensor... Here is the picture they show...