Hondaboyracer

Any advice or comments appreciated

There is so many MAP sensors on ebay that state they're "oem genuine denso" selling for less than $20 but Honda quote me just shy of $500. Obviously they are not oem genuine. So my queries are;

What makes the dealers sensor so much better than the generic denso?
Will it cause premature wear or damage to my engine if i go generic?
Or is it just more likely to play up sooner, or throw signals that are slightly incorrect to the ecu?

Ive been putting off an idle issue for long enough. I dont want to start throwing cash at it when i dont exactly know what the cause. Ive heard of guys replacing a list of parts out and still having no luck. I might just buy generic parts until i find whats causing the issue, then purchase the problem part directly through Honda.

Sorry about the noob question. Im just interested in the science of why we shouldnt use certain cheap parts and what we can get away with. A mate of mine cheaped out with a coolant temp sensor ages ago and its been working a treat

What do you guys think?

Midnightdennis

OEM is denso. Check out pro import tuners. They sell genuine map sensors cheap. I’ve used their denso map sensors without issue.

As to the issue of whetger you should go oem or ebay. Just do what works for others: check reviews, forum feedback etc.

Billman250

Idle issues are typically not MAP related.

The OEM map sensor can be freed up, or “map whacked”. I did mine 120k ago. It is has been great since.

With the engine running, go under the hood and rev the engine frequently up and down (only need to go to 2k with each rev)

While doing so, lightly tap the map sensor with a small screwdriver handle (2-3 times per second)

Do this for 20 seconds.

Thomas Guide

What kind of idling issue are you experiencing? If you could describe it someone might have a solution for you. The OEM sensor is made by Denso and is around $80 including shipping, not sure what the dealer is trying to sell you for $500... If you're going to replace it, go with OEM it's a few bucks more and a piece of mind that you have genuine Denso and not cheap Chinese knock off. Because the way the S is tuned and setup, its important that certain parts be of high quality like the sensors IMHO.

2004 S2000 S2000 MT Throttle Body

Here's my recent experience the last few weeks of resolving an idle issue that had been getting progressively worse over the last few months and I also did not want to spend a lot of money on parts.

I resolved an idle issue where it would drop to 500-600 RPM and shudder as if it would stall (it never did). I was doing the MAP whack technique more and more, it wasn't a connection issue as there were zip ties already on the sensor. I ended up replacing the MAP sensor with an OEM one (I returned an Amazon one that claimed to be Denso but had all the labels removed, they claimed it was Denso but it looked completely generic with no labels, I didn't want to trust it) and for a couple weeks it seemed fine then it slowly started to come back. I felt this couldn't have been the MAP sensor then so why did it fix itself then come back?

I researched this a lot, and determined that in my attempt to remove the original MAP sensor I almost stripped the screws. During the process of backing them out, I had to hammer a JIS screwdriver into the nearly stripped screws to get a good grip, in effect doing a very solid 'MAP whack' on the throttle body and most likely loosening some carbon build up in the throttle body air intake channel (that's the little channel of air that goes from the MAP sensor). I tried a suggestion of removing the MAP sensor and spraying compressed air directly into that tiny hole (cold engine and let it sit for a bit afterwards to ensure any fluid from the compressed air that may have accumulated dried before starting engine). I did it a few times and the idling issue got much, much better. I concluded I had carbon build up in my 103,000 mile (original owner) S and the intake manifold nor IACV were ever taken off and cleaned.

So I decided to clean out both the throttle body by completely taking it off and also the IACV. The battery was completely disconnected for this effort which required an idle relearn afterwards. I took off the throttle body and there was some crud in the channel at the bottom, I probably did blow a bunch out from the look of it using the compressed air. I also took off the IACV and cleaned it up real good as the roller valve inside was binding from the carbon gunk. Overall I feel it was a success. Just make sure to replace all your gaskets with new ones, the throttle body one was very difficult as it had fused with the metal so it took some time to scrape it off.

Parts you need (depending on year, this is for 2004)
16176-P73-004 Throttle Body Gasket
36461-PAA-A01 Rotary Air Control Valve Gasket
08700-9204 Honda OEM Throttle Plate Cleaner

These two video will help immensely, (I also purchased the T20 Tamper proof Torx bit as prescribed):

Clean the IACV:

How to remove the Throttle Body (the beginning part of how to take it off was really helpful to understand visually):

Idle relearn:

Super relevant threads that will help you decipher your problem, as you may have something completely different along the path that is causing your problem.

https://www.s2ki.com/forums/s2000-ta...lution-515674/

and

https://www.s2ki.com/forums/s2000-un...itions-478799/

Hondaboyracer

Ahhh, thank you sir.
I have already tried this but by the sound of that, i was doing it all wrong. I only tapped it about half a dozen times over 2 or 3 seconds.

Will try it out when i have a chance to get out to the shed and then post back with my results. I must say though, im a little sceptical it will fix it

Hondaboyracer

My idle dips down to 400-500rpm when i come to a hault. And when im in a car park using pretty much no throttle and i suddenly stand on it a little it starts jumping/ surging like im learning to drive a manual for the first time. I come off the gas and ease back on slowly and i can take off fairly smooth but i still feel it wanting to start hopping again. Mine also has progressively gotten worse over time.

I cleaned my iacv like that a few weeks back now and didnt really notice any change. Also cleaned my throttle body, manifold and the hole for the map out a few months ago. I never blew it out with compressed air though. I think i may pull it apart again and give it another good clean out following your instructions right after i try doing the map whack.
Thanks for the good info guys

Thomas Guide

When you cleaned the IACV did you take off that black plastic part using the tamper proof hex bit so you can freely spin the roller with your fingers?

Also no need to run the compressed air through the hole if you are taking your throttle body off as you will have complete access to the air channel.

If neither of those two fix your issue, I would replace the MAP sensor and zip tie it down per the TSB.

After that, I would ask when was the last time you had a valve adjustment? Also knowing more about your S, (year, mods, maintenance) would be helpful.

good luck

Hondaboyracer

Sorry for late reply, been busy with christmas duties.

When i split the sensor from my iacv, i was able to spin the mechanism with my fingers but it did have a little resistance. It wasn't spinning freely enough for me to spin it, let go, and it continue spinning at all. As soon as i let go it would stop. It felt it was normal l so i put it back together after cleaning 90% of the gunk built up in the iacv. Some of it was on there too good to remove, but i was happy that i had removed enough at the time.

My car is a 2000 model with only basic mods; exhaust, intake, final drive, catch can and radiator

HarryD

Sounds like you didn't do the job properly then...

https://www.s2ki.com/forums/s2000-un.../#post23351041

Hondaboyracer

Very informative thread. I have read many forums about this issue but never came accross that one. I will try oiling it up a little in the morning and hope for the best.

If i cant seem to get it spinning smooth and freely, is there a fair chance it could be past its use by date?