RobEvans

Hello, i am starting to get really annoyed with my car in traffic with it hesitating and jumping when hot so i have been keeping a keen eye on my sensors for the past few week with torque app. Everything seems OK though?

One thing i have noticed is the air intake temp sensor stays at 20 deg even though it is 2 deg outside and the car has been stood for hours?! Is this normal? It reaches as high as 60 deg in traffic!


So far i have ...

Checked the TPS with torque app and tried adjusting (can i remove and clean?)
Changed plugs
Tightened the throttle cable
Cleaned the MAP and passages to the MAP
Checked for air leaks
Cleaned the throttle
Cleaned the ISCV
Fitted a K&N with heat shield
Cut holes in my bonnet to try and stop heat soak!
Checked map, intake temp, tps, lambda with torque app

Any advice would be great! I have ordered a new MAP sensor also

Thanks. Rob

rob-2

Sounds like heat soak. Pretty common in stop and go traffic. I feel it most at 4500 feet when it's above 70f out.

zeroptzero

Have you cleaned the idle air control valve ?. Are you running an aftermarket intake ?.

ronnuke

I had similar issue with mine. I thought it was heat soak as well but it turned out to be bad spot on the TPS near idle so that it would hesitate when trying to accelerate from stop then surge ahead strongly as it got past the bad spot on the TPS rheostat. I fixed it by purchasing a new throttle body with new TPS attached. Larger bore doesn't hurt either. HTH

RobEvans

Well for the past 12 month I just put up with it thinking it was heat soak but it's effecting normal day to day driving even when it's cold, this can't be normal can it?

I also suspected the TPS thanks for that information! If new Map doesn't work I will try that next.

My fuel trims are - 12 in traffic and - 8 on motorway if that is normal also?

Thanks for the info guys

unclefester

https://www.s2ki.com/s2000/topic/856...roblems-fixed/

Have a look at that

RobEvans

Thanks unclefester i removed and cleaned my idle air control valve, lots of black crap cleaned out with carb cleaner but the problem still exists. Thanks for posting though!

xviper

Yes, it can. My car and many, many others have done this since new. Even though it may be cold outside, the intake manifold can be hot. I can make my car do the bunny hop and idle so low, it'll rattle when it's -20*C outside during stop and go traffic. Meanwhile, the intake air temp can be over 60C. Knowing how to make it happen and knowing under what conditions it can happen, it choose to not let it happen.
1. Make sure the engine is in a good state of maintenance - plugs, air filter, clean injectors - the usual normal stuff, nothing special.
2. When driving in such conitions where the engine has a tendency to fluctuate in rpm or the car tends to "kangaroo", learn how you need to drive it so the condition is minimized or even eliminated. Learn to clear the intake of hot air, especially when the car is operating in stop and go traffic. Just before you are ready to get rolling again for those few meters, either use higher rpms to help clear the intake of the accumulated heat air or learn to be very delicate with the clutch so you aren't demanding so much TQ and HP to get it moving. Learn to "feather" the clutch and throttle. The more you blip the throttle, the more it will tend to dip into very low rpm. Trying to drive at near idle speeds when the intake is hot will produce a tendency to jump and kangaroo, so don't do it. Don't let the clutch all the way out and try to drive like that. If it's only to close up the gap in slow moving traffic, feather. If traffic finally gets going and you want to speed up, use more revs, use more clutch control till the rpm gets past that "near idle, hippity hoppity" phase.
3. You don't have to believe me. You can continue to search for the answer to a non-existent problem.

RobEvans

Thanks for posting xviper I was hoping that would be the case to be honest. Is their a design flaw in the s2000 engine that causes the intake chamber to warm up excessively when off the throttle? Do all S2000s do this or just the odd one?

The only reason i ask this is because i have owned lots of cars and never experienced a problem like this with any other petrol engine?

I will get my fuel injectors cleaned as soon as I have sorted the seized geo bolts =)

xviper

The AP engines are very high output, high performance and high strung. Many such engines can exhibit similar traits. However, some people are simply better at operating those vehicles so as to minimize these behavioral quirks. A lot of it has to do with driving habits. We all operate a car in a slightly different way and some will show these tendencies while others won't. In a lot of cases, the operator would just like to blame the car rather than attribute it to the way they drive. In some cases, it may very well be the car or the way it's been maintained.
My previous Dodge Viper did it (if I let it). My previous Corvette ZR-1 did it (if I let it). My 13 year old AP1 does it (if I let it). We sometimes forget that the S2000 is powered by an engine that cranks out extremely high numbers per litre. To make such an engine run well for daily domestic street duty requires the monitoring of a lot of parameters and constantly adjusting to the motor's tendency to just quit. Sure, you can program out (for the most part) all such tendencies, but then, you end up with an engine that's like any other run of the mill engine. A lot of motors these days can crank out 240+ HP out of 2L, but they use turbos or superchargers - not quite the same.
This thing runs what, in the "old" days, could be called "high race" cams, even before VTEC kicks in. Such engines don't want to idle or run at low rpm. The fact that it does, much credit must be given to the engineering behind it. Well, every once in a while, you'll run into operating parameters that can tax the limits of the ECU's ability to operate the engine smoothly.
Of course, it's always easiest to just say that there's wrong. What could it be?