Cyclon36

My S has been running horrible for the past few months and I just haven't had any luck whatsoever in figuring out what's wrong. I've been reading threads constantly trying to figure things out and have already start throwing more money at this problem than I probably needed to. My local Honda mechanic can't seem to figure it out and I've exhausted all my ideas so I'm posting here as a last ditch effort to find a solution.

First, let me fill you in on the car so you all know what we're working on here:

2005 w/180k miles on the odo
No engine mods besides Injen CAI

What's going on and what's been done to try and fix it so far:

It started with a rough idle a few months back and what felt like misfires on the highway (short bursts of power loss on steady acceleration). No codes were being thrown so I didn't know where to start. It was due for a valve job and new plugs so I started off with that to see what happened (plugs showed good combustion). Unfortunately, it did not fix the problem. A few days later, the car finally threw a code (1129 - map value too high)so I give it the ol' map whack. This actually solved the problem for one day and it ran great but the problem came back. I figure the map sensor had just seen better days so I went ahead and bought a new OEM map sensor. Again, it ran great for one day and the problem came back. Next line of reasoning was to check the IAC valve and clean that up but nothing changed with that. For some reason, it seemed as though every time I plugged and unplugged one of the harnesses it ran better. So, I got a can of the electronics cleaner from Autozone (made for cleaning harness ends/etc). I went to work on the harnesses in the area and when I was done, everything ran great....for a day. All this time, the 1129 code was being thrown every now and then with very rough idle and the car would go into limp mode sometimes. It also turned off constantly every time I stopped. I tried the cleaner a few more times and it seemed to work at first, but after a while I noticed no change regardless of my cleaning.

I finally gave up and went to my local Honda mechanic (not Honda, just a specialist that works on Hondas). After a bit of diagnosing he came back with a low reading on the throttle position sensor. He tapped it a few times until the reading came up to spec and sent me on my way telling me to keep on the lookout for another one. The car ran fine, again for just a day. It almost seemed like it wasn't getting enough fuel since it kept shutting down on me. I tested out the theory by turning my key on twice and priming the fuel a bit more that way. When I did that, it seemed to start up and run smoother. I did that for about a week until that stopped working altogether. By that time, I had received a used throttle body I bought and replaced the sensor on mine with the one from the purchase. The replacement throttle position sensor didn't seem to solve the issue so I took it back to my mechanic. After a bit more looking around, he said that my injectors were leaking causing too much fuel to get into the system. I didn't want to fool with troubleshooting o-rings and what not so I bought four new injectors from Honda and replaced them last night. After the install, it seemed all my troubles were gone...until today. It seems that no matter what I do, the car can't stay running good for more than a day. At the moment, it only stalls out when the engine is cold but rough idles otherwise. When I press the gas, it doesn't do anything for about 2 seconds or so and then you can feel the power kick in but not as much as it should. Starting off the line is horrible as I need to keep my revs up or it will bog down completely. Oh, and the ECU was reset several times trough this whole ordeal as I tried new solutions. I also cleaned and checked the PCV to be working correctly.

I don't know if this is related or not, but I've had a modifry temp gauge adjuster installed pretty much since I got the car. It was actually the first one he made since he used my car to design it for the AP2. It doesn't seem to be reaching the normal operating temp but falling one bar short which should be around 180F or so. The mechanic says it does reach normal operating temp so I'm guessing this isn't working right either. Not sure if it's related since it doesn't tie into the fuel system at all.

Sorry for the long story. Just for a recap for those that don't like to read but still like posting suggestions here's everything that's been done to attempt to fix the issue:

Valve Adjustement
Plug replacement (all plugs showed normal operation)
IAC valve cleaning
Wire Harnesses in area cleaned
PCV cleaned and checked to be OK
TPS replaced w/OEM
MAP replaced w/OEM
Injectors replaced w/OEM

Thanks for any help.

-Joe

MR.T

I was going to hold my comments because I am new to S2000's, but no one ha replied so I'll throw in my thoughts. Keep in mind they may be way off.

While resetting the ecu the procedure per HElMS is to:
-Reinstall backup fuse
-rev motor to 3k while using no lights, radio, etc.
-Wait until rad fan kicks on (meaning car reaches operating temps)
-Then let car idle for 5+ minutes
This is an idle learn process.

So basically, I wonder if there is a link between your temp sending unit not letting the ecu know that it's up to temp, thus never allowing a complete idle learn process.

Just a shot in the dark, but maybe it'd be worth replacing the temp sensor and trying to reset the ecu once more.

When I first got my car I disconnected the battery, but didn't know about doing a proper idle learn process. My S was cutting off almost every time I would come to a stop.

MR.T

Also, the o ring on the map, did you bother replacing that? Beyond that look for vac leaks too.

Has anyone tried pulling any freeze frame data from your dtc's, or air fuel ratio?

I know how you feel man, I just got my 03 about a month ago and it hasn't been right for over 3 weeks now.

Cyclon36

Thanks for the tip. I'll try to reset the ECU per those instructions. The MAP came with a new o-ring so i'm good there. Oh, and forgot to mention I also replaced my throttle body gasket as some have mentioned those could cause similar symptoms when old. I've checked for vac leaks. All the hoses seem good and seal up tight.

My mechanic pulled some data and showed some misfiring (probably the power loss I was feeling at cruising speed). He didn't mention anything other than that though.

Cyclon36

Well, that didn't work. Did the procedure till I reached temp. Let my foot of the gas and the car promptly died. Also, it's running really rich. I can smell it the second it starts up. Something is telling the pump to dump fuel in.

MR.T

I guess I was saying that maybe your car never recognized the fact that it's actually up to temp, hence the gauge not showing full heat, so it can never complete or correctly complete the idle learn.

That's assuming that reaching operating temp is a necessity to the idle learn process. Like I said, I'm new to These cars, so maybe the best thing to come out of my replies is for someone to tell me I don't know what I'm talking about and offer you some real advice, haha.

Good luck though man.

Cyclon36

Ok, threw a few more codes just recently. P0172 - System too rich (bank 1) and P0128 - Coolant temp below thermostat regulating temp

I pulled the plugs to see if any one was off. They all seem to be light brown and in normal condition.

The temp one gets me wondering. Is my thermostat broken and stuck open or is my water temp sensor bad. If the thermostat is stuck open, I would figure it would at least reach full temp if it was sitting still in the sun which hasn't happened according to the temp gauge.

zeroptzero

Hey Joe, sorry to hear of your issues, it certainly sounds very frustrating. I'll throw out some ideas.

Firstly, spray down the small orifice under the map sensor, it goes from the map sensor into the throttle body to the manifold air flow. Spray it down with some parts cleaner in case it is blocked up. Make sure you still have an o-ring under the map sensor and it didn't get lost during the MAP swap.

Secondly put a zip tie around the map sensor clip and the map sensor to keep the parts tightly connected, some s2k's have had issues with the two pieces being loose.

I had the coolant temp code that you had and my thermostat was stuck open, my car wouldn't warm up properly, the car runs weaker like that but I didn't have any driveability issues like you described. My stat was jammed open with a piece of aluminum weld material from my aftermarket radiator.

You should have swapped in the used throttle body the way it was rather than swapping the TPS sensor in case the readings of the sensor changed during the swap. I have a spare throttle body if you want to test it out - no charge - hit me up by pm if you want me to send it to you.

Good luck with things buddy.
Joey

Cyclon36

Joey,

Thanks for the feedback. I cleaned out that little hole when I changed out the map and again when I changed the body gasket. I opted to put hex screws in for the TPS so I can change it out easily in the future. After I did the TPS swap, I took it back to my mechanic so he could set it at the proper spot. I'll take you up on the offer though. There's always a chance the used throttle body I bought was a stinker. PM coming...

MR.T

There are ways to check O2's with a simple volt meter. Just YouTube "diagnosing O2 sensors"

You could get an infrared temp gauge and measure at your upper and lower rad hoses. This will help diagnose wether you have a bad t stat or just a bad temp sensor. Personally, I'd track the temp problem down first.
I wonder if your O2's aren't simply heating up enough if your car's not reaching temp. Does your fan kick on if you let it idle for awhile?