vermillion

Ok guys, I need some help with this. I've written about this subject before, but now that my car is at the Honda dealer waiting to be fully diagnosed, I want some educated opinions on what may be happening.

Some back ground on the car, its MY2000 that I have owned since new. I have 52K on it and have SOLO II the car regularly since 01. The only thing modified is a K&N filter. I have been religious about changing the oil, checking the oil to make sure that is at the right level, and always running good gas in the car (95 % Sunoco 94).

About a year ago I started having an idle problem. It would typically happen when the car had been driven pretty hard; when approaching a stop the car's idle would stick at 2k rpm, and then slowly drop though idle, ending up at 300 rpm, with the car stumbling badly. Unfortunately for me, this was always an intermittent problem. I could run the car for weeks and not have a problem. Then it would reappear - but it never threw a CEL.

I lived with this for about a year until it got progressively worse. I decided to replace the idle air controller. This helped the problem for a while. Then my problems came back with a vengeance.

A week and half ago, the car started poorly for three or four days. Then one morning, it started and immediately threw a flashing CEL. The car stumbled, hesitated, and then it cleared up. I drive the car to work, but I was very concerned about the engine. The next day I had to run several errands in the car that demanded a lot of stop and go driving. Well the idle problem reared its ugly head and the car finally threw a solid CEL, started missing really badly, and finally wouldn't hold an idle at all.

I had the car towed immediately to the dealership, which is where it has been this week.

They started to diagnose the problem, and found that the car had thrown MAP and TPS codes (I'm not sure what else). They have contacted Honda, who have given them a number of procedures to follow, but currently Honda is suggesting a bent valve.

But the kicker is that the dealership is currently saying that the car starts and runs fine (with no CEL).

I find it hard to believe that a bent valve would allow the car to run OK on start up, but then poorly after it had warmed up.

Oh yes another detail: I had the puffing exhaust which others have written about on this forum.

So my questions are: before I battle the extended warranty and have the head re-built, is there a less expensive, more likely cause? (I have long suspected the fuel injectors - it seems that several people have had similar problems traced to that). Could it be the throttle body? Could it be a bent or lose valve? (Yes a red line the car frequently, and I do occasionally bump the limiter, but never hard, and never for long).

To their credit, the dealership is still looking into the problem and have not yet made their final recommendation. I'm looking for any ideas or advice you guys have.

moparacker

I see you have a '00 model car. Have you had the spark plug recall performed? Engine miss and a CEL can both be caused by loose spark plugs, which the recall/tsb addresses.

TSB 02-042

You might want to have the dealership check into this....

vermillion

Thanks, I meant to mention that I have had all of the TSB's for MY2000s done at the same dealership. In fact the idle problem appeared AFTER that TSB was done.

xviper

On what basis does the dealer say you have a bent valve? I don't see that throwing a MAP or TPS code would lead them to this conclusion.
I think they should key in on the MAP thing. You indicate that when you run the car hard is when these symptoms show up. It has been noted here in the past that running hard produces more oil vapours that can contaminate the MAP sensor. They should simply replace the MAP sensor and go from there. If you still had the car in your possession, I would suggest to do the "MAP whack" and ECU reset but telling them to do this may serve no purpose. Most service techs don't know of this technique and cannot think outside the box.
The few days of poor starts may only be a coincidence and have little or nothing to do with your situation. About this time of year, many S2000 owners will experience this phenomenon. It is not uncommon for the change of season (ambient temps, humidity, barometric pressure, etc) to give the ECU a momentary brain fart. Most owners having this scenario will report that after a few days, the ECU "learns" and the car will not do it again till a year later.
The "flashing" CEL, however, does concern me and should not be taken lightly. This could mean anything from a misfire to this TPS thing that was mentioned. Only checking the functioning parameters of the TPS, can they be sure that it's not the cause. Worst case scenario is a bum ECU. But since they now tell you that the car is running fine, it would be hard to justify an engine tear down. If you can have the whack and reset done, that might be a very useful exercise.

(Perhaps once you get this stuff behind you, an oil catch can might be a good idea considering the type of use you put your car through.)

vermillion

xviper, thanks for the input. I've tried the MAP-whack and ECU reset a number of times and it has never seemed to help the situation. I was very concerned about the flashing CEL as well, but since it cleared up quickly I initially though it might not be anything bad. But that was probably not the case.

So far its Honda that is suggesting a bent valve, but this doesn't seem right to me. I would guess that a mechanical fault such as that would cause a constant problem.

There is a recent post here about a bad TPS - since that threw a code, I'm hoping that it might be prudent to replace the MAP and the TPS (throttle body) before tearing down the engine.

If you have any other thoughts let me know.

xviper

Be prepared. They may be setting you up for the "OWNER ABUSE" scenario.

vermillion

Yeah, I'm wondering about the owner abuse scam myself. I guess I'm pondering if I should simply instruct them to replace both the MAP and TPS sensors a go from there. A motor tear down doesn't seem right to me.

I'm hoping some others will chime in on this subject.

marcucci

First, and it's a technicality, but you won't get a bad idle from "a" bent valve. Multiple bent valves, yes. This will really only occur with an overrev and generally happens to all the exhaust valves.

The good news is that you can ID this easily- have them perform a leakdown test. That will tell you if it's intake valves, exhaust valves, or the rings that are leaking.

I don't see the MAP and TPS codes being thrown for a bent valve. I forget the exact code but it should be the one that is for the valve adjustment being off (another good thing to check).

My guess if the MAP and TPS codes are being tossed is some kind of electrical gremlin, or a poor/missing ground connection. The probability of the MAP AND the TPS both being intermittent is basically zilch.

vermillion

Thanks for the input. I'm planning on visiting the dealership tomorrow to find out exactly what codes they have found. This should hopefully explain what may have gone wrong.

So let me try to clarify this: it seems that most are argreeing that a bent valve is unlikely. The next steps, as I see them, would be to replace both the MAP and TPS sensors. If the problem persists, move to the Injectors, and then the ECU itself.

I'm I correct in this assesment?

Since I'll be footing the bill for most of this myself (even with the warranty) I'd like to progress in a logical and relatively inexpensive manner.

Am I incorrect?

Slows2k

If the CEL was flashing, It will have misfire DTC's stored. Period. That is the only cause of a flashing CEL, a misfire bad enough to damage the convertor.

A mechanical overrev only occurs from a downshift to to low of a gear, usually by accident. If you are under acceleration and hit the limiter, you won't bend a valve.

Valves that are too tight can throw a P1129, and will also show leakage through the effected valves on a leakdown. I'd wait to get the DTC's before guessing anymore.