I was driving my car into the shop today. It warmed up just fine and I was about halfway through my 7 mile journey when I accelerated hard into VTEC to pass someone. The car just hiccupped at about 7000 rpm. It was so quick I wasn't sure that it was the car and not me, or a pavement irregularity, who knows.

Next stop light, I take off quickly and the car feels very sluggish, I can't even rev it high enough to get to VTEC and it doesn't want to accelerate at all. Smells rich. I cruise at part throttle and its fine, but try to accelerate and it bogs. Next stoplight, it idles for a minute, goes rough and stalls. Now I'm worried about a loose plug, but I replaced mine with irridiums already and tightened them properly. Car takes many cranks, but restarts and idles, slightly rough.

I'm only a mile from the shop now, and would rather have the car there than home, so I limp it in. I've got about a half hour before my customer shows up, so I pull out the scan tool, pop the hood and grab my toolbox. A check of the scantool shows no codes triggered and none pending. That is weird considering how poorly the car was running. I look under the car to make sure that nothing has come disconnected on the header (Mugen), nope, looks good. All vacuum lines are fine. I pull the plugs, they are all dark, as if the car had been running rich. That's no surprise. But no signs of detonation, oil fouling, etc. All were tight. A check of the dipstick shows plenty of oil and its clean.

At this point, I want to finish up before my customer gets in cause I have to leave right after we finish, so I thwack the MAP sensor with a rubber handle, regap and reinstall the plugs and reset the ECU. Everything works fine now - in fact, the car felt much peppier than I remember in a long time on the bottom end and at part throttle. Perhaps this problem had been creeping up on me? Due to my time crunch I wasn't able to do a systematic "one change at a time" correction process and see what fixed it. Since the fix I've driven 90 miles with no problems.

I've never had a bog/stall like that before. My gas mileage has been somewhat erratic (very low city mileage, then occasionally it goes through the roof) for a couple years, but I never had any of the MAP sensor symptoms. And of course, my warranty is up on Friday :-) I did a search and didn't note any experiences quite like mine, so if anyone wants to share, its appreciated. Mods are the Mugen header and AEM intake.

Oh, the interesting data point? I took my OBDII scantool with me as a diagnostic tool just for peace of mind. On my way home tonight I stopped at a fast food joint and got a burger. 20 minutes later I got in the car and started it. Ambient temps were 55-60 F. Intake air temp after the heat soak? 172 F!!!! I've never seen it get that high before (usually hits 150 or so). No wonder the car can feel sluggish after a short heatsoak. 20 minutes must have been the peak time. Just long enough to absorb plenty of heat, but not long enough to start cooling off. I really need to install that Hondata gasket.

UL

 

My Map sensor has seen more than one healthy smacking.

Josh and I both have had issuses with this for a long time. Replacing the map doesn't make a difference, it will come back.

So far my map's seen maybe 4 whacks. Josh's on the other hand has shown the business too many times to count.

-Ry

 

UL,

How often do you reset your ECU? If I reset my ECU every few weeks, I generally notice a slight increase in performance. If I reset it every time I drive it (pull the ECU backup fuse, and leave it out), it starts running crappy after a few days. I think the ECU reset restores the WOT performance, but makes it run too rich at partial throttle, so the plugs start to foul.

A few weeks ago, I started working on a 555 timer circuit to automatically reset the ECU once a week, but I got side tracked.

 

Hmm, I wonder if we're getting oil build on the MAP. The last month I've done a couple of track events and was getting more hard right turn oil smoke than ever before (slight setup change). Maybe the extra oil getting through the breather is screwing up the MAP. Might be time for that catch can.

Gernby, the only time I reset the ECU is if I change something on the car.

UL

[QUOTE]Originally posted by krazik
[B]My Map sensor has seen more than one healthy smacking.

Josh and I both have had issuses with this for a long time.

 

can you tell me why we need the lines at all? Why does the head need to breath?

I have been told before it was a smog thing.

Smoking is becoming even more of a common occurance on my car.

 

I had the exact same thing happen on my car one morning while driving into work. I had just stopped at a signal when all of a sudden, my car started to idle rough and the check engine light came on. The car nearly died. While waiting at the red light, I decided to see what would happen if I shut off the motor and started it again. So I did, the check engine light turned off, and idle returned to normal. The light turned green and the car has driven normally since then.. *knocking on wood*

After reading many of the threads, I attributed it to the Map sensor. So now, I just give it a good whack with the head of a plastic screwdriver every so often. Seems to be keeping those MAP sensor gremlins at bay..

 

I had problems with the MAP early in my car's life and once since then. Whacking is effective and have had to shake up my new sensor as well as the old one. I do think we have more reports in cool weather.. maybe a combination of contamination, temperature, and humidly causes a sticking of the mechanism.

 

I had the high-rpm hiccups, but never the idle problem. What fixed me was re-seating the wires that go to the sensor. I've never done anything with the actual sensor. No problems since then.

 

Positive crankcase ventilation. Its primarily emissions. However, the line to the intake just in front of the TB is an _intake_ line, so you could just put a filter on the end. However, oil might come dripping out of it, so you'd still need some sort of catch can.

UL

[QUOTE]Originally posted by krazik
[B]can you tell me why we need the lines at all?

 

I've been getting that hiccup every so often and have only noticed it in Fall temperatures, will Fall humidity.

UL, what ECU are you running. When I last got the hiccup condition, I swapped out the Mugen ECU for the OEM (I wanted the dealer to diagnose it), however that hiccup went away.

I've plugged the Mugen back in, a few driving cycles later and no more issue.