Long time no see guys! I have a problem.

This only happens in the mornings on the way to work after the car has sat all night.

Civic, 1998, D16Y8, 5 speed.

About 5 miles into my commute on normal city roads (not highway) I feel a shutter and the power drops. If I let off the gas the rpms jump from the normal 50-80 to right at 1200. Then I stop at a red light and turn the car off. I give it a ten count and crank it up. After I turn it off and start it up again it runs fine the rest of the 10 mile trip to work. On the way home in the afternoon it runs great.

So what is going on with this thing?

 

Bump?

 

Check for vacuum leaks

 

Take a look at your main relay, but first I would just clean my injectors with a injector cleaner you can get from walmart. Also take a look at your spark plugs.

EDIT: Vacuum leaks too, could also be a washed up 02 sensor or map sensor. Any cels?

 

Yeah, the CEL is on. I need to get the coeds rechecked as it has been on and off again several times over the last few months. I ran Lucas with a full tank of gas last week.

The problem is getting worse I swear by the day. I use to get several miles from home before it would start. Now it is only a mile or two before it starts. Turning the car off and letting it sit for a few minutes fixes it for the rest of the trip to work, but this is really weird.

 

Don't expect any car to run properly with the CEL on. Pull the code and go from there.

 

Just got my codes pulled.

P0108 MAP sensor circuit high voltage.
P0420 Cat efficiency low-bank 1

So as I understand it the MAP would cause the idle issue, but why in the hell would it only do it in the morning and not on the way home in the afternoon? Should I go ahead and clean the IAC and throttle body? What about bleeding the coolant system?

Also, since MAP sensors are $70...can you clean a MAP sensor?

 

I am going to keep posting here in case it helps someone else down the road and so that maybe someone will chime in with some advice.

Well after a fun afternoon of cleaning, scrubbing, and more cleaning... She still is running weird. I cleaned the IAC, MAP sensor, and throttle body. I am going to get a new MAP sensor in the morning. There is a new symptom though...When I press the gas pedal lightly the revs dip sharply and the engine almost cuts out. I think it would die all together if I didn't let my foot off the gas quickly. I have tried this about 30 times and every time it tries to die.

Could a bad TPS cause this? Or is it just a MAP issue?

 

You can't clean a MAP sensor. It is a solid-state device with no moving parts.

 

Sorry, I meant I cleaned the contacts on the MAP, not the MAP itself.

Also, I finally got the battery I needed for my multimeter and tested everything. The MAP was dead as a doornail.