Answer me this...starting problem.

[Coitis1]

alright, tell me if this is my main relay. my car pretty much always starts fine, except on quick errands. like when i turn my car off and run into somewhere and come back out and try to start it within 20 min. It will start then die. this happens for about 5 min. then it starts and is fine. but its only happens when i come back to it after a short period of time. after school i came home and then left agian about 30 min. later and it started fine. :help:

[offthahook]

Hmmm... I think if it is the relay, you will not be able to start it at all. Sounds like a fuel problem perhaps, but I dunno how the car could start at all if the fuel pump was not fucntioning properly. Some of the other fellas will know more I'm sure. BUt your problem is consistent with the crappy solder joints expanding in the heat.

[88LXi/87CRXSi]

Had that problem too. It' probably your ect sensor. does this describe your problem?
SYMPTOM:
The symptom is hard to start when hot. This most often occurs right after a Honda has been driven to operating temp, parked, and restarted a short time later. This symptom may be intermittent and the car may fail to start until the car has cooled back down.
THE CAUSE
The problem most likely is a defective engine coolant temperature (ECT) sensor. The ECT sensor on Hondas will many times fail. The typical pattern is that they look fine at normal temperature, but go "cold" as the car approaches normal operating temperature. You can see this easily by monitoring the sensor voltage. It will start high and will be dropping towards .5 volt and then take off to a high voltage reading again. Some even will bounce around from high to low voltage. The screen capture to the left is a voltage waveform of a malfunctioning ECT sensor on a fully warmed Legend. The ECT voltage would jump from .6 to 4.5 volts.

So now the engine control module (ECM) thinks the car is cold again, when it is actually at normal operating temperature. This really does not create all that much of a problem while the car is running. The injector pulse width (PW) will only vary about .5ms from full hot to full cold.

The problem is when you cut the car off and do a restart. When the ECM "sees" a start signal and a cold signal at the same time it increases the injector PW from the normal running width of 2-3ms to as high as 100ms. A hot engine typically can not handle this much fuel, and the engine floods.

At least it was on mine!

-Steve

[Coitis1]

thanks, i'll try to take a look at that.

[anchovies]

Yes. ect sensor. I've got this problem few years ago. But, after I also changed the main relay, all starting problems were gone (hard to start when hot, dificult to start when engine is hot).

[AZmike]

Thanks Steve. I rebuilt my main relay and have still be having some problems starting. I'll try the sensor too. Could a little bit of air in the cooling system cause the same problem if the sensor is good?

[cruznz]

if ect,cooling sys,main relay ok ,it may be leaky injectors which can cause hardstart conditions when hot,.....just a thought...

[AZmike]

I've had this problem for two sets of injectors so I'm thinking they're not the problem. I'm pretty sure it's just the air in my cooling system. I have a slow leak that I need to track down. No puddles so it's going to be a fun search... :rolleyes:

I figured since the air in the system causes the gauge sender to give bad readings the ECU temperature sender right next to it could easily be doing something similar when I try to start the car after a short drive.

[AZmike]

The ECT sensor is the one the Honda manual calls 'TW', right? closest to the head on the thermostat housing? (under the white clip, not the green one)

Is that the one? Mine was giving me some crazy readings and it has a little corrosion on it. Contact cleaner helped, but it still seems dead sometimes. I just want to be sure I replace the correct one.

[anchovies]

yeah TW sensor. about $37+ from Honda.

[88LXi/87CRXSi]

Originally posted by 89LXi4dr
The ECT sensor is the one the Honda manual calls 'TW', right? closest to the head on the thermostat housing? (under the white clip, not the green one)
Correct on all counts! The service manual refers to it as a TW (temperature water) sensor. White clip, not green one, closest to the head. Erratic readings, sure sounds like it may be causing trouble.

-Steve

[AZmike]

Sometimes I'd get 200-400 ohms as expected, other times I wouldn't even get continuity. I've been trying for a long time to find why I've having hard starts sometimes. At first I thought it was the main relay, but now it looks like I've found the real cause. I'll find out shortly.

Any idea the 'thermo switch' sensor under the green clip does?

[AccordEpicenter]

If I remember correctly there is also one in the radiator, in the bottom near the drain valve, and somtimes those go bad too, just like the upper ones.

[anchovies]

Originally posted by 89LXi4dr

Any idea the 'thermo switch' sensor under the green clip does?

It's the switch for the radiator fan.

[AZmike]

i thought that the sensor on the bottom of the radiator controlled the fan. Which one is it? Or does the computer take a look at both before deciding to turn on the fan?

[anchovies]

The different switches control different fans at different temperatures. The computer does not control the fan. The computer just monitors the temperature via the TW sensor. The temperature switches control the fans. Hope that clear things up a little.

[dXsquared]

well why not try the TEHSKDO SJD SENSOR!!! i was amused at all the letters about sensors!!!

Travis

[1987HondaAccord]

So thats my problem... Ive been trying to track down the problem and a few days ago i found this wonderful site. :) I looked at the blinking led for the pgm and it says its the ect sensor. But i also have bad injectors... which should i do first?

[anchovies]

If injectors are leaking...I guess that's a no brainer which to replace 1st. The ect sensor might just give you starting problems or bad fuel mileage and power.

[1987HondaAccord]

All of this sounds like my car. I dont think the previous owner did as much as he should have to maintain it :( But I like working on this car :D

Its all good

:cool: