My car: 1990 LX 4AT. All stock, well maintained. Work done:
-Main relay replaced OEM used.
-Replace new OEM cap/rotor, NGK blue wires.
-Replace valve cover, no oil in spark plugs.
-Fuel filter changed.
-Valves adjusted.
-EGR ports and valve cleaned.
-Change both accessories belt.
-Trans fluid change twice with Honda ATF.
-Oil change regularly and running synthetic with no leaks.
-Timing is good and idle stable at 750.
-Clean air filter and throttle.
-Throttle cable: no slack and not too tight as idle cold at 1500 and warm at idle 750.
-Alternator brushes changed and regulator within the alternator replaced.
-Coolant changed.
-Clean the IACV and FITV

Here's the intermittent problem and I live in Orange County, CA:

-This only occurs so far only when the engine is cold in the morning. And I think this occurs when I adjusted my base idle a few days before, not sure if it's related.
Last winter: With the temp some what cold, I had trouble starting. The car would start easily but it would turn off right away. As soon as it starts, I had to keep my foot on the gas pedal slightly to keep it running. I kept my foot on for about a minute or less and it stay running as normal from cold 1500rpm to warm 750rpm. This only occurred 3X last winter and , and only in the morning, never happens again. Once the car warms up and even if it cools down to a cold during that same day, it never have any trouble starting or holding idle again.

-Well, this morning, a similar thing happens. First, when I start the car, the car would turns over but very weak and it won't starts. I then turn off the key and turn it back on, same thing. The third time, I held the key on and it weakly struggled to turn over, then it starts. But to keep it running as above, I had to hold my foot on the pedal slightly for a minute or less and the it holds idle fine. It has not occurred again today. It fires right up without any hesitation. We'll see how it is tomorrow. I also adjusted my base timing last week but it did not happens until today this morning. The tempt is rather warm at 10AM today so I don't think it is temperature related.

What do you guys think?
I don't think it's fuel or sparks as I get it to run fine once started. I don't think it's the starter as I can start the car all day and it won't occur again. The battery is less than a year as it was replace last January. I checked the voltage and it reads 12.5-12.7V. With the car running and everything is off, and revving up, voltage reads 13.5-14.3V. So it's not the alternator.
What could it be? Any suggestions or any one experience this before?
I have checked all battery connections and cable connections.

Thanks for helping.

 

I have this exact same problem, I can't answer what's wrong with it but it's really bugging me. It happens every once in a while, and the other day it took me 3-4 turns to get it to start. I heard from a buddy it could be the injector but why does it run fine after it has been on? My car overheated about 3 months ago (stripped radiator cap) and that is when this problem started happening. Any answers would be greatly appreciated from both of us!

 

Well my car didn't over heat and the radiator cap is new. Fuel injector. Hmm. Could the fuel injectors do this?

 

Starter and battery tested good. The problem didn't occur today and as mentioned it's rarely happens but I want to know what is causing it before it become too often. In case I get a job or some thing.
I wonder if any one else ran into this problem?

 

Either water in the lines, put in some isoheet. Or you could swap in another FITV. Make sure to take off the top and screw it down all the way.

Your injectors could be dirty. What could be happening is that they need to spray more fuel when your car is cold to offset the excess air due to the air being more dense when your car is cold. You can get a rebuilt set from injectorwhse.

You could also try using some fuel injector cleaner.

 

Suggest leak down test.....sounds like coolant in the cyl's to me.

 

It's possible. You can pull the spark plugs and see if they're coolant color. There would be crystalization on them.

 

It sounds like the TPS (throttle positioning sensor) is going bad

 

Could you explain please what would make you think that?

Thanks

 

Hummm....How would the TPS cause a slow or (to quote the OP) "very weak crank"? Step back and think about this for a second.

 

I checked for every thing suggested. The spark plugs cables are bone dry. No fluid of any kind. TPS is good as no idle or acceleration or bogging down. It has not happen again since that one time this and the winter. This is too rare to have any consistency to diagnose. I guess I'll have to wait for more frequent problem to diagnose it.
Thanks guys.

 

With a leak down test you don't need to wait for the "next time", it will prove or dis-prove (I HOPE I'M WRONG) if the HG is leaking.

 

We never said anything about spark plug wires or cables.

 

Been there done that and it was the tps. In my experience if you got to hold the gas pedal for it to stay on, the tps is a suspect. the only difference is that it only happens to you in a blue moon in winter or cold mornings mines didn't. Btw I found out by testing everything while the car was giving me the problem, a leak down is also a good idea

 

So can that sensor be cleaned or replace by itself? Other than the deal and the JY, where online could I find it? Does it have to be OEM? I found a Dorman brand for about $30.
Thanks.

 

I wouldn't encourage just throwing parts at the problem without properly testing it. I ended up replacing the whole throttle body since the the screw on it was mess up. Do a leak down test since it is more common, then make a plan or list of things (sensors) to check when the problem is happening. A voltmeter helps a lot

 

You have to take the throttle body off. Then you need to use a dremel to grind in a groove into the sensor screw so that you can use a screwdriver to unscew it off. They don't have regular screw heads on them. The factory screws them in then breaks off the head. It might be best to use a impact drive to remove it tho.

Get a multimeter and test it first. You can do that with the throttle body still on the car. You will need a paper clip. I believe there's a sticky in the faq.

It's not often these things go bad, but they do.