Random Misfire/Hard to Start Question

[WhiteTsiAwd]

Car is a completly stock 90 AWD. Not the car in my profile.

Symptoms: After sitting for a long period of time(over night), takes about 1 good full minute of cranking then letting off and cranking again before it will even try to run. Then takes about another minute before it will start to run. Every time you crank it after the first minute it will try harder and harder to get running. Acts like it was the fuel filter, but I just changed it and thats not the problem. Sounds to me like it has something to do with the fuel.
Also, after it gets running, everytime you step on the gas pedal it hesitates and wants to die immediatly then revs up.

Things I have checked/replaced:
1. coil
2. plugs
3. wires
4. fuel filter
5. fuel pressure regulator(stock)
6. coolant temp sensor(is bad so im in the process of getting a new one to replace it, but I dont think that that would cause it to do what it does)
7. ECU-caps are fine, as is everything else

So if anyone has any ideas, their grealty welcomed.

Thanks,
Cody

 

[Old Mitsu Tech]

Back in the days of carburetors we had what was commonly known as a choke. This was a cold enrichment device that would allow a richer than normal fuel mixture to facilitate easier cold starting of your engine. Flash forward to present day. We no longer have chokes due to the modern convenience of fuel injection. What we have is a computer that takes input from various sensors and makes a decision based on those inputs to modulate the injectors appropriately. The very first sensor any fuel injected engine sees believe it or not is your temp sensor. If the temp sensor registers 195 degrees on a cold engine the computer does not know any better. Remember, it's stupid and only does what it is told. It modulates the injectors very little as very little is needed on a warm engine. Now, if it goes full cold, -40 I believe is the bottom, you will have flooding and black smoke, general bad disposition on an otherwise fine engine because it is holding the injectors open due to the very cold perceived climate. Remember in the old days when you would flood an engine? You held the throttle open to "clear" it out? Now, on an ambient temp engine when you hold the throttle to the floor, the tps registers full throttle and the pcm seeing this will not modulate the injectors. This is called "clear flood" Both technologies work toward the same results, just drastically different ways.

With that being said, I would do a computer scan to see if you have any codes. Most likely could be coolant temp and or tps code. Tps could be your hesitation if it has intermittent contacts in its windings. Scan and post the results. Good Luck

 

[WhiteTsiAwd]

It throws a CEL after about a minute of running. Its 21, coolant temp sensor. So I know its bad, its reads -75 on the logger. I'm waiting on one I just bought.

So you think that a bad coolant temp sensor would be the reason why it takes so long to start up after so long?

Thanks by the way.

Cody

 

[Ultimatedsm]

Check if your ECU caps are leaking. Those are a common problem for 1g's and can cause all sorts of problems.

 

[WhiteTsiAwd]

ECU is perfect condition. Forgot to add that to what I have checked already.

 

[Old Mitsu Tech]

Good Job