Hot Start Problems
 

When I start the car hot, it would crank for for 0.5 sec, then hesitate a little bit and then fire up slowly. But when I start it cold, there's no problems. Sometimes the hot start is a little rough, but not that bad. However, it just pissed me off today. Any ideas?

It doesn't take long for it to start, but it's just rough.

Anyone?

Heat soak.

?

sup uh, I think the next question would be if you have any coolant loss?

No coolant loss. The rough hot starting happens sometimes, not every time.

how's your comperssion?

Hot starting problems are normally due to worn apex seals/low compression. When it gets bad you might not even be able to start your car after filling up at the pump. It's easier to blow a seal under boost when the seals get worn too so you might consider getting a rebuild once things progress a little more.

Now that might be jumping the gun a bit, just because his car is harder to start when it is hot it does not give a definite sign that he needs a rebuild. It could be a lot of things, I mentioned heat soak as one. I have seen heat soak problems on a couple of cars I have owned, when you shut the car off at full operating temp everything in the motor/under the hood rises in temperature, including your coolant and oil since it is no longer flowing and receving air passing over it. Get a compression test done and you can rule out the motor issue..

Matt
93 touring

When I started having hot starting problems, it progressed into bad o-rings & a rebuild.

I believe the compression is low because there's 85k miles on the motor. But I dont know about the apex seals and o-rings.

I experienced the same problem, but it was right after I installed my power FC. I re-installed the factory ecu and I had a bad h20 temp. thermosensor, and bad intake air thermosensor (I knew about the air sensor before). My car would not hot-start with the PFC and sometimes at low idle it would die and give me problems. Before you worry about your compression, make sure it's not something you did, or a bad sensor or something.

good luck,
eric

did you actually get a compression check? or are you just assuming?

85k miles doesnt mean jack... ive got 90k and runnin very strong

i have a similar problem w/ my FD, however the situation is a little different... from a cold start, my car fires right up, i don't even have to hit the gas, and idles pretty easily after about 30 seconds at 1100rpm. after a good bit of driving, my car seems harder to start, like it has to crank a little more to get going, and the idle is low... very low sometimes, where i have to force-feed it gas a bit to keep it idled up enough to run. the difference is that my motor is freshly rebuilt, w/ only 250 miles on it so far... i do have a pretty aggressive street-port (ceramic coated), but don't know if that would make a difference in this scenario or not. any chance there is something horribly wrong w/ my motor too?

Well, mine cranks much less when it's hot. But like I said, it would hesitate a little bit and then fire up slowly.

hello,
so if the mightyslash's compression was low, then would the ATF trick thing work? I'm not positive about it, but something like adding ATF after removing spark plugs and stuff, letting it sit a while then replacing the plugs, is supposed to help bring compression levels up.(yes i'm missing other events...but) here is a link:
https://www.rx7club.com/forum/showth...&highlight=atf

laters!

I own a 93 RX. Rebuilt the engine. MODS: Single Turbo, Jacobs box and coil, 850cc (p) 1300cc (s), and others.

Using EFI "piggy back" computer. Getting NO ERROR messages. Car starts (fuel pressure = aprox 45 psi, vac about 18) and will run fine at Idle and POT (using EFI adjustments). Car usually dies after 10 minutes, etc unless you increase RPM. Once it dies, it will not start back up unless the engine cools off (usually a few hours later). I tried a work-around from EFI (Push button switch for the fuel pump relay until the engine starts to turn over, but this still does not solve the problem.

Any suggestions will be very helpful.