1G hard starts after hot shutdown

GSLENK · Apr 8, 2012

Car takes extra time to start while cranking. When the engine finally catches, it starts rough out low (like ~3-4-500 rpm) and quickly but roughly gets up to normal cold starting idle (around 1400, then down to 1200, then 1100 and eventually to the 900 rpm idle as it reaches operating temp.

It seems to get worse with the hot weather. It seems like the car is heat soaking after shutdown and causing something to happen. I drive calm for the last 5 minutes of my drives (no/minimal boost), and often idle my car for a few minutes (or a complete auto fan cycle, fan off, fan on, fan off, shutdown).

Ecmlink shows my temps maxing at 213 on hard driving/hot day, 200-206 normal hot daytime driving. 196-200 cool night. I dont think im over heating.

I am not running the oem fuel system at all (only the tank to filter, and afpr lines are oem)

I read about hot starts and the need for hot start enrichment, but this happens on a cold car, in the morning, after driving at night.

Im running one radiator fan until I find a good solution or fit the a/c fan properly.

This has been getting progressively worse with the hot summer temperatures.

Any idea whats going on? and a fix?

EAKEREAK · Apr 9, 2012

Check your ect

Jason023 · Apr 9, 2012

did you check your coolant temp sensor, when mine was loose i had a hard time starting the car and my car tended to over heat, its a cheap fix and something to try bud. hope this helps. :hmm:

Alan11 · Apr 9, 2012

i am curious about this too.. it happens to my 1g... i was thinking about the coolant sensor as well, but there is no cel.. I am confused at this point... when cold its starts right up.

Jason023 · Apr 9, 2012

well if its starting fine but your getting an overheat or runnign real hot, make sure u check your fluid level and another cheap fix for that is the thermostat.

Alan11 · Apr 9, 2012

no overheating whatsoever. levels are fine.

Jason023 · Apr 9, 2012

I run 1 fan as well for now, its hot wired to come on once the key is in and turned over without the car even on. Its not the best thing it kills the fans faster but it helps alot. Turbo cars always run rougher in the heat. If its just your idel thats messed up its probly idel surge, but that wouldnt explain the cooling/heating issue only the idel issue.

GSLENK said:
Car takes extra time to start while cranking. When the engine finally catches, it starts rough out low (like ~3-4-500 rpm) and quickly but roughly gets up to normal cold starting idle (around 1400, then down to 1200, then 1100 and eventually to the 900 rpm idle as it reaches operating temp.

It seems to get worse with the hot weather. It seems like the car is heat soaking after shutdown and causing something to happen. I drive calm for the last 5 minutes of my drives (no/minimal boost), and often idle my car for a few minutes (or a complete auto fan cycle, fan off, fan on, fan off, shutdown).

Ecmlink shows my temps maxing at 213 on hard driving/hot day, 200-206 normal hot daytime driving. 196-200 cool night. I dont think im over heating.

I am not running the oem fuel system at all (only the tank to filter, and afpr lines are oem)

I read about hot starts and the need for hot start enrichment, but this happens on a cold car, in the morning, after driving at night.

Im running one radiator fan until I find a good solution or fit the a/c fan properly.

This has been getting progressively worse with the hot summer temperatures.

Any idea whats going on? and a fix?

How much boost are you running, and are you using stock SMIC? is 213 yourwater temp or your intake temp?

GSLENK · Apr 10, 2012

All the listed temperatures are water temps, my AITs are low 100s (I really dont check them they havent caused alarm)

ECT Im guessint is engine coolant temp, I believe I stated those. They are logged from ecmlink.

Anywhere from 200-213 even doing hard pulls. never higher than 213. Not in any of my 20-30 most recent logs.

I might try a "lower" thermostat. how low is safe not excessive? 170*?

I really dont wanna do that or especially not lower than that. I would like to see 185*-195 max engine temps.

Mods are in profile and up t date... 20g turbo

right now, 11psi max. Im tuning from a new install a month ago. almost got the low end dialed in nicely.

Aphix · Apr 10, 2012

Have you removed your fuel pressure solenoid? The FPS raises fuel pressure to richen up your hot starts due to fuel being evaporated in the hot ports.

GSLENK · Apr 10, 2012

yup it is gone. I have an afpr of the fuel lab flavor. Also I mentioned this happens on cold starts also. (hot runs at night, then sits all night, then in the morning hard start)

Im also running rottella t6 synthetic, that may have something to do with it, although I doubt it since its made to be run in a diesel truch which is harsher than my lil 4 banger. Im sure its a 5w40 oil. I might go back to mobil 1 for a lil bit (that T6 really did clean the system out well...)

The1G_Guy · Apr 10, 2012

What size injectors? The bigger the Injectors the harder it is to start during cold weather. Also what do you have your FP set at on the FPR?

I don't know anyone that runs 5-40 everyone I know runs 10-40 or 10-30. Its a shot, how long have you been using the 5-40?

GSLENK · Apr 10, 2012

look up rotella t6 synthetic. Its meant for deisel, but many people use it. really popular on subies, some on evo, even saturns, and some on here use it :thumb:

nice zinc content. I do think it may be a bit light for summer though, Ill do my next change to mobil 1 synthetic... ugh. The detergents in this oil really cleaned shit up.

1050 injectors. they are tuned in via link and have a duty cycle near 1.1-1.4% at idle.

5-w40 since winter. no probs in winter started like a charm. Since I did the AFPR at the same time as the summer heat happenned IDK which one is doing this, just wanted some ideas. I suppose rotelle did as much cleaning as it will do for a while, back to mobil...

1983gsp · Apr 10, 2012

The fuel pressure solenoid opens on hot start to increase fuel pressure in the rail. My fpr at idle with the line disconnected reads 43.5 psi. Connect the vac line and it drops pressure to around 35-38psi. On hot start the fpr opens(disconnects the line) and with the increase in line pressure your injectors spray more fuel enrichining the mix. Hot fuel is less dense than cold fuel so you need more of it to maintain your afr until fresh cold fuel can cool the rail.
Dem der sneaky Asians thunk of ere'thing.

GSLENK · Apr 13, 2012

I dont think its a hot fuel issue. I dont have the factory fpr, or the solenoid. I start the car especially easily about 0-30 minutes after a hot shutdown.

Switching back to 10w30 seemed to help a little, but not as much as I would expect. Cold cranking times after sitting overnight are a little better. Ill see how it gets with time.

ampsyco · Apr 14, 2012

mine was doing the same thing. i replaced the fuel filter. it was full of junk. been fine ever since.

The1G_Guy · Apr 15, 2012

Just a quick question, not sure if this would help, but did you happen to move your battery to the trunk? If so, and you haven't fixed the problem get a higher cold cranking battery.

GSLENK · Apr 15, 2012

ampsyco said:
mine was doing the same thing. i replaced the fuel filter. it was full of junk. been fine ever since.

Same thing? Doesn't matter if its hot or cold, as long as the car sat for a while its hard to start? I have an extra filter... Might as well try.

ampsyco · Apr 15, 2012

yup, hot or cold. idling at like 300 rpm for a few seconds. i would have to rev it a bit to get it to clear up.

GSLENK · Apr 15, 2012

sweet. I cannot try it today, but I will try tomorrow. It was with a Fuel lab 818 series 10 micron paper filter with like 10k or less miles on it. IDK how it got so dirty so fast... I'll see though

bjmauck · Apr 15, 2012

Ive had this happen on both of my cars. My almost stock 95 gst and my modded 99 Gsx. Never have figured it out. Drive for about 30 min then let it sit for about 30 min extended crank, running rough and wanting to stall. Try to rev it and runs like crap.

GSLENK · Apr 15, 2012

bjmauck said:
Ive had this happen on both of my cars. My almost stock 95 gst and my modded 99 Gsx. Never have figured it out. Drive for about 30 min then let it sit for about 30 min extended crank, running rough and wanting to stall. Try to rev it and runs like crap.

Doesnt sound the exact same as mine or ampsycho, unless I/U missed something. After an extended period of wait time from a hotter shut down, the engine starts rough, it stays around 300 rpm for about 10 seconds tops, or stalls. unless throttle is applied. then after the engine reached idle speed, it runs smooth as butter no hiccups unti I shut it down and try again later after enough time.

pksystems · Jun 15, 2020

Bumping an old post to see if anyone can point me in the right direction.

6-bolt swapped 2G with 2G head, that is running great when cool.

If I've been driving the car for awhile, the factory dash gauge never goes over midway. My after market coolant gauge is usually between 200-215 while driving around, which as far as I can tell is pretty much standard operating temp. If I stop the car to get gas, I sometimes cannot restart the car, unless I open the hood for a couple minutes, disconnect and reconnect the battery. It also seems to help, if I open my gas cap, to release some pressure in the tank. I have done the EGR and charcoal canister delete, but left the check valve in place.

I tried driving with the factory radiator, and a Mishimoto, but have the same problem with both.

When I try to crank the car, it acts like the battery is dead, and doesn't even try to crank. Does this sound like a coolant temp sensor?

lasershark · Jun 15, 2020

Sounds like a voltage problem to me, I would check grounds (clean them up), clean up battery terminals (even if visibly looks ok) check starter wires etc...

The Top DSM Community on the Web

1G hard starts after hot shutdown

GSLENK

EAKEREAK

Jason023

Alan11

Jason023

Alan11

Jason023

GSLENK

Aphix

GSLENK

The1G_Guy

GSLENK

1983gsp

GSLENK

ampsyco

The1G_Guy

GSLENK

ampsyco

GSLENK

bjmauck

GSLENK

pksystems

lasershark

Similar threads

Latest posts

Build Thread Updates

Vendor Updates

Latest Classifieds