Start when cold, but won't restart hot.

[byebye_sti]

O2 sensor was wired incorrectly. Grey and Black wire were switched.

I swapped in (4) 450cc injectors that all had similar resistance (2.4ohms). The car IS getting spark when the car is cold.

After swapping in the injectors, and zero-ing out the SAFC, the car fired right up and ran smoothly. Revs were smooth, idle wasn't boucning or choppy, but the idle was high. 2,000-3,000 RPM. It came down a little with the adjustment of the BISS screw.

The car idled fine, but some smoke start to come from the radiator - almost like oily finger prints were burning off, but I didn't want to chance it and shut the car off.

Once shut off, the car would NOT restart.

So, I let the car cool down for an hour. When I went back to it, it fired right up, and held idle perfectly fine. I let it run for about 20 seconds and shut it down. I wanted to see if it would restart...and it did, but it was a little tougher. I let it run for another 20-30 seconds and shut it down. It tried to start, but just kept cranking.

Now, what would cause the car not to start when the car is warmed up? Power Transistor Unit (PTU)? Would a coilpack do this?

 

[byebye_sti]

Check timing

Timing is good - forgot to mention I've checked/tested nearly everything; TPS, ISC, Resistor pack, MAF, ECU (awaiting a new one).

Could it have anything to do with my Fuel Pump Relay having a bunch of gunk in it? White grease and looks a little rusty? I went to go bypass the relay and found a nasty mess.

FIAV is blocked off, as well as EGR.

 

[ervin00]

Is there a way for you to check the fuel pressure? That could explain a lot and help you narrow it down.

 

[luv2rallye]

Check for bad FP solenoid to relieve vapor lock: http://www.dsmtuners.com/forums/newbie-forum/217349-vapor-lock-hot-start.html#post1821514.

Other hot start Possibilities: Hot Start Problem Fixes

 

[byebye_sti]

Is there a way for you to check the fuel pressure? That could explain a lot and help you narrow it down.

I need to add a gauge on the rail. It would be nice if I could see fuel pressure.

On 1G's, does the Fuel Pump prime when the key is in the ON position? If I remember correctly, from my reading, it does not.

Check for bad FP solenoid to relieve vapor lock: http://www.dsmtuners.com/forums/newbie-forum/217349-vapor-lock-hot-start.html#post1821514.

Other hot start Possibilities: Hot Start Problem Fixes

Thanks for the links; extremely helpful. I will be testing out most of those fixes today.

As for the Fuel Pump Solenoid, if I don't have have one, would it make sense to find another and reinstall? The previous owner HACKED this car up, and I'm trying to fix all the gremlins that seem to be arising all at once.

My Fuel Pump Relay is caked with white grease, and looks a bit rusty. Could this be causing me some issues? My plans are to clean up the connector and bypass the relay to see if this solves my problem. I can't imagine all the grease would be helping any...

 

[ervin00]

I had a similar problem and it ended up being the fuel pump relay. That is the reason I mentioned the fuel pressure gauge. It would randomly not turn on the fuel pump. Relay usually don't go bad but it does happen and from what you are saying it seems like you are narrowing it down to the relay( being rusty and having grease on it). Good luck!

 

[byebye_sti]

I had a similar problem and it ended up being the fuel pump relay. That is the reason I mentioned the fuel pressure gauge. It would randomly not turn on the fuel pump. Relay usually don't go bad but it does happen and from what you are saying it seems like you are narrowing it down to the relay( being rusty and having grease on it). Good luck!

Good to hear that you've had a similar issue resolved! If I have time today, I'm going to clean it up, and bypass it. It's definitely disgusting and I don't even know how the grease got there, or how it would function...

I also have another ECU on it's way with a cleaned board and new caps. Praying that it all comes together.

When the car DOES start, it has a high idle (2-3k) and isn't really effected by the BISS. I'm not going to touch anything until the new ECU comes, but what else would cause this?

No boost leaks, TPS tested good, ISC tested good, FIAV is blocked.

 

[luv2rallye]

On 1G's, does the Fuel Pump prime when the key is in the ON position? If I remember correctly, from my reading, it does not.

For 1g's and 2g turbo: Fuel pump runs only while engine is cranking - ie. getting CAS pulses (not just ON).

 

[byebye_sti]

Ugh....

 

[gofer]

Test your coolant temp sensor.

 

[clipto]

Also try swapping the power transistor unit to another one and see if it runs now.

 

[Jesse2012]

Sounds like a fuel pressure problem like others have said, obviously different designs but I had this same problem with my Silverado, almost same symptoms, changed the fuel pressure regulator and problem solved.

 

[byebye_sti]

Test your coolant temp sensor.

I have...multiple times now. I testing the wiring, but now I can't find the thread that would verify my numbers. I believe I am suppose to see 5V on one of the wires, and the other is a ground. Which, when I tested, was good.

The car will turn over in the bitter cold, so I think it's working. I could be wrong though, and I will go over everything again.

Also try swapping the power transistor unit to another one and see if it runs now.

Trying to find a PTU on the boards, but having trouble. Everyone who PM's me with one for sale, doesn't respond. If I don't find one by today, I'm going to go and buy a new one.

Sounds like a fuel pressure problem like others have said, obviously different designs but I had this same problem with my Silverado, almost same symptoms, changed the fuel pressure regulator and problem solved.

I will swap out the FPR and see if this helps.



EDIT:

Okay, the car fired right up this morning - even in the bitter cold of 6*. It idled around 1200-1500RPM for about 5 minutes and then slowly started to climb. During this time, the car ran pretty smoothly - didn't sound like it was on 2 cylinders, nor sounded like a Subaru.

The idle went up to about 2500RPM, and I shut the car down. When I attempted to restart the car, I had no like. It just cranked and cranked and cranked.

So, I tested spark. I am getting good spark on the two outside cylinders (1&4), but very weak spark (almost non-existent) on cylinders 2&3.

This leads me to believe that the ECU, and CAS are working - as the car is getting SOME spark.

Do these signs lead to the PTU?

 

[gofer]

I have...multiple times now. I testing the wiring, but now I can't find the thread that would verify my numbers. I believe I am suppose to see 5V on one of the wires, and the other is a ground. Which, when I tested, was good.

That means you're testing the harness (signal) to the ECU, you want to test the coolant temperature sensor itself. Check resistance across the back of the sensor as the car warms up, the below checks are coolant temp changes. You'll notice resistance should DECREASE as the car warms up...

32* - 5.9 K-Ohms
68* - 3.5 K-Ohms
104* - 2.7 K-Ohms
176* - 0.3 K-Ohms​

This is how the ECU knows that the car is warmed up, if the sensor fails the ECU thinks the CT's are -40* and will continue dumping fuel which causes a rich no start condition.

 

[byebye_sti]

That means you're testing the harness (signal) to the ECU, you want to test the coolant temperature sensor itself. Check resistance across the back of the sensor as the car warms up, the below checks are coolant temp changes. You'll notice resistance should DECREASE as the car warms up...

32* - 5.9 K-Ohms
68* - 3.5 K-Ohms
104* - 2.7 K-Ohms
176* - 0.3 K-Ohms​

This is how the ECU knows that the car is warmed up, if the sensor fails the ECU thinks the CT's are -40* and will continue dumping fuel which causes a rich no start condition.

I have tested all three of the sensors I've tried. The original sensor failed, and the resistance did not move.

The other two (new sensors) the resistance changed in my hand, and in a bowl of warm water. So they tested good.

 

[gofer]

I have tested all three of the sensors I've tried. The original sensor failed, and the resistance did not move.

The other two (new sensors) the resistance changed in my hand, and in a bowl of warm water. So they tested good.

Is this something that you just did? I read thru your entire thread and didn't see anything about you testing/replacing a coolant temp sensor.

Well, if you know that the one installed in the car is functioning properly and the wires going to the back of it aren't broke then it isn't the CTS.

 

[byebye_sti]

Is this something that you just did? I read thru your entire thread and didn't see anything about you testing/replacing a coolant temp sensor.

Well, if you know that the one installed in the car is functioning properly and the wires going to the back of it aren't broke then it isn't the CTS.

Should be in my other thread; I've posted a few.

Weird no-start problem after CTS replacement | Galant VR-4 > Technical Discussions | GalantVR-4.org Mitsubishi Galant VR4 Forum

But, the first thing I did was swap in a new CTS, and re-do some of the brittle wiring. The car ran great for two days (when I got the car), but had a high idle.

It wouldn't fire up in the cold, but on a warmer day would fire no problem. Other than that, zero drivability issues during those two days.

Now, once cooled down, the car will fire up once, idle smoothly (but continue to idle higher and higher until it reaches 2500-3000RPM), rev freely and smoothly, but once I shut it off, it will not want to restart.

 

[gofer]

Ahhh. Don't have an account on GVR4.

Since you're getting weak spark on 2&3 after it has ran (warmed up) you should test the coil pack with a multimeter before you warm it up (cold) and after you shut it off and try to restart it (hot).

Compare the resistance measurements between the cold/hot readings...

You must be logged in to view this image or video.

 

[byebye_sti]

Awesome! Thanks for the info.

I'll do that right now.

Cold:
A coils - 10.61
B coils - 10.81

Hot:
A coils - 10.76
B coils - 10.97

Also, I guess at some point I blew a fuse for the gauge cluster lights and tail lights.

 

[89Patches]

I actually had this same problem before. Would always start when cold but as soon as it warmed up it would just crank over. I Changed the CAS it seemed to work for a little while but started doing it again. I went over everything. The last thing I checked was the ECU and that's what caused my problem. One of the boards burnt up, replaced it it haven't had a problem since.

Sounds just like the symptoms my car had. Just something for you to consider.

 

[byebye_sti]

I actually had this same problem before. Would always start when cold but as soon as it warmed up it would just crank over. I Changed the CAS it seemed to work for a little while but started doing it again. I went over everything. The last thing I checked was the ECU and that's what caused my problem. One of the boards burnt up, replaced it it haven't had a problem since.

Sounds just like the symptoms my car had. Just something for you to consider.

(GST with psi) sent me a know good ECU, and no change. Ran fine in his car.

My coil pack tested bad. Luckily, I was able to meet up with Mike Rizzoti and he hooked me up with a coil pack, and PTU to test.

His coil pack tested good (resistance was 12.89 and 12.97). Compared to mine (see last post).

Hope all goes well tomorrow.

Swapped in the good PTU and Coilpack...

...no change.

Car fires up first time, and once it gets warm, it doesn't want to start again.

Known good ECU
Good PTU
Good coilpack
Good Coolant Temp Sensor

Going to do a compression test.

At this point, I'm ready to replace the entire engine harness.

 

[bigassogre]

check power at the pump when it wont start. u might also try to manually apply power

 

[spooling 1g]

you ever get this fixed?