Warm hard starts, test or just replace FPR?

[rationull]

OK, on the subject of cleaning, forgive me if I should've understood this from previous discussion but I think I'm a bit confused. Keeping in mind my "warm start" issue seems to be related to engine temp or the fact that the engine was running 10 mins before, NOT to ambient temp (maybe ambient temp under the hood I suppose, after the engine's been running). It also does NOT happen if the engine is shut off and restarted, say, 1 minute later (starts right up).

I can obviously see why dirty or plugged injectors would cause hard starting, but as mechtech alludes to it seems like they would cause hard starting when cold too, wouldn't they? On the flip side, I can see how a leak while under pressure would cause hard starting when warm (i.e. when residual fuel pressure helps the leak to flood a cylinder or two) BUT given:

- used oil analysis have not shown fuel dilution.
- It seems like in order for a big V8 to fail to start you'd need a fair amount of fuel in multiple cylinders.

The FPR just seems more likely to me. Granted the car gets driven mainly for 12+ miles at a time on the highway so maybe the fuel would've burned off? Am I thinking about this the wrong way?

My conundrum is essentially that this is a relatively minor problem, and I'm not sure I want to disturb the injectors' connection to the rail (and all the associated clips) if I can avoid it, although I may be overestimating the difficulty or fragility those parts given I am undertaking the whole LIM replacement job anyway. IOW it's not the end of the world to me if I get this back together and this problem still remains, I'm just trying not to be stupid and ignore something simple I can do that has a high likelihood of fixing it.

 

[mechtech2]

First check the coolant and air temp sensors.
[Not the gauge sensors]

 

[Trav]

Quote:
it seems like they would cause hard starting when cold too, wouldn't they?

Not necessarily, the injectors if there is any plugging will not be totally plugged or you would have a dead cylinder.
The ECM is capable of commanding more fuel that's why many times dirty injectors go unnoticed until there is an issue.
When cold the ECM instantly demands more fuel because because the cold engine needs a richer mixture to run properly (like a choke back in the day).


I don't think you have a leaking injector problem as you say it doesn't have high fuel dilution.
Put the engine together and test the FPR or change it if its cheap enough and go from there.
Trying to accurately diagnose this with it in bits is a little difficult, you are kind of behind the eight ball now.

With the engine running you can look at fuel trim, temps, baro, MAF, etc and come up with a better idea of where the problem lies.
Did you check for a leak in the intake with propane (or the dirty way with starting fluid) and the fan off while checking the STFT?

 

[ltslimjim]

Originally Posted By: mechtech2
First check the coolant and air temp sensors.
[Not the gauge sensors]


Yes, check the voltage back to the computer compared to the FSM's specs when cold vs when hot.

Thanks for explaining things Trav. I'm still in the mode of collecting tools for proper mechanical/technician work so I'll need to go rent/loan or buy some. I do have a harbor freight nearby, but I've curiously had some either ignition(timing possible) or fuel/air mixture related problems in this LEAN BURN Civic that feels some hesitation at times. Talking with some other VX owners on some other forums trying to get a handle on it. My issue seems to be from a stop/or relative to 1st-2nd-3rd gears. I do have the noisy/varied sounding injectors so it could still be mechanical.

Then, throw in the typical idle control issues on a Honda and you've got a recipe for chasing your butt. So, I'm just going to rule out the fuel pump(new fuel filter so good time lol) and FPR, for kicks.

Thanks to the OP for bringing up the subject, not trying to take away from the thread here.

 

[rationull]

Originally Posted By: ltslimjim

Thanks to the OP for bringing up the subject, not trying to take away from the thread here.

No worries!


Originally Posted By: Trav

I don't think you have a leaking injector problem as you say it doesn't have high fuel dilution.
Put the engine together and test the FPR or change it if its cheap enough and go from there.
Trying to accurately diagnose this with it in bits is a little difficult, you are kind of behind the eight ball now.

With the engine running you can look at fuel trim, temps, baro, MAF, etc and come up with a better idea of where the problem lies.
Did you check for a leak in the intake with propane (or the dirty way with starting fluid) and the fan off while checking the STFT?


I did not check the intake for a leak. TBH it didn't even occur to me to to any diagnosis on this problem when everything was hooked up -- I got it in my head long ago that the FPR was probably the cause and when I started to think about doing the LIM job myself I just assumed that everything would be easily testable or observable with the thing taken apart (obviously I was not correct).


I think I'm back to square one. I think I will most likely hedge by just buying an FPR, b/c I honestly don't see myself taking the upper manifold off again just for this problem, once I get it back together.

I really appreciate all the great responses here, btw, I'm learning a lot.