starting issues after car sits for a while
 

hi guys,

2000 base boxster, 140k miles on the clock. never failed to start since i got it 3 years ago. recently refurbished all injectors and mechanic had to remove the intake to get to the ones on the air box side.

car starts first crank in the morning. once i shut the engine off and i come a few hours later it struggles to start as if it's not getting gas. acts similarly to when you run out of gas and you have to crank it for a few seconds until gas reaches the engine after refill. it typically starts after 3-4 seconds of cranking, most of the time depending how long it was since it ran when i return to the car. in the morning it starts perfectly.

is all the gas going back to the tank somehow?
mechanic did mention he noticed my gas pump was loose in the tank and he tightened it down. did he mess something up?

where should i look first?

thanks,

Cristian

I would start by running the car with a fuel pressure test gauge attached, reading the pressure. Then shut it off with the gauge still attached and let it sit to see if the pressure bleeds off. It should not.

i'll order a fuel pressure gauge and test.
i tested a few months ago and it was within specs but this does seem to be a fuel pressure issue somehow.

could this be related to the fuel regulator in any way?

Possibly.........

i did the fuel pressure tests.

- ignition on without cranking the engine shows 52 psi which is on the lower end of the spec which i understand is 55 +/-3 psi but i'd say acceptable.

- with the engine on at idle it sits at 46-47 psi which should be good as spec is 48 +/-3 psi

- I pulled the vacuum out of the regulator as well, there's good vacuum, no leaks and no smell of gasoline on the regulator or line. fuel pressure jumps up a few psi when I pull it which indicates the membrane inside is working correctly.

- here's a video of idle, steady revving at 3000 rpm and short revs. doesnt seem to indicate anything might be wrong with the fuel pressure.

https://www.youtube.com/watch?v=j8OGCSFgcLY

- lastly, i turned it off and left it for 30 minutes. pressure went down 1-2 psi which i think is ok? or should it not drop down at all?


not sure what's going on, i was expecting a quick bleed out since it had issues starting after just a few minutes. weirdly enough yesterday while doing all these tests the car started fine.

remember these issues started as soon as i refurbished injectors and the gas tank was opened as well by my mechanic who supposedly tightened down the fuel pump which was loose. car never had an issue starting up before.


i heard if an injector o ring is pinched it could cause a slow leak. i also heard the gas pump has a valve that opens and closes when you start/stop the engine to prevent losing pressure. if that doesnt close it might cause a pressure bleed.


any idea guys?

thanks,

Cristian

i'm starting to think it's not fuel pressure related, according to the above it seems to hold up just fine.
someone correct me if i'm wrong.

the strange thing is in the morning with the engine cold it starts perfectly, even after 3-4 days. if it was fuel pressure it should drop after not using the car for a few days.

could this be starter related? a few weeks ago when i had injector issues and mechanic cranked it up a bunch of times when it was not starting it could have messed up the starter.

what are the typical symptoms of a failing starter?

Have you checked your crankshaft position sensor?

I did not. Is that done with durametric or how?

A failing starter should be easy to diagnose, it just cranks the engine over slowly.

Hmm.. I’m really starting to think it’s the crankshaft position sensor. A quick search reveals symptoms similar to mine where it would start normal when cold but once the engine was up to temperature it would have difficulties starting. It’s most likely on its way out.

Since the CPS feeds info to the DME, I’m wondering if this could cause some of the long term trim issues I’ve been having for a good while?

so i went ahead and changed the crank position sensor and it did not fix it. i'm back to suspecting a fuel pressure issue. when testing with the gauge it did seem to drop 1-2 psi and from what i understand it should not drop at all.

what i dont understand is why it starts perfectly every morning after sitting for a week? a fuel pressure issue should cause a starting issue after the car has been sitting for that long.

could it be the fuel pump or some injector i recently refurbished?

thanks,

Cristian

Maybe a rich condition caused by the EVAP system? You could try blowing out or even disconnecting the EVAP purge valve, plugging both ends and see if that helps.

I'm thinking that if you had a bad valve in the EVAP system that fumes could be flooding the intake, same as the "hard start when hot" issue. After sitting for an extended period, the fumes would dissipate and the problem doesn't occur.

you might be on to something here! whenever i have the starting issue and the car eventually starts i do get this strong smell of gas fumes.

My son’s Boxster had same problem and it was CPS.

wish i was in his shoes since i'm tired of chasing this issue but replacing CPS didnt do it for me :(

I'm ignorant of the cause... but I'd be running with Particleweave's recommendation. It appears there are no clues left.

yeah im going with that, looking into how i can test

UPDATE:

i went ahead and replaced the EVAP purge valve. i only bought the valve itself, not the whole valve and line assembly ($46 vs $200 difference) and from the source website it mentioned i should reuse the line. big fat lie as that line is plastic that i believe is heat shrunk on to the valve itself. i bought a $2 fuel hose and some clamps and made my own line for under $5.

BUT! unfortunately it didnt fix my hot start issue. 2 hours after the car sat it still struggled to start a bit. ugh!! patience is running low on this one.

very strange though, i drove the car for about an hour after replacing it and my god did it idle good! i'm talking not one dip on the needle, it was perfect! drove home feeling like a champ, patting my wife on the back who helped with the swap.

half a mile from home i get the dreaded P1130 code which i've been eluding for a couple of months (somehow). i reset, idles like "meah" again, take it for a drive around the block, with durametric hooked on, check for codes again when i park and voile P1128 and P1130 lurking there, no CEL on the dash yet, but they were in the memory.

oh man is my patience running low. didnt fix anything, still having hot start issues, and same old codes keep coming back for 2 years.

i'm just about to call it quits and take it to a specialist, i have a road trip coming up in 10 days. maybe have it smoke tested again and see if they can figure out why the start issues.


any other advice before i give into the darkness??

thanks guys,

cristian

P.S.: I miss my Honda S2000 days. CEL? what's a CEL?

:cheers: whiskey time to drown the sorrows!


oh! another code in memory after replacing the purge valve was this guy: P1671.
did some research and it's a weird one, most likely a fluke so i ignored it. didnt come back after reset.

rom the 7.8 DME Manual:
P1671
DME relay/control module faulty (computer monitoring: reset) – signal implausible


Possible fault cause
◆ Undervoltage
◆ DME relay faulty
◆ DME control module faulty
This fault may be entered if the control module has been operated with undervoltage.
Affected terminals
I/1 and I/8
Diagnosis/troubleshooting
Note!
• If no fault is present, erase the fault memory.
1) Check voltage supply, terminal 15
◆ Measure voltage between pin I/1 and ground.
> 11 V
2) Check DME relay ◆ Switch on the ignition
◆ Measure voltage between pin I/18 and ground
Battery positive voltage
Check triggering of DME relay
Replace DME relay
3) Replace DME control module.
4) Perform adaptation. ◆ Switch on the ignition
◆ Wait one minute
◆ Do not press the accelerator
◆ Switch off the ignition for at least 10 seconds
◆ Read out the fault memory
-> End -> End

Regarding the codes, do you have a Durametric to check fuel ratios? Have you tried disconnecting the MAF to see if it idles better? Smoke tested the intake for leaks (or sprayed with starting fluid)? Are you certain your new purge valve and lines are absolutely sealed?

Since the injectors were just refurbished, there could also be an issue there.

I’m pretty sure new valve and line are ok, double checked everything and it was good.
I did disconnect the MAF and doesn’t idle any better. I had it smoke tested a year ago came out air tight everywhere.

I did think maybe injectors might be the issue since it started after replacing, like maybe a slow leak from a pinched o ring but that wouldn’t be the case since the car sits for a week and starts at first crank, pressure would be all gone by then.

I have durametric, which values should I check and what am I looking for in terms of fuel trim?

updating this thread.

I havent had a CEL for a couple of years now, granted i drove it a lot less. But i continued to have the "hot start" issues, where if the car would sit for a while after being hot it would have a bit of an issue to crank, like take 2-3 seconds and maybe a touch of throttle to get it going. Also had this issue when starting right after filling with gas on a hot day.

The other day i was driving and P0455 pops up. because i already checked fuel pressure, smoked for leaks and replaced the purge valve (next to the intake), i went ahead and bought the Fuel Tank Bleeder Valve and Purge Valve that's on the charcoal canister (figured, while in there). i'm going to replace these soon, reset the CEL and see if i still have the hot start issues. oh, i replaced the crankshaft position sensor a long time ago to eliminate it as a possible cause.

i'll report back after these fixes

Cris, did you ever get this issue resolved ??

Not yet. I drove the car less and kinda lived with it because it wasn't a big problem. Im driving the car more now so will need to get back on it, maybe replace that one valve that I haven't yet, the one behind the headlight. Ill probably do that soon, if that doesn't do it, its back to the drawing board..

Cris,
Your P1128 and P1130 codes are telling you that the fuel system on both banks has reached the rich limit trigger point. So your fuel trims should be showing negative trims or taking fuel away. Your P0455 is as you know a fuel tank ventilation major leak.
So what is happening is you have a situation where fuel fumes from the fuel tank are coming into the intake from the EVAP system.
Causing hard starting when hot and most likely the P1128 and P1130 codes

Because of the above condition when the car is hot or warm it has trouble starting because the fuel mixture is to rich.
When you step on the gas pedal the reason that it helps is because you are giving the engine more air not more gas. Thus leaning the fuel mixture in the cylinders out and allowing the engine to start.

On a car with electronic fuel injection the ECU controls the fuel.
All that happens when you step on the gas pedal is the throttle plate opens farther allowing more air in and also the throttle position sensor tell the ECU/DME the throttle plate position.

"remember these issues started as soon as i refurbished injectors and the gas tank was opened as well by my mechanic who supposedly tightened down the fuel pump which was loose. car never had an issue starting up before. "

thanks,

Cristian[/QUOTE]

When this happens to me, I always go back to the old saying "If it was working and you did something and now it no longer works..... you broke it. Go back and retrace your steps"

Good luck. We can feel the frustration in your posts.

Wanted to update this post, because i did and learned some things in the meantime. The P1128 and P1130 codes were actually caused by having the wrong MAF version, i did sort that out quite a while ago and no more codes, definitely closed the book on those.

The P0455 code was indeed from a major evap leak, it was actually the fuel sender unit. Under the battery tray the plastic neck that the line connects to snapped of, it was old yellow brittle plastic. i replaced the fuel sender, made sure the fuel pump was sitting right and fixed that issue right away, no more fuel fumes coming into the cabin.

I still have the hot start issue, and i believe what is happening is what Blue62 and particlewave (in an older post here) mentioned, fumes ending up in the intake, when i press the gas a bit more air is mixed in and it starts right up, never takes more than 2-3 seconds. it's most likely something in the EVAP ecosystem that is not doing its job.

I was going to change that valve that sits behind the right headlight, i have the part just never got around to replacing it. I thought it was supposed to go on the charcoal canister according to DYI guides but i guess that was for a different version, mine goes behind the headlight along with another valve. If that doesnt do it i'm considering replacing the charcoal canister.

I'm gonna do that soon and report back. Thanks to all that shared really valuable info, very much appreciated!

Not sure where you read that, but that isn't right at all. 1128 & 1130 make many people think it's the maf and it almost always isn't the maf.

I know what you're saying. Those codes were the first issue I ever had with the car and i did the whole shebang, smoke tested for vacuum leaks and all that good stuff. I later realized that I didn't buy the correct MAF for my car, I bought the updated one but it wasn't the right one for my ECU. When I replaced the MAF with the right one the codes went away. This was a few years ago.

Cris,
The EVAP system can cause all kinds of issues.
It is a simple system the issue is access to all the hoses and valves.
Stay with it and concentrate on that system. As you know your hard starting is from an over rich mixture when hot.
Not many things can cause that.
The EVAP system is the most likely at this point.
Let us know how you go. Always interested in outcomes.;)

STILL wondering...........IF the car didn't have this problem BEFORE you had your mechanic work on the car AND NOW YOU DO.........why didn't you just take it back to the mechanic and tell his "it's not right, fix it!".........Just wondering?

Cris,
Have you tried reclibrating your E-gas (throttle)?????
To see if it helps your hard starting when hot issue???
It's a long shot but easy to do.

I do really think it is an EVAP issue.
Perhaps when the mechanic removed the intake he did something to the EVAP hoses valves or connections. Hoses and some valves for the EVAP are right there.

If you want to give recalibrating the E-gas a shot, this is what you do.
Disconnect the battery for a few minutes so the ECU drops the E-gas calibration settings.
Reconnect the battery.
Turn the ignition to the on position "do not start the car"
Do not touch the gas pedal.
Let it set that way for at least 1 minute.
Turn key off for at least 10 seconds.
Start car.
Thats all there is to it.

Looking back, i think i might have had that issue before but i didnt realize it or pay attention to it. In that time i was only doing round trip drives with the car and would almost never shut the engine off and restart except once when first starting up so i didnt notice. I think i noticed the hot start issue when filling up with gas on a very hot day but chalked it up to "probably not a big deal" since it started right up.

the only work the mechanic recently did was taking the injectors out, i got them refurbished and then he put them in again. i think i did eliminate the possibility of the injectors not sitting correctly or having a pinched seal and losing fuel pressure because i did the fuel pressure test and it seemed fine (also documented on here). Also, the car starts right up even after sitting for days so that tells me the pressure doesnt bleed out.

I'll try that, nothing to lose :)
also, i'm doing the plenum and 74mm throttle body upgrade soon and will have a look around the intake. The only thing i tried there was replacing the purge valve that sits on the left side of the engine, what else is there from the EVAP system that i could look for?

There is a diagram of the system in the Bentley service manual if you have one.
Or do a search here on the forum. I am sure there is a picture.

If that purge valve and the vacuum hose is easy to get to????
you could try pinching it off or disconnecting it from the intake.
Plug the intake where it disconnects.
Take the car for a drive to get it warmed up.
Then see how it restarts while hot.

If something is in the EVAP system that is causing the hot start issue.
disconnecting it for a short time may make a difference.

Keep us posted.

Just another thought: Have you looked at your fuel trims????
If your getting fuel vapors in the intake from the EVAP system, you should be showing Negative Short Term Fuel Trims.