dontek

Hey guys, I need a bit of help trying to diagnose a possible warm-start issue I am having. The basics of the problem are this:

1) when the car is run for a short or long period of time, after it is turned off, attempted starts within 20 minutes to a few hours fail.

2) the car doesn't necessarily need to be completely warmed up for the condition to exist, but it does have to sit for a bit; repeated starts within a few minutes of turning it off fire right up.

3) upon trying to start, the car cranks, but no turn over or any kind, or firing happens, regardless of how long I crank the ignition.

4) if the car sits approximately 4 or more hours, it starts up without any issue what-so-ever.

This all started happening after my new fuel system install, which consists of the following:

1) Buschur Double-Pumper
2) Deatschwerks 1300 Injectors
3) Fuel Rail
4) Aeroquip FPR
4) Golan in-line filter
5) AN-6 lines all the way around from feed hardline to return hardline

I installed the Double-Pumper prior to the rest of the system and the problem did not exist at that point. However, I do notice that the fuel pumps do not 'pre-charge' when the ignition is turned on, until I actually crank the ignition. I don't remember if this was the case before the fuel pump swap or not.

My first inclination is that my injectors are leaking fuel after the car is turned off. However, if this is the case, it is happening with 2 sets of DW1300 injectors. My original set was a set of the 'old' blue ones which I could not get tuned-in because they were bad. (horrible idle, misfires) My current set is a 'new' set, that are the dark reddish-brown-almost-black color. They tuned-in fine and my LTFT for both Cruise and Idle are +/- 2% now.

My second inclination is that I may be experiencing some type of vapor lock, air space in the fuel filter, or pump pressurization problem.

One strange aspect of this case is a 'cure' I stumbled across while trying to figure out what was going on the first time this happened. I noticed there was an electrical humming noise coming from my throttle body when the ignition was turned on, prior to cranking. With the ignition turned on, I disconnected the wiring harness to the throttle body, waited 10 seconds, and plugged it back in. The humming noise was gone and the subsequent time I attempted to start the car, it started, but the idle was surging terribly. A second pass at unplugging and re-plugging the throttle body wiring harness and the car started up and ran perfectly normal.

I can reproduce the 'cure' with unplugging and re-plugging the wiring harness on the throttle body, although, it's not always a '2-pass' deal. It sometimes takes several more times of doing this before the car will start. The one constant is that the start where the idle surges always happens, and always happens 1-2 start attempts before the car starts and runs normally. I have since found that the humming noise coming from the throttle body is present when the car starts normally when cold, so maybe this was always the case and I just never noticed it before.

This all led me to speculate some problem with the throttle body motor or TPS.

So here I am asking you fine folks to shed some light. Here are some aspects I do not understand:

1) Does the throttle body always make that humming noise with the ignition in the on position prior to cranking?

2) What behavior in the throttle body / ECU am I inducing by unplugging the wiring harness? (throttle position reset, choke, etc..?)

3) I currently have no way of monitoring my fuel pressure, could an issue there cause injector leaking after the car is turned off?

4) Should by Buschur Double-Pumper be charging the fuel system when the ignition is in the on position, prior to cranking? Does the stock pump do this?

Any ideas or answers are much appreciated.

sideway180sx

iTrader: (4)

i am having the same exact problem you are having. The car would be hard to start after the car have been running, but if i let it sit for a while it would start with no problem. It kind of seem like the injector are leaking when the car is off, i am also running the DW1300 and this is my second set of dw injectors.

Optiblue

iTrader: (5)

Do you have an open element (cone) filter?

01CBR929

iTrader: (8)

My car has a humming in the engine bay, but I havent confirmed it with the throttle body as you have described. On a side note, my car has always started well when it's cold. It starts when it is warm... but it takes normally 1 or 2 seconds of cranking instead of firing right off the bat. I have found a blip of the gas sometimes helps it get started. All this has been with ID1000cc injectors... I recently got ID1600s and I havent drove it enough to confirm it is the same. It does seem better though since installing these new injectors.

blk-majik

iTrader: (6)

sounds like a cranking enrichment issue. I think Highboost had the same issue when tuning Dr Sotos car (also on DW iirc. 1300's would be right for his build, too). Might be worth pinging him.

fostytou

iTrader: (15)

If you have to hit the gas then I believe your startup tables may be too rich. It is very situational though.

dontek

I got tired of speculating, so I swapped the stock injectors back in to see if the problem would go away. I have had no warm-start issues since.

So, leaking injectors or tuning issue? My guess is my tuning, as this new set of DW1300 injectors seems solid in all other aspects.

When you guys say "blipping" or "hitting" the gas, are we talking pre-start, or after it fires up? (gassing it to keep it running)

If we are talking pre-start, holding the peddle on the floor while cranking does nothing. If we are talking post-fire, the car does not fire at all during this warm-start condition.

fostytou

iTrader: (15)

I was talking while cranking. I wouldn't consider the pedal on the floor to be a blip

dontek

I don't remember specifically trying to bounce the pedal while cranking, but I imagine I did, as I tried just about everything I could think of a few times it happened at really inopportune times.

What I do know, is that I am rich during cranking when this happens, because my wideband tells me so.

Are there separate cranking enrichment maps dependant on engine/coolant temp or something? Or does cylinder or injector temperature just have that much an effect that it necessitates fuel adjustment for larger injectors?

What's the condition that would cause larger injectors to need more or less fuel for cranking only when the engine is warm?

RazorLab

iTrader: (8)

Yes, I take it you haven't touched the cranking enrichment table then?

Looks like this:

dontek

I'm retarded. I've looked at that map several times and it _just_ clicked in my skull, looking at your post, that it is scaled on coolant temperature.

Thanks Bryan

So, is the consensus then that I probably need to pull a bit of fuel during cranking with the larger injectors?

RazorLab

iTrader: (8)

Yup, try that and see if it helps.

FYI, I had the same type of warm start issues with ID1000's and zeroing out the bottom of that table helped a bunch.

In winter I never had the issue, in summer when it gets warmer is when the problem crept back up.

cowboy14

I have same problem in my ones... and search a lot in net ..at last i went in professional ..and it solved

LVSBB6

iTrader: (4)

Dontek: did you ever find the cure for your problem? I'm experiencing similar issue with my ID1000cc.

dontek

Yes, pulling some fuel out of the Cranking Enrichment table fixed me up, like Bryan suggested.

I just selected the whole table and decremented the values until the bottom two cells were zeroed.