system: MAP TPI with 7730 ECM on 5.7L L05 engine (i used a GMPP crate engine)

i still can't figure out where the problem could be

sometimes (mostly with cold engine) it starts perfect, but sometimes it needs very long to start - because i can't really describe it, i made two videos

heres a good start with cold engine: http://www.lnoperformance.de/files/cold.MOV

here a bad start with little bit warmer engine: http://www.lnoperformance.de/files/warm_problem.MOV

with hot engine it starts fine again, but after staying a while (maybe one hour), the problem comes again

i think i've changed everything possible, heres a list of new parts i put in the last weeks:

- throttle body with new IAC and TPS (TPS is set to .54V and IAC is learned with the 30-second method)
- MAP sensor
- all vacuum lines
- whole distributor with EST module and pickup coil
- coolant- and intake-air-temperature sensors
- O2-sensor (i'm using a heated 4-wire)
- fuel pump and fuel pump relay
- fuel filter
- Accel 24 pph injectors

for the TPI-swap i used a Painless wiring harness

i checked the fuel pressure, it's ok around 41 psi, and i even opened one line to verify there are no air blebs in the fuel, it flows fine shortly after switching the prime connector at the relay

 

That sounds like my car! The only problem is that mine has gotten worse!!

The only thing on your list that I didn't see replaced was the fuel pressure reg. I have to go out and get a fuel pressure gauge and check that it is actually working. There is a bunch of tests to make sure.

I know you say the pressure was at 41 psi but I think it supposed to drop when it's running so it may be flooding??? Also the 41 psi is on the LOW end of the scale? I think the magic number is 43.5?? Not sure...

Anyway when my car is warm/hot and I shut it off I have a hard time trying to get it started again! (and I can smell fuel) almost like it is flooding.

Let me know what you find....

 

i just forgot to list it - i put in a new pressure regulator when i installed the TPI to the motor

i can smell fuel too, so i thought it must be a ignition-issue

but then i talked to the guy from tpiparts.net, he said it could be a tuning issue, so i again looked at the start-tables in Tunercat, and zeroed-out the "Crank Fuel Delivery Delay vs. MAT" Table, since that it mostly starts quickly but after a quick start its running very rich and at very low rpm (under 400) for a few seconds - that area of the MAP table i haven't tuned yet (i have to tune it, because i don't have a real TPI motor, basically it's only a L05), so my next step will be to try to make those cells of the MAP table appropriate to the motor ...

 

Is the pressure regulator adjustable? My motor is stock, but if I can figure the Camaro out then I have a 2000 Grand am that has a hard starting issues (cold only)

I had acess to "mitchel on demand" and I am wondering if your pressure is set too low?

I did notice that you are running larger injectors, do they require more or less pressure (I know you have to change the injector constant)?

Also what are you using to tune and burn chip (Moates?)

Does tunercat allow you to look at all the sensors in real time?

I haven't modded the engine at all yet and I don't have the chip burning/tuning stuff yet. But I do have the hard starting hot so it has to be something basic to fuel injection.

 

i don't have larger injectors, they're around 23 pph @ 41 psi, so nearly at the stock configuration of a 5.7L TPI engine

no, i have the stock pressure regulator, it's not adjustable

To make my chips i'm using Tunercat and a Flash-EPROM soldered into the MEMCAL, so i can easily erase and re-write in the programmer (don't need to change chips), i too have a ROM-Emulator, similar to the ostrich from moates, but i only used it when i did my MAP calibration. Tunercat is for programming only, not for datalogging/scanning; for that i'm using TunerPro RT with my own datastream definition ( http://www.efiparts.de/files/ads/1227730_90-92_TPI.ads ) together with the moates ALDL cable

sorry, i had no time to do anything at the Caprice yet...

i hope we both can figure out our issues here seems to be a common TPI problem, so where are the TPI pros?

 

okay, update: i played around with all the crank-related tables in the PROM, but all i achieved was that it smells more from unburned fuel after such a bad start, and found out that the problem happens only with warm engine, after the engine was off for about 30 Mins. With completely cold engine, or shortly after turning it off, it starts fine.

So, let's assume my problem is not a tuning/software problem, but somewhere in the hardware: It smells from unburnt fuel, so i guess the ECM fires the injectors correctly, but theres no spark. But why? i unplugged the EST bypass connector to see if the culprit could be the ECM when it switches the bypass over to "ECM control" but isn't giving the firing-order soon enough, but with unplugged bypass the problem is still the same.

Please, give me some input what else i could try, its really not funny to have a car with all EFI parts new that can't even start like a normal car.

 

ok, since many people i talked to said this is a typical sign for a bad distributor (mine is a reman one from S&P), i put in the distributor from another (running) TBI engine today, with no change, same problem