Manolis_D

iTrader: (2)

I had the car running a couple years ago, then stored it. While it was stored, I switched out the stock (high-impedance) primary injectors with new siemens low-impedance (3 ohm) injectors.

Now the car refuses to start (doesn't even make an effort to catch). I was able to get it to run twice, briefly, by switching from 'staged' injection to 'batch-fire', and then changing back to staged. This 'trick' no longer seems to have any effect.

I have verified good spark. I have fuel pressure at the rails. What else could be going on here?

To try to see if the injectors were firing, I disconnected the plugs from the secondaries, and put a multimeter across the injector wires. I then switched the ECU to 'multipoint' injection mode (should fire all four injectors at once). While cranking, I measured 2.8% duty cycle at 3.6Hz from the secondary injectors. 3.6Hz corresponds to 216rpm, and at 216rpm the 2.8% duty cycle corresponds roughly to 7.75ms, which seems excessive (bar height is about 2.7ms.

Any ideas here? has anybody else experienced such problems? I'm on my way to the garage now to see if the primary injectors are getting a signal (couldn't do it last night, as I dumped fuel everywhere disconnecting the primary's).

Manolis_D

iTrader: (2)

Update - I checked the signals going to both primary, and secondary injectors with a multimeter.

The primaries are getting a 3.6Hz signal with 1-1.1% duty cycle. This corresponds to about 3ms injection time (this is close enough to correct, by the time correction factors are added). The secondaries, however, usually get about a 2.8% duty cycle signal of the same frequency (way too long), and occasionally will get a 2.2% duty cycle signal.

Just for reference, the primaries are siemens 85lb/hr injectors with 3ohm resistance, while the secondaries are bosch 160lb/hr injectors with 5ohm resistance.


Claudio, any ideas? It seems that the ECU managed to fry itself sitting in the garage for 2 years. Not happy....

Manolis_D

iTrader: (2)

Update 2 - I went down to the garage again and did a much more controlled experiment on the injector signals. Results (copied below), indicate something weird going on. The secondaries are firing approximately twice as long as they should be. Additionally, the injection time is changing slightly depending on whether or not injectors are plugged in while I run the test. I have yet to test the primary injector signals while both primaries are plugged in, but so far it seems like the car should start (what gives?). The ECU shows 180 cranking rpm the whole time it is cranking. The only strange thing displayed by the haltech software is the fuel injector duty cycle. It hops around a bit, settling around ~20%, but occasionally jumps to 100. This seems highly suspicious, but I don't remember it ever working particularly well. Any ideas? Should I pull the ECU and send it back to Haltech to be inspected? This has taken up about 40 hours so far....

Injector setup Injection setting Frequency (Hz) Duty cycle (%) Corresponding Injection time (ms)
no injectors plugged in
staged, bar low
primary signal 3.6 1.1 3.06
secondary signal 3.6 2 5.56
staged, bar high
primary signal 3.6 1.1 3.06
secondary signal 0 0 N/A

1primary, 1secondary plugged in
staged, bar low
primary signal 3.6 1.1 3.06
secondary signal 3.6 2.3 6.39
staged, bar high
primary signal 3.6 1.1 3.06
secondary signal 0 0 N/A

no injectors plugged in
multipoint
primary signal 3.6 1.1 3.06
secondary signal 3.6 2 5.56

1primary, 1secondary plugged in
multipoint
primary signal 3.6 1.1 3.06
secondary signal 3.6 2.3 6.39

2primaries, 1secondary plugged in
multipoint

secondary signal 3.7 2.3 6.22