Fuel Injector question.. all 4 at idle?
 

My 88 turbo is smoking like crazy, mostly at idle, and hesitating when the throttle is depressed. It reaks of gasoline, so much so my eyes water. I checked the injectors with a stethoscope and i can clearly hear the primaries AND secondaries clicking at idle. Clicking means they are passing fuel, no? What should i check...

Dont mean to thread jack but I think I am having the same problem, so can anyone help.

It's unlikely that the secondaries would fire at idle. You'd have to have the wires shorted together.

To be sure, backprobe the injectors at the ECU, while the motor is at idle. You should see a distinct difference in voltage between the primaries and secondaries.

Is your motor burning more oil than normal? It could be oil leaking into the turbo hotside that's causing the smoke.

im having some what of the same problem man

Per the shop manual, all 4 injectors are supposed to see 12v at idle. Im confused

Oil burn is normal, other than a slight leak on the hot side of the turbo. Its coming out of the mufflers and waters my eyes from the distinct gasoline stench. So, are all 4 injectors NOT supposed to be clicking at idle? Im assuming if they're clicking they're passing fuel.

Alright, I did some searching on using a multimeter to monitor injector pulse-width. And it seems a standard multimeter is too slow to detect the opening and closing (cycling between 12V and 0V). This explains why the FSM just says all 4 injectors will have 12V at idle. 0V is open, 12V is closed, but it's all happening too fast to see the change. Here's a link that explains in more detail (http://www.picoauto.com/applications...njection.html).

But like I said before, it's really unlikely that the secondaries are firing at idle. If you know you have an oil leak in the hotside of your turbo, then that's the obvious reason you have smoke. You realize that the products of both burning oil and burning gasoline are going to be essentially the same? (Hydrocarbons, CO2, CO, NOx) You're probably just smelling the oil that's burning off.

an easy test would b eto disconnect the secondaries and see if it smokes as much

Yeah, but it's not as easy on a turbo as on a NA. The UIM has to come off, which might require a replacement manifold gasket (depending on age).

Watch the voltage at a primary injector wire at idle. It'll read batt voltage. Now either rev the engine or just drive around the block. The voltage will drop when you rev or drive around the block, indicating they are operating. Then do the same for a secondary injector wire. The voltage won't drop when you rev or drive around the block, indicating they are not being used.

All four injectors get alt voltage. What makes them pulse is a pulsed ground from the ECU.

I'd bet your not hearing the secondarys clicking, but the BAC's pulsing duty cycle.

Or if your really interested in knowing, depin the secondary wires at the ECU.

It's very, very unlikely the secondarys are working at idle. Too many WEIRD things would have to happen. Like the fellow said, all the four wires from the injectors would have to be shorted to each other and getting the pulsed gnd from the ECU. Ain't a gonna happen. Nope.

Ah, this makes much more sense. Thank you.

The leak is very minute, and i suppose i neglected to mention that this problem arose since the installation of an Rtek1.7 ecu and a new walbro 255lph pump... which leads me to believe its fuel related. Still hearing clicking at the secondary injectors..

Could be. I've probed around with the stethoscope some more and the BAC is making a similar noise. Im going to pull off the TB to get a better look. Assuming the secondaries are working properly, what else should i check with the TB off?

I also think the smoke is from the turbo. Possible water in the combustion chamber problem due to bad seal. Not likely since you don't mention overheating.

Might be a injector stuck and leaking. That's hard to figure out as to which one.

Pull the upper intake manifold, tie the fuel injectors to the rails, pull the fuel injectors from the holes...
Have a friend crank the engine while you watch the tips of the fuel injectors.
This test will determined if something is fucked about your fuel injectors, period.


-Ted

You know what you might be hearing. Not the BAC as I suggested above, but the PD pulsiing. I'd bet money on it. It's a normal thing to hear.

my only guess would be something wrong with the TPS if all four are firing, make it think your at enough throttle to need all four. I hate our TPS.

TPS has zippity doh dah to do with when and if the fuel injectors come online or not. He's hearing the PD pulse and there is no way all four injectors can be active at idle. If they did, then the car would not...........idle. We need to get the idea of the secondarys operating at idle out of our minds. Gone.

Indeed. Removed the injectors, tied them to the rails and cranked the motor= no fuel from secodaries. Still running rich.

I bought a universal FPR im going to install. I have the s4 threaded rails, whats the adapter size/what exactly do i need to replace the stock FPR?

Also, how long should the fuel system remain pressurized after pressure testing? When i bridge the check connector the pump runs constantly (walbro 255 pump modded with the fuel pump re-wire)

The FUEL AND EMMISSIONS section of the FSM has passage that deals with how long the rail will stay pressurized aftert the key has been turned to OFF. I've seen the rail hold pressure for up to an hour. It slowly bleeds off. The fuel gets trapped b/t the fuel pump check valve (stock pump) and the FPR.

If your asking for safety, I'd just wait for maybe fifteen minutes then just back off one of the large 19mm banjo bolts on the rail with a rag around it to keep from being sprayed. I assume the engine is partly ...apart or I'd suggest pulling fuel pump plug off and then starting it til it quit running. That would get rid of MOST of the pressure in the rail.

I know less than nothing about the adapter question.

Thanks, HAILERS, that sounds about right.

I pulled off the OEM FPR and now i need a banjo bolt. I've heard different numbers and fitting sizes thrown around, i believe im looking for an M12x1.25 banjo bolt, correct? Also does anybody make high temperature vaccum caps? I have the need to cap off some vacuum lines on the TB