308 still doesn't run, updated, work so far....

encouragement? you're doing great!

you're getting down to stuff I've never done, but a lean condition at this point that is not something you already checked could be:

vacuum/snorkel hose leak

a vacuum gauge might help...and someone coming up with a number for what vacuum should be. Otherwise, the old way of shooting starter spray around likely spots.

blockage in the control plunger slits in the fuel distributor

I think you have to take the fuel distributor apart to get at it. Since you drive the car, it's not a likely issue.

fuel injector(s) blocked/bad spray pattern

I've seen pictures of people popping out all the injectors and sticking them in jars, then running the fuel pump while pushing down the airflow plate. That'll squirt the injectors, and you can see the spray pattern and volume. I dunno how painful it is to remove the injectors on a qv...hopefully people who have done it can suggest the best way. I think they pop out of the bung without removing the circlips, so the fun part is freeing up the crazy straw fuel lines from wherever they are mounted.

fuel flow/delivery too low

what I think you are supposed to do is disconnect the fuel line at the fuel distributor, run the pump for a while, and measure how much fuel pumps out. Scott's page says 1100cc in 30 seconds for the "308 gtbi and gtsi 1980-", and he said elsewhere it's the same through all the 328's.

have you checked the fuel pressure when the car is running and at higher rpm's? If it drops, the pump is definitely having trouble. Either a blockage in the lines, a current starved pump due to the fuse block or the fuel pump relay (try jumping 12V directly to the pump), or the pump itself is heading south.

since the problem occured while you were running, I'd check this first...especially those fuses if you don't have a birdman box.

blockage in fuel distributor chambers feeding each injector

blegh...checking the injector output while on the car would check this at the same time

spark timing

the above is assumping that spark is happening at the right time. You've already made sure the spark is happening without missing, and the plugs are good.

Bad timing would be either a digiplex, or a cam jumped a tooth on a timing belt.

I guess one way to find out, though probably not a good way, would be to intentionally run on one bank at a time. That'll let you swap digiplexes to see if the problem follows the digiplex. 'course, I dunno whether a digiplex that is essentially just picking the wrong advance curve (or the vacuum measuring device inside the digiplex is going bad/getting stuck) would be enough to give you the symptoms you are seeing. Problem with this approach is the fuel getting dumped into the bank you have disconnected.

if it is the vacuum thing inside the digiplex getting stuck, disconnecting and/or blowing into the vacuum line may do something.

Ideally, find someone who is nice enough to let you borrow their ecu plate and see what happens. Unfortunately, I just have a 328 and a couple MED801A's, so unless the 801A will run a QV (you have the 805A's, right?), I can't help ya there.

oh, and on the rest pressure thing. Places where the pressure can leak away are:
- fuel pump check valve
- fuel accumulator
- system pressure regulator in the fuel distributor
- push valve in fuel distributor (shuts off drain path for/from wur)
- frequency valve
- the injectors

Good rest pressure says the injectors aren't stuck open, but doesn't prove they aren't stuck closed or spraying poorly.

you didn't suck a few cloves of garlic into the intake when passing through gilroy, did you?

 

Sounds like fuel pump volume or bad O2 sensors.

Dave

 

My PO had a similar problem with bad crank sensors or connections- only 1 bank was firing.

 

Now do not laugh, I had a similar problem on my 84 Mondial, its a Euro.
Similar running conditions, the problem, water in the fuel. I drained the tank, bought some Wynns fuel dryer, I believe thatTectron is the same, put a couple of galls of clean fuel in with the magic goo, and bingo problem solved.
Good luck!!!

 

I also drained the tanks, and saw no trace of water, the problem as I understand it is that small globules of water, very small !!! get inside the distribution unit and do not move, hence the running lean and appearing to run on 8 cylinders.
I went though pretty much the same as you, then used the snake oil.
Funnily enough, it was Verrall that suggested a fuel drier in the first place.

 

that's not good. If you unplug the fv while the car is running, you should get an immediate effect.


I don't remember if you measured the resistance of the FV...if not, yank out the plug and see what you get.

If the injection ecu is not going into closed loop, then the O2 sensor input is ignored and the FV should be running at a fixed duty cycle (50-60%), which may not be ideal for emissions, but should/did run the car just fine. The car runs open loop anyway until it's warmed up.

if you have access to a scope, backprobing a pin on the FV should show something that looks roughly like a square wave. In closed loop, it's frequency should be oscillating around 50%. A dwell meter can also be used to measure the fv frequency, though I didn't have much luck using a digital one. When the car is in closed loop, it's easy to tell by watching the o2 sensor output (while it's connected to the ecu)...it'll bounce between values greater than and less that 0.5V as the frequency valve (over)adjusts the pressure.

water trapped in the fuel distributor chambers is an interesting idea. The frequency valve varies the pressure in those chambers by acting on a diaphram in the chamber bottom (see attached), and if water is stuck in the chamber, seems reasonable it could effect the pressure.

you have the same FV as I have in my 328 (part #121513). If the dry gas doesn't work, and you want to try swapping in another fv, I can swing by and you can see whether a transplant helps. pm me if it comes to that.
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Hi Larry,

Bothers me that grounding/1.5v into the O-2 sensor lead doesn't affect anything. As Phil mentions, disconnecting the lead shoud force the car into "open-loop" run configuration and excepting running with duty cycle around 60%, should do fine.

Do you have access to a spare FV relay? I understand the 328 version (that I posted earlier) will work in QV if you swap over the terminal connections in the block. Alternatively, I could send you mine & you could make a set of jumpers with spade terminals.

Another option would be to make a set of leads (I used single strands of copper wire) to record the DC at the FV, which will give an idea of the "output signal" from the FI ECU.

Sorry I also have a 328, or you could borrow my ECU.

Carl

Hang in there. Image the feeling of accomplishment when you figure this out!

 

hi carl,

are you using your digital meter when looking at the FV DC voltage?

I guess if the meter is sampling fast enough, and showing the average of the sample values, then a higher duty cycle would mean a higher DC voltage.

Seems like it would depend a bit on how the meter works. As an experiment, what numbers are you getting at idle for open loop and closed loop operation?

later today I'll dig out some meters and try again to get some numbers. A couple of my meters supposedly can measure duty cycle also. I'll also get AC numbers.

one of these days I'm just going to get a scope so I can watch what's happening. I keep looking at the bitscope...give me use for those old laptops which are currently only good for wheel chocks.

 

Oy vey... Good luck, Larry! Hope to see you back at Santana Row soon.

 

had a similar problem with a mercedez with K injection once, changed the fuel distribuitor

and on a porsche 924 had a similar but was , turned out to be a piece of debry that was clogging a small hole on the fuel distrubutor so it started missing when ever it wanted