As of this season, I've been having some crazy issues. Some of you may read bits about it on the boards. I've been getting a lot of help from Grumpy offline as well.

The issue was knock at idle, knock randomly, etc. Blms changing randomly with no changes in tps/mat/map.

Grumpy suggested I get a 3-wire heated o2 sensor (delco) so I ordered one. It hasn't shown up, and I had free time today so I figured I'd fix the "sv0 injector tick" issue as referenced in some theads here.

It was suggested that, by putting 1/16 rubber washers between the fuel rail and the baseplate, it would help with the vibration from the ford injectors. THe fords are apparently longer, and bottom out. The fact that you couldn't turn them, shoulda been enough evidence of that to me, but I didnt really think about it.

I took the plenum, and runners off and noticed the regulator was dripping fuel. i had someone turn the key on to enable the fuel pump, and it sprays fuel downward, and back under the dist. (Now imagine the fire that coulda caused).

The seal was leaking, and it was on the line that connects the regulator to the left (driver fuel rail). I shouldn't say leaking, spraying. I think the only reason I didnt smell fuel all this time, was the location of my air filter (from the blower) right over the valve cover.

I replaced all the seals, put it back together, and immediately on idle the gauge showed 5psi more than before. I recalibrated the AFPR to match what I had before (50psi idle, 55-60 wot) and will test with the laptop soon. I'm just waiting on my 3-wire DELCO o2 sensor to show up from GMpartsdirect.

I grabed a mechanics stethescope (sp?) And put it at various parts of my engine. I never used one before, and must say they are a really cool tool. I listened for rocker noise, valve noise, lifter, etc. had it up against the oil pan, block, even headers. At various points I flapped the throttle to see if I heard knock, or poping . None.

The loudest thing in the whole engine (other than the gears in the blower) were the injectors. If you put it on the injector, rail, line you here the pulses. No rapping anywhere else..

-- Joe

 

I would definetly want to rule out bad O2 sensor first. I had knock counts from not having enough spark in spots, added 8 deg, and now very little knock.

 

Work/play/tune on 4 cars here with SVO injectors, 2 of them my own and have not had any issueswith knock being caused by them :-)

However:

check your air tubes(if still fitted)

Engine mounts(lots of people miss these and mine were taco'ed)

accessories(bad bearings/tensioner getting flaky/belt resonance)

I never have a unknown knock issue mechanically (internal) always ends up being somehting dumb obscure and unheard:-)

Dropping 5 psi of pressure ,especially at the top end or when entering boost(if erratoic during) would have to cause havoc with your tune along with some weird spikes in the fuel tables if it was cutting in and out

later
Jeremy

 

\Beavis
He said air tubes.
/Beavis

 

FYI, during the tests for knock I:

Removed blowr, and discharge tube, all belts from the system, msd ignition box. Still gets some knock on crank/first start.

I switched back to $58 for a while to get some logging with that. That still gets tons of knock everywhere, but no retard.

-- Joe

 

Since your running a 749, I blieve u posted before u also run the 730 as well....

Since u seem............ to have eliminated everything mechanical in nature, do u have a issue with the knock sensor or the wiring for itself? If u pick up any voltage on that wire your going into knock central... Would pull the wire from the sensor and then check the continuity of the wiring from the sensor to the ecm..... figure .1 ohm per connection or so and most liekly want to see .3 or less on the wire...

Key on check it for voltage as well, should have zero

later
Jeremy