96ZRDR

Symptoms:

- runs extremely rich, Long Term Block Learn at 108 on both sides. Have a BLM split in short term readings with Right side runner richer.

- runs leaner as more throttle is applied, blm’s shoot to 135 or higher. Idle fuel pressure set at 43.5 psi with vaccum line disconnected. Runs at 37 psi once engine is on and shoots to about 40-42 psi at any WOT event. Car is equipped with 30# SVO injectors and is programmed for them by Alvin.

- Low vaccum readings, 8-9 inches at 950 rpm idle. Has a rough idle, and seems to miss under load conditions. Had to crack open the TB blades a little, even after drilling the IAC hole a little. IAC counts drop to 0, once the engine sets idle. It used to stall completely (shut off) after WOT run, with the TB blades completely shut.

- No top-end power. Best ¼ mile trap of 102mph, with a 2.4 60 foot. Timed at 14.xx seconds. Low low end power, but that may be the effect of low 3.23 stock ratio, and 2800 stall converter. Will hardly spin the tires, even at WOT standing start.

- Heats up, although it never goes to redline. Tempature increases as much as 20 degrees anytime during WOT, and slowly drops back to normal temps. Highway temp is more than 220 degrees. Fixed blown head gasket when I first got it. No oil in water, no loss of coolant, no smoke.

Other than these symptoms, the car runs very well, acceleration is smooth all the way up to red line, no hesitations. Has excellent part throttle drive-ability.

Problems I think I have noticed:

- At times, fuel pressure bleeds out anywhere between 1 to 5 hours. With key forward (engine off), we checked for the correct 12V source at each injector harness. At first, I did this by probing the pink wire and used the frame as a source to ground. But, I then proceeded to check for ground at the injector harness and there was. This means that these injectors are open with key on (engine off) all the time. Is this suppose to be OK?

- #1 header primary does not get as hot as the others. I tested by spraying water at it.

Things we have done:

Confirmed dot to dot alignment at timing chain.
Compared cam lobe orientation to stock cam.
Replaced lifters with stock GM lifters
Replaced Optispark with new unit.
Replaced stock coils
Bypassed MSD amplifier
Replaced Opti Spark wire harness
Replaced MAP sensor
Replaced TPS sensor
Replaced IAC sensor
Replaced IAT sensor
Converted to head 3-wire O'2 sensors
Checked for exhaust leaks
Checked for vaccum leaks
Replaced Knock sensor
Replaced ignition plugs
Checked ignition wires
Checked fuel rails
Checked and Replace fuel pressure regulator
Replaced fuel filter

Major Mods Are: Ported LT1 castings, XE230/236 cam, Hooker Lt, 2800 stall. Fully Rebuilt on year ago (355 cid).

Thanks Very Much

BPS

Hi

a couple of thoughts
first are we talking about a 96 (username) or a 93 (sig) are ther are programming differences.

I'd look at cyl 1 and try to see what it's not as warm as the others - this may be a bad plug, shot wire or something in the valve train but it should be as hot as the others


are your new o2's GM - i've tried others brands and have had poor reading from them.

you've done a lot of the usual steps - try bleeding the rad again, i did not see that on the list.

see if you can use something like datamaster and log the engine while you take it for a drive - no WOT - just a regular trip to the store.

that's it for now