89form

When I floor the car it occasionally will feel like its pulsating the power.( best way I can describe it) This seems to happen only when I am at cruising speed (55) and then floor it say to pass. The car acelerates but in a slight bucking fashion. All other times it runs fine and if I let up on the throttle just a little bit so it isnt floored it takes off smooth. Actually faster then when it is floored. I set the fuel pressure using the O2 sensor voltage. Could the pressure be too light? My timing is about 12 degrees advanced.

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1989 Formula 5.0 TBI w/ T Tops, bosch +4 plugs, accell 8mm, accell cap&rotor, K&N air filter, relocated IAT, 3.42 open rear, Energy Suspension's poly bushing kit, 14x3 Edelbrock Open Air Filter, AFPR, and much more to come!!!

Rock90rs

iTrader: (3)

Hows your fuel filter?

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Self ported TBI, 4x3 K&N, TBI spacer, ADS Superchip, Flowmaster catback, Vette servo & Shift kit, L98 cam

My RS

89form

The filter is about a year old.

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1989 Formula 5.0 TBI w/ T Tops, bosch +4 plugs, accell 8mm, accell cap&rotor, K&N air filter, relocated IAT, 3.42 open rear, Energy Suspension's poly bushing kit, 14x3 Edelbrock Open Air Filter, AFPR, and much more to come!!!

Andy89RS

Seems like your problem is when you go into open loop, fuel pressure would definitely make a difference then since the O2 sensor is ignored and it just follows a preset map. Also, 12* is a hell of alot of advance for a pretty much stock L03. The only time I ever ran 12* advance was when I foolishly poured a whole bottle of octane boost into a less than 1/2 full gas tank and ended up with waaay too high octane to do any good. Otherwise on 92 pump gas I got best results at about 4*, any more and I'd get knock.

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"Racing is life. Everything else is just waiting." - Steve McQueen - LeMans

305 TBI, T-5. 15.4@92 mph
Member Southern California Third Gen F-Bodies

AOL IM: Andy89RS

Eggplant Jeff

Andy may have hit on the problem. If you're getting a few knock counts at WOT, your computer may be retarding the timing, then letting up a bit, then retarding it when it gets more knock. Thus creating a pulsing feeling. The EGR valve (when it's dying/dead) can cause a similar thing but that is usually when cruising at a constant speed, NOT when accelerating so I don't think that's your problem.

Dan W

Yep sounds like youve got too much advance.

FastBroker

If you unhook your knock sensor and isolate the sensor connector (like in baggie, to make sure it doesn't short on something) you'll probably knock a hole all the way to China. This check will basically diasble your knock retard and allow full advance. As these guys are saying, that's a lot of advance, man!!!

I like to unhook knock sensor, run the ****tiest 96-97 octane gas I can find. Then, I advance timing until I can JUST find knock (I leave knock connected and use scan tool to look for knock counts). Then, I hook back knock sensor and put in 90 or so octane. This may give you lower advance than some of you guys run but if your ECU retards from knock, you are hurting your overall power and the ECU is just retarding the spark for you, anyway. Plus, if you end up retardin a couple degrees my way, will lower engine temp a little, usually...

[This message has been edited by FastBroker (edited September 15, 2000).]