I’m having a problem with my car not wanting to start. Yes I’ve searched the boards but I still would like to ask some questions, thanks to those who will take the time to reply to my post. First off here’s what I’ve attempted to do, and what’s in the car.
1991 Z28
383ci 10.54:1 comp
zz-409 cam Adv. duration 287/287, duration @.050 226/226, Lift .520/.520. 112 LSA
Afr 190cc heads
Msd ignition setup
HSR intake
30lb injectors @40psi
Tpis chip
I read out the ALDL and have no codes other than 12.
I set the Tps to .54
I set timing to 6* btdc
If I crank the engine over it will not start, when I step on the gas pedal it will. So it’s one of two problems. 1. Not enough gas or 2. Not enough airflow.
I checked the gas theory by having someone crank the engine while I gradually increased the tps lever, and not moving the throttle plates. This didn’t start the car so I go with theory 2. I tried adjusting the IAC, the engine was not warmed up but here’s the problem. I already have the stop screw adjusted as far forward as it will go. I have some thoughts as to what the problem might be please set me straight if I’m going in the wrong direction here.
1. When they machined the holes in the HSR the put them to far forward, and the throttle
Cables have too much slack in them?
If that’s the case I might have to try a throttle body spacer and see if that fixes the problem?
2. My iac valve is shot or the passages are just really dirty? But I don’t think so because I have to move the gas pedal a fair amount of distance. And I already cleaned that stuff out.
3. I don’t know Cam theory to well, Is the Cam to big I’ve been told that’s it’s “fairly aggressive” but not “to wicked”
4. I’ve yet to put a vacuum gage on the car, kind of wanted to be able to start it first. Would a vac leak cause this type of problem?
Any other ideas will be greatly appreciated

 

What TB are you using? Did you try adjusting the minimum air?

 

So, just to clarify, your car will not start unless you depress the gas pedal some? How much would you say, 1/4, 1/2, more? My car has a similar issue when its hot. Sometimes I have to just open the throttle plates a little to get her to fire over. Or the engine will need to crank longer than I like it to. My problem was worse before I adjusted the minumum air properly.

 

i've got to depress it about a 1/4 to 1/2 inch. It's the stock t/b bored to 52mm. The thing about the min air is that the set screw is extended to the max limit already. ????

 

Yeah. The procedure I followed from a Chevrolet fuel injection book tells to reset the IAC and adjust the set screw on the TB to allow enough air into the engine for it to idle. Do this when its warm. Oh yeah, unplug the IAC so it won't move while adjusting the set screw.

 

so i went a bought an IAC valve, and the car starts with no gas pedal now. kinds pisses me off that it was something so stupid giving me such a hard time. now it's time to tweek the machine into perfection. thanks to those who replied. Dan