I have the motor together and running! However it is adamantly refusing to start with no throttle or idle if I take my foot off the gas. It isn't a stumble and then die either, if I shut the throttle, the car instantly stalls. It has spark, and the distributor isn't perfect on the money, but I have adjusted my PROM to the correct base timing to try to make it idle and no dice. I also upsized my injectors from Bosch 22s to stock style Accel 30s, and also updated that information in my PROM. Does anyone have any idea what my problem could be? Going from stock to Edelbrock base, SLP runners, and siamesed plenum.

My first go-to is IAC valve being stuck shut but I don't know enough about it to know definitively if that's the issue, and I would rather not throw parts at it to find out.

 

I would look at the IAC first. Take the IAC out and clean it off, along with the passages. If that doesn't work, then replace it. If it doesn't run, return the new IAC. Also, make sure you have all the vacuum lines connected properly. It's easy to miss one, particularly the one that goes to the brake booster.

 

I'd start with the minimum idle adjustment. Should keep the idle to at least 450 rpm. Then you can scan and watch the throttle position sensor and the idle air valve operation.

 

Oh, and check the voltage on your TPS sensor as well.

 

On your injector swap, did you input the voltage offsets into the calibration?

 

I did not. How would I do that?

 

First you need to get the datasheet from Accel which has the offsets on it.

Then in the calibration you find the table for the injector voltsge offset and then enter in the data. Sometimes the voltages don't line up one for one you have to do a little interpolation.

What prom mask are you running? 8d? 6e?

 

I'm running the 6E mask, and I plan to switch to 5D to use my 165 ECM with a MAP sensor In the next month or two, but for now I just need it to run.

 

So I did this using a datasheet I found here on thirdgen. The car starts now before quickly dying, and hesitates then dies after I take my foot off. So it helped but didn't do it all! Thanks for the tip

 

Like others have said you probably need to set and/or trouble shoot the IAC.

 

Yeah. I think I destroyed the coils cleaning it with brake cleaner like an idiot. I have a new one coming Tuesday

 

Do you have the correct throttle body and plenum combo or is it a mix of parts?
certain combo won't get idle air without mods. Think its early t-body and late plenum.

 

Both the throttle body and plenum are stock except for the siamese porting I did to the plenum

 

Are the runners stock?

 

No, SLP second design

 

Do they have the small port on driver side blocked off?
are they for 85-88 or 89-92? With or without cold start inj?

 

They do have a small port blocked off on the cold start injector side, but I also deleted the 9th injector a year ago. The car is an 86, as is the plenum and TB. I wanted to take the plugs out but the manifold just rounded itself out.

 

On the driverside runner, with 85-88, the small tube has to be open. That feeds the idle air to lower intake. They changed that in 89.
you could modify the back of the throttle body(like 89-92s) so the air just goes into plenum.