I've just finished a 305 to 350 swap on an 87 TPI Camaro, and it starts and roars! But....I can't keep it running on idle. I haven't changed any of the components b/c i know most are the same, and the ones that aren't should make it run, just not very well. But the sensors are only important when the EST is connected right? I'm thinking the TPS is the culprit, but i'm open to any other ideas. It sounds like a fuel delivery problem, but the fuel pump is getting right up to spec pressure on S/U and there appears to be adquate flow when i'm trying to prime the pressure gauge. Argh, so close to being done!!...i hope, lol

 

I had the same problem when I didn my L03 to L98 swap. Come to find out, the under-dash connectors changes between the years, so my injectors weren't getting any power. The cold start injector would give the motor enough gas to fire up for a few seconds, then die. First step, check the injectors. Set the TPS to .55v +- .05v while you're at it. Also set the idle. Ground the ALDL terminals A&B then turn the key on for 30 seconds. Then unplug the IAC and start the engine. Using the idle set screw on the throttle body, set the idle to 1000RPM or wherever you want it. Then shut the car off, plug in the IAC motor and the ECM will adjust to the idle.

 

Interesting, but how exactly do i check the injectors? I've already checked the resistance, which came out to be fine, and i read that you put a continuity light on the FI's while they're running, but as i can't get my engine to run.... Would having the starter crank it over a few times be suffiecient?

Edit: Oh yea, i forget to mention this actually, i can keep the engine running by opening the throttle, so i think that would cross out the FI's not having power. Any other ideas? I've reset the TPS (and broke of the head of the top bolt, DOH!!!) and i'm gonna take a look at the idle air motor tommorrow.

 

I agree to reset your idle. Did you change TBs? If so you will need to open up that set screw some.

 

Yeah, IAC setting would seem relevent

 

Well, i got it to start again!!! Unfortnately the headers were w/in 2 minutes. I think this is b/c i don't have anything after where the catalytic converter used to be. Is there a minimum length for exhuast pipes? I really need a "for dummies" car manual, lol. i also found out the reason it wasn't starting was that i was twisting the distributor to fast. Argh! Well, tommorrow i'm going to finish out the exhaust w/ a dynomax high flow cat and the stock exhaust. (flowmasters coming) and tighten down bolts, check fluids, etc... Then i'll set the timing better. I'll post the results asap! Thanks again

 

The headers were what within 2 minutes??

 

Glowing maybe?

 

Then the timing is severely retarded. Make sure the EST wire by the a/c box is plugged in. Otherwise you won't have any advance. When setting the timing be sure to unplug the EST wire, then set the timing to 6-8* at idle, then plug the EST back in. The ECM will advance your timing at idle but if the EST wire is unplugged it wont which will make it retarded and cause the headers to glow.

 

LOL, sorry about that. the very sad thing is my attention to detail w/ cars is about that good Yes, the headers were glowing cherry red. I attached the catalytic converter and set the timing at 8*BTDC (and followed EST procedure). That seems to have fixed the glowing problem. It's running now, but here are a few gremlins i could use some advice on.
1) Appears to run VERY hot (had to stop and pull over at red line temp (260F)
My thoughts:
- Fuel psi is 45-50 psi (higher b/c i have 305 injectors for my new 350)
- fan does not switch on
-timing
-still need to finish exhuast

2) Throttle appears to stick (need to "kick" the pedal to reduce RPM's)
- TPS?
-need to lubricate throttle cable (how?)

3) Seems to run better w/o the MAF connected, BUT i don't have the harness for the Manifold Air temp sensor, any connection? (go figure i have that harness the entire rebuild until the night b4 i need it!!!

I'd like to thank everyone on this website that has helped me, i can't not have done any of this w/o the enormous amount of help i have recieved.

 

1. Without a fan running your car WILL overheat. Get that fixed first. Check motor, relay, switch, wiring, etc...

2. I don't know how to lubricate a throttle cable, if it were me, I would replace it. Also check to make sure the spring on the TB itself is working correctly, not binding or sticky.

3. I am confused about that one. Did you convert to Speed Density? If you did, than yeah, it should run better without the MAF restricting airflow.