I installed edelbrock intake manifold and runners which were ported and I ported out the stock plenum to match the intake and runners. The problem now, when cold start(s) I get really bad surging as low as 400 rpms and as high as 2500 rpms. It surges for a few minutes then it idles normal around 700rpms. It idles and starts fine after is warmed up. Ive checked for vacuum leaks, all checked out good. Iac valve was reset, tps is at .54volts. Cold start valve (injector) is working properly. Not sure what else to look for. Does my car need to be tuned? It's a 1988 camaro tpi 5.0 manual transmission.

 

I'd be a bit surprised if it was tune related more than a vacuum leak, or something dry/brittle that cracked while you were making the change, or that was left disconnected. The hard vacuum lines like to shatter with age, rubber likes to dry and crack. Injector O-rings like to tear. A TPI car will still run pretty good with a folded under gasket, or the brake booster hose disconnected, but it won't be right.

Go back to the beginning and work through it. Visually inspect everything. Every hose, wires, plug wires. Make sure the distributor is dropped in the right spot. Doublecheck the firing order. Make sure all the clamps and hardware is tight. Etc.

If you haven't already, be sure you reset the ECM so it can 'learn' the new setup. I.e. disconnect the battery for a minute or two, then reconnect and drive the car a bit. Probably not high on the list of likely culprits, but it doesn't cost you much to try.

 

Vacuum leak 99.99999999999999999999999999999999999999999999999999999999999999%

 

everyone likes to say vacuum leaks but why is it all good when the car is warm?... i have the same problem with cold start (mine is running in another thread).... i also know vacuum is not the problem.

When the car is warm it starts and idles fine.... that doesnt sound like a vacuum leak...

 

Simple.

​​​​​Heat + metal = expansion = often some leaks at manifolds can go away at higher temps.

 

The thermal coefficient of expansion of the metals used in these engines is not so great that it would close up the gaps necessary to cause the type of problems the OP is seeing.... certainly not enough to have the engine running normally.

 

Sure the timing is set right? Smoke test it or start cold and spray starter fluid all over and see if idle changes

i dont think it should have issues with intake swap on stock tune. But a data log would confirm suspicions

 

Thanks for the input guys, and actually this was the second time I removed the intake manifold and everything thing else above it and start all over again and make sure everything was nice and tight. The main reason I re-did it again is because I had the same problem the first time, and for peace of mind. Also, I thought about a possible vacuum leak between the intake manifold and heads since i only added a thin layer of rtv on intake gasket so this time I added a bit more.

all sensor are functioning like they should, I did reset the ecm. Bought new gaskets, "O" rings, vacuum lines. I checked and rechecked everything as I was putting it back together. No vacuum leaks at all, spark plug wire are in correct order, timing is also at specs (6*) I'm guessing I good tune is the way to go. What about getting a burn chip for ecm?

 

Perfect time for you to buy a burner and download tunerpro rt. Couple small changes you could try and it will run well again. Assuming no mechanical issues but sounds like you covered your bases

 

I've never done anything related to tuning. What burner should I buy? I'm sure youtube video's would help understanding with tunerpro, Thanks.

 

Moates.net has everything you need. The burn2 is what i use

 

Honestly, I wouldn't immediately start buying stuff and try to tune my own car out of the blue with zero research.

I would buy an ALDL to USB adapter from 1320 electronics and datalog my car.

http://www.1320electronics.com/12pinALDLUSB.html

I'd then begin to get an understanding of what is happening, and maybe consider buying the tuning stuff then, or reaching out to an existing tuner to do it for me to save me the time/effort (and extra $ on one time use burn parts). Either way, step 1 would be ALDL to USB so you can datalog to TunerPro

 

ok. So, I had some time this weekend to try to find why my car was running bad at cold starts. I was hesitant to take out the intake manifold all over again, but i did it anyways. As you can see in the picture I shined a flashlight thru the side of the intake at the vacuum port and notice bad workmanship done to this intake. The red arrows show where the vacuum leaks were coming from. They drilled the egr vacuum ports too close to the egr bolt threads creating a passage of vacuum. Story of my life! Anyhow I end up porting out the stock intake manifold and installed it back in the car which run awesome again. I don't think I'll be using this edelbrock intake anymore, who's know what other imperfections in might have internally. Too bad since I have the edelbrock runners and headers to match it up. I do thank all of you for your input though.

 

How did you find the leak ? Carb choke cleaner ?
the only flaw I’ve seen on a batch of the edelbrock bases is where a runner bolt connects to the coolant passage. Not a problem to use the base you just need to use liquid Teflon on the runner to intake base bolts.

 

I have a question also. Did you notice a big difference in performance when you went from the Edlebrook back to your stock base that you ported yourself? Loss, gain, indifferent?

 

you got it, I used carb cleaner and BINGO! rpm's went up when I sprayed at the egr bolt.

 

honestly it felt better at midrange with the ported stock intake, maybe because of the vacuum leak in the edelbrock intake. I bit more responsive too maybe due to the 52mm BBK throttle body I put in.

 

Might be worth getting a new prom burned too...keep your fuel trims in order...