Just went out to take my 89 rs with a mild 350 out for a run with its new injectors put in and its smoking like crazy.

Background/Details:
I had swapped in a fairly mild 350, ran with the stock injectors and cop car chip for about 500 kms and all seemed fine. Now it wasnt perfect but it ran/idled alright and I was happy with it. Last week I purchased a set of reman #65 injectors to finish things off since I figured it needed the 350 injectors put them in and now its smoking like crazy.

Is this normal for new injectors until they work in or something? I have never swapped injectors prior to this, so I am hoping that is all it is and its normal for the first bit.

Ideas?

 

What injectors were you running before?

 

They were the stockers on the original 305 (L03)....so I think they were #45

 

Stockers on a 305 are 55#, stock 350 Trucks/non 9C1 B-car got 61#, and Caprice and some Vans got 65# or 68#.

Here is what likely happened or is happening. You left the stock 55# injectors in it and the Caprice chip was programmed for 65s. The pulsewidth would be too low to supply the necessary fuel, so the long term fuel trim (BLM) was driven up to compensate. Now the BLMs are very high and you put in larger injectors. Thats a 1-2 punch, more fuel from both the software side and the hardware side. I would atleast attempt to disconnect the ECM, wait a couple of minutes then plug it back in. This will reset the BLM values back to a neutral value. Also look over the vaccum lines going to the TBI, if you pulled the TBI off its possible one was not hooked up correctly or broke. Especially check the MAP sensor vacuum tube.

EDIT- You might also disconnect the injector connectors and try to start the engine. You may have pinched an injector o-ring and fuel maybe entering the engine un-metered. If it starts and stays running more than a couple of seconds with the injector connectors disconnected, you have a problem.

 

Just disconnected both the ECM and battery for about 15 min to be safe. Re-started it and same problem, also rechecked all vaccum lines and electrical connections, all seems fine.

Disconnected the injector connectors and the engine started, then died about a second or two after. Tried to re-start it again and no luck.

So you think maybe it maybe like you were saying (fuel entering un-metered...so I am guessing next plan of attack would be to remove the injectors again and re-install/see if I can see anything "weird".

Any other ideas?

 

If the old injectors worked better, then why not go back to using those?

 

That is kinda what I was thinking to be honest....but based off everything i read etc it should be running #65's given the prom I have, so that is what I wanted to put in it.

However like you said if it ran better with the stock 305 injectors maybe I should just run with them.

 

How much fuel pressure are you running??? If you are above 20 PSI your original 55# would feed that 350 just fine and #65 would supply just too much fuel until BLM's lean out mixture over time. (note that at idle you might be running open loop and ECM will not be able to correct for rich mixture)

//RF

 

Hi RFmaster...I am running the stock Fuel Pressure...have not changed anything with respect to Fuel Pressure

 

A bad coolant temp sensor will cause vehicle to run extremely rich. Maybe you could test that sensor? any codes?

 

Hi Ronny...I thought about that, but dismissed because the CTS is only a couple years old...but only had about 2,000 Km's on it.

No codes other than a phantom ERG code (think its 34) which shows up every now and again.