Ok so my car was down recently while I replaced the injectors. Now that I've got it back together I can't get it to idle at all. U can tell the ECM is idling it up but once it gets near 1000 rpms it starts to surge from 1000-500 and will eventually die. Also even when the ECM is idling the car up u can't put it in gear it dies. Also it seems like the problem only starts once the car starts warming up. I'm thinking it's the IAC valve. The only things that I've done in the injector swap process that could have affected the IAC were I changed out the throttle body plate and I deleted the heater bypass valve by capping the return and routing the line that comes off the tb directly to the heater core. Also I've went from 22lb injectors to 24lb. Any thoughts?

 

have you checked for vacuum leaks? If you go into diagnostic mode this will force the iac in.

 

Are you datalogging it?
Did you change the injector constant on the PROM to match your new injectors?

 

No I don't have data logging equipment and haven't messed with the tune at all. I was hoping not to have to retune it. Also it runs great all throughout the rpm range accept for idle.

 

Ok so I did some tinkering today. I haven't fully tested for vac leaks. I replaced the iac and it's doing better but when it gets close to idle it still floods out. You can tell its too rich at idle cuz while it's running and once u start it after it dies all u can smell is gas. I just hope getting the ecu tweaked doesn't cost me an arm and let cuz if so the TPI might be getting dropped and sold and my 750 dp in its place.

 

Idle surging and dying is most often a vacuum leak.
Since you just changed injectors that seems most likely.
Each injector O-ring must seal into the base or it becomes a vacuum leak.

Generally, installing larger injectors without a very good reason, and without correcting the injector constant on the EPROM is asking for trouble, especially if you are not monitoring your AFR with a wideband, or at the very least watching your fuel trims with scanning/datalogging software.
Tuning a TPI requires these sort of actions as the "norm".

A wideband would be very handy for tuning even with a carburetor.
For example it will show you that the gas smell in the exhaust when it idles or dies can be caused by lean misfire/surging. You can't always assume "rich" when you have raw fuel escaping the exhaust.

Datalogging will show your BLMs (fuel trims) excessively high at idle if you have a vacuum leak, and if you have a MAF, then your MAF output would be low at idle. Getting this information can save you a lot of parts replacing and troubleshooting time in the future.

 

By the way, correcting your injector constant only requires a chip burner.
I believe you can get one used or new from around $50 to $150, depending on how nice you want to go, but the cheap one will do the job fine.

The software for using the burner and changing your calibration is free.
Datalogging software is free. A nice cable to connect to your car costs around $40.
All the information you need is in stickies in the DIY PROM section.

 

Update! Did a vacuum test today with a gauge. I couldnt do a very accurate test being that the car wont hold a very steady rpm down low. When i could get it to cooperate, it surging between 1100 to 1300 the vacuume read 17.5 yo around 18.2 varying with the rpm surge. But down low towards idle 750 to 500 rpms it only had around 8-10 vacuum. Also i pulled the #1 plug and it was very black, even worse than the 4 plugs on the cylinders that previously had the leaky injectors. I think it might have a small vac leak at the PCV and im going to replace the hose and PCV later. But other than that i dont think its a vacuum leak. Because during the injector swap i made sure all the gasket surfaces were clean and preped, followed all instructions on reasembly and i have confidence in my work. Also since you cant get to all the gasket surfaces once its assembled (mainly the lower gaskets) you cant do the soapy water test. Im thinking it might have a very small leak at the PCV, causing the little 100-200 rpm surge but other than that i think it needs some tuning. Its just frusterating cuz i really dont have the cash to get a autoprom like i want and putting a carb on it wont be much cheaper even tho i already have one but having to buy rebuild kit, jet kit, and Bypass fuel reg aint so cheap either. MAN THIS IS FRUSTERATING.

 

Soapy water test is for looking for compressed air/gas leaks, not vacuum leaks.

There is absolutely no comparison between the cost of correcting your chip calibration and swapping to a carbureted system.

You are not making much sense. You may have confidence in your work, but it was you who installed the injectors that were too big before you had the means to correct the calibration.
I suggest not driving the car until you are able to correct the fueling problem.
Once the injector constant is corrected, I would put in a fresh set of sparkplugs to eliminate misfires caused by fuel fouling.

 

Well at the cost of getting rebuilt 24lbs for $75 or only able to get a new set of 22lbs for $350+ then ill go with the 24s all day long! Also I dont see how im not making any sense because I typed all of my reply in clear english. Also soapy water can be used for both since you can watch the soapy water being pulled into the leak.

 

Well you're right cheaper is cheaper, but
did you see your new injectors tested on a bench? Where were they from?
I have to wonder for that low of price if your good deal might not have been so good. I think I might try a set of known good injectors as a test before moving forward.
Also what type of injectors are they? Can you post a photo of one?

I'd also be looking for a good deal on the chip burner.

 

From a reputiple dealer on ebay. They were from a 97 Cobra. And im always looking for a deal.

 

https://www.thirdgen.org/forums/diy-...-injector.html

 

Thx for the link. I already have a AFPR so ill bump it down to 39.

 

I don't mean to hijack the thread or anything but I'm suffering from the same problem and it seemed to of started when I unplugged the fuel injector fuse from the fusebox and plugged it back in. I haven't checked if the fuse is burnt out but if it is could that also cause the car to die at idle?