I recently just did a MAF tpi retofit on my 69 camaro, It has no problem strting when cold but after running for 15 minutes or so the idle is all over the place and it will die and not start until it cools off. The only code i am getting is a code 44. which is a lean code, and it doesnt pop the code all the time, b ut im getting lean pops through the throttle body. have the timing set to 8 btdc. the tps is at .55 . the computer is new and the ignition module tests out good. I also seem to be having problems setting the minimum idle. If i put a jumper in A and B wait the 30 seconds unplug the iac then pull the jumper and start the car i cant seem to get it set. its almost like it makes no difference. I have went over all the vacuum ports and have no leaks, not sure what to do next, besides go back to a carb

 

I had the exact issue with my tpi setup and after replacing the injectors, regulator, and fuel pump it turned out that my timing mark on my balancer was off. I figured out the correct markings and reset timing and all was well again. Might be worth a shot.

 

I had a code 44 also, and it was solved with a new regulator diaphragm and new injectors to replace my old leaky injectors. I wound up placing the old injectors and the fuel rail on top of some paper towels and pressurizing the rail, 4 of my 8 injectors were leaking and it was easy to see the evidence on the paper towels. Code 44 is set when the ecm sees the O2 sensor voltage below .2 volts for 50 seconds, but this "lean" code can be set by an overly rich engine. The O2 sensor operates best at hotter exhaust temp, but a very rich engine will cool the exhaust gas temps and fool the O2 (and ecm) into thinking the engine is running lean.

I would start by checking the fuel pressure at the fuel rail (40-47 psi, off idle). Next leave the gauge attached and stop the engine and note how long it takes for the fuel pressure to drop.

If you have a scanner it can be very valuable here. Use it to look at the BLM and O2 values for a rich/lean trend over time.

 

i unfortunately do not have a scanner for the obd1. My fuel pressure is 51 psi at idle and never drops below 47 all through the rpm range to full throttle. I stays up for a minute or two after shut down, which i am not surprized, it is a new fuel pump and new bbk regulator diaphram and adj. cover. i know its lean due to the lean pops through the inake and the first couple inches of the headers will glow, and the idle doesnt drop like it should after a quick blip of the throttle. I am running the stock 19# injectors and stock memcal for the 165 ecm, and im starting to wonder if i will have to program the chip differently to richen it up. Am i thinking along the right lines?

 

What engine are you running this on. Unless it is a stock TPI 305 you will need to tune it, even if it was the stock 305 you may still need to tune it due to the weigth and transmission on your car.

 

it is a bare bones 350 with nothing special, really just a reliable driver is what i wanted. I was hoping to just be able to turn up the fuel pressure and be ok since the car is lighter than the camaro the tpi came out of, but i guess i might be wrong.

 

With a different cam and heads minimum air flow and fueling conditions will be different. You may be able to fiddle with initial timing setting and fuel pressure but understnad that will modfy the whole timing and fuel curve in the maps in the ECM. Your best bet is a WBo2 and the ability to burn new chips. If that sounds daunting it is. Not sure what your money situation is or level of expertise with EFI but I believe you would be much further down the road to purchase one of the used Holley 950 or megasquirt ECMs out of the classifieds and wire it into your harness. They both come with the logging and programming changing ability you need with no additional equipment and they have the provisions for upgrades and engine modifications.

 

Is the holley 950or megasquirt ecm a better bet than just getting the hardware and equipment to reflash chips for the gm 165 ecm? and do the also work with maf systems or are they sd ecms

 

In my opinion yes both of those are a better choice. They will run on speed density, but in all truthfulness the MAF 165 system is nothing like the MAF of today it is comparing air mas to a predicted air mass stored in the ECM, If you are not near that predicted air mas you have what you have now.

If you go with the aftermarket system the vacuum vs RPM tables for timing and fuel are for the most part universal to any tuner worth his beans and is very easy for the novice to learn. If you pair these table with a WBo2 You should be able to get a solid tune very quickly. After that there are various tables to improve idle cruise and cold start up.

The GM ecms were great for there time. I have literally burned thousands of chips. I still have the hardware, but those ECMs in my opinion are of the past and really take more work to iron out on retrofits than the money your saving is worth. Unless you are well versed in electronics chances are it will hold your combo back.

 

thanks for all the info, it sounds like i need to make up my mind on what to do.