I just finished my 350/T5 swap in my 91 RS. Car was originally a 305/700r4 and I retained the TBI (after doing all the ultimate TBI Mods( system for my 350. Engine is an older 4bolt main block with some ported l98 heads and ported L03 intake (I know its still restrictive). I took an L05 EPROM tune and converted it to manual trans and used it to break in the new motor along with driving it 45 miles before taking it to the exhaust shop. When I went to pick up my car it clearly didn't run right but I still took it and drove it home. I had to nurse it when ever I came to a stop to keep it from stalling out. I have since played with the tune and realized it made no difference and even replaced the ecu and it still doesn't accept the tune. I have tried my stock ecu with: the stock prom chip, the stock prom on my chip, the tune I used to break it in, various others on that ecu. I have also tried the replacement ecu with the L03 w/ T5 eprom that came in it, and the tune that I had it running with originally. I have also tried both ecu's with no prom chip in. No matter what tune/ecu I used it acts the same, like there is no prom chip installed. I know that it isn't a fault of my soldering on the '8746 because the engine was broken in on it. I am at a loss. I really want to get my car running so I can enjoy the rest of the summer. I really appreciate any help

check spark plug wires, they messed with your exhaust right. could of burnt one. check vacuum hoses by spraying carb cleaner on them. an increase in idle rpm means it sucked in the spray. use fuel cleaner like black bottle stp or gumout in the clear bottle with orange fluid. check for codes, clean the iac, oil full? oil pressure runs the fuel pump. check the injector resistance by going point to point with an ohmmeter, should have 15-16ish ohms, otherwise its stuck open

What matt said with the exception of the injector resistance. TBI's are about 1.2 ohms.

For some testing of the ECM/PROM check for the SES blink at key-on, engine-off. That is: at key-on, engine-off, the SES should: light up, blink off, then light up solid. Need to key-off for 10 seconds or more to re-run the test.

The blink-off is important as it shows that the ECM is running the code in the PROM, and not in limp mode. With the PROM removed, at key-on, engine-off the SES should blink rapidly. If not then the ECM is toast, or it isn't getting power, or the SES light is burned out or removed.

RBob.

As I typed the above replay I was thnking, wow, this is the second guy in the past week that this happened to. Not so.

I take it that it is still having an issue. After the changes/tests you have made I would start looking at the EFI harness. Check at the ECM for ignition power and battery power (Battery is on pins C16 and B1. Ignition power is on pin A6).

Then check the EFI grounds on the back of the head(s). Don't recall if there are two grounding bolts or just one. Disconnect the MAP and TPS connectors and cehck them for +5 volts. Then plug one in and check for +5 at the others connectors. Then do the opposite (unplug that one, plug in the other one, and check for 5 volts).

It has to be something that is preventing the ECM from running properly.

RBob.

Yeah that was me in the ecm forum but since I swapped ecms I figured I would try another board. I am in class right now but I will for sure check the grounds on the heads, you are correct there were grounding points,one on either head. I am going to get up early tomorrow and do those tests.

I just checked and my SES light comes on for a second, flashes off, then remains on solid during key on engine off.

I checked and both the grounds on the back of my heads are nice and secure and I am 100% positive that I attached all of the grounds back on the heads when I swapped the engine.

I came on here to check what pins RBob said to check at the ECM and the TPS and MAP.

I should add that I do have a 91 Camaro FACTORY service manual at my disposal.

Ok I checked the pins RBob said to check on the ECM harness and at the MAP and TPS and all checks out. I also checked the ECM grounds and they all check out too.

I also checked the injectors and they each hold a perfect 1.2 ohms

I appreciate the quick response. I have gone through and checked spark plug wires, vacuum system, and all electrical connectors to make sure they are good.

With the SES blink that means that the ECM is running from the PROM. Which is a good thing.

Reading through this again it sounds like your EGR valve is open. This can be caused by a bad EGR valve, bad solenoid, or a bad driver in the ECM. I would start looking into the EGR and checking if it is indeed the issue.

RBob.

Last time I saw my egr was as i tossed it out. I should have mentioned that in my original post.

I made my own delete plate and used "form-a-gasket" between the plate and the manifold. I put a rubber vacuum cap on the TB unit to cover the hole. I also tuned the EGR out as per instructions in BMONTE's sticky on the TBI forum.

OK, not surprised, but it does eliminate that possibilty.

At this time a scan tool would be helpful. Just to check what the sensors are reporting.

At key-on, engine-off (have the SES blink still?), short pins A&B together on the ALDL connector. Only code 12 should flash out. Any others? Does the ECM at least flash out code 12?

Remove the top cover on the ECM(s), check the two 16 pin DIP chips back near the harness connector. They are the drivers for stuff like the SES, TCC, AIR, EGR, and so on.

Any physical damage to either? Such as a crater blown out, cracked in half, burnt through the PCB? If so then it is possible that a solenoid is shorted, or that the driver was damaged during welding on the exhaust.

Have you checked the exhaust? You didn't list what was done, maybe they crimped a pipe, or damaged something else while under there. Fuel line and return look OK. Along the full length?

Are the knock sensor and head temperature switch for the fan still connected properly? They can be switched unknowingly.

RBob.

The exhaust is true duals with no cats, just bullet mufflers. The guy had it up on the rack when I got there and he pointed out how he kept away from the brake and fuel lines, but I will double check that in a bit.

I disassembled the "new" ecu before I hooked it up and compared it physically with the one I thought to be burnt out and they looked identical, no visible damage to any part of either of them.

My friend broke the fan switch connector during the engine swap so I know that and the det. sensor didn't get switched around.

I just checked the CEL codes and just got Code 12.

I am to the point that I am willing to throw parts at it, if anyone has a suggestion.

fuel filter? fuel pump? vacuum leak? heat from new exhaust causing vapor lock?

It doesn't get a chance to heat up, and the fuel filter has less than 7k on it. I know I said I would throw parts at it, but right now I can't put a fuel pump on a non running car in good conscience without being sure its the issue.

I can no longer get WINALDL to work either, if that offers any help

EDIT I just checked the resistance between Pin "E" at the ALDL connector and Pin "A8" on the ecu and it comes up good. Circuit 461

Another note, i disconnected one injector and the car ran slightly better with only one injector. I was actually able to take my foot off the gas and it didn't shut down instantly. With both injectors connected its like a golf cart, the second you take your foot off the gas it shuts off.

I am going to keep posting my info up just in case in the future someone has a similar problem.

I went back to the ecu/prom shuffle today and I don't know if I missed it last time or if something changed but, I am no longer getting a SES blink with my burnable chip, 27SF512, (the one that was in the car when it got welded on) on either ecu. My stock original auto trans chip no longer gets the blink either, I could care less. The only chip that is still getting the blink is the stock one from my manual trans replacement ecu. It gets the blink in either ecu. Yes I did wait 10 seconds before testing each ecu/chip combo.

I had 3 people come over, because my car running like crap all sounds the same to me now, and had them listen and they said it sounds better with the stock manual trans chip and either ecu, than any other combo. They couldn't tell the difference between the 27SF512 and no chip. Either way it runs like complete garbage still.

I ordered a new 27SF512 from Moates so that should be here in a few days.

Either way my WINALDL still doesn't work with any combo of ecu and chip.