blacknineteen97

Long time listener, first time caller. I first found this board around 2002, mainly just lurked around and took in information. This place is the best place for TPI third gen information hands down. So thank you to all of you who share your information with the world, and thank you to everyone else who makes this place happen, it’s awesome.



My first car was an 89 Camaro RS TBI 305 (bought with a bad tranny and then sold it after it was fixed), my main car was a 87 Trans Am TPI 305, I’ve had several LT cars, Z’s and a formula, a few mustangs (don’t hate me), a lightning, and I just recently purchased this 86 Trans am. Here’s what I know about this car:

· The previous owner swapped a 350 into it with a mild cam (was told it’s a 268 with .488 lift?), mid length headers, full exhaust, 52mm throttle body, also no A/C, no EGR. The guy I bought it from seemed more familiar with carbureted cars and didn’t seem to know much about the TPI. This thing is running extremely rich, so much so that if you don’t get it to start right off the bat it will flood out. It sounds good at idle minus what sounds like an enormous vacuum leak, sounds so big that it should be obvious, but I can’t find a leak anywhere. Here’s what I’ve checked:

o Fuses at panel, and in line fuse near battery-all good

o Cleaned IAC

o OHM’ed injectors, all good there

o Checked for injector leaks

o Injectors show to be 22lb Bosch

o Fuel pressure at rail shows to be 44psi with key on (it bleeds off after a while, but always returns to 44psi)

o New AFPR set to directions supplied by manufacturer (haven’t had it running long enough to dial in)

o With return line pinched pressure comes up to 70psi and holds at 60psi

o New TPS set to .54V

o Checked spark (did not do kV test)

o New plugs

o Has the 1227165 ECM with a stage 2 JET chip (or MEMCAL?) (I know these aren’t the greatest, but it was on there already) chip is for auto 350 car

o Checked grounds at ECM-all good

o Checked grounds and vacuum lines-couldn’t find anything out of place

· The first thing I did when I got it home was to try and pull codes, jumped the ALDL and got nothing. Car had a SES light on, but would not flash codes. So I came in and jumped on Thridgen.org, first indications were bad ECM, but didn’t want to jump right in and replace the ECM, so I did all that other stuff. Here’s a weird part, I was messing with the cigarette lighter one night to try and power up an old scan tool that someone loaned me, the key was on there was no jumper in the ALDL and out of no where it starts flashing code 12, nothing else just code 12 out of the blue. Yesterday we were messing with it and it decided to code out a 21, but that was it.

· I gave up and took it to my mechanic and he can’t figure it out. We pulled the ECM out and then pulled the MEMCAL, we thought it may have been in backwards, since the only way to get the MEMCAL out was to disassemble the ECM box, it would not come out through the window on the box, and it would have if it were rotated 180 degrees. We flipped it and it made no difference, and now we’re not sure what way is the correct way.



We think the car is stuck in limp home mode due to a bad ECM. Not sure if the IAC is bypassed, or wide open during limp home mode, but would that explain the vacuum leak sound?

Is it time to get an ECM or is there something else I’m missing?

Thanks again for all you guys do!

GeneralDisorder

iTrader: (1)

If you cannot reliably pull codes (check the ALDL wires back to their origins, etc) - swap the ECM. My 86 Trans Am had a bad 7165 when I first got it running and one of the symptoms was inability to pull codes except for one random occurrence. Tapping on the ECM case would often cause it to stall or sometimes run better.

Better yet - get the EBL system, convert to speed density, and toss that 7165 in the garbage where it belongs.

GD

Drew

iTrader: (58)

It sounds like a rather slap dash mix-and-match of random parts that don't necessarily work well together. The cam is probably a bit aggressive without custom tuning. Jet and Hypertech chips, over the counter off the menu chips that are intended to work with stock injectors, generally don't do much. A very mild 350 under an otherwise stock 305 TPI setup will run OK, but not ideal. Throw in a cam that's not compatible with EFI, and things get worse. Change the injectors without reprogramming the chip to match, and you're probably going to have driveability problems. When you've got someone who doesn't really know what they're doing using a catalog chip for a 350, piggybacked with an original stock 305 TPI memcal, and aftermarket injectors, with a mystery "3/4 race cam"... Well it's probably going to run terrible.

Now I'm not 100% positive, but pretty sure the stock MEMCAL is keyed so it'll only plug into the ZIF socket one way. With the proper application of super human retard strength or a big *** hammer, a person can probably make it fit, but it'd likely damage the ECM and potentially the chip in the process. I'd expect plugging the chip in backwards and powering up the system would probably damage the electronics.

If it were me, and I didn't know exactly what I was working with, I'd start by verifying what's what first. If that meant replacing the ECM, tracking down a stock MAF 350 chip, stock replacement 350 injectors, a 350 knock sensor, 350 knock module, and using a dial indicator to measure the cam or pull the timing cover and chain to look for a identifying marking, that's what I'd do. Otherwise you're just trying to brute force a bunch of mixed and matched random garbage into a system, and it's never going to work. I might even go as far as just ordering a new camshaft that I know will play well with the EFIs limitations... Maximize the chances of success.

blacknineteen97

GD, I think that's what I'll do, not real sure where to find an ECM though. Heard the refurbs from CARDONE might be suspect. Any ideas on a good place to find one?

Drew, you make valid points, it's hard picking up someone else's project and not knowing what has been done. I was hoping this thing had a stock chip for a 305 in it and that was the problem. It is a bunch of mix matched stuff that seems to be thrown together, but I figure it should somewhat run ok without dumping fuel like it is. The plan was to get this thing somewhat running and get some data to get a custom burn. I'll probably pull a valve cover and get some numbers for the cam so I know what I've got, then I think the plan is to start with the stock ECM and stock chip.

Thanks for your replies.

GeneralDisorder

iTrader: (1)

Ebay is usually a good source for stock ECM's

Really though, by the time you mess around with used ECM's, multiple custom chips, and all that foolishness..... you will have spent as much or more than the EBL Flash II. For less than $500 you can have a proper ECM with self tuning ability, and a ton more features:

https://www.dynamicefi.com/EBL_Flash.php

GD

blacknineteen97

GD, you were more than likely 100% correct, and bunches of it is my fault. I finally identified the PROM out of the ECM, it's the bad one from the 86 305 TPI, I can't remember exactly, but it's the one with the TSB out on it about not having good parameters. So basically, I had this not good PROM from the factory, with a JET stage II chip for a 350 piggybacked on top of it into what I'm pretty sure was a bad ECM. I did order an ECM before I dug into the PROM p/n's. I'm also pretty sure the ECM was bad after seeing the "new one" the old one was loose inside the case and would not code out. The new ECM did allow the car to start, and code out, but I'm pretty sure we're still not where we need to be with the 305 PROM and 350 JET Chip piggybacked on top.

Pretty sure I need a 8674ABWT PROM since my car is a 350 AT with 3.27 gears, and those seem pretty rare to come across. Would I just be better off getting a custom tune from someone else? GD, your point about getting the EBL Flash is great, but I don't plan on doing more to this car, just driving it around town here and there. Does anyone know if the JET chip bypasses the 305 parameters on the PROM, just curious if I can get this to run ok first, then get a good tune. Any recommendations on a custom PROM tune that doesn't cost an arm and a leg? Any help appreciated.

My mechanic is Jeff give him a hard time for having mustangs in his profile picture.

GeneralDisorder

iTrader: (1)

The JET chip *IS* the programming. The MEMCAL is just a socket for the chip. It has the resistor network chips that are used for "limp mode" in case of a chip failure but those are not used at all unless the ECM detects a chip failure of some kind and most people just ignore this resistor network limp mode feature as it really runs so poorly as to be mostly useless anyway. If the JET chip is for a 350 then there will be no 305 parameters in it.

If you think ABWT is a good starting point you can likely find a copy floating around one of the forums, burn it, and modify from there.

Though personally I would start with a $6E mask for an 89 and modify from that. 89 $6E microcode is completely different and deletes the cold start injector, plus it has highway mode and tends to run better than the $32 and $32B variants from 86 - 88.

Too bad you aren't closer to my shop. I don't do Mustang's, but I do have a 2000 HP chassis dyno and I daily drive my 86 TA. Could tune that right up for ya.

GD

blacknineteen97

Thanks again GD. What do you mean closer? It's only a 25 hour drive. I didn't think that they allowed your kind in Portland, with your V8's and your fossil fuel burning cars. Speaking of stereotypes, I don't know how long it would take me to get there on horseback...

GeneralDisorder

iTrader: (1)

Well I stay far away from downtown unless I can help it. But yeah we do have a fair number of Tesla's.... because trendy and it's more acceptable to pollute some lithium mining province in China than our own air. Never mind the grid power used to charge them that comes from fossil fuels that do it anyway or from hydro that kills all their precious fish.

Most of Oregon outside of the major metros is actually Republican and mostly farmers, ranchers, and dairy..... you just don't hear about all the rest of us with our guns and hot rods. The metros all dominate the media.

GD