S10Wildside

I'm finishing up a carb-to-TPI conversion on a 350 Targetmaster engine in an 83 Silverado and am fighting a very strange problem.

First Occurance
I got the engine running yesterday and it sounded perfect. Drove around the block, pulled into the driveway, shut it off, turned it back on to check tranny fluid level (we lost some fluid when changing the TV cable), then the engine just shut off. No stumbling, no warning, it was like someone turned the key to off. It would not restart. We thought the problem was fuel level (new tank with under 4 gallons and the truck was on a small incline when it stalled). We pushed it in, let it sit for about 10 min, then it started right up and ran great.

Second Occurance
We drove the truck about 1 mile to the gas station to fill the tank. Just before pulling into the driveway after getting gas, the engine stopped again! Just like turning off the key, no warning, no stumbling, just died. It would not restart. All of the interior power was still on. We pushed it into the driveway, let it sit for a short while, then it started up again and ran flawlessly.

Thinking it could be computer related, I swapped with another 727 and another memcal. We got to the point where memcal "A" would sometimes not allow the engine to run and, so far, memcal "B" has never given us problems.

Third Occurance
Using memcal "A", the engine decided to run again, so we pulled the truck outside the garage and let it run for awhile. Using my Auto X Ray, I watched the temperature get to 190, the thermostat opened, coolant temp dropped to about 180, then the engine shut off again, no hesistation, no stumble, just shut off. I doubt this is temperature related, but wanted to mention that this is in closed loop and the coolant temp is within normal operating temps.

The TPI unit is completely clean, no carbon whatsoever. Freshly serviced injectors (Cruzin Performance), new fuel pressure regulator, new tank, sending unit and fuel pump. When this engine runs, it sound execellent. No issues with hesitation at all and the throttle response is excellent.

Any ideas?

ibmtech

iTrader: (1)

Take a look at your fuel pump. I have some knowledge with engine swaps.. I do know that the TPI and Carb engines do require different intake PSI pumps and fuel lines, Of course I don't remember what the pressures are. Just a suggestion. Looks like you got a good project, I would like to see larger pics if available.

Vader

[longthread]
Isn't that a coincidence? I just took the '86 out yesterday for a little warmup and toying around before the streets start to get their annual coating of seasonings. I started and backed it out, and let it warm a bit. As I was rinsing off the dust, it faltered a bit and almost died. My first thought was "WTF?" I got in and saw the MIL staring me in the face, shut it down, and went for the ALDL jumper. On power-up, the MIL didn't bounce, and no codes were displayed - not even a '12'. I pulled the jumper, pulled the ECM fuse for a few minutes, reconnected, and restarted. Again, no MIL bounce on power-up, but it started with a steady MIL. Back into the garage it went. I pulled the RH lower dash trim, ECM, and cover. Playing with the harness connectors did nothing, but tapping on the ECM and CALPAK made the lamp come and go, and altered the running state. Flexing the PROM through the "window" in the CALPAK cover would also clear or relight the MIL. Out comes the ECM fuse, then the CAPLAK. On goes the loupe.

It seems that in all the R&D on PROMs and sockets I'd been doing, I inadvertently forgotten to solder down the DIP socket to the CALPAK contacts before assembling that last one. Shame on me. A few minutes with the solder iron, then some reassembly, and everything was back to normal.

Since changing the CALPAKs seems to solve your issues, you may have a similar connection problem on your CALPAK base pins, DIP socket, or possibly even a PROM burn problem. [/longthread]

EDIT: Sorry, I missed in your post that you also changed the ECM with the CALPAK. Have you tried to switch JUST the CALPAK between the two ECMs? You may be able to discern whether is is indeed a CALPAK or the ECM itself. There may be some connection / solder joint heating issues in one of the ECMs.

S10Wildside

We definitely have the correct fuel pump. It's a new Camaro/Firebird TPI pump. Many of the images can be clicked for a larger view.

We swapped ECMs, then even swapped the two memcals around and I was able to get both ECMs to fail at one point or other with memcal "A". The truck owner is mounting the electric fans today and is going to play around with memcal "B" to see if he can make it fail.

Memcal "A" is a new GM memcal. I erased the prom and reprogrammed it. Memcal "B" is a used speed density memcal with Craig's adapter and a flashable prom. None of that should matter, but thought I'd mention it. I have a 305 TPI engine running on a test stand in my garage (for building harnesses). Tomorrow I'm going to try to make memcal "A" fail on the test stand.

Thanks for the replies! I'm also up for more ideas.

Vader

It seems that you have one very suspect CALPAK.

92blue

iTrader: (1)

I'd like to see if the same thing happens on the engine on a test stand.

I've had funny things happen in the past reprogramming memcals. I can't remember enough details to make for a complete story though. In all of my cases, erasing and reprogramming once more has solved the problem. I never understood why, since the prom contents matched the bin file I was using at the time.

On a side note, GM seems to use whatever proms they can get their hands. I recentl pulled the silver sticker off a new in the box AUJP only to find that it was a one time programmable. There was no window to erase it.

3.8TransAM

My GTA just did the same thing when I grabbed it out of storage and swapped the TTA back to storage.

Maybe its some kind of freak coincedence, perhaps aliens trying to communicate?

later
Jeremy

S10Wildside

I attempted to test the memcal yesterday on my test engine, but after I have the engine running and my laptop turned on, I realized that I left the ALDL cable for my AutoProm with the Silverado...and I let the owner borrow the Auto X Ray.

The prom did verify to the buffer...that's why I thought I had a good burn. I'll get some thorough testing on this memcal and see what I come up with.

I haven't seen that yet, but it'll be frustrating when I do.

Update:
Using memcal "B", the engine ran flawlessly last night. We must have put an hour of run time on the engine and drove around for awhile to adjust the TV cable.


Thanks for the suggestions and sharing your experiences.

Brians92Z28

I have the same problem with my 92. It is VERY intermittent and usually happens when I shut the engine off and try to restart it. I pull the fuse to the computer and it resets its self and runs like a champ. I have been attributing the fact to a bad board or chip. I haven't looked into it much further because I am in the process of building a 383 and will have to reprogram everything anyway. Keep us posted, I am very curious what the culprit is

Zepher

iTrader: (1)

Are you losing power when this happens?
My Formula did that every now and then, car would just turn off, but I'd loose all power and then the power would come back on.
It was a loose wire on the starter.

Vader

^ I'm with stupid... ^ Oh, wait. That's ME!

See above. Seems pretty straighforward to me. Bad PROM? Burned one too many times? Weak voltage on programming? Weird stuff can happen with these old PROMs. The CALPAK contacts are also suspect.

3.8TransAM

Just me or do all of us "tuners" have girlfriends and wives that know to push on the chip/memcal when the car bucks or flashes a SES when going down the road?

lol

Jeremy

92blue

iTrader: (1)

Seems like I'm not the only one with the ecm laying on teh passenger side floor...

Driving around on an Ostrich lately, gotta tell people to watch their feet. People look at me all weird when they get in my car for the first time.

3.8TransAM

Thats ok.

First time my gf and I ever went out.

She was like "Owww" something fell on my foot.

Damn silly ecm doesnt like to play nice lol

later
Jeremy

92camaroRS25th

i have the same problem with mine.... im new to TPIS.... ive had carbed 3rd gens forever this is my first tpi .... i do have a loose starter wire and when i press on the prom the mil light goes out and it runs fine.. im gonna fix the starter wire tomorrow but what should i do about the prom?

3.8TransAM

Well if it has a Zif or a socket, its probably that itself.

If u just have a stock memcal in a stock ecm, try cleaning everything first and making sure no pins are bent

later
Jeremy

Brians92Z28

my ECM fell on my fiance's feet too. I think its a third gen thing.... lol


~Brian