Hey guys!

I'm diagnosing a bit of an odd problem with my TPI setup.

Basically, I've narrowed it down two one of two problems. Either my timing is horribly messed up, or my fuel injectors are not working correctly.

My primary thinking is that it is a problem with the timing. Basically, to get the 355 to start up, I have to set the timing to over 50 degrees BTDC. Now, I am sure that most of you will immediately say, well, you are a tooth off with the dizzy, or you've got it 180 out or something. However, this isn't the case. I pulled the computer controlled distributer out, put my old HEI in, pulled all the TPI related fuses, shoved my acetylene torch in the throttle body, and hit the starter. Voila, truck fired right up, and ran on the propane that was in the throttle body for several seconds, until it consumed all the available propane, and died (little 20 lb tank from the bbq can't keep up with the demands of a hungry V8, wasn't about to put acetylene into my engine, lol)

Thats with the dizzy installed at 0 degrees, just like the new electronic dizzy was. However, if I tried to do the same thing with the electronic dizzy, by unplugging only the injector fuses (both banks, and the cold start) the engine acted just like it did running on the fuel injectors, it only sputtered a bit, but wouldn't fire. But, if I set the dizzy to almost 50 degrees BTDC, then it'd run on the propane, at least till it backfired through the throttle body and had me scrambling to shut off the propane, lol

So, this is with the EST connector undone, so the computer shouldn't have any influence over the timing.

I am 90% sure that once I figure out what is wrong with that dizzy, my truck will run. If not, then I can be certain it has to do with my injectors. The fuel system builds up 45 PSI when you jumper the fuel pump test terminal on the ALDL connector, and only drops to about 39 PSI after a minute has passed. The injectors were just flow tested, with the guy telling me that they are all fine, however, he also told me that they started to "cut out" between 40 and 45 PSI, but that it may have been caused by his generic testing equipment, as compared to the TPI ecm designed to pulse them.

So, if my ignition isn't the only problem, I am pretty sure that it'll be my injectors going static on me and simply pouring fuel in (my plugs are all gas fouled)

Or, its a combination of both, lol

So, my question is, could my EST module have any drastic effect on the dizzy, or would it be the dizzy itself thats at fault? I checked the ECM, and according to it, its thinking that it has the timing set at about 12 degrees at 1000 rpm, which is the best I can achieve at the moment, and a tap of the throttle has it bumping that number way up to more like 25 - 30 degrees. If a guy watches the timing tab, it does dissapear when you tap the throttle, however, to see the tab at all, you have to have the timing light set to 50 degrees. That means that the ECM is advancing it beyond 50 degrees, which makes absolutely no sense to me. Having the EST connector done up, or undone makes no difference on where the tab is at an idle, but having it plugged in is the only time that the tab appears to move.

So, I don't think that the engine should even run at all at 50 degrees, but if its less than that, it will not fire up, and run at all. It just sits there and coughs every couple of engine cranks. BTW, having the timing at 50 degrees results in some pretty brutal backfiring, both out of the intake, and the exhaust.

This setup has just been nothing but trouble. I know that my engine is just fine mechanically speaking. Probally could use a running valve adjustment, but other than that, its all good. I've got fairly fresh (though gas fouled) AC Delco plugs, with a set of good, brand new plug wires, new cap, and coil. The dizzy internals (module, pickup, etc) are all stock, and I have not touched them at all.

Anyone have any advice? Maybe there is a common problem I've missed all together? Maybe just even tell me if it is remotely possible if my EST module could be causing the crazy dizzy timing, even with the EST connector undone?

Thanks for listening to my rant, and thanks in advance for any help you can offer

 

Oh, and on a side note -- Why does my ECM turn on, and leave my primary electric fan at all times when the engine is running?

I know my wiring is fine, I tested it manually before giving the ECM control over it.

 

Is it running real rich? That fans on may be a hint that the ECM can't tell what temp the motor is (bad CTS) or the intake air charge (IAT sensor) or the secondatry cooling fan switch is shorted out/grounded out somehow.

Have you used a scanner to verify all the sensors are reading something reasonable?

 

Yep. Coolant temp is about 20 degrees before I start the engine, which is a wee bit on the warm side as compared to the ambient temp, but within 3 - 4 degrees (talking celcius here BTW) The IAT is reading almost exactly on with the outside air temp.

The MAF reads a bit high as compared to what it should be, and the 02 sensor needs to be replaced with a heated version, as the truck never really seems to get into closed loop for very long.

I'm in the process of switching my truck over to a known good small cap HEI, and it's module, so we'll soon find out if it is a problem with the ignition, or if it is a problem with the fuel.

 

Well, we can rule out ignition as being the problem now. Put the new dizzy in, and its the same problem as before. I'm gonna get a new set of Bosch style injectors for it, and see if that works, if not then there has to be something wrong with my wiring, though I made absolutely sure that everything was right before I installed, it, and tested all the circuits before I put them onto the ECM.

I guess I can try another ECM / chip too, and see what happens.

 

I was going to say.. I think if you put a non CC disty in you have to go all the way and remove the rest of the CC parts since they all work together... I know it is that way with CC- Carbs.. If you remove the CC dizzy you need to remove the cc carb and put a regualr one on.. else you can have problems...

 

The old dizzy was from an 85 TPI car, so it technically was fine. But, the small cap fits better, and will make an upgrade to an MSD 6AL box a lot easier in the future